Import risk analysis: citrus 
(Citrus  spp.) fresh fruit for 
human consumption   
Version 1.1 
19 October  2021
ISBN No: 978-1-99-101954-7 (o) 
Disclaimer  
While every effort has been made to ensure the information in this publication is accurate, the Ministry 
for Primary Industries  does not accept any responsibility or liability for error of fact, omission, 
interpretation or opinion that may be present, nor for the consequences of any decisions based on this 
information.  
The material and information contained in the import risk analysis  is preliminary  and will be updated 
based on any feedback received during consultation on any related import health standards  or any 
further feedback that may be provided by  internal or external experts.  
 
 
 
 
 
 
 
 
Recommended citation:  
MPI (20 21) Import Risk Analysis:  Citrus  (Citrus ) fresh fruit for human consumption . Version 1.1. 
October  2021. Ministry for Primary Industries, New  Zealand.  
 
Ministry for Primary Industries  
PO Box 2526  
WELLINGTON  6140  
Email: brand@mpi.govt.nz  
Telephone: 0800 00 83 33  
Facsimile: 04 -894 0300  
 
This publication is also available on the Ministry for Primary Industries  website at  
http://www.mpi.govt.nz/news -and-resources/publications/   
 
 
© Crown Copyright - Ministry for Primary Industries  
  
i • Citrus fresh fruit for consumption IRA, October 2021, Version 1.1  Biose curity New Zealand   
 
 
 
Import risk analysis: Citrus  (Citrus  spp.) for human consumption  
 
Version 1.1 
 
19 October  2021 
 
 
Approved for general release  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
© Crown Copyright - Ministry for Primary Industries  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • ii Version information  
Version No. Comments  Approved by  Date of approval  
1.0  Enrico Perotti  28 May 2021  
1.1 Updated with risk status of Armoured 
Scale insects  Enrico Perotti  19 October 2021  
    
New Zealand is a member of the World Trade Organisation and a signatory to the Agreement on the 
Application of Sanitary and Phytosanitary Measures (“The Agreement”). Under the Agreement, 
countries must base their measures on an International Standard or an  assessment of the biological 
risks to plant, animal or human health.  
This document provides a scientific analysis of the risks associated with the importation o f Citrus  fresh 
produce from selected countries. It assesses the introduction of pests and path ogens associated with 
Citrus fruit imported from selected countries, and assesses the potential impacts of those organisms 
should they enter and establish in New Zealand.  The document has been internally and externally 
peer reviewed and is now released pub licly for feedback . Any significant new science information 
received that may alter the level of assessed risk will be included in a review , and an updated version 
released.   
Contributors to this risk analysis  
The following people provided significant inpu t into the development of this risk analysis:  
1. Authors  
Deb Anthony    Senior Adviser   Biosecurity  New Zealand, Wellington  
Kaavya Benjamin    Senior Adviser   Biosecurity  New Zealand, Wellington  
Jo Berry     Specialist  Adviser  Biosecurity  New Zealand, Wellin gton 
Abigail Durrant    Senior Adviser   Biosecurity  New Zealand, Wellington  
Helen Harman    Senior Adviser   Biosecurity  New Zealand, Wellington  
Stephan Halloy    Senior Adviser   Biosecurity  New Zealand, Wellington  
Huimin Lin     Senior Adviser   Biosecurity  New Zealand, Wellington  
Melanie Newfield   Manager   Biosecurity  New Zealand, Wellington  
Shola Olaniyan    Senior Adviser   Biosecurity  New Zealand, Wellington  
Justyna Paplinska   Senior Adviser   Biosecurity  New Zealand, Wellington  
Bruce Philip    Senior Adviser   Biosecurity  New Zealand, Wellington  
Karen Wilson    Senior Adviser   Biosecurity  New Zealand, Wellington  
2. Internal peer review  
Deb Anthony    Senior Adviser   Biosecurity  New Zealand, Wellington  
Kaavya Benjamin    Senior Adviser   Biosecurity  New Zealand, Wel lington  
Jo Berry     Specialist  Adviser  Biosecurity  New Zealand, Wellington  
Allan Burne     Senior Adviser   Biosecurity  New Zealand, Wellington  
Kim Crook     Senior Adviser   Biosecurity  New Zealand, Wellington  
Abigail Durrant    Senior Adviser   Biosecurity  New Zealand, Wellington  
Stephan Halloy     Senior Adviser   Biosecurity  New Zealand, Wellington  
Huimin Lin     Senior Adviser   Biosecurity  New Zealand, Wellington  
Andi Makiola    Senior Adviser   Biosecurity  New Zealand, Wellington  
Hossein Narouei -Khandan  Senio r Adviser   Biosecurity  New Zealand, Wellington  
Shola Olaniyan    Senior Adviser   Biosecurity  New Zealand, Wellington  
Justyna Paplinska   Senior Adviser   Biosecurity  New Zealand, Wellington  
Bruce Philip    Senior Adviser   Biosecurity  New Zealand, Wellington  
Karen Wilson    Senior Adviser   Biosecurity  New Zealand, Wellington  
3. External  peer review  
Anastasia Korycinska   Pest Risk Analyst   Defra, York, UK  
Alan MacLeod    Pest Risk Analyst   Defra, York, UK  
Diana Perez    Research Professor   University of Veracruz, Mexico  
Claire Sansford    Plant Health Consultant   York, UK  
Chris Weldon    Associate Professor   University of Pretoria, SA    
iii • Citrus fresh fruit for consumption IRA, October 2021, Version 1.1  Biose curity New Zealand  Import Risk Analysis  
Background  
This import risk analysis (IRA) has been developed in response to a request to review the  current  
import health standards (IHSs) for fresh Citrus  fruit for human consumption, and to develop new IHSs 
for new countries and/or for  new Citrus  fresh  fruit commodities . 
Exporting countries covered by current IHSs  and included in the scope of this IRA : 
• Australia  
• Egypt  
• Japan  
• Mexico  
• New Caledonia  (France)  
• Samoa  
• Spain  
• United States  
• Vanuatu  
New countries (not covered by an existing IHS) that will also be included in the scope of this IRA : 
• Brazil  
• China  
• Cook Islands  
• Fiji 
• Korea  
• Peru  
• Solomon Islands  
• Viet Nam 
Citrus fresh fruit commodities as submitted by exporting countries or listed in existing IHSs and as 
classified in this IRA are provided in Summary Table 1.  
Summary Table 1  List of Citrus  commodities as submitted or in current IHSs against those assessed in 
this IRA . NB: F or the purposes of this IRA, the naming system of Swingle  has been used (see section 2.2).  
Citrus  commodities as submitted or in current IHSs  Citrus  commodities as classified in this IRA  
Lemon  (C. limon ) Citrus limon  (L.) Burm.f.  
Limonia  (Citrus limonia ) Citrus limon  (L.) Burm.f.  
Meyer lemon (C. meyeri ) Citrus limon  (L.) Burm.f.  
Grapefruit  (C. paradisi ) Citrus paradisi  McFad.  
Hassaku (C. hassaku ) Citrus paradisi  McFad.  
Orange  (C. sinensis ) Citrus sinensis  (L.) Osbeck  
Iyokan (C. iyo ) Citrus sinensis  (L.) Osbeck  
Mandarin /Tangerine  (C. reticulata ) Citrus reticulata  L. 
Mandarin (C. unshiu × C. reticulata var. Shiranuhi ) Citrus reticulata  L. 
Satsuma mandarin (C. unshiu ; C. unshiu × C. sinensis 
var. Kiyomo ) Citrus reticulata  L. 
Tahitian/Persian lime (C. latifolia ) Citrus latifolia (Yu. Tanaka) Tanaka  
Mexican/Key lime (C. aurantiifolia ) Citrus aurantiifolia  (Christ.) Swingle  
Sweet lime (C. limettioides ) Citrus aurantiifolia  (Christ.) Swingle  
Pomelo/Pummello  (C. maxima ) Citrus maxima  (Burman) Merr.  
Tangelo  (C. reticulata × C. paradisi ) Citrus reticulata × Citrus paradisi  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • iv Citrus  commodities as submitted or in current IHSs  Citrus  commodities as classified in this IRA  
Tangor  (C. reticulata × C. sinensis ) Citrus reticulata × Citrus sinensis  
Unshu (C. reticulata ) Citrus reticulata  L. 
Note that the taxonomy of commercial ly grown  Citrus  is complex; almost all cultivated Citrus  “species” 
are hybrids derived from the same three or four parent species.  
Objectives  
Biosecurity New Zealand’s objectives in developing this IRA  for Citrus  fresh fruit for human 
consumption  are to determine which pests  and diseases  are: 
1. associated with Citrus  fresh fruit, and  
2. meet the risk evaluation criteria for additional measures beyond the commodity description  
proposed for the IHSs , 
in order to ensure that the known biosecurity risk from regulated organisms associated with imported 
Citrus  fresh fruit is managed appropriate ly. 
IRA m ethodology  
The IRA process involves t wo principal stages:  
• Hazard identification  
• Pest risk assessmen t 
IRA Scop e 
The scope of the IRA considers  the following key questions:  
• What are the risk management questions?  
• What is the commodity description?  
• What basic measures  to manage known risks  will be required for all commodities from the 
listed  countries?  
 
Risk management question s 
General description  Specific question s that the risk manager needs answered in order to make a 
decision . They are based on  the commodity description and basic measures 
(see description below) for that commodity type . 
Description specific 
to this  Citrus  fresh 
fruit IRA Does each assessed pest and disease (note that “pest” refers to both 
arthropod s, such as insects and mites, and pathogens, such as fungi and 
bacteria):  
1. meet the criteria to be a quarantine pest1, and 
2. meet (or potentially meet) the criteria to be considered for additional 
measures (i.e. over and above basic measures)?  
For the pests and diseases that  meet  or poten tially meet  the criteria to be 
considered  for additional measures, the following question  is considered:  
1. Which specific Citrus  fruit pathways are they associated with (i.e. 
which countries and types of Citrus  fruit)? 
 
 
Commodity description  
General description  The commodity description defines the form of the commodity that is covered 
by the IHS, e.g. the commodity species and the countries under 
consideration . The commodity description may  also include commercial  
production and/or  grading requiremen ts or other commodity quality 
specifications.  
                                                      
1 A quarantine pest is an organism tha t is not present in New Zealand (or is present but still represents a biosecurity risk, e.g. is 
capable of vectoring pathogens not present in New Zealand) and is capable of establishing and causing harm in New Zealand.   
v • Citrus fresh fruit for consumption IRA, October 2021, Version 1.1  Biose curity New Zealand  Description specific 
to this  Citrus  fresh 
fruit IRA Commercially produced fresh Citrus  fruit belonging to any of the fruit 
types/species requested by exporting countries  (see summary , Table 1) . The 
fruit may have the calyx attached but not  the stem, leaves or other plant 
parts. The commodity definition excludes material or produce that is visibly 
damaged (e.g. fruit must have an intact skin, free from defects such as splits 
and cuts).  “Commercially produced” i s defined as a p rocess /system where 
activities, such as in -field monitoring, in -field pest control activities, 
harvesting, cleaning, sorting and grading have been undertaken to produce a 
commodity that is free of defects such as broken skin, rot and damage . 
Depending on the systems in place, these activities can be undertaken at 
any stage from the point of planting to the point of export.  NB: this definition 
is for the purposes of risk assessment. The definition of “commercial 
production” in the context of risk management is slightly different (see the 
Glossary and Abbreviations section).  
 
Basic measures  
General description  The minimum level of risk management for a particular commodity that all  
exporting countries must meet. They are not pest -specific but  are likely to 
manage, or partially manage, a wide range of pests.  Basic measures are 
based on information already known about the risks, e.g. from previous risk 
assessments, previous IHSs for the same or similar commodities.  
Description specific 
to this Citrus  fresh 
fruit IRA  Consignments of fresh Citrus  spp. fruit imported into New Zealand must:  
1. be free from contamination (including visible disease and pests, soil 
and other organisms, objects or material capable of harbouring or 
spreading pests of biosecurity concern) and other extraneous 
material not included in the commodity description;  
2. be free  from conditions that may indicate pest or disease 
contamination (including rots and damage);  
3. comply with the commodity description (e.g. have an intact skin  (on 
export) , be free from defects such as splits and cuts, have no leaves 
or stems attached , and b e commercially produced ); 
4. be packaged in clean and either new or refurbished material; and  
5. be secured in a manner to prevent contamination.  
 
Hazard identification  
A hazard is a pest  (including arthropods and pathogens)  or disease  that: 
• is not present in N ew Zealand ( or is present but still represents a biosecurity risk, e.g. is 
capable of vectoring pathogens not present in New Zealand) , 
• has the ability to establish and cause harm in New Zealand, and  
• is associated with imported risk goods and import pathway s. 
Hazard identification (hazard ID) is the process where, depending on the scope of the IRA, a list of 
pests and diseases  potentially associated with the commodity is compiled and then assessed against 
specified criteria, in order to determine which poten tial hazards  require further assessment. The 
objective for hazard identification in this IRA is to identify all pests and diseases that meet , or may 
meet,  the risk evaluation criteria for requiring additional measures  over and above basic measures . 
The risk evaluation criteria  for pests and diseases of citrus fresh fruit  to be considered for  additional 
measures  are: 
• The pest or disease  and associated damage are not easy to see on the Citrus  fruit, 
including when undertaking visual inspection, because  
o the pest can burrow into the fruit without obvious symptoms,  or 
o the pest can hide in the navel and/or under the calyx of the Citrus  fruit, or 
o a pest or disease  may take time or require particular environmental conditions to 
cause the fresh fruit to show signs of contamination ; and  
• the pest or disease  has an ability to get off the fruit  and onto a host in the New Zealand 
environment ; and Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • vi • the pest has the potential to establish and cause harm in New Zealand.  
Because this IRA will be used to develop IHSs for  a number of different Citrus  fruit types and for a 
number of countries, the hazard ID needs to take into account pests and diseases  that are associated 
with any of the commercial Citrus  types and any of the countries within the scope of this IRA . 
The r esults of the hazard ID  provide the following : 
• Pests and diseases  identified as associated with the commodity, present in at least one 
exporting country and potentially not being managed by  compliance with the commodity 
description and  basic measures and t herefore requiring further assessment . These  are 
addressed in the pest risk assessment  section below and listed in Summary Table 2.  
• Groups (e.g. genera or famil ies) and high-profile pests and diseases  that did not meet the 
criteria to require pest risk ass essment . These  are listed in Appendix 1 , along with the 
rationale for excluding them . 
Pest risk assessment  
The purpose of risk assessment is to determine the level of risk that hazard pests and diseases 
(identified at the hazard ID stage as requiring further assessment) p ose to New Zealand. Specifically, 
the pest risk assessment (PRA) concludes whether the pest or disease , based on assessment against  
the risk evaluation criteria , may need  to be considered for  additional measures  over and above basic 
measures.  
Pests and diseases that may need  to be considered  for additional measures are those that:  
• are associated with fresh Citrus  fruit of any species/types requested by exporting countries 
and meet ing the commodity description;  
• are present in any of the exporting countries within the scope of this IRA ; 
• have traits (see the ‘Hazard identification ’ section above) that indicate they may not be 
adequately managed by the basic measures; and  
• have the potential to establish and cause harm in New Zealand.  
The PRA  addresses the following : 
• Likelihood of entry:  
o The strength or frequency of the association with the host fruit  
o The l ikelihood of entry given the application of basic measures  
• Likelihood of exposure and establishment:  
o The ability of the pest or disease to move from imported fruit and into a suitable 
environment to allow establishment (exposure)  
o The suitability of the New Zealand environment for the pest or disease (including 
climate, host plants and vectors)  
• The potential impacts in New Zealand:  
o Economic impacts: on Citrus  and other economically  important plants (symptoms on 
individual plants, crop yield, costs of management practices, trade restrictions , etc.) 
o Environment al impacts: on native plants and ecologies  
o Other impacts (e.g. human health,  sociocultural)  
 
 
Summary Table 2 shows pest species for which PRAs were carried out, and the PRA conclusion with 
respect to consideration  for additional measures.  
 
 
   
vii • Citrus fresh fruit for consumption IRA, October 2021, Version 1.1  Biose curity New Zealand  Summ ary Table 2: Pest species for which PR As were carried out, and the management considerations  
Pest group  Species requiring PRAs  PRA recommendation  
Fungi  Elsinoe australis , Phyllosticta  spp. Require consideration for 
additional measures  
Bacteria  Xanthomonas citri  Requires consideration for 
additional measures  
Oomycetes  Phytophthora palmivora  Requires consideration for 
additional measures  
Insects: Order Diptera , 
fruit flies (receiving 
individual PRAs)  Anastrepha fraterculus , Anastrepha 
ludens , Bactrocera dorsalis , Bactrocera 
minax , Bactrocera trilineola , Bactrocera 
tryon i, Bactrocera tsuneonis , Bactrocera 
xanthodes , Ceratitis capitata , Zeugodacus 
cucurbitae , Bactrocera zonata  Require consideration for 
additional measures  
Insects: Order Diptera , 
fruit flies ( not covered 
by other PRAs and 
assessed in a single 
group PRA)  Anastrepha obliqua , Anastrepha 
serpentina , Anastrepha sororcula , 
Anastrepha striata , Anastrepha suspensa , 
Bactrocera aquilonis , Bactrocera 
carambolae , Bactrocera correcta , 
Bactrocera curvipenn is, Bactrocera , 
distincta , Bactrocera  frauenfeldi , 
Bactrocera jarvisi , Bactrocera kirki , 
Bactrocera kraussi , Bactrocera latifrons , 
Bactrocera melas , Bactrocera 
neohumeralis , Bactrocera psidii , 
Bactrocera trivialis , Bactrocera melanotus , 
Bactrocera passiflorae , Bactrocera  sp. nr 
passiflorae , Zeugodacus tau  Require consideration for 
additional measures  
Insects: Order 
Lepidoptera (moths, 
butterflies)  Gymnandrosoma aurantium , Marmara 
gulosa , Spodoptera littoralis  S. littoralis : does NOT  require 
consideration for a dditional 
measure s 
Others: require consideration for 
additional measures  
Insects: Order 
Hemiptera , 
family Pseudococcidae 
(mealybugs)  Nipaecoccus viridis , Planacoccus 
kraunhiae , Planococcus minor  Require consideration for 
additional measures  
Insects: Order 
Hemiptera , 
family Diaspididae  
(armoured scale 
insect s) See Appendix 3  
Insects: Order 
Hemiptera , 
family Psyllidae 
(psyllids)  Diaphorina  citri, Trioza erytreae  Require consideration for 
additional measures  
Insects: Order 
Thysanoptera (thrips)  Caliothrips fasciatus , Chaetanaphothrips 
orchidii , Scirtothrips dorsalis , Thrips palmi  T. palmi : does NOT  require 
consideration for additions 
measures  
Others: require consideration for 
additional measures  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • viii Pest group  Species requiring PRAs  PRA recommendation  
Subclass Acari (mites)  
(families Eriophyidae, 
Tenuipalpidae, 
Tetranychidae)  Aculops pelekassi , Eotetr anychus lewisi , 
Tetranychus kanzawai  Require consideration for 
additional measures  
Insect vectors of 
pathogens  Aphids:  Aphis craccivora , Aphis gossypii , 
Aphis spiraecola , Brachycaudus persicae , 
Macrosiphum euphorbiae , Macrosiphum 
rosae , Myzaphis rosarum , Myzus persicae , 
Toxoptera aurantia , Toxoptera citricida  
Mealybugs:  Planococcus citri , 
Pseudococcus calceolariae , 
Pseudococcus longispinus , Pseudococcus 
viburni  
Thrips:  Frankliniella occidentalis , 
Frankliniella intonsa , Thrips tabaci  Do NOT  require consideration for  
additional measures  
Mite vectors of 
pathogens  Brevipalpus  californicus , Brevipalpus 
obovatus , Brevipalpus phoenicis  Require consideration for 
additional measures  
   
ix • Citrus fresh fruit for consumption IRA, October 2021, Version 1.1  Biose curity New Zealand  Annex 1: Supporting Evidence  
 
Contents  Page 
 
1. Risk analysis background and process  11 
1.1 Background  11 
1.2 Scope and approach for this risk analysis  11 
1.3 The risk analysis process  14 
1.4 References for Chapter 1  19 
2. Commodity and pathway description  20 
2.1 Commodity description  20 
2.2 Taxonomy of plant commodities under consideration  21 
2.3 General information related to likelihood of entry  23 
2.4 General information related to likelihood of establishment  23 
2.5 General information related to impacts of pests and diseases  30 
2.6 References for Chapter 2  31 
3. Hazard identification  35 
3.1 References for Chapter 3  36 
4. Risk assessment  38 
4.1 Risk management questions  38 
4.2 Criteria and traits for additional measures  38 
4.3 Assessment method  38 
4.4 References for Chapter 4  42 
5. Pest risk assessments: Fungi  43 
5.1 Elsinoe australis  (sweet orange scab) and E. fawcettii  (citrus scab)  43 
5.2 Phyllosticta  citrica rpa (citrus black spot)  59 
6. Pest risk assessments: Bacteria  77 
6.1 Xanthomonas citri  pv. citri and Xanthomonas citri  pv. aurantifolii  (citrus canker)  77 
7. Pest risk assessments: Oomycetes  93 
7.1 Phytophthora palmivora  (brown rot, gummosis of citrus)  93 
8. Insects: Diptera, Tephritidae (fruit flies)  105 
8.1 Anastrepha fraterc ulus (South American fruit fly)  105 
8.2 Anastrepha ludens  (Mexican fruit fly)  117 
8.3 Bactrocera dorsalis  (Oriental fruit fly)  126 
8.4 Bactrocera minax  (Chinese citrus fly)  139 
8.5 Bactrocera trilineola  (Vanuatu fruit fly)  149 
8.6 Bactrocera tryoni  (Queensland fruit fly, Qfly)  160 
8.7 Bactrocera tsuneonis  (Japanese orange fly)  173 
8.8 Bactrocera xanthodes  (Pacific fruit fly)  183 
8.9 Bactrocera zonata  (peach fruit fly)  198 
8.10  Ceratitis capitata  (Mediterranean fruit fly, medfly ) 209 
8.11  Zeugodacus cucurbitae  (melon fly)  221 
8.12  Other fruit flies  236 
9. Insects: Hemiptera, Pseudococcidae (mealybugs)  300 
9.1 Nipaecoccus viridis  (spherical mealybug)  300 
9.2 Planococcus kraunhiae  (Japanese mealybug)  315 
9.3 Planococcus minor  (Pacific mealybug)  328 
10. Insects: Hemiptera, Psyllo idea (psyllids)  340 
10.1  Diaphorina citri  (Asian citrus psyllid)  340 
10.2  Trioza erytreae  (African citrus psyllid)  352 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • x 11. Insects: Lepidoptera (moths, butterflies)  362 
11.1  Gymnandrosoma aurantianum  (citrus fruit borer)  362 
11.2  Marmara gul osa (citrus peelminer)  372 
11.3  Spodoptera littoralis  (African cotton leafworm)  380 
12. Insects: Thripidae (thrips)  390 
12.1  Caliothrips fasciatus  (bean thrips)  390 
12.2  Chaetanaphothrips orchidii  (orchid thrips)  398 
12.3  Scirtothrips dorsalis  (yellow tea t hrips)  407 
12.4  Thrips palmi  (melon thrips)  418 
13. Mites  428 
13.1  Aculops pelekassi  (pink citrus rust mite)  428 
13.2  Eotetranychus lewisi  (Lewis spider mite)  437 
13.3  Tetranychus kanzawai  (kanzawa spider mite)  444 
14. Vector analysis  453 
14.1  Insect vector analysis: aphids, mealybu gs, thrips  453 
14.2  Mite vector analysis: Brevipalpus  spp. (flat mites or false spider mites), vectors of citrus leprosis 
viruses  486 
Appendix 1: Summary of taxa excluded at hazard identification  497 
Appendix 2: Glossary and Abbreviat ions 517 
Appendix 3: Risk Status of Armoured Scale Insects  520  
11 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  1. Risk analysis background and process  
1.1 Background  
This import risk analysis (IRA) has been developed in response to a request to review the import 
health standard  (IHS) for fresh Citrus fruit for human consumption . Some of the existing 
country /commodity Citrus  IHSs and schedules in  IHS 152.02: Clearance and Importation of Fresh 
Fruit and Vegetables into New  Zealand  have not been reviewed for a significant number of years. 
Additionally, there a re a number of countries wishing to gain market access for Citrus  to New 
Zealand ; this IRA  also addresses the exten sion of  the IHS to cover  these  new exporting countries . 
 
The purpose of the IRA is to identify and assess biosecurity risks associated with t he commodit ies. 
The decisions that this IRA will inform are:  
a. whether any pests and diseases2 on fresh Citrus  fruit require  consideration for  additional 
measures ; and 
b. whether to remove any pests  in the current fresh Citrus  fruit IHSs  that do not require 
additional measures due to new scientific evidence . 
 
The objective of the IRA is to:  
a. identify pests and diseases  which are associated with the commodity and may require 
additional measures ; and 
b. assess these pests and diseases  using a method which provides sufficient evidence about 
the biosecurity risks for a robust and transparent decision on whether additional measures 
may be  required to manage these pests . 
 
For any particular risk good3, there is a commodity definition that describes the minimum condition of 
the commodity that is covered by this IRA. The commodity definition is important as many pests and 
diseases may not be associated with a commodity th at is defined in a cert ain way (e.g. more pests 
may potentially be assoc iated with a comm odity definition of fresh beans for consumption than a 
comm odity definition of frozen beans for consumption ). 
 
For particular types of risk goods, there are existing basic measures  in IHSs that apply to all 
commodities that come under that  particular type of risk good. The basic measures manage the risks 
of a wide range of organisms, regardless of whether those organisms are named in a pest list.  
 
Commodity definitions and basic measures for commodities are proposed during the planning pha se 
of the IHS development process, prior to the development of the IRA. The commodity definitions and 
basic measures are based on the nature and risks of a particular commodity class (e.g. germplasm, 
fresh produce) and other information related to that par ticular commodity. The basic measures also 
mean that risk assessments and IHSs are robust in the face of many emerging and unknown risks.  
 
1.2 Scope and approach for this risk analysis  
This risk analysis considers the effects on the New Zealand economy, environment , society  and 
human health from organisms potentially associated with the importation of fresh citrus fruit for 
consumption.4 
  
This Citrus  IRA will be assessing the current IHSs and new market access requests for commercial 
imports of fresh Citrus fruit for human consumption.  
                                                      
2 Quarantine pests under IPPC  
3 Regul ated article under IPPC  
4 Specifically, this IRA covers sections 23(4)(b)(i), (ii) and (iii) of the Biosecurity Act:  
(i) the likelihood that the goods will import organisms:  
(ii) the nature of the organisms that the goods may import:  
(iii) the possible eff ect on human health, the New Zealand environment, and the New Zealand economy of the organisms that 
the goods may import  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 12   
The scope of the Citrus  IRA project includes  reviewing and assessing pests and diseases  associated 
with fresh Citrus  fruit from the countries listed in Table 1 .1. 
 
Table 1 .1  Countries and Citrus  species5 included in the Citrus  IRA Project , as either submitted by 
exporting countries or listed in existing IHSs.  See Table 2.2 for the taxonomy used in this IRA.  
 
Country  Review of 
or new IHS Commodities  (as submitted)  
Africa  
Egypt  New Lime  (Citrus aurantiifolia ), Lemon  (C. limon ), Grapefruit  (C. 
paradisi ), Mandarin  (C. reticulata ), Tangelo  (C. reticulata × 
paradisi ), Pomelo  (C. maxima ) 
Egypt  Review  Orange  (C. sinensis ) 
Asia  
China  New Mandarin (C. reticulata ), Orange (C. sinensis ), Pomelo (C. 
maxima ), Grapefruit (C. paradisi ), Lemon (C. limon ) 
Japan  Review  Mandarin  (C. reticulata ) 
Japan  New Mandarin  (C. unshiu × C. reticulata var. Shiranuhi), Satsuma/ 
Mandarin (C. unshiu × C. sinensis var. Kiyomo) , Iyokan (C. iyo ), 
Hassaku (C. hassaku ) Ponkan  (C. reticulata)  
Korea  New Unshu (C. reticulata)  
Viet Nam New Pomelo (C. maxima ), Mexican Lime (C. aurantiifolia ),  Tahitian  
Lime  (C. latifolia  ) Limonia  (C. limonia ) 
Europe  
Spain  Review  Orange  (C. sinensis ) 
North America  
Mexico  Review  Orange  (C. sinensis ) 
Mexico  New Persian lime (C. latifolia)  
United States  Review  Lime  (C. aurantiifolia ), Lemon  (C. limon ), Grapefruit  (C. paradisi ), 
Mandarin /Tangerine  (C. reticulata ), Orange  (C. sinensis ) Tangelo  
(C. reticulata × paradisi ), Pomelo  (C. maxima ) 
South America  
Brazil  New Tahitian lime (C. latifolia ), Lemon (Citrus limon ), Orange (C. 
sinensis ), Mandarin  orange  (C. reticulata/C. deliciosa ) 
Peru  New Key/Mexican lime (C. aurantiifolia ), Tahitian lime (C. latifolia ), 
Mandarin (C. reticulata ), Satsuma mandarin (C. unshiu ), 
Grapefruit (C. paradisi) , Orange (C. sinensis ) 
                                                      
5 The taxonomy of commercial citrus fruit is complex. Almost all of the cultivated citrus “species” are hybrids derived from th e 
same t hree or four parent species. Details on the taxonomic system used in this IRA are provided in Section 2.   
13 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Country  Review of 
or new IHS Commodities  (as submitted)  
Oceania  
Australia  Review  Lime  (C. aurantiifolia ), Lemon  (C. limon ), Grapefruit  (C. paradisi ), 
Mandarin /Tangerine  (C. reticulata ), Orange  (C. sinensis ) Tangelo  
(C. reticulata × paradisi ), Tangor  (C. reticulata × sinensis ) 
Cook Islands  New Tahitian lime (C. latifolia ) 
Fiji New Tahitian lime (C. latifolia ), Meyer lemon (C. meyeri ) 
New Caledonia  Review  Tahitian lime  (C. latifolia ) 
New Caledonia  New Mexican lime (C. aurantiifolia ) 
Samoa  Review  Tahitian lime (C. latifolia ) 
Samoa  New Pomelo  (C. grandis ), Meyer lemon  (C. meyeri ), Grapefruit (C. 
paradisi ), Mandarin /Tangerine  (C. reticulata ), Tangelo  (C. 
reticulata × paradisi ), Orange  (C. sinensis ) 
Solomon 
Islands  New Lime (C. aurantiifolia ) 
Vanuatu  Review  Lime  (C. aurantiifolia ), Tahitian lime  (C. latifolia ), Lemon  (C. 
limon ), Grapefruit  (C. paradisi ), Mandarin /Tangerine  (C. 
reticulata ), Orange  (C. sinensis ) Tangelo  (C. reticulata × paradisi ), 
Pomelo/Pummello  (C. maxima ) 
 
For the purpose of  scoping the IRA, the risk evaluation criteria are based on the minimum intervention 
to manage pest risk on Citrus  fresh produce . For most commodities this includes a combination of the 
commodity description and basic measures. The commodity description de fines the minimum form of 
the commodity that is covered by the IHS. The commodity description may include commercial 
grading requirements or other commodity quality specifications. Basic measures  are the minimum 
level of risk management that all Citrus fresh produce  exporting countries  must meet. The import risk 
analysis process aims to determine which  pests and  diseases  may be associated with the commodity 
as defined by the commodity description , may not be managed by  the basic measures , have the  
ability to move from the commodity to a host in the environment and the  potential to establish and /or 
cause harm in New Zealand . Such pests and diseases  may need  to be considered for  additional 
measures . Refer to Chapter 2 fo r detail s of the commodity descriptio n and basic measures . 
 
The import risk analysis will answer the following questions:  
1. Which pests and diseases  may need  to be considered  for additional measures?  
2. For the pests and diseases  which m ay need  to be considered  for additional measures , which 
specific Citrus  fruit pathways are they associated with (i.e. which countries and types of Citrus  
fruit). 
 
Pests and diseases  which m ay need  to be considered  for additional measures are those that:  
1. are associated with fresh Citrus  fruit of any specie s listed in Table 1 .1 which meet the 
commodity description (see “IRA scope ”, page v); and 
2. are present in any of the countries listed in Table 1.1; and  
3. have traits which indicate they may not be adequately managed by the basic measures  listed 
in section 2.3  
4. have a viable establishment pathway from fruit ; and 
5. have the potential to establish and /or cause harm in New Zealand.  
 
The traits of a pest or disease  which indicate it may not be adequately managed by basic measures  
would mean that the pest or pathogen and/or associated damage is not easy to see on the Citrus  fruit, 
including when undertaking fruit grading or visual inspection . This may occur because:  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 14 1. the pest can burrow into the fruit without obvious symptoms,  or 
2. the pest can hide in  the navel and/or under the calyx of the Citrus  fruit, or  
3. the pest or disease  may take time or require particular environmental conditions to express 
symptoms.  
 
The pests and diseases  which meet the criteria above  will undergo a risk assessment that consid ers 
the following factors:  
a) the strength or frequency of the association with the host fruit ; and 
b) the extent to which the basic measures  will reduce the risk ; and 
c) the suitability of the environment in New Zealand for the pest or disease (including climate, 
host plant(s) availability and presence of vectors) ; and 
d) the ability of the pest or disease  to move from imported fruit to a suitable environment to allow 
establishment (see section 2.4 ); and 
e) the impact on host plants in New Zealand ( Citrus  and other plants including native species) , 
and the consequent potential economic, sociocultural and environmental impacts ; and 
f) potential impact on human health . 
 
The World Trade Organisation Agreement on the Application of Sanitary and Phytosanitary Meas ures 
(SPS agreement) states that phytosanitary measures must be supported by a risk assessment and 
not be maintained without sufficient evidence. That is,  Biosecurity New Zealand  must have evidence 
that a pest or disease would not be sufficiently manage d by the commodity description (including 
basic measures ) in order to require additional measures.  
 
1.3 The risk analysis process  
1.3.1 Overview  
The Biosecurity New Zealand process for undertaking an IRA builds on the existing international 
frameworks for risk analysis under the World Organisation for Animal Health (OIE) and the 
International Plant Protection Convention (IPPC), and extends the scope under the SPS Agreemen t 
to include all of the values required by the Biosecurit y Act (1993)6. 
 
The individual steps in the process for developing an IRA are the same for both the OIE and IPPC. 
However  the standards, guidelines and recommendations for animal health (sanitary) and plant health 
(phytosanitary) measures are developed by different international bodies. This means that there are  
differences in the detail of how IRA is done for animal health (OIE) and plant health (IPPC). The MPI 
process and methodology for undertaking an IRA is summarised in Table 1.2. 
 
The main output is an IRA which is used in the development or review of an IHS under the Biosecurity 
Act (1993). An IHS specifies the requirm ents to be met for the effective management of risk s 
associated with importing risk goods7. 
 
Table 1.2  The basic process of import risk a nalysis  
 
Commissioning  Drafting  Signoff and 
closeout  Hazard 
identification  Risk assessment  Reviewing  
Aproval  to 
start Plan the 
project  Manage the project  Closeout  
 
                                                      
6 Biosecurity Act section 23(4)(b)(iii) “…human health, the New Zealand environment, and the New Zealand economy…”. As 
defined in section 2(1), environ ment includes “(a) ecosystems and their constituent parts, including people and their 
communities; and (b) all natural and physical resources; and (c) amenity values; and (d) the aesthetic, cultural, economic, a nd 
social conditions that affect or are affec ted by any matter referred to in paragraphs (a) to (c)”.  
7 Section 22, Biosecurity Act 1993.  
  
15 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  The Biosecurity Act (1993) requires a Chief Technical Officer to begin the process of developing an 
Import Health Standard by “analysing or assessing the risks associated with importing a class or 
description of goods ”8. 
 
While the Biosecurity Act does not state how the risks are to be assessed or analysed, it does state 
that the Chief Technical Officer must have regard to certain matters when developing  an IHS for 
recommendation to the Director -Gener al. A number of these are part of an IRA as described by the 
OIE and IPPC:  
• The likelihood that the goods will import organisms9 
• The nature of the organism that the goods may import  
• The possible effect on human health, the New Zealand environment10, and the New Zealand 
economy of the organism that the goods may import  
• In relation to risk management measures  proposed for inclusion in an IHS, the extent to which 
the measures  reduce or manage the likelihood or impacts of adverse effects from organisms 
that may b e imported on or in association with goods11. NB: in this IHS project, information 
relevant to risk management considerations has been provided, by the risk analysis team to 
the risk management team and the MPI treatments group, in documents outside the IRA . 
 
An IRA is also a relevant factor in how a country meets its obligations under the SPS agreement and 
other agreements such as the Convention on Biological Diversity (CBD). Under the SPS agreement, 
risk management measures either must  be based on existing international standards, guidelines or 
recommendations, or  must be  supported by a scientific justification12. Measures must not be 
maintained without sufficient scientific evidence13. Measures must also not be unnecessarily trade -
restric tive14. In order to meet these obligations, the SPS agreement requires that measures are based 
on a risk assessment . Under the CBD, countries must consider environmental impacts in decision -
making and prevent the introduction of, control or eradicate alien species that threaten ecosystems, 
habitats and species.  
 
The MPI process is equivalent to the process for plant health risk analysis under the International 
Standards for Phytosanitary Measures (ISPM) under the IPPC 15. The main difference is in 
terminology.  The most important aspects of this process are:  
• The formulation of the risk management question s. These are  an essential part of initiating or 
commissioning a risk analysis16.  
• The risk management question s are formulated based on the  commodity  description and  
basic measures  for that commodity type.  
• Risk evaluation criteria are based on the risk management question, so that the risk  
assessment directly address es the specific questions of the risk manager and the conclusions 
are clear to readers . 
 
In MPI, the  IRA is used by the commissioning team to develop a Risk Management Proposal and to 
develop or amend an IHS or Craft Risk Management System (CRMS) . The Risk Management 
Proposal provides the rationale for the risk management decisions , while t he IHS and CRMS are the 
                                                      
8 Section 23(1) Biosecurity Act 1993  
9 From Section 2(1) Biosecurity Act 1993:  “organism —(a) does not include a human being or a genetic structure derived from 
a human being: (b)  includes a micro -organism: (c) subject to paragraph (a), includes a genetic structure that is capable of 
replicating itself (whether that structure comprises all or only part of an entity, and whether it comprises all or only part  of the 
total genetic structure of an entity): (d) includes an entity (other than a human being) declared by the Governor -General by 
Order in Council to be an organism for the purposes of this Act: (e) includes a reproductive cell or developmental stage of a n 
organ ism: (f) includes any particle that is a prion ” 
10 From section 2(1) Biosecurity Act 1993, “ environment  includes —(a) ecosystems and their constituent parts, including people 
and their communities; and (b) all natural and physical resources; and (c) amenity values; and (d) the aesthetic, cultural, 
economic, and social conditions that affect or are affected by any matter referred to in paragraphs (a) to (c)”  
11 Section 23(4)(b) and (d) Biosecurity Act 1993  
12 SPS Agreement 1995 Article 3(1) and (3)  
13 SPS Agreement 1995 Article 5(7)  
14 SPS Agreement 1995 Article 5(6)  
15 ISPM 2: Framework for Pest Risk Analysis 
https://www .ippc.int/static/media/files/publication/en/2019/05/ISPM_02_2007_En_Framework_PRA_2019 -04-
30_PostCPM14_InkAm.pdf  and ISPM 11 : Pest Risk Analysis for Quarantine Pests  
https://www.ippc.int/static/media/files/publication/en/2019/05/ISPM_11_2013_En_PRA_QPs_2019 -04-
30_PostCPM14_InkAm.pdf  
16 Refer to FAO Biosecurity Toolkit http://www.fao.org/3/a1140e/a1140e.pdf , e.g. P7 3 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 16 legal document s issued under the Biosecurity Act 1993 that include the requ irements that 
commodities  must meet before biosecurity  clearance can be given for import into New Zealand17. 
1.3.2 Commissioning and planning  
The process for scoping and planning a risk analysis is described here as commissioning . During this 
process, information is gathered, shared and discussed, and decisions are made about what needs to 
be assessed and how the analysis will be done.  
 
The information covered  in the commissioning process can include:  
• the current context for the work (e.g. new measures or a review of existing measures ); 
• input from stakeholders and interested parties (the process may include meetings with and 
gathering information from key stak eholders) ; 
• the commodity description ( e.g. the commodity  species  and the countries under 
consideration) ; 
• the pathway description (e.g. the production system and intended end use of the commodity) ; 
• the risk management question or questions (a risk managemen t question is a specific 
question that the risk manager needs answered in order to make a decision ); 
• criteria and methods for identifying hazards ; 
• the analytical approach , including the hazard groups to be considered18 and the likely level of 
detail ; 
• definitions and/or criteria for risk descriptors ; 
• basic measures  for the commodity class or proposed for the specific IHS or CRMS ; 
• peer review, signoff and closeout processes ; 
• information about consultation or publication ; 
• expected timelines.  
 
The commodit y and pathway information provides context for the hazard identification and risk 
assessment.  
1.3.3 Hazard identification19 
Hazard identification is the process for identifying pests and pathogens associated with imported risk 
goods and which have the ability to cause harm to New Zealand. The process consists of compiling a 
list of potential hazards and then assessing them against criteria to see whether they warrant further 
consideration. The ha zard identification answers two different questions:  
• Does the species  meet the criteria to be considered a biosecurity risk or quarantine pest  for 
New Zealand?  
• Is the species associated with the commodity that is being assessed?  
 
The criteria for a quarantine pest for New Zealand are derived from the Biosecurity Act and ISP Ms 2, 
5 and 11. These criteria are:  
• Is the species absent from New Zealand?  
• OR is the species present in New Zealand , but it meets one of  the following criteria?  
o The species is under official control . 
o The species is a vector of quarantine pests . 
o There are subspecific taxa (subspecies, varieties, strains , etc.) within the species that 
are an increased risk to New Zealand compared with those already present . 
                                                      
17 https://www.mpi.govt.nz/importing/overview/import -health -standards/  
18 For a review of an IHS or CRMS, it is not necessary to consider all groups of hazards – it may be necessary to only consider 
some of the associated hazard groups. However, for a new IHS or CRMS, all groups of hazards should be considered, even if 
they are not assessed in any detail.  
19 Under the IPPC, the hazard identification process is known as pest categorisation in ISPM 2 and ISPM 11.  
  
17 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  o There are other factors that would mean that the species may still be of concern in 
associated with im ported goods (e.g. increased exposure to people through imported 
goods20). 
• AND does the species have the potential to establish in New Zealand and /or harm “human 
health, the New Zealand environmen t, and /or the New Zealand economy21”? 
 
Association with the commodity is based on:  
• association with the host species or genus ; 
• association with the specific parts of the plant ; and 
• whether a particular pest will stay associated with a commodity when it is being handled – for 
example , a large flying insect is unlike ly to stay on a piece of fruit when it is picked.  
 
For the hazard identification:  
a) A list of potential  hazards must be compiled . 
b) Potential  hazards must be assessed against criteria which meet relevant international 
standards and the requirements of the Bios ecurity Act 1993 . 
c) The hazard identification conclusions must be documented and supported by suitable 
evidence . 
 
Different approaches may be  taken to compiling  and presenting  the list of potential hazards 
depending on the information needed for  organisms in  each pest/pathogen  group . The approach for 
each group is determined during the commissioning process, once the risk management question and 
risk evaluation criteria have been established. The approaches to be used are documented in the 
plan. The specific approaches to hazard identification used in this import risk analysis are discussed 
further in section 3.  
 
At the end of the hazard identification process, the list of hazards that warrant further assessment 
may be peer reviewed or discussed with risk mana gers and key stakeholders.  
1.3.4 Risk assessment  
A risk assessment evaluates the likelihood of introduction and consequence for a particular hazard, 
as well as the uncertainty in the conclusions. The SPS agreement describes the factors to take into 
account when assessing risk. These factors include:  
• available scientific evidence;  
• relevant processes and production methods;   
• relevant inspection, sampling and testing methods;  
• prevalence of specific diseases or pests ; 
• relevant ecological and environmental conditio ns; and 
• potential harm  in the event of the entry, establishment or spread of a pest . 
 
A qualitative approach is suitable for the majority of  import risk analyses and is currently the most 
common type of assessment undertaken to support the development and review of import 
requirements. Qualitative descriptors of likelihood, consequence and uncertainty are  provided . 
 
The risk assessment stage of the IRA process:  
a) must be documented and supported by suitable evidence , and  
b) must answer the risk management question by following definitions or criteria agreed 
on during commissioning.  
 
As part of a pilot project to streamline IRAs , the assessments  for the Citrus  IRA have been structured 
using the CASE schema22, which is a tool for developing and presenting logical reasoning to make 
the a rguments clearer to the reader.  The use of this approach will be reviewed at the conclusion of 
the project.  
                                                      
20 One example is venomous spiders on fresh frui t. Even if present in a country, there may be a higher likelihood of people 
getting bitten if the spiders are associated with fruit sold at a supermarket.  
21 Biosecurity Act 1993  
22 The CASE schema is based on presenting a Contention  (the conclusion of the r isk assessment) supported by Arguments , 
Evidence  and Sources . Further information can be found at: https://timvangelder.com/2019/04/07/what -is-the-case-schema/  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 18  
The appro ach to pest risk assessment used in this IRA is discussed further in section 4.  
1.3.5 Assessment of uncertainties  
The SPS agreement states that measures must be applied only to the extent necessary  and must be 
supported by  sufficient scientific evidence23. Therefore, if there is insufficient evidence indicating that 
an organism  may requir e consideration for  additional measures ( based on assessment against the 
risk evaluation criteria),  then the lack of evidence suggests that it does not meet the critera to b e a 
hazard  (see section 1.3. 3). However, in some cases there may be good reason to consider a pest or 
pathogen even when evidence is insufficient (e.g. similarity to known pests or pathogens)24.  
 
Documenting significant uncertainty is an essential part of a risk assessment. Uncertainties such as 
contradictions in the evidence or a lack of evidence are documented in the IRA. Where the risk 
assessment identifies significant uncertainty affecting the conclusion, this is indicated in the wording 
of the conclusi on. The risk management proposal  (see section 1.3. 1) gives further consideration to 
these risk assessments. See Chapter 4 for further information on how  uncertainty is documented.  
1.3.6 How the risk analysis informs risk management decisions  
The conclusions of t he risk assessments are used to develop a risk management proposal  and the 
IHS. Specifically, the risk management proposal  considers additional measures for those hazards that 
the risk assessment concludes will not, or may not, be managed by basic measures . The risk 
management proposal  gives a rationale for the risk management decisions based on the 
assessments with significant uncertainty.  
1.3.7 Review and consultation  
The IRA must  be reviewed to check that it is based on the best available and most credible 
information, that the document is clear and logical, that assumptions are valid and that conclusions 
are consistent with the evidence, with other conclusions in the IRA and with relevant conclusions in 
other  assessments. The review process involves relevant experts within MPI and may involve experts 
from outside MPI, either from New Zealand or overseas where considered necessary. A 
representative from the team commissioning the IRA may be included in the revi ew process.  
 
The IRA may be reviewed as a whole or in parts.  For example , it is common that individual 
assessments for pests or diseases  are reviewed by an expert in that group.  
 
For an IRA review:  
a) The IRA must be reviewed by relevant staff from within MPI . 
b) Individual  pest or pathogen  assessments may be reviewed by  relevant experts within 
MPI and also  subject matter experts and/or relevant stakeholders from outside MPI , 
either from New Zealand or overseas . 
c) All review comments must be considered, and if inte rnal or external reviewers ’ 
feedback25 is not incorporated into the IRA, the rationale for the decision not to include 
that feedback must be clearly documented , and, where necessary, discussed with the 
reviewer . 
1.3.8 Conclusions of the risk analysis  
The conclusi ons of the risk analysis are summarised in a risk management proposal that 
accompanies the draft IHS being consulted on. The risk analysis provides additional technical detail 
should submitters wish to see a more detailed scientific analysis of the biologi cal risks.  
 
                                                      
23 SPS Agreement 1995 Article 2.2  
24 SPS Agreement 1995 Article 5.7  
25 Note that this point does not apply to editing comments such as corrections to spelling, punctuation or grammar.   
19 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  All submissions received from stakeholders will be analysed and compiled into a review of 
submissions. The IRA, risk management proposal  and draft IHS will be modified where appropriate 
depending on the outcome of consultation.  
1.4 References for Chapter 1  
FAO (1995) Guidelines for pest risk analysis . International Standard for Phytosanitary Measures No. 
2. Published by FAO on behalf of the Secretariat of the International Plant Protection Convention 
(IPPC); Rome, Italy.  
FAO (2013) Pest risk analysis for quarantine pests . International Standard for Phytosanitary 
Measures No. 11. Published by FAO on behalf of the Secretariat of the International Plant Protection 
Convention (IPPC); Rome, Italy.  
WTO (199 5) World Trade Organization (WTO) Sanitary and Phytosan itary Measures Agreement 
(SPS). www.wto.org/english/tratop_e/sps_e/sps_e.htm . 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 20 2. Commodity and pathway description  
2.1 Commodity description  
The commodity for the IRA is commerci ally produced26 fresh Citrus  fruit belonging to any of the fruit 
types/species listed in Table 2.2. The fruit may have the calyx attached but not stem, leaves or other 
plant parts. The commodity definition excludes material or produce that is visibly damage d (e.g. fruit 
must have an intact skin, free from defects such as splits and cuts ).  
 
Table 2.1 puts the risks associated with Citrus fruit in the wider context of relative risks of different 
commodities, pathways  and plant species. The information in the general commodity risk assessment 
and the section on the transfer of pests and pathogens will be used in the IRA when assessing the 
risk of pests which may be considered  for additional measures.  Further detail is given in subsequent 
sections.  
 
Table  2.1  General commodity risk explanation  
 
Question  Factors to consider  
What is the relative risk 
associated with the 
commodity class?  Fresh produce  – intermediate, it is not intended for propagation, but is 
not processed (refer to FAO 2017 ). Both types of plant material 
(produce  for consumption and germplasm) have invertebrate pests 
and pathogens but many pathogens are only a risk on material that is 
propagated.  
What is the relative risk 
associated with the  type of 
material making up the 
commodity?  Fruit – while “consumption” pathways are intermediate in terms of risk, 
a number of pests of major importance (mainly economic rather than 
environmental) are known to be associated with fruit , e.g. fruit flies . 
How likely is the 
commodity to carry pests 
that can establish in New 
Zealand?  Citrus  is native to, and grown commercially in, areas overseas that 
have a similar climate to New Zealand, for example , parts of China, 
Japan and Australia. It is also grown in areas that are less similar to 
New Zealand.  Citrus  is therefore intermediate in terms of likelihood – it 
is higher than species  grown in very specific climates, for example , 
mango, but lower than temperate species, for example , cherries.  
 
Citrus  is grown c ommercially and in home gardens in New Zealand , 
although wild records are r are27. Therefore , associated pests and 
pathogens, including those that are host -specific, are likely to come 
into contact with host plants in New Zealand.  
                                                      
26 Process (system) where activities, such as in -field monitoring, in -field pest control activities, harvesting, cleaning, sorting and 
grading have been undertaken to produce a commodity that is free of defects such as broken skin, rot and damage. Depending 
on the systems in place, these activities can be undertaken at any stage from the point of planting to the point of export.  
27 Allan Herbarium  
https://nzflora.landcareresearch.co.nz/default.aspx?selected=NameDetails&TabNum=0&NameId=0BDA3A5C -4DA1 -4289 -
9B8B -C0B3B3A7A6D6    
21 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Question  Factors to consider  
How likely is the 
commodi ty to carry pests 
that cause major impacts 
in New Zealand? What are 
the values associated with 
the commodity species 
and the related species in 
New Zealand?  The pests and pathogens associated with Citrus  fruit may affect many 
different host plants in New Z ealand. However , the likelihood that 
particular hosts will be affected may be  dependent  on how closely 
related those hosts are to Citrus . There is a strong relationship 
between how closely related plant species are and how likely they are 
to share pests and pathogens (Gilbert and Webb 2007 ). Therefore , the 
host plants most likely to be affected by pests and pathogens carried 
on Citrus  fruit are Citrus  species. The next most likely are members of 
the same family (Rutaceae). There are both native ( Melicope  and 
Leionema ) and introduced ornamental (e.g. Choisya, Coleonema ) 
genera  of the Rutaceae  family  in New Zealand . Some pests and 
pathogens associated with Citrus affect a wide range of other species, 
for example , fruit flies and mites . 
 
Pests and pathogens  that are associated with Citrus  but affect other 
members of the family have the potential for environmental impacts as 
well as impacts on amenity values. The native genera Melicope  and 
Leionema  do occur overseas in regions where Citrus  is native or 
cultivat ed, e.g. Hawaiian Islands, across the Pacific to tropical Asia 
and Australia. Ornamentals in the family Rutaceae, such as Choisya, 
Coleonema , are widely grown around the world. Therefore , many 
common Citrus  pests and pathogens have had the opportunity to 
switch hosts to these genera. This means that if pests of Citrus  have 
not been recorded on these genera overseas, they are less likely to 
affect members of these genera in New Zealand.  
 
Citrus  is an importan t crop in New Zealand and is the third largest 
fresh fruit crop after kiwifruit and apples. The New Zealand Citrus  
industry comprises around 1,600 hectares located in  the Bay of Plenty, 
Gisborne and Northland regions. In 2018, the domestic and export 
sales  of fresh Citrus  fruit were NZ$58.5 million and $ 12.0 million, 
respectively ( Plant & Food Research  FreshFacts 201 9). 
What is the level of 
knowledge of the pests 
associated with the 
commodity and related 
species in New Zealand 
and overseas?  Citrus  is a wel l-known fruit crop that is widely cultivated. Thus, there 
are reliable literature sources for some pests and pathogens 
associated with Citrus  across a wide range of countries/continents. 
There is likely to be less information on native Rutaceae in New 
Zealand and abroad.  
 
In conclusion t here is an intermediate risk associated with the importation of citrus fruit for human 
consumption. The risk is lower than for  commodities  imported for propagation and lower than for other 
fresh fruit commodities  that may be more temperate in their distribution or that have many related 
native and economically important plants species  in New Zealand  (e.g. Prunus  and Malus ). The risk  is 
higher than for fresh produce such as mango, which is more tropical in its distribution and has few 
related plants of importance in New Zealand. All citrus fruit are fruit fly hosts, which increases the risk 
associated with these commodities, compared with fresh produce that is not a fruit fly host, such as 
ginger.  
2.2 Taxonomy of plant commodit ies under consideration  
 
The taxonomy of c itrus fruit species is unclear  because of a long history of cultivation and 
hybridisation . The current wide diversity of commercial citrus fruit is believed to be derived from three 
or four  ancestral species ( see, for example , Barrett and Rhodes 1976 , Nicolosi et al. 2000, Wu et al. 
2018 ). Some of the lesser -known types (such as yuzu) also have parentage of other species. The 
ancestral species are  believed to include : Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 22 • Citrus maxima  (pomelo)  
• Citrus reticulata  (ancestr al mandarin)  
• Citrus medica  (citron)  
• Citrus micrantha  (small -flowered papeda)  
 
All main  commercial citrus are hybrid s involving parentage of those four species. The hybrids include 
both natural and  deliberate crosses. As well as hybridising freely, many types of citrus have 
adventitious embryony (i.e. apomixis  (Zhang et al . 2018) , a form of asexual reproduction without 
fertilisation ). 
 
As a result of this complex history, there are various names app lied to different types of fruit , and 
many fruit are only known by their common or trade name . Whether a plant is considered a hybrid or 
a species is a taxonomic question not necessari lly relevant to the question of biosecurity risk.  
 
The complexity of citrus taxonomy presents difficulties when it comes to categorising and grouping 
commodities for IHSs. Groupings need to be consistent with known phytosanitary risks ( similar 
susceptibility to particular pests and pathogens) , and this may be associated with the degree of 
relatedness (shared parentage) of commodities  or shared physical characteristics . Fortunately, in 
2002 , INRA -CIRAD28 published a review of all of the known cultivars, varieties, hybrids and species of 
Citrus  in cultivation from around the world ( INRA -CIRAD  2002). The review lists all the Citrus  that 
were then known by  the two major Citrus  naming systems  published by Tanaka and Swingle.  While  
INRA -CIRAD  (2002) will not contain more recent Citrus  cultivars or varieties, the list is the most recent 
attempt to produce a coherent description of the cultivated Citrus  complex. For the purposes o f this 
IRA, the more simple naming system of Swingle is  considered  the most consistently aligned with the 
risk characteristics of the fruit. A list of the Citrus  commodities from Table 1.1 , but renamed according 
to the Swingle taxonomic system, is provided  in Table 2. 2. 
 
Table 2. 2  List of Citrus  commodites assessed in this IRA based on  the Swingle naming 
system and  Table 1.1 , using  SRA  INRA -CIRAD (2002 ) 
Citrus  species (or hybrids)  Synonyms  Common names  
Citrus aurantiifolia  (Christ.) Swingle  Citrus limettioides  Lime, Sweet lime,  Key lime, 
Mexican lime  
Citrus latifolia (Yu. Tanaka) Tanaka   Tahitian lime , Persian lime  
Citrus limon  (L.) Burm.f.  Citrus limonia , Citrus meyeri  Lemon , Meyer lemon ; 
Limonia  
Citrus maxima  (Burman) Merr.  Citrus grandis  Pomelo , Pummelo  
Citrus paradisi  McFad.  Citrus hassaku  Grapefruit , Hassaku , Ruby  
grapefruit  
Citrus reticulata  L. Citrus unshiu , Citrus deliciosa  Mandarin , Tangerine , Unshu , 
Satsuma  
Citrus sinensis  (L.) Osbeck  Citrus iyo  Orange , Iyokan , Valencia  
orange , Navel  orange  
Citrus reticulata × Citrus paradisi   Tangelo  
Citrus reticulata × Citrus sinensis   Tangor  
                                                      
28 Station de Recherche Agronomique, Institut National de la Recherche Agronomique - Centre 
International de Recherche et d’aide au Développement (INRA -CIRAD)   
23 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  2.3 General information related to likelihood of entry  
2.3.1 Pathway description  
Basic measures  are the minimum level of risk management that all citrus exporting countries must 
meet. The basic measures  for importing  fresh Citrus  spp. fruit for consumpti on into New Zealand are:  
1. Consignments of fresh Citrus  spp. fruit imported into New Zealand must:  
a. be free from infestation and contamination (including visible pests  and disease s, soil, 
biotic material, or abiotic  material capable of harbouring or spreading pests or 
diseases of biosecurity concern) and other extraneous materia l not included in the 
commodity description ; 
b. be free from conditions that may indicate pest or disease contamination (including 
rots and dama ge); 
c. comply with the commodity description (e.g. be sourced from a production site that 
uses standard commercial production methods29, have an intact skin  (on export) , free 
from defects such as splits and cuts , no leaves or stems attached ); 
d. be packaged in c lean and either new or refurbished material; and  
e. be secured in a manner to prevent contamination.  
 
2. Fresh Citrus  fruit will undergo official inspection in the export country and be sampled  prior to 
being exported to New Zealand  at a 95% confidence  level that pest or disease infestation is 
less than 0.5%  and the level of contamination by abiotic material  is less than 0. 1% w/w. Fruit 
lots with biosecurity risks (pests, rot or damage, trash  and soil) or not complying with the 
commodity description ( broken skin , stems, leaves) should  not be exported to New  Zealand  
as fresh produce . If the pest or disease  is 100% detectable , a sample of 600 will provide  a 
95% confidence level that the level of pest or disease infestation is less than 0.5%. If the pest 
or disease  is less than 100% detect able on inspection, the sample size will need to be 
increased to provide a 95% confidence level that the level of infestation is less than 0.5%  (see 
ISPM 31 for an explanation) . 
2.4 General information related to likelihood of establish ment  
2.4.1 Exposure  
When a pest or pathogen arrives in a new area, it usually needs to find or come into contact with a 
growing host plant in order to establish. This is termed “exposure” in MPI risk assessments and 
“transfer” under the IPPC.  
 
In the case of germplasm, imported plant material is  maintained in a habitat favorable for plant growth 
and is likely to be multiplied up to substantial numbers, resulting in a high likelihood of exposure , with 
low uncertainty for pests and pathogens associated with germ plasm/propagation pathways.  
 
In the case of fresh fruit and vegetables, the intended use is consumption, not propagation. There are 
two ways a pest or pathogen arriving with fresh fruit and vegetables may come into contact with a 
growing host plant:  
1. A pest may fly or be blown off the fruit and find a host plant. Examples include  mobile pests 
such as  thrips  and psyllids , as well as some fungi.  
2. The fruit  is discarded in to an environment that allows the pest or pathogen to continue its life 
cycle and event ually come into contact with a host plant . Examples include  flies, scales and 
citrus canker.  
 
                                                      
29 Definition: a process (system) where activities, such as in -field monitoring, in -field pest control activities, harvesting, cleaning, 
sorting, and grading have been undertaken to produce a commodity that is free from defects such as broken skin, rot and 
damage. Depending on the systems in place, these activities can be undertaken at any  stage from the point of planting to the 
point of export.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 24 The likelihood of the first case (mobile pest) occurring depends largely on the mobility of the pest. 
However, the more mobile the pest is, the less likely it is  to be associated with harvested and packed 
fruit in the first place , due to the level of handling the fruit  receives  during these processes.  
 
The likelihood of the second case (discarded fruit material) occurring depends on waste material 
generated from the commodity (either parts of the commodity not generally consumed, e.g. rinds or 
seeds, or parts generally consumed that have degenerated to the point of being considered inedible).  
Waste material discarded into bagged rubbish that goes to landfill, or i nto kitchen disposal units that 
flush into the sewerage system , is unlikely to be a risk. However, waste discarded into compost bins , 
under plants as mulch  or distributed as animal feed  presents a potential exposure pathway . 
 
2.4.2 Waste analysis  
 
Citrus  fruit has inedible skin and produces a moderate amount of waste, more than a commodity such 
as fresh ginger but less than a pineapple , and whole fruit being disposed of is not uncommon during 
wholesale and retail marketing and even in the consumer stage . Culled and unsold fruit, uneaten fruit 
and fruit remains may be disposed of by wholesalers, retailers, food services ( e.g. restaurants, 
hospitals) and consumers  (MPI, 2014) . In addition,  Citrus fruit can be a  high-volume fresh produce 
commodity . Therefore , pests and pathogens associated with citrus fruit waste have a moderate  to 
high level of exposure  in comparison to other kinds of fresh produce . However , this likelihood is much 
less than with germplasm, as only a limited amount of the commodity ends up in a n environment 
suitable for associated pests and pathogens to establish.  
 
In New Zealand, landfilling has been the most common method of disposing of municipal solid waste 
and organic waste ( Aska rany & Franklin -Smith 2014).  Fresh produce food waste may be di sposed of 
by wholesalers, retailers, food services and consumers. The accurate proportion of commercial and 
household fresh produce  waste that is disposed of by different disposal methods  is difficult to survey 
(Waste Not Consulting  2009) . It is important to note that the proportions in some of the following 
studies are for total food waste or organic waste , and as such,  the proportion that comprises imported 
produce or citrus fruits is likely to be much smaller  and affected by seasonal differences in fruit 
supply . In North America, Australia and New Zealand, the total los s of fruit and vegetable s during 
distribution/retail marketing and at the consumer stage is 12% and 28% respectively (NRDC 2012 in 
Porat et al. 2018) .  
 
For c ommercial food waste:  
• A waste analysis in New Zealand shows that approximately 20.3% of retail and 6.9% of non -
domestic outlets (hospitals, restaurants , etc.) used high -risk methods (e.g. garden compost) 
to dispose of waste (Wigbout 1991,  in MPI 2014).  
• MPI (2014 ) also noted that w holesale fruit disposal pathways and practices were not covered. 
Although normal commercial practice is to reduce waste, fruit waste in New Zealand may be 
collected from unpacking areas (e.g . supermarket preparation rooms) and taken to rural areas 
where it is placed on the ground for eventual consumption by pigs or other farmed animals . 
• A more recent survey on waste from supermarkets in New Zealand (Goodman -Smith 2018) 
found that 46% of super market food waste was used as animal feed, of which 30% w as fresh 
fruit waste.  
• 23% of supermarket food waste was landfilled , of which approximately 6% w as fresh fruit 
waste  (Goodman -Smith 2018 ). 
• 1% of supermarket food waste was composted, of which  approximately 65% was fresh fruit 
waste ( Goodman -Smith 2018 ). It is not known whether th is waste was composted in garden 
compost or commercial compost. Garden compost is a high -risk method , as compost sites 
are not always cover ed and often close to weeds,  grasses and garden plants. In contrast,  
commercial compost is a low -risk method, as the waste will be put in tunnels for a few days , 
and the high temperature (a period  of three  to four days at greater than 55°C) is likely to kill 
most insects and mites  and many pathogens (WasteMINZ , 2009 ).  
• 15% of food that w as not sold in supermarket went to food donation, of which fresh fruit 
comprised 13% ( Goodman -Smith 2018 ). 
 
For d omestic food waste:   
25 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • A 2010 survey in New Zealand found that 71% of household organic waste was landfilled 
(Hogg et al. 2010).  
• Approximately 13 % of household organic waste was disposed of in d isposal units  (Hogg et al. 
2010).  
• Approximately 13% of household organic waste was  composted (Hogg et al. 2010).  
• In rural areas, o ne study in Taranaki found that 75% of farmers fed food waste to farm 
animals (Waste Not Consulting 2009) , but the proportion of food waste that w as fed to 
animals is unknown . 
 
 
Figure 2. 1  Disposal of fresh fruit and vegetable waste in New Zealand. Disposal methods in blue text are 
a low biosecurity risk; those in red text present a higher risk.  
 
Note  that when considering the likelihood of exposure of the pest  or disease associated with th e risk 
of waste from the commodity, there is a moderate level of uncertainty on the waste data , due to data 
limitation s. First, waste data may not be very accurate or up to date. Data o n household waste (Hogg 
et al.  2010) for fresh fruits and vegetables we re estimated from organic waste, of which fresh fruits 
(including citrus ) may only account for a small proportion. Apart from the supermarket survey 
(Goodman -Smith , 2018), the waste data w ere ob tained  about 10 years ago, although landfilling is still 
considered  the primary means  of dispos ing of waste in New Zealand. Second, it is uncertain how 
frequently suitable hosts would be present near composting sites in gardens or animal feeding 
locations, as no report has been found to investigate this.  
 
Potent ial for the exposure of Citrus  seed -transmitted and vector -transmitted  pathogens  
 
There is no evidence that seed from discarded Citrus  fruit results in seedlings except under rare 
circumstances. That is, despite being commonly cultivated, few types of Citrus are reported to be 
naturalised in New Zealand , and those that are naturalised are not common or widespread in the 
wild30. Seed from imported Citrus  fruit could be deliberately planted ; however, given that this is not the 
intended end -use and is unlikely to happen frequently, deliberate propagation is not considered 
further in this IRA.  Pathogens that could only be transferred into the environment via seed growth 
have therefore been excluded from this IRA.  
 
There are also vector -transmitted pathogens  that may be detected in fruit, for example via PCR tests, 
but have no way of getting from fruit and onto a growing host in the absence of a vector. These have 
also been excluded from this IRA  if the vector is not in New Zealand and not likely to be associated 
with the commodity under the commodity description . 
                                                      
30 Allan Herbarium  
https://nzflora.landcareresearch.co.nz /default.aspx?selected=NameDetails&TabNum=0&NameId=0BDA3A5C -4DA1 -4289 -
9B8B -C0B3B3A7A6D6  
 
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 26 2.4.3 New Zealand climate  description  
New Zealand in general exhibits a mid -latitude oceanic temperate climate ( Cfb temperate with 
maritime climate in the Köppen classification (Köppen 1936 ; Rubel and Kottek 201 0)). Annual 
precipitation varies substantially due to topography, from dry eastern and inland areas to very high 
precipitation (on a global scale) in west coast areas31. The driest New Zealand climates barely reach 
a conventional water deficit on average (a lthough they can do so in extreme years and months).  The 
New Zealand climate ‘space’ can be visualised  as a three -dimensional simplified climate niche ( Fig. 
2.2). This represents the average monthly temperature and precipitation for each month of the year 
for 42 New Zealand climate stations.  
 
Figure 2.2  Climate niches of New Zealand. Thin grey lines: average monthly temperature (1981 –2010) 
for 42 New Zealand climate stations (data from NIWA (2020) ). Each polygon is composed of the 12 months 
of the year. Small black ellipse: average conditions for those 42 sites. Large ellipse: 95% inclusive ellipse.  
 
As a consequence of being a small landmass in a large ocean, New Zealand has  relatively low diurnal 
and seasonal temperature fluctuations (equable climate).  Rainfall is close to evenly distributed 
between summer and winter. These feature s are similar in equatorial climates.  However, there can be 
relatively rapid variations between days as large weather systems alternate over the oceans. 
Although such variations may also occur in continental climates, a key difference for organisms is the 
proximity of these variations to biological thresholds (such as frost).  
 
Unlike many Northern Hemisphere continental climates with reliable lengthy warm and cold perio ds, a 
small temperature variation in a mild oceanic climate means a more significant change in the number 
of days crossing threshold degrees , which may in some cases restrict the ability of some organisms to 
establish. This feature is also common to smalle r land masses and mountains of the Southern 
Hemisphere, which is why , globally , some of the most similar climate conditions to New Zealand are 
in the montane regions of the Andean Yungas cloud forests and grasslands (Halloy et al. 2008) . This 
is reflected in high morphological similarities of adaptations (Halloy & Mark 1996) . 
 
Together with tussock grasslands, temperate rainforests are the global biome  climate types most 
represented in New Zealand. The northernmost areas of New Zealand approximate subtropic al 
temperature conditions, with an ability to grow a range of subtropical plants.  
 
The northern part of New Zealand is the most climatically suitable for the establishment of new pests 
and pathogens coming from a subtropical/tropical climate. The area incl udes Kaitaia, Kerikeri, 
                                                      
31 This summary is written with crop pests and diseases in mind, focusing on the climate in inhabited and cultivated areas of 
New Zealand. Rainy outliers (e.g. Milford and Mt Cook) and high mountain climates are not considered, as they represent 
extremes wit h relatively low human and agricultural activity  
050100150200250300
-10 0 10 20 30precipitation, monthly (mm)
temperature, average monthly (oC) 
27 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Whangarei, Auckland (New Zealand’s largest city) and Tauranga. The latter two cities both contain 
large active sea ports.  
Citrus  species are from the warmer temperate climates of the world , and most parts of New Zealand’s 
coastal en vironments are ideal for them , as long as they are sheltered. Mature trees are either 
flowering or fruiting and commonly doing both together. The genus Citrus  is widespread throughout 
the country with households commonly having Meyer lemon trees in their g ardens. If conditions allow, 
other species of Citrus  can be found growing in home gardens. C. × aurantium  L., sour orange, C. × 
limon , especially cv. ‘Meyer’, Meyer lemon, C. reticulata  Blanco, mandarin, tangerine or satsuma 
orange, and C. × sinensis  are v ery commonly grown in warmer North Island areas.  The Bearss 
cultivar of Tahitian lime, C. × latifolia  cv. Bearrs (Yu . Tanaka) Tanaka is also common and will also 
grow in cooler areas of the North Island.  Nevertheless, within New Zealand proper , no Citrus  spp. has 
been reliably reported wild.  
The main citrus-growing areas of New Zealand are the Northland, Auckland, Bay of Plenty and  
Gisborne region s. Most commercial production tak es place in the Gisborne and Northland regions, 
followed by Auckland, Bay of Plenty and Hawke’s Bay, with much less in other regions through out the 
North Island and in parts of the South Island ( Plant & Food Research  2019). 
Climate in the regions where citrus is grown commercially:  
• Northland:  Kerikeri is a well -known orcharding to wn, with many varieties of Citrus  fruit grown 
there. Avocado, kumara, macadamia and tamarillos are the other main crops grown there 
(HortResearch , 2005; Plant and Food Research , 2010). This is a subtropical zone, with warm 
humid summers and mild winters. Typical summer daytime maximum air temperatures range 
from 22 °C to 26 °C, but seldom exceed 30 °C. Winter daytime maximum air temperatures 
range from 12 °C to 17 °C (NIWA 2008).  
• Auck land:  This region has the largest population in the country, with the greatest quantity  of 
incoming goods and people , and contains the largest sea and air ports. Therefore it is likely to 
be one of the first places pests and diseases could establish. The A uckland region produces 
a variety of crops , including Citrus  species such as mandarins, as well as strawberries, herbs, 
Asian vegetables, brassicas, chestnuts, greenhouse crops, lettuce, olives, onions, 
persimmons, pumpkin s and silverbeet (HortResearch 200 5; Plant and Food Research 2011). 
Auckland has the highest rate of naturalised plants of any city in New Zealand. The prime 
reasons for the high numbers of plant species are considered to be the moderate climate , 
favouring species from many climatic zones,  and the availability of habitats (Esler 1988).  
• Bay of Plenty:  During summer , the region experiences average daily air temperatures over 
20°C. The low -lying, coastal areas experience mild winters (NIWA 2013). Tauranga produces 
feijoas, citrus, avocado s, asparagus, tamarillos and kiwifruit (HortResearch 2005; Plant and 
Food Research 2010).  
• Gisborne:  The climate is generally  congenial , with a large number of sunshine hours and low 
wind. Rainfall is unevenly distributed, with a prominent winter maximum.There  are small 
areas of the region with high productivity for fruits and vegetables (NIWA 2016). Prominent 
crop species include citrus, wine grapes, apples and squash (FreshFacts 2019).  
The large number of p ests associated with Citrus  species means that a deta iled assessment of 
establishment and potential distribution is not possible. With respect to establishment and range, 
climate is generally a more important consideration for invertebrate pests than for pathogens. 
However,a lthough climate is not the primary  indicator of a pathogen’s ability to establish, it is a useful 
piece of information to consider , particularly if pathogen spread is dependent on a vector, and also in 
relation to the  extent of disease expression. The climate overlap between New Zealand an d where a 
pest has been reported is assessed using the tool described in Phillips et al. (2018). This tool is based 
on the c limate  (or composi te) match index (CMI) CLIMEX -MCR of CLIMEX version 3.3. The tool 
allows the comparison of New Zealand’s climate in general, or citrus -growing areas specifically, with 
areas where a p est occurs overseas. The higher the CMI, the more similar the climate of the region  to 
which the CMI pertains and the New Zealand climate. A CMI of 0.7 or more between the New 
Zealand clima te and the existing range of the p est indicates a high likelihood of climatic suitability for 
that pest to establish in New Zealand  (Phillips et al. 2018).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 28  
For many of the pests assessed, this tool is likely to be a sufficient indication of climatic suitability in 
New Zealand for the pest to establish.  Figure  2.3 shows the  whole -world map with CMI data from 
Phillips et al. (2018). When using the tool, the map can be enlarged to show more detail at a regional 
level.  For some pests assessed, more detail ed climate niche envelop es (see Fig. 2.2 above) have 
been developed to compare the climate of the pest’s known range with the New Zealand climate.  
 
 
 
Figure 2.3  Climate match index (CMI). World climate similarities with All New Zealand (Phillips et al. 
2018) . 
 
2.4.4 Shifting New Zealand climates with climate change  
The global climate is warming rapidly and will continue to warm even faster as a result of greenhouse 
gas emissions (IPCC_WGI 2013 ; Allen et al. 2018 ; WMO 2019) . Severa l studies have examined the 
effects of these changes on the New Zealand climate (NIWA 2017 ; MfE 2018) . Warming 
temperatures and changing precipitation patterns will affect existing biodiversity, pests and diseases, 
and will change the likelihood of establishment of new arrivals  (Gerard  et al. 2013 ; Kean et al. 2015) . 
However, climate change is not just a scenario for the future. Average New Zealand temperatures 
have risen substantially over the last century, with concomitant but more variable changes in 
threshold and extreme conditions (including frosts, heatwaves, droughts, tropical storms, etc). Sea 
surface temperatures (SSTs) around New Zealand are closely correlated with atmospheric warming, 
and in recent decades (since 1981) , have been  rising in the order of 0.1 –0.3°C per decade (Sutton & 
Bowen 2019) . This would equate to 1 –3°C per century, close to the modelled predictions for 2100. 
Such trends are , to some degree , hidden by inter -annual variability, but are already significant for the 
biota, agriculture and human occupation.  
 
29 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Figure 2 .4  Shift of New Zealand climate niches with climate change. Grey polygons and black ellipses as 
in Fig. 2.2 (1981 –2010 climate baseline). The orange ellipses represent the expected shift with a moderate 
climate change scenario (simplified as a +2 °C increment and +10 -mm monthly addition to precipitation).  
 
These ‘shifting goal posts’ may lead to some confusion when reading climate change scenarios. 
Climate scenarios are expressed as degrees of change up to 2100, for example , a 2°C increase. 
However the baseline for that increase may not be explicit to the reader. The baseline is sometimes 
referred to as ‘conditions pre -industrial age’, or ‘beginning of 20th century’. Other times , it may be the 
‘1961 –1990 average’, or more recently , the ‘1981 –2010’ average. Because of the continuous change 
since the pre -industrial period, the first baseline would lead to a 2 °C increase by 2100. However, 
adding the same 2 °C to a 1981 –2010 baseline would mean ~3 °C increase by 2100 in respect to pre -
industrial con ditions.  
 
In New Zealand, some of the last years have already approximated a 2 °C increase on pre -industrial 
levels. Although cool years will still occur, for an organism , some conditions in some years already 
approximate some models for 2100.  Model scenari os for temperature increases for 2100 depend on 
many factors, but most scientists now expect there is little chance of  keeping the  increases below 2 °C 
(Wallace -Wells 2019) . For illustration’s sake, exploring a conservative 2 °C average increase (as in 
NIWA scenarios32) and a 10 -mm monthly increase in precipitation allows us to investigate the 
consequences without making any judgement as to which is more likely.  
 
We can then consider the likelihood of such scenarios. To give an idea of how conservative a +2°C is, 
consider that  the average temperature in the last century has already climbed >1 °C over pre -industrial 
values. As averages shift, so do the extremes of the distribution and the thresholds for frosts, degree 
days, etc. Note , for example , that the m idpoi nt of July 2009 –2018 is where extreme warm years were 
in 1928 –1937; the extreme has already  become the norm ( Fig. 2. 5)33. Moreover, the pace of increase 
is accelerating, greenhouse gas emissions are still rising, and a series of potential tipping points may 
soon be breached. Due to prolonged lag times, the abrupt decline in emissions triggered from March 
2020 due to the Covid-19 pandemic are not likely to affects trends in the next decades. If such 
declines were to continue , they could reduce the centennial temperature increase.  
                                                      
32 2°C is an 'in between' of the 0.7 °C to 3 °C range of scenarios in NIWA: https://niwa.co.nz/our -science/climate/information -and-
resources/clivar/scenarios, 20171221. However, in more detail, https://ofcnz.ni wa.co.nz/#/localCharts shows an increase to 
2100 of 2 °C (RCP 6) to 3 °C (RCP 8.5) annual mean (for six -model average) for Christchurch. Annual precipitation remains 
almost the same. Spring °C and mm follow the same pattern. Summer (DJF) increases less (1.5 °C to 2.3 °C). For rainfall, 
possible increases are around 10 mm; however, there will be considerable geographic variation and this is only illustrative.  
33 Note that climatologists typically prefer to use 30 years to represent a climatic period. Decadal peri ods are, however, useful 
for biological systems, as a decade is a long enough time to determine whether an organism can perish, establish or invade.  
050100150200250300
-10 0 10 20 30precipitation, monthly (mm)
temperature, average monthly (oC)Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 30  
Figure 2.5: Schematic normalised frequency distribution of mean monthly temperatures for July (l eft) 
and January (right) for Wellington, New Zealand. The blue line is 1928–1937, the orange line  2009–2018. 
Calculated from NIWA National Climate Database ( https://cliflo.niwa.co.nz/ ). Note that actual frequency 
distributions tend to skew further right.  
 
As a result of such shifts, in future scenarios, frost s decrease substantially, by 30% (RCP 2.6) to 50% 
(RCP 8.534) for the year 2040 (MfE 2018) . 
 
2.5 General information related to impacts of pests and diseases  
2.5.1 Plant  family  to which  the commodity belongs  
Citrus  belongs to the family Rutaceae, a cosmopolitan family with around 150 genera (The Plant List 
2013). Citrus  is the main economically important genus, although there are other species which 
provide fruit, such as  Casimiroa , and flavouring, for example , Galipea officinalis , which is the source 
of angostura bitters , and Murraya  koenigii , used in Indian and Sri Lankan cooking (Mabberley 2008). 
There are also a number of  ornamental species grown in New Zealand, such as Boronia , Choisya  and 
Coleonema  (Landcare Research 2020).  
 
New Zealand has three endemic species in the Rutaceae: Leionema  nudum, Melicope simplex  and 
M. ternata  (Landcare Research 2020). The two Melicope  species are found in lowland areas in both 
the North and South Islands, while L. nudum  is found only in the northern half of the North Island 
(AVH 2020). Neither the Leionema  nor Melicope  species are considered threatened ( de Lange et al. 
2018 ). 
 
The Ruta ceae is  a common family in cultivation in New Zealand, but few species have naturalised , 
and none have done so extensively  (Landcare Research , 2020).  
2.5.2 New Zealand  industry related to the plant commodity  
The New Zealand citrus industry comprises around 1, 660 hectares divided between approximately 
316 growers, with most commercial production taking place in the Gisborne and Northland regions, 
followed by Auckland, Bay of Plenty and Hawke’s Bay, with much less in other regions through out the 
North Island and in  parts of the South Island ( Plant & Food Research  2019). 
 
                                                      
34 In the latest IPCC report, RCPs (representative concentration pathways) are used to indicate emission scenarios, where 2.6 
and 8.5 are the lowest and highest (e.g. (IPCC_WGI 2013; MfE 2018) ).  
 
31 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Growers were estimated to have produced 34,096  tonnes of citrus in 201 8/19 (Plant & Food 
Research  2019). 
Commercial crops include oranges, mandarins, lemons, tangelos, limes and grapefruit ( Plant & Food 
Research 2019). Most produc e is grown for the domestic market (NZIER 2016). In 201 8/19, the New 
Zealand domestic sales of fresh citrus fruit were NZ$58.5 million  (mandarins $2 5.2 M, oranges $1 8.0 
M, lemons $1 2.0 M, limes $2.0  M, tangelos $1.0  M, grapefruit $0.3  M) (Plant & Food Research  2019). 
In 201 9, export sales (free -on-board value) of fresh fruit were NZ$12 million  (lemons $ 9.8 M, oranges 
$1.7 M, mandarins $0.4  M, tangelos $0.1  M) (Plant & Food Research  2019). Processing mainly 
involves juici ng citrus and other human consumption items (NZIER 2015). Domestic and export sales 
in relation to the processing of citrus has been estimated to be $55.4  million , with the citrus 
processing value estimated as $11.7  million  (NZIER 201 6). In 2012/2013 (Apri l year), the impact of 
citrus on the GDP was estimated to be $27.1 million (NZIER 2016). This was calculated from tree 
sales, farm gate sales, domestic sales, processing (mainly juice) and export sales.  A summary of the 
New Zealand citrus industry is provi ded in Table 2.3.  
 
Table 2.3  How big is New Zealand’s citrus industry?  (NZCGI , accessed 23 Oct ober  2020 ) 
 Growers*  Hectares  
Planted  Tonnes 
(Fruit)  Number of  
Trees  Domestic  
Sales  Export  
Sales  
Citrus , total  320 1,663 29,740  1+ million  $58.3 M $12 M 
Mandarins  198 556 10,920  513,87 0 $25 M $0.4 M 
Oranges  183 783 10,100  320,84 0 $18 M $1.7 M 
Tangelos  28 22 640 11,105  $1 M $0.1 M 
Lemons  180 260 7,000 153,73 0 $12 M $9.8 M 
Limes  50 27 710 8,960 $2 M – 
Grapefruit  18 15 370 4,247  $0.3 M – 
* Many growers produce more than one citrus variety.  
The average yield is 18 t/ha over all varieties . Information on the New Zealand citrus growing and 
import seasons are provided in Figures 2. 6 and 2. 7 respectively.  
 
 
 
Figure 2.6  When is citrus in season in New Zealand? (NZCGI, accessed 23 Oct ober  2020)  
 
 
Figure 2. 7  When is citrus fruit imported into New Zealand? (MPI 2020)  
 
2.6 References for Chapter 2  
Allan Herbarium (2000) Ngā Tipu o Aotearoa – New Zealand Plant Names Database. Landcare 
Research ; NZ. https://nzflora.landcareresearch.co.nz/default.aspx?NavControl=home . Accessed 11 
May 2020.  
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 32 Allen, M; Babiker, M ; Chen, Y; de Coninck, H; Connors, S et al. (2018) Global Warming of 1.5 °C - 
Summary for Policymakers. Intergovernmental Panel on Climate Change (IPCC) 
https://www.ipcc.ch/sr15/ . 
Askarany, D; Franklin -Smith, A W ( 2014) Cost benefit analyses of organic waste composting systems 
through the lens of time driven activity -based costing. Journal of Applied Management , 12(2): 59 –73. 
AVH (2020) Australasian Virtual Herbarium. https:/ /avh.chah.org.au/  Accessed 11 May 2020.  
Barrett, H C; Rhodes, A M (1976) A numerical taxonomic study of affinity relationships in cultivated 
Citrus  and its close relatives. Systematic Botany , 1(2): 105 –136. 
CABI (2019) Citrus deliciosa  (Mediterranean mandarin). In Invasive Species Compendium . 
Wallingford, UK: CAB International. https://www.cabi.org/isc/datasheet/13442  
Citrus Resource. Citrus ID: Citrus iyo hort. Ex Tanaka. 
http://idtools.org/id/citrus/citrusid//factsheet.php?name=Iyo  
Curk, F; Ollitrault, F; Garcia -Lor, A; Luro, F; Navarro, L; Ollitrault, P (2016) Phylogenetic origin of 
limes and lemons re vealed by cytoplasmic and nuclear markers. Annals of Botany , 117(4): 565 –583. 
DOI: 10.1093/aob/mcw005. www.aob.oxfordjournals.org  
De Lange, P J; Rolfe, J R; Barkla, J W; Courtney, S P; Champion, P D; Perrie , L R; Beadel, S M; 
Ford, K A; Breitwieser, I; Schonberger, I; Hindmarsh -Walls, R; Heenan, P B; Ladley, K (2018) 
Conservation status of NZ indigenous vascular plants, 2017. New Zealand Threat Classification 
Series 22 . Department of Conservation; Wellington . 82 pages. 
https://www.doc.govt.nz/documents/science -and-technical/nztcs22entire.pdf  
FAO (2017) Categorization of commodities according to their pest risk . Internati onal Standard for 
Phytosanitary Measures No. 32. Published by FAO on behalf of the Secretariat of the International 
Plant Protection Convention (IPPC); Rome, Italy.  
Gerard, P J; Barringer, J R F; Charles, J G; Fowler, S V; Kean, J M; Phillips, C B; Tait, A  B; Walker, G 
P (2013) Potential effects of climate change on biological control systems: case studies from New 
Zealand. BioControl , 58: 149 –162. 
Gilbert, G S; Webb, C O (2007) Phylogenetic signal in plant pathogen –host range. PNAS , 104(12): 
4979 –4983 . 
Goodman -Smith, F (2008) A quantitative and qualitative study of retail food waste in New Zealand. 
MSc thesis. University of Otago; Dunedin, NZ.  
Halloy, S R P; Beck, S G; Ledezma, J C (2008) Central Andean Grasslands (Páramo, Puna) and 
High-Andean (central and southern Perú, western Bolivia, northern Chile and northwestern 
Argentina). InPeart, B (ed) Compendium of Regional Templates on the Status of Temperate 
Grasslands Conservation and Protection . IUCN; Quito, Ecuador; pp 148 –159. 
Halloy, S R P; Mark, A F (1 996) Comparative leaf morphology spectra of plant communities in New 
Zealand, the Andes and the European Alps. Journal of the Royal Society of New Zealand , 26(1): 41 –
78. 
Hogg, D; Wilson, D; Gibbs, A; Holmes, A; Eve, L (2010) Household Organic Waste Cost Be nefit 
Analysis Report to Greenfingers Garden Bags/Earthcare Environmental Limited & Envirofert Limited. 
Eunomia Research and Consulting Ltd, Auckland, New Zealand.   
33 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  IPCC_WGI (2013) Working Group I contribution to the IPCC Fifth Assessment Report Climate 
Change 2013: The Physical Science Basis - Final draft (Accepted). Intergovernmental Panel on 
Climate Change.  
Kean, J M; Brockerhoff, E G; Fowler, S V; Gerard, P F; Logan, D P; Mullan, A B; Sood, A; Tompkins, 
D M; Ward D F (2015) Effects of climate change o n current and potential biosecurity pests and 
diseases in New Zealand. Ministry for Primary Industries; Wellington, NZ.  
Köppen, W (1936) Das geographische System der Klimate. In Köppen, W; Geiger, R (eds) Handbuch 
der Klimatologie . Vol. 1, Part C. Gebrüder  Borntraeger; Berlin, Germany; pp C1 –C44.  
Mabberley, D J (2008) The Plant -book: A portable dictionary of plants, their classifications and uses . 
Cambridge University Press; UK. 3rd edition.  
MfE (2018) Climate Change Projections for New Zealand: Atmosphere  
MPI (2014) Generic Pest Risk Assessment: Armoured scale insects (Hemiptera: Coccoidea: 
Diaspididae) on the fresh produce pathway . Ministry for Primary Industries (MPI); Wellington, NZ.  
MPI (2020) Imports and Domestic Seasonal Calendar 2020.  
https://piri tahi.cohesion.net.nz/Sites/SAI/PP/PIM/PROD/_layouts/15/WopiFrame.aspx?sourcedoc=%7
bF0FBC96D -41A7 -478F -AA89 -
2CB0ABCA2EC2%7d&file=20200309%20Imports%20and%20Domestic%20Seasonal%20Calendar%
202020.xlsx&action=default&DefaultItemOpen=1  
Nicolosi, E; Deng, Z N; G entile, A; La Malfa, S; Continella, G; Tribulato, E (2000) Citrus phylogeny 
and genetic origin of important species as investigated by molecular markers. Theoretical and Applied 
Genetics , 100: 1155 –1166. https://link.springer.com/article/10.1007/s001220051419  
NIWA (2013) National Institute of Water and Atmospheric Research. 
https://niwa.co.nz/static/BOP%20ClimateWEB.pdf  
NIWA  (2016) National Institute of Water and Atmospheric Research. https://niwa.co.nz/our -
science/climate/publications/regional -climatologies/gisborne  
NIWA (2017 ) National Institute of Water and Atmospheric Research. Climate change scenarios for 
New Zealand. https://niwa.co.nz/our -science/climate/informa tion-and-
resources/clivar/scenarios#regional . 
NIWA (2020) National Institute of Water and Atmospheric Research. The National Climate Database. 
https://cliflo.niwa.co.nz/  
NZCGI. New Zealand Citrus Growers Incorporated. https://www.citrus.co.nz/  
NZIER (2016) How valuable is that plant species? Application of a method for enumerating the 
contribution of selected plant species to New Z ealand’s GDP. MPI Technical Paper No: 2016/62. 
Prepared for the Ministry for Primary Industries by NZIER, New Zealand Institute of Economic 
Research. (227 pp.)  
Phillips, C B; Kean, J M; Vink, C; Berry, J A (2018) Utility of the CLIMEX ‘match climates regio nal’ 
alogorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 34 Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd; Auckland, New Zealand. https://www.freshfacts.co.nz/file s/freshfacts -
2019.pdf  
Porat, R; Lichter, A; Terry, L A; Harker, R; Buzby, J (2018) Postharvest losses of fruit and vegetables 
during retail and in consumers’ homes: Quantifications, causes, and means of prevention. 
Postharvest Biology and Technology , 139:1 35-149 https://doi.org/10.1016/j.postharvbio.2017.11.019  
Projections Based on Simulations from the IPCC Fifth Assessment, 2nd Edition . Ministry for the 
Environment (MfE); Wellington, NZ.  
Rubel, F; Kottek, M (2010) Observed and projected climate shifts 1901 -2100 depicted by world maps 
of the Köppen -Geiger climate classification. Meteorologische Zeitschrift 19: 135 -141(137)  
SRA INRA -CIRAD (2002) Citrus of the world. Version 2.0. Station de Rech erche Agronomique, 
Institut  National de la Recherche Agronomique - Centre International de Recherche et d’aide au 
Développement. 62 pages.  
Sutton, P J H; Bowen, M (2019) Ocean temperature change around New Zealand over the last 36 
years. New Zealand Journal of Marine and Freshwater Research 53.  
The Plant List (2013) Rutaceae. Version 1.1. Published on the Internet; 
http://www.theplantlist.org/1.1/browse/A/Rutaceae/  Accessed 29 March 20 19. 
UCR (a). University of California Riverside, Citrus Variety Collection, New Zealand grapefruit, Poor 
man’s orange, Citrus  paradisi  Macfadyen. 
https://citrusvariety.ucr.edu /citrus/new_zealand_grapefruit.html  
UCR (b). University of California Riverside, Citrus Variety Collection, Hassaku pummelo hybrid (CRC 
3942), Citrus hassaku  hort. ex Tanaka. https://citrusv ariety.ucr.edu/citrus/hassaku.html   
Wallace -Wells, D (2019) The Uninhabitable Earth, Annotated Edition Intelligencer, New York. 
http://nymag.com/intelligencer/2017/07/climate -change -earth -too-hot-for-humans -annotated.html.  
Waste Not Consulting (2009) House hold sector waste to landfill in New Zealand. Waste Not 
Consulting, Auckland. Ministry for the Environment, Wellington.  
WasteMINZ (2009) Consent Guide for Composting Operations in New Zealand. Waste Management 
Institute of New Zealand.  
WMO. 2019. The State of the Global Climate in 2018. http://ane4bf -datap1.s3 -eu-west-
1.amazonaws.com/wmocms/s3fs -
public/ckeditor/files/Draft_Statement_26_11_2018_v12_approved_jk_0.pdf?VXUDp1UTysIkHog4_TT
uiHsIzZ6A9D93 .  
Wu, G; Terol, J; Ibanez, V; et al. (2018) Genomics of the origin and evolution of Citrus . Nature , 554, 
311–316. https://doi.org/10.1038/nature25447  
Zhang, S; Liang, M; Wang, N; Qiang, X; Deng, X; Chai, L (2018) Reproduction in woody perennial 
Citrus: an update on nucellar embryony and self -incompatibility. Plant Repr oduction , 31: 43 –57 
https://doi.org/10.1007/s00497 -018-0327 -4 
   
35 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  3. Hazard identification  
 
A hazard is a pest or disease that is associated with imported risk goods and import pathways and 
that has the ability to cause harm to New Zealand. Hazard identification (hazard ID) is the process 
where , depending on the scope of the IRA,  a list of pests and diseases  potentially associated with the 
commodity is compiled and then assessed against specified criteria , in order to determine which 
species require further assessment.  The objective for hazard identification in this IRA is  to identify all 
pests and diseases  that may requir e additional measures , based on assessment against th e risk 
evaluation criteria  (see “Hazard identification” section of the IRA overview, page v) . 
 
In order to identify pests and diseases  that may require additional measures , hazard ID focused on 
the following traits  (risk evaluation criteria) : 
• The pest or disease  and/or associated damage is not easy to see on the citrus fruit, 
including when undertaking visual inspection,  because  
o the pest can burrow into the fruit without obvious symptoms,  or 
o the pest can hide in the navel and/or under the calyx of the citrus fruit, or 
o a pest or disease  may take time or require particular environmental conditions to 
develop or to express symptoms ; and 
• the pest or disease  has an ability to get off the fruit  and onto a host in the New Zealand 
environment . 
 
While the ability of a pest to establish and cause  impacts is part of the definition of a hazard, this is 
generally only  considered  indicatively at the hazard identification stage. It is assessed in depth at the 
risk assessment stage.  
 
Because this IRA will be used to develop IHSs for a number of differen t citrus fruit types and for a 
number of countries , the hazard ID needs to take into account pests and diseases  that are associated 
with any of the commercial citrus types and any of the countries under consideration.  
 
Hazard identification  for this projec t used a range of sources including:  
• CABI Crop Protection Compendium (2018/ 19) 
• CABI horizon scan, list of all potential risks for Citrus  imports to NZ, CABI horizon scan 
extract_20180319)  
• CAB Abstracts  
• Google Scholar  
• Google  
• EPPO Global Database  
• Existing pest lists from Citrus IHSs  
• New Zealand border interception data (LIMS, QuanCargo)  
• Farr & Rossman (2017/2018) (for fungi and oomycetes)  
• García Morales  et al.  (2016) (for scale insects)  
• Migeon & Dorkeld (2018) (for mites)  
• Ferris (2020)  (for nematodes)  
• MPI Emerging Risks System database  
• general literature searches  
 
A list of species identified at the hazard identification stage as associated with the commodity, present 
in at least one exporting country and potentially not being managed b y basic measures, and therefor e 
requiring further assessment (a Pest Risk Assessment) , is provided in Table 3.1 . 
 
Table 3.1  Pest groups and conclusion s for risk assessment following initial  hazard identification  
 
Pest group  Species requiring Pest Risk Assessments  (PRAs)  
Fungi  Elsinoe australis , Phyllosticta  spp. 
Bacteria  Xanthomonas citri  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 36 Pest group  Species requiring Pest Risk Assessments  (PRAs)  
Oomycetes  Phytophthora palmivora  
Insects: order Diptera , 
fruit flies (receiving 
individual PRAs)  Anastrepha fraterculus , Anastrepha ludens , Bactrocera 
dorsalis , Bactrocera minax , Bactrocera trilineola , Bactrocera 
tryoni , Bactrocera tsuneonis,  Bactrocera xanthodes , Ceratitis 
capitata , Zeugodacus cucurbitae , and Bactrocera zonata  
Insects: order Diptera , 
fruit flies ( not covered by 
other PRAs and assessed 
in a singl e group PRA)  Anastrepha obliqua , Anastrepha serpentina , Anastrepha 
sororcula , Anastrepha striata , Anastrepha suspensa , 
Bactrocera aquilonis , Bactrocera carambolae , Bactrocera 
correcta , Bactrocera curvipennis , Bactrocera distincta , 
Bactrocera frauenfeldi , Bactrocera jarvisi , Bactrocera kirki , 
Bactrocera kraussi , Bactrocera latifrons , Bactrocera melas , 
Bactrocera  neohumeralis , Bactrocera psidii , Bactrocera trivialis , 
Bactrocera melanotus , Bactrocera passiflorae , Bactrocera  sp. 
nr passiflorae , Zeugodacus tau  
Insects: order Lepidoptera 
(moths, butterflies)  Gymnandrosoma aurantium , Marmara gulosa , Spodoptera 
littoralis  
Insects: order Hemiptera , 
family Pseudococcidae  
(mealybugs)  Nipaecoccus viridis , Planacoccus kraunhiae , Planococcus 
minor  
Insects: order Hemiptera , 
family Psyllidae (p syllids ) Diaphorina  citri, Trioza erytreae  
Insects: order 
Thysanoptera (t hrips ) Caliothrips fasciatus , Chaetanaphothrips orchidii , Scirtothrips 
dorsalis , Thrips palmi  
Subclass Acari (m ites) 
(families  Eriophyidae, 
Tenuipalpidae, 
Tetranychidae ) Aculops pelekassi , Eotetranychus lewisi , Tetranychus kanzawai  
Insect vectors of pathogens  Aphids:  Aphis craccivora , Aphis gossypii , Aphis spiraecola , 
Brachycaudus persicae , Macrosiphum euphorbiae , 
Macrosiphum rosae , Myzaphis rosarum , Myzus persicae , 
Toxoptera aurantia , Toxoptera citricida  
Mealybugs:  Planococcus citri , Pseudococcus calceolariae , 
Pseudococcus longispinus , Pseudococcus viburni  
Thrips:  Frankliniella occidentalis , Frankliniella intonsa , Thrips 
tabaci  
Mite vectors of pathogens  Brevipalpus  californicus , Brevipalpus obovatus , Brevipalpus 
phoenicis  
  
Groups (e.g. genera or family) or high -profile species that did not meet the criteria for 
requir ing pest risk assessment are listed in Appendix 1, along with the rationale for 
excluding them at the hazard identification stage.  
 
3.1 References  for Chapter 3  
CABI Crop Protection Compendium . Information on crop pests.  https://www.cabi.org/cpc/   
37 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  EPPO Global Database.  European and Mediterranean Plant Protection Organization (EPPO)  
database for all pest -specific information that has been produced or collected by EPPO.  
https://gd.eppo.int/  
Farr, D  F; Rossman, A  Y. Fungal Databases, U. S. National Fungus Collections, ARS, USDA. 
https://nt.ars -grin.gov/fungaldatabases/  
Ferris, H (2020) Nemaplex. The nematode -plant expert information system. Department of 
Entomology and Nematology, U niversity of California, Davis. http://nemaplex.ucdavis.edu/  
García Morales , M; Denno, B D; Miller, D R; Miller, G L; Ben -Dov, Y; Hardy, N B (2016) ScaleNet: a 
literature -based model of scale insect biology and systematics . Database , 2016: 1 –5. 
https://academic.oup.com/database/article/doi/10.1093/database/bav118/2630093  
LIMS. Laboratory Information Management System.  Database of identified organisms intercepted at 
the New Zealand border.  Ministry for Primary Industries internal database.  
Midgeon, A; Dorkeld, F  (2020)  Spider Mites Web: a comprehensive database for  the Tetranychidae. 
http://www1.montpellier.inra.fr/CBGP/spmweb  
MPI (2014) Generic Pest Risk Assessment: Armoured scale insects (Hemiptera: Coccoidea: 
Diaspididae) on the fresh produce pathway. Ministry for Primary Industries, Wellington, New Zealand.  
QuanCargo. MPI Internal database (Imports/exports).  
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 38 4. Risk assessment  
 
The purpose of  the risk assessments in this import risk analysis ( IRA) is to assess the level of risk that 
hazard s (i.e. pests and diseases ) present to New Zealand.  
 
4.1  Risk management questions  
Each individual pest risk assessment answer s the following questions:  
1. Does the pest or disease  meet the criteria to be a quarantine pest under IPPC?35 
2. Does the pest or disease require  (or potentially require ) consider ation  for additional 
measures?  
 
For the pests and disease s that require, or potentially require,  consideration  for additional measures , 
the following question  is considered : 
• Which specific Citrus  fruit pathways are they associated with (i.e. which countries and types 
of Citrus  fruit)? 
 
4.2 Criteria and traits for additional measures  
Pests and diseases  that that require, or potentially require,  consideration  for additional measures are 
those that:  
1. are associated with fresh Citrus  fruit: 
a. that is of any species listed in Table 1 .1, and  
b. that meets the commodity description (see additional information below) ; 
2. are present in any of the countries listed in Table 1 .1; and  
3. have traits that indicate they may not be adequately managed by the basic measures  listed in 
section 2. 3.1; and  
4. have a viable establishment pathway from fruit; and  
5. have the potential to establish and cause harm in New Zealand.  
 
Some  traits that indicate a pest or disease may not be adequately managed by basic measures  are 
listed below:  
• the pest or disease and/or associated damage is not easy to see on the Citrus  fruit, including 
when undertaking visual inspection ; 
• the pest can burrow into the fruit without creating obvious damage ; 
• the pest can hide in the navel and/or under the calyx of the Citrus  fruit; or 
• the disease may take time or require particular environmental conditions to become apparent . 
 
The SPS Agreement states that phytosanitary measures must be supported by a risk assessment and 
not be maintained without sufficient evidence. That is, MPI must have evidence that a pest or disease 
would not be sufficiently manage d by the commodity description and basic measures  in order to 
require additional measures.  
4.3 Assessment method  
 
A range of different approaches can be used for risk assessment. The most important factor in 
determining the approach is the risk management question and the level of assessment needed to 
support a robust and transparent risk management decision.  
 
In the case of the Citrus  fresh produce IRA, the risk management question is spec ific, aiming to 
identify pests and diseases  that may need measures in addition to  basic measures . 
 
                                                      
35 This question is a part of hazard identification (or pest ca tegorisation in IPPC) but is documented in more detail as a part of 
the risk assessment.   
39 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  The PRA used is called a targeted PRA , as it is targeted at answering a limited range of questions. 
The PRA method used covers the following questions:  
• Does the pest or disease  meet the criteria to be a quarantine pest under IPPC?  
• Is the pest or disease  associated with the commodity?36 
• Based on assessment against the risk evaluation criteria, d oes the pest or disease  require, or 
potentially require, consid eration for measures in addition to  the basic measures ? 
 
In some cases, uncertainty in the assessment means that it is unclear whether the pest or disease  
meets the criteria or not. The pest or disease  may pose a risk with respect to some risk evaluation  
criteria but not others, or the evidence may be limited. In other cases, the status of the pest or disease  
as a quarantine pest may be uncertain, or the association with the commodity  may be weak. In these 
cases, the pest or disease  requires further conside ration in the risk management proposal, taking 
articles 2.2 and 5.7 of the SPS Agreement into account.  
 
In the PRAs in this IRA the answer to the risk management question is given as either:  
• The pest or disease m ay be considered for additional measures : or 
• It is recommended t he pest or disease  does not require  consider ation  for additional 
measures . 
 
To answer these questions, the PRAs use the CASE schema. Under the CASE schema, the 
contention  or conclusion  (that is, the answer to the risk management questio n) is presented first, 
followed by the arguments  supporting this contention and the evidence  and sources  supporting 
each argument.  
 
For fresh produce IRAs, past experience has shown that the critical aspects of the risk that needs to 
be assessed are : 
 
1. Likelihood of entry : 
a. The strength or frequency of the association with the host fruit  
b. Likelihood of entry given the application of basic measures  
2. Likelihood of establishment : 
a. The ability of the pest or disease  to move from imported fruit and into a suitable  
environment to allow establishment (exposure)  
b. The suitability of the New Zealand environment for the pest or disease (including 
climate, host plants and vectors)  
3. The potential impacts  in New Zealand : 
a. Economic impacts: on Citrus  and other economic ally impo rtant plants (symptoms  on 
individual plants , crop yield, costs of management practices, trade restrictions, etc. ) 
b. Environment  impacts: on native plants and ecologies  
c. Other impacts (e.g. human health, sociocultural).  
 
For each of the critical aspects listed  above, the following criteria and rankings are used in this IRA to 
assess the overall risk of each pest or disease considered to be a hazard on the pathway.  
 
1a. Strength or frequency of association with the commodity . 
 
Strong  There is a clear biological reason that the pest or disease  is on or inside citrus fruit 
and remains associated with the commodity . 
Moderate  There is a link between the pest or pathogen and citrus fruit but not under all 
circumstances, for example , only when the pest is in high numbers, or the pest or 
disease  is mobile and unlikely to remain on fruit during harvesting/processing , or 
there is an other less strong or frequent relationship . 
Weak  The pest or disease  is only rarely associated with the co mmodity as described for 
this IRA.  
                                                      
36 These first two questions are part of hazard ID but are included if there is further risk assessment done.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 40 Negligible  The association of the pest or disease  with the commodity as described for this 
IRA is so improbable it is  not worth considering . 
 
For each of the following likelihood and impact scores, the following ranking  scales will be used 
against the listed criteria:  
 
High Extending above the normal or average level  
Moderate/Medium  Around the normal or average level  
Low Less than average, coming below the normal level  
Very low  Close to insignificant  
Negligible  Not worth considering; insignificant  
 
1b. Likelihood of entry into New Zealand after the application of minimum measures  
 
Criteria  The effect the biology and epidemiology of the pest or disease , the commodity 
description, the trade pathway and the applic ation of the basic measures will have on 
the likelihood that the pest or disease  will be associated with the commodity on arrival 
in New Zealand  
 
2a. The ability of the pest or pathogen to move from imported fruit and into a suitable environment to  
allow establishment, that is, onto a host plant (exposure)  
 
Criteria  The effect the biology and epidemiology of the pest or disease , the commodity 
description, and the commodity pathway and end use in New Zealand, will have on the 
likelihood that the pest  or disease  will be transmitted from a fruit  into the environment 
and infest or infect a host immediately or survive in the environment until suitable 
hosts become available  
 
2b. Suitability of the NZ environment  
 
Criteria  The effect the biology and epide miology of the pest or disease  will have on the 
likelihood that it will establish and build a population and spread into the environment, 
based on factors such as climate suitability and the availability of hosts or potential 
hosts  
 
3a,b,c . Impacts on New  Zealand  
 
Criteria  The effect the biology and epidemiology of the pest or disease  will have on the extent 
to which the pest or disease will cause impacts on New Zealand plants and 
subsequently cause wider impacts on the econom y, environment, sociocultural,  and/or 
human health  
 
 
Confidence in the evidence – weight of evidence, uncertainty  
 
Weighing the evidence is an inherent part of every scientific assessment . The analyst  review s all 
available data and come s to conclusions based on an assessment of their overall confidence in the 
results of all reviewed studies. The approaches  and methods used in conducting such a  ‘non-
formalised ’ inherent weighing of the evidence are mostly not spelled out, however  (ESFA 201 7). 
 
Weight of evidence assessment is defined as a process that determines the relative support for 
possible answers to a scientific question. Reliability, relevance and consistency can be seen as three 
basic considerations in the weight of evidence assess ment: how applicable the evidence is to the 
question of interest, the quality of the evidence and how consistent it is with other evidence for the 
same question  (EFSA 2017).   
41 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Weight of evidence assessment and uncertainty are closely related. For example, S CENIHR (2012 , in 
EFSA 2017 ) state that ‘strength of evidence is inversely related to the degree of uncertainty’, while 
Suter and Cormier (2011 , in EFSA 2017 ) state that ‘the weight of the body of evidence, based on the 
combined weights of individual pieces  of evidence, may be used to express confidence or uncertainty 
in the results’ . EFSA  (2017)  defines uncertainty as ‘a general term referring to all types of limitations 
in available knowledge that affect the range and probability of possible answers to an assessment 
question .’ 
 
 
 
Figure 4.1: Diagrammatic illustration of weight of evidence assessment as a three -step process , which 
may occur at one or more points in the course of a scientific assessment (EFSA 2017).  
 
 
In the PRAs in this project, the uncerta inty associated with a conclusion/contention is stated in each 
contention. Unless the uncertainty is rated as low, the rationale for the uncertainty rating will be stated 
in the text.  
 
Uncertainty will be rated as follows (taken from Defra 2011 ): 
 
High • Scarce or no data available; evidence provided in unpublished reports; or  
• Few observations and personal communications; and/or  
• Authors’ or experts’ conclusions vary considerably  
Moderate  • Some or only incomplete data available; evidence provided in small number 
of references; authors’ or experts’ conclusion vary; or  
• Limited evidence from field observations; or  
• Solid and complete data available from other species that can be 
extrapolated to the species being considered  
Low • Solid and complete data available; strong evidence in multiple references 
with most authors coming to the same conclusions; or  
• Considerable and consistent experience from field observations  
 
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 42 4.4 References for Chapter 4  
 
Defra (2011) Department for Environment, Food and Rural Affairs: Guidelines for Environmental Risk 
Assessment and Management - Green Leaves III. Prepared by Defra and the Collaborative Centre of 
Excellence in Understanding and Managing Natural and Environm ental Risks, Cranfield University, 
November 2011. 
https://assets.publishing.service.gov.uk/government /uploads/system/uploads/attachment_data/file/69
450/pb13670 -green -leaves -iii-1111071.pdf  
 
EFSA (2017) European Food Safety Authority: Guidance on the use of the weigh of evidence 
approach in scientific assessments . EFSA Journal , 15(8): 4971. 
https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2017.4971  
 
 
   
43 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  5. Pest risk assessments: Fungi  
5.1 Elsinoe australis  (sweet orange scab) and  E. fawcettii  (citrus scab)  
 
Elsinoe  australis  (sweet orange scab)  is a fungus that causes premature fruit drop and unsightly corky 
blemishes (scabs) on citrus fruit and occasionally leaves and twigs, particularly in sweet oranges and 
mandarins. This disease causes yield losses and reduces the market v alue of fresh citrus fruit.  
 
Elsinoe  fawcettii (citrus scab)  also causes fruit drop, and causes scab symptoms on leaves, young 
twigs and fruit of many  citrus species but does not usually affect sweet orange. Elsinoe fawcettii is 
present in New Zealand, bu t there are some pathotypes that affect different hosts and have not been 
reported in New Zealand.  
 
Scientific name: Elsinoe  australis Bitancourt and Jenkins  (1936 )  
Order/Family: Myriangiales (previously Dothideales)/ Elsinoaceae  
Other names include: Spha celoma australis  Bitanc ourt & Jenkins (1936) , sweet orange scab, SOS 
(CABI 2020a)  
 
Scientific name: Elsinoe fawcettii Bitancourt and Jenkins  (1936 ) 
Order/Family: Myriangiales (previously Dothideales)/ Elsinoaceae  
Other names include: Sphaceloma fawcettii Jenkins (1925) ; Sphaceloma fawcettii var. scabiosa  
(McAlpine & Tyron) Jenkins (1936);  citrus scab (CABI 2020b)  
 
Taxonomic notes  on Elsinoe spp. associated with citrus:   
 
There are several pathotypes of E. australis , and they differ in their ability to cause disease in citrus . 
 
The sweet orange scab (SOS) pathotype of E. australis was first reported in Paraguay in 1882 and 
mainly occurs in South America (Argentina, Bolivia, Paraguay, Uruguay and Brazil) (Bitancourt an d 
Jenkins 1937; Sivanesan  and Critchett  1974). It affects a range of citrus hosts, but sweet oranges 
(Citrus sinensis ) are the major host (EFSA 2017).  
 
Hyun et al. (2007, 2009) reported a new pathotype of E. australis  from fruit of natsudaidai ( C. paradisi  
as per SRA INRA -CIRAD 2002 ) in Korea. This pathotype has also been detected  in Honshu, Japan37 
and is recently invasive in the USA, where it causes lesions on a much wider range of citrus hosts, 
including oranges, lemons and grapefruit (Kunta et al. 2013).   
 
Two pathotypes of E. australis  are reported from Australia, from finger lime ( Citrus austral asica (F. 
Muell.) ) (Miles et al. 2015) and from jojoba ( Simmondsia chinensis ) (Ash et al. 2012).  
 
Elsinoe  australis  (natsudaidai pathotype) was recently reporte d from poplar ( Populus tomentosa and 
P. deltoides)  in China (Zhou et al. 2020).  
 
The closely related species E. fawcettii (citrus scab) is present in N ew Zealand  and causes scab 
symptoms on several citrus hosts , but most pathotype s of this species do not affect sweet orange ( C. 
sinensis ), and there is no evidence of scab disease in sweet orange in New Zealand. NZFungi2 
(2020) and PPIN (2020) have no collections of E. fawcettii from C. sinensis  in New Zealand . There 
are several different pathotypes of E. fawcettii , and the Florida broad host range , Jingeul and satsuma 
mandarin pathotypes have not been reported in New Zealand  (CABI  2020a ). 
 
The E uropean Union regulate s E. australis  at the species level  (EPPO , 2020). G iven that there 
appear to be different pathotypes , it may be possible to justify measures for some countries by 
regulating at the pathotype level . However, this option should be approached with caution , because 
the recently invasive and very damaging pathotypes  in USA appear more closely relate d to the 
natsudaidai pathotype s from Japan and Korea than the South American pathotypes .  
                                                      
37 IPPC pest report 2014. Accessed September 2020 from 
https://www.ippc.int/static/media/files/pestreport/2014/05/28/detection_of_elsinoe_australis_in_japan.pdf . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 44  
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Elsinoe  australis and the Florida broad host range (FBHR) and satsuma mandarin (SM) 
pathotypes of E. fawcettii meet the criteria to be a quarantine pest for New Zealand.  There 
was insufficient information about the pathotypes of E. fawcettii to assess them against the 
criteria for additional measures.  
• Elsinoe  australis has a strong association with citrus fruit , with low uncertainty . 
• Basic measures  reduce  the likelihood of entry by a moderate degree , with low uncertainty . 
Consequently , the likelihood of entry is considered t o be moderate , with low uncertainty . 
• Elsinoe  australis has a low ability to move from imported fruit and into a suitable environment , 
that is, onto a host plant , to allow establishment, with moderate uncertainty . 
• The suitability of the New Zealand environment for E. australis  to establish is considered high , 
with low uncertainty . 
• Impacts of E. australis are likely to be restricted to citrus and areas where citrus is produced , 
so the level of impact caused by E. austral is is likely to be low overall for New Zealand , with 
low uncertainty , but moderate for the citrus industry and domestic citrus growers.  
• Elsinoe australis  may be considered  for additional measures.  
 
Summary of risk assessment against criteria  
Criteria  Rating Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Moderate  Low 
The ability to move from the imported commodity onto a suitable host  Low Moderate  
Suitability of the N ew Zealand  environment  High Low 
Impacts on the New Zealand economy, environment, health and society  Low Low 
 
 
5.1.1 Hazard  identification: quarantine status  
Given the arguments and evidence below,  Elsinoe  australis meets the criteria to be a 
quarantine pest for New Zealand .  
The c riteria for being a quarantine pest relevant to this assessment are : not present in  New Zealand, 
and of potential importance (able to establish and cause harm).  
 
Elsinoe  australis is recorded as absen t from New Zealand .  
• It is recorded as absent in NZ Fungi2 (2020) and NZOR  (2020) . 
• It is not recorded in PPIN (2020).  
• It is listed as ‘ regulated’ in B RAD and ONZPR  (2020) . 
 
Elsinoe  australis has the potential to establish and spread in New Zealand . 
• Elsinoe  australis is commonly  reported from areas with a very similar climate to New Zealand , 
indicated by a climate match index (CMI) of ≥0.7 (Phillips et al.  2018) . The sweet orange 
pathotype is reported in South America, including Argentina, Uruguay (and Rio Grande do Sul 
in Brazil (EPPO 2020).  The natsudaidai pathotype  has been reported from Jeju Island, Korea 
and Honshu, Japan  (Hyun et al. 2007; EPPO 2020). A closely related pathotype  is recently  
45 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  invasive in some US states (Louisiana, Florida, Mississippi, T exas, Arizona and parts of 
California ) (Kunta et al. 2013).  
• Elsinoe  australis is most often reported from Citrus and Fortunella  species (CABI , 2020a; 
EPPO , 2020) . Citrus is  commercially  grown in New Zealand and commonly grown in  gardens . 
 
Elsinoe  australis has the potential to cause  impacts to New Zealand . 
• Elsinoe  australis has the potential to harm citrus that is of economic importance to New 
Zealand.  
• Elsinoe  australis has the potential to have soci ocultural impacts: citrus is commonly planted in 
home gardens.  
 
 
Given the arguments and evidence below,  Florida broad host range (FBHR) and 
satsuma mandarin (SM) pathotypes of E. fawcettii meet the criteria to be a 
quarantine pest for New Zealand . 
There are several different pathotypes of E. fawcettii  of which only the Florida broad host range 
(FBHR) pathotype has been reported to infect sweet orange (Timmer et al. 1996; Hyun et al. 2009). 
China has at least one additional pathotype of E. fawcettii  (SM) , which was  found  pathogenic to 
Satsuma mandarins ( C. unshiu  × C. sinensis  var. Kiyoma) but not to other hosts tested (Hou et al. 
2014).  
 
Korea also has an additional pathotype (Jingeul), isolated from Jingeul clementine mandarin ( C. 
sunki ), which was not found in New Zealand (Hyun et al. 2009). However, it is not clear whether this 
citrus cultivar is present in New Zealand, so the Jingeul pathotype has not been assessed in this 
PRA.  
 
The Florida broad host range (FBHR)  and satsuma mandarin (SM) pathotypes of E. fawcettii  have not 
been reported in New Zeal and: 
• There is no mention of different pathotypes or strains  of E. fawcettii  in NZFungi2 (2020), 
NZOR  (2020) or PPIN (2020 ). 
• A study by Hyun et al. (2009) did not find the FBHR pathotype in any of the isolates from New 
Zealand citrus that they tested.  
 
The FBHR  and SM pathotypes of E. fawcettii have the potential to establish and spread in New 
Zealand . 
• These pathotypes  of E. fawcettii  have been reported from areas with a very similar climate to 
New Zealand , indicated by a climate match index  (CMI) of ≥0.7 (Phillips et al.  2018) .  
o The Florida broad host range pathotype is reported from Florida, USA; Jeju Island, 
Korea (Hyun et al. 2009). Jeju Island and parts of Florida have a CMI of 0.7 (Phillips 
et al.  2018) . 
o The SM pathotype was isolated in China from sats uma mandarins in  Chenggu, 
Shanxi ; Yidu, Hube i; Meizhou , Guangdong; Jinping ; Guizhou; Lingchuan ; Guangxi; 
Huaning, Yunnan; Laozhu, Zhejiang  and lemons in Mengdia n Yunnan (Hou et al. 
2014). Many of these areas have a CMI of 0.7 –0.8 (Phillips et al.  2018) . 
 
• Hosts of the FBHR  and SM pathotypes are commonly grown in New Zealand in commercial 
production and home gardens:  
o The FBHR pathotype causes scabs on fruit and leaves of lemon ( C. limon ), rough 
lemon ( C. limon  syn. C. jambhiri ), grapefruit ( C. paradisi ), sour orange ( C. aurantium ), 
Temple and Murcott tangors ( C. sinensis  × C. reticulata ) and the fruit of sweet orange 
(C. sinensis ) (Timmer et al. 1996).  
o The SM pathotype is reported from leaves and fruit of satsuma mandarin and leaves 
of lemon (Hou et al. 2014 ). 
• Other pathotypes of E. fawcettii are already in New Zealand (Hyun et al. 2009; PPIN 2020; 
NZFungi2 2020; see below) , and it is assumed that environmental conditions in New Zealand 
would also be suitable for the FBHR  and SM  pathotypes  to establish.  
 
The FBHR  and SM pathotypes of E. fawcettii have the potential to cause  impacts to New Zealand . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 46  
• Elsinoe fawcettii (citrus scab)  causes scab symptoms on leaves, young twigs and fruit of 
many  citrus species and can cause premature fruit drop (Timmer et al. 1996;  EFSA 2017) . It 
does not usually affect sweet orange ( C. sinensis ) (Timmer et al. 1996; EFSA 2017) . In 
severe infections , E. fawcettii  can cause malformation and stunting of leaves and defoliation 
(EFSA 2017). Warty lesions and scabs on young twigs, shoots  and stems can lead to stunting 
of young plants in nurseries (EFSA 2017).  
• Citrus scab does not currently affect sweet oranges in New Zealand , and satsuma mandarins 
are only mildly susceptible to the pathotypes present in New Zealand.  
o The lemon, Tryon’s, Fl orida narrow host range and SRGC (satsuma, rough lemon, 
grapefruit, clementine) pathotypes have been reported in New Zealand from Meyer, 
Villafranca, Yen Ben and rough lemon s, clementine mandarins and grapefruit (Hyun 
et al. 2009).  
o Citrus cultivars common ly grown in New Zealand that are currently considered highly 
susceptible to E. fawcettii  are Yen Ben, Villafranca  and Meyer lemons ; Clementine 
and Kara mandarins ; and Lemonade (Fullerton et al. 2019).  
o Currently , satsuma mandarins are considered mildly sus ceptible to the pathotypes of 
citrus scab currently present in New Zealand (Fullerton et al. 2019).  
o NZ collections of E. fawcettii in the Landcare databases (NZ Fungi2) and PPIN are 
mainly from Auckland, Northland and Bay of Plenty but also Coromandel, mid -
Canterbury, Wellington, Nelson, Taranaki and Wanganui from  fruit, leaves and 
occasionally shoots of C. aurantiifolia, C. limon, C. reticulata, C.  paradisi, C. grandis, 
and Tangelo . Neither database records E. fawcettii  from C. sinensis . 
• The FBHR  and SM pathotypes of E. fawcettii cause citrus scab on hosts that are 
commercially important in New Zealand, including some hosts that are currently unaffected or 
only mildly affected by citrus scab:  
o The FBHR pathotype causes citrus scab  disease in lemon , rough lemon , grapefruit , 
sour orange , Temple and Murcott tangors  and sweet orange (Timmer et al. 1996) . 
o The s atsuma mandarin (SM) pathotype was isolated from leaves and fruit of satsuma 
mandarin and lemon and caused citrus scab symptoms in fruit and leave s of satsuma 
mandarin in pathogenicity testing (Hou et al. 2014).  
• Therefore,  the FBHR  and SM pathotypes of E. fawcettii have the potential to cause impacts to 
citrus production in New Zealand through direct damage to citrus crops, damage to citrus 
plants, particularly young plants in nurseries, and through increased costs of managing the 
disease with fungicides.  
 
The FBHR  and SM pathotypes of E. fawcettii were not assessed further at this time, because there is 
very little information about their distributi on in areas not included in the study by Hyun et al. (2009) , 
and most studies do not assess their impacts separately from E. fawcettii sensu stricto.  
 
However, it is recommended that a status of quarantine is assigned for FBHR  and SM pathotypes of 
E. fawc ettii. 
 
5.1.2 Hazard identification: commodity association  
Given the arguments and evidence below,  Elsinoe  australis  is associated with citrus 
fruit. 
Elsinoe  australis is reported from citrus fruit . 
• Elsinoe  australis occurs on citrus fruit , especially oranges and mandarins (Bitancourt and 
Jenkins  1937; Kunta et al. 2013 ; EFSA 2017).   
47 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  5.1.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Elsinoe  australis has a strong association 
with citrus fruit.  
 
There are many  reports of E. australis infecting citrus fruit . 
• Elsinoe  australis infects young citrus fruit, causing scab lesions from which the fungus can be 
isolated (Bitancourt and Jenkins  1937; Timmer et al. 1996; Timmer 2000; Chung 2011, Kunta 
et al. 2013) .  
• The major host of E. australis is sweet orange (C. sinensis) , and it has also been reported 
from many other citrus species (Table 6.1.1):   
 
Table 6.1.1  Citrus species susceptible to sweet orange scab caused by E. australis (Kunta et al. 
2013; Farr and Ros sman 2020; CDFA 2020)  
Scientific name  Common name  
C. sinensis  Sweet orange  
C. aurantiifolia  Mexican lime  
C. aurantium   Bitter orange  
C. australasica  Finger lime  
C. limon  Lemon  
C. reticulata × C. sinensis  Tangor  
C. paradisi   Grapefruit  
C. reticulata   Mandarin , Satsuma mandarin  
C. maxima  Pomelo (detected in a survey in Japan38)  
C. latifolia  Tahiti lime  
 
• Elsinoe australis has been isolated and cultured from lesions on infected citrus fruit 
(Bitancourt and Jenkins 1936,1937; Timmer et al. 1996; Hyun et al. 2001; Kunta et al. 2013)  
 
Elsinoe australis can be associated with Citrus fruit commodities . 
• Elsinoe australis can be spread to new areas through the movement of infected fruit (Chung 
and Timmer 2008; EFSA  2017; CDFA 2020 ).  
• Elsinoe  australis is frequently detected during border quarantine inspections of fruit. The 
EPPO Reporting Service (2020) report that E. australis was intercepted 10 times on Citrus  
fruit (oranges, lemons and mandarins) from South America (Argentina, Guatemala an d 
Uruguay) since 2008. Searches of CAB Abstracts found frequent mentions of E. australis on 
citrus fruit (lemon, sweet, sour and mandarin oranges, and Mexican  lime) entering USA from 
Brazil in annual USDA lists of intercepted plant pests. CDFA (2020) repor ts that dozens of 
interceptions of infected fruit have been made on shipments entering California from Florida, 
Louisiana, Puerto Rico and Texas.  The closely related species E. fawcetti,  was intercepted 
five times at the New Zealand border on lime fruit fr om the US and several Pacific Islands 
between 1997 and 2016 (LIMS , 2020).  
• Elsinoe  australis is recorded in several countries in the scope of this IRA, although not always 
in natural infections of Citrus (see Table 6.1.2 ). In Brazil and some U .S. states, E. australis is 
reported as causing economically important citrus disease. In Korea, E. australis has only 
been reported from natsudaidai and not from citrus commodities considered for importation 
into New Zealand  in this IRA. In Japan , it has been reporte d from several citrus species , but 
with only minor symptoms.  
• In the USA,  E. australis was first reported in Texas and Louisiana in 2010 and is now found in 
six US states (Louisiana, Florida, Mississippi, Texas, Arizona and parts of California), causing 
scab symptoms on fruit and sometimes leaves of citrus hosts including sweet orange, 
                                                      
38 IPPC pest report 2014. 
https://www.ippc.int/static/media/files/pestreport/2014/05/28/detection_of_elsinoe_australis_in_japan.pdf  Accessed September 
2020.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 48 grapefruit and mandarin (Kunta et al. 2013; USDA -APHIS 2020). Isolates from Texas cluster 
with the Korean natsudaidai pathotype in molecular analysis (Kunta et al. 2013 ). 
• In Australia , two pathotypes of E. australis have been reported, one from finger lime and one 
from jojoba, but natural infections have not been reported from citrus commodities that 
New Zealand will be importing. In China, E. australis has recently been repor ted from poplar , 
but not from natural infections of Citrus. 
 
Table 6.1.2  Distribution of E. australis in countries included in the scope of this IRA 
Country  Pathotype  Distribution in country and reported 
hosts  Uncertainty  
Australia  Finger lime; 
jojoba black 
scab 
(nats udaidai -
like);  Finger lime ( Citrus australasica ) and 
jojoba ( Simmondsia chinensis ) in New 
South Wales and Queensland. Not 
reported from other citrus commodities in 
natural infection.  
• The finger lime pathotype caused 
scab symptoms on C. aurantium  cv. 
Murcott tangor in pathogenicity tests 
but could not cause scab symptoms 
on the other orange, mandarin, 
lemon or grapefruit varieties tested 
or on natsudai dai (Miles et al. 2014)  
• The jojoba black scab (JBS) 
pathotype did not cause symptoms 
on any Citrus species tested, even 
C. paradisi  (Ash et al. 2012).  
• No report of natural infection of other 
Citrus hosts found in searches.  High uncertainty about whether the 
pathotypes of E. australis , other 
than the finger lime  pathotype  in 
Australia , infect commercial citrus 
varieties in natural infection.  
Brazil  Sweet 
orange  Reported from Citrus, especially sweet 
orange and mandarin in Goias, Minas 
Gerais, Rio de Janeiro, Rio Grande do 
Sul and Sao Paolo (Bitancourt and 
Jenkins 1937; CABI  2020 a; EFSA  2017; 
EPPO 2020).  Low uncertainty. There are many 
reports of E. australis from Citrus 
fruit in Brazil.  
China  Natsudaidai -
like Poplar – Populus tomentosa and P. 
deltoides from Nanjing and Wuhu in 
southeastern China (Zhao et al. 2020). 
Not reported from citrus commodities in 
natural infection (affected one hybrid 
Citrus species but not on fruit of orange, 
lemon or grapefruit in pathogenicity 
testing). No report of natural infection of 
Citrus found in searches.  High uncertainty about whether the 
pathotype  of E. australis in China 
infects Citrus in natural infection, 
given there is only a single report 
from poplar. The natsudaidai -like 
pathotype reported by Zhao et al. 
(2020 ) was not found in natural 
infections of Citrus.  
Cook 
Islands  N/A Absent, unreliable record (EPPO 2020)  
and E. australis is not on the pest list 
provided by the Cook Islands NPPO . 
However, CABI  (2020 a) record s it as 
present.  Moderate uncertainty due to 
conflicting records. CABI  (2020 a) 
reports E. australis in the Cook 
Islands , and it was reported 
present in distribution maps from 
1998 and 2012 (CAB Abstracts 
search, September 2020).   
Egypt  N/A Not recorded (CAB Abstracts ; Farr and 
Rossman 2020 ; Google ; Google 
Scholar). The MPI Importing Countries  
Phytosanitary Requirements for Egypt 
lists E. australis as a quarantine pest in 
the table of unrecorded pests to be 
declined entry into Egypt.   Low uncertainty .  
Fiji N/A Absent, invalid record  (e.g. EPPO 
considers a local record  invalid) (EPPO, 
2020). However, CABI  (2020 a) record as 
present.  Moderate uncertainty due to 
conflicting records. CABI  (2020 a) 
reports E. australis in Fiji , and it 
was reported present in distribution 
maps from 1998 and 2012 (CAB 
Abstracts search, September 
2020).  
49 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Country  Pathotype  Distribution in country and reported 
hosts  Uncertainty  
Japan  Natsuda idai Restricted distribution, Honshu (EPPO 
2020). Minor symptoms initially detected 
on pomelo fruit (C. maxima ), and E. 
australis was detected in Aichi prefecture, 
Honshu in satsuma mandarin, navel 
orange and hybrid of natsudaidai  and 
orange in a subsequent survey (IPPC 
pest report , 201439). Symptoms were 
reported as minor , with no substantial 
damage or economic losses (IPPC pest 
report , 2014).  Low uncertainty . 
Korea  Natsudaidai  Natsudaidai fruit from Jeju Island (Hyun 
et al. 2001;  2007; 2009). Isolates from 
natsudaidai were non -pathogenic to 
satsuma mandarin, rough lemon, sour 
orange, grapefruit, cleopatra mandarin, 
and natsudaidai leaves and were only 
pathogenic to natsudaidai fruit. CABI  
(2020 a) and EPPO (2020) record it as 
prese nt. Low uncertainty about presence in 
Korea, but moderate uncertainty 
about whether the Korean 
natsudaidai pathotype infects 
commercial varieties of citrus. 
Pathotypes identified as the 
natsudaidai pathotype in Japan and 
USA affect a wider range of hosts.  
Mexico  N/A No report of E. australis  found in 
searches (CAB Abstracts ; Farr and 
Rossman 2020 ; Google ; Google 
Scholar).  Low uncertainty.  
New 
Caledonia  N/A Absent, Invalid presence record ( CABI  
2020 a; EPPO 2020). Symptoms of scab 
on Citrus in New Caledonia initially 
attributed to E. australis  are now thought 
to have been caused by E. fawcettii 
(Sivanesan and Critchett 1974) . Low uncertainty .  
Peru  N/A No report of E. australis  found in 
searches (EPPO 2020 ; CAB Abstracts ; 
Farr and Rossman 2020 ; Google ; Google 
Scholar).  Low uncertainty.  
Samoa  N/A Present ( pest list provided by Samoan 
NPPO).  High uncertainty due to conflicting  
records. Elsinoe  australis is on the 
pest list provided by the Samoan 
NPPO and was reported prese nt in 
CABI distribution maps from 1998 
and 2012 (CAB Abstracts search, 
September 2020).  However, EPPO 
(2020 ) and  CABI  (2020 a) now 
record it as “A bsent, Unconfirmed 
presence record .” 
Spain  N/A Not reported in Spain (EFSA 2017) No 
report of E. australis  found in s earches 
(CAB Abstracts ; Farr and Rossman 2020 ; 
Google ; Google Scholar).  Low uncertainty.  
Solomon 
Islands  N/A No report of E. australis  found in 
searches (EPPO 2020; CAB Abstracts, 
Farr and Rossman 2020 ; Google ; Google 
Scholar) . Low uncertainty.  
USA  Natsudaidai  Sweet orange, tangerine, grapefruit, 
lemon, mandarin and other citrus fruit 
and sometimes leaves (Kunta et al. 
2013). USDA -APHIS (2020) record s that 
sweet orange scab is found in Arizona, 
Florida, Louisiana, Mississippi, Texas 
and portio ns of California.  Low uncertainty.  
Vanuatu  N/A No report of E. australis  found in 
searches (EPPO 2020; CAB Abstracts ; Low uncertainty.  
                                                      
39 Accesse d September 2020 from 
https://www.ippc.int/static/media/files/pestreport/2014/05/28/detection_of_elsinoe_australis_in_japan.pdf .  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 50 Country  Pathotype  Distribution in country and reported 
hosts  Uncertainty  
Farr and Rossman 2020 ; Google ; Google 
Scholar) . 
Viet Nam  N/A No report of E. australis  found in 
searches (EPPO 2020; CAB Abstracts ; 
Farr and Rossman 2020 ; Google ; Google 
Scholar) . Low uncertainty.  
 
Given the arguments and evidence below,  basic measures  reduce likelihood of entry 
by a moderate degree . Consequently , the likelihood of entry is considered to be 
moderate , with low uncertainty.  
Infected fruit is usually easily detected and  likely to be removed.  
• Symptoms of E. australis  are likely to be visible  on fruit  (see Figure 6.1.1 ). Symptoms range 
from small, flattened off -white pustules to l arge coalesced round or irregular lesions of corky 
tissue (Bitancourt and Jenkins 1937; Kunta et al. 2013). The lesions may be deeply furrowed 
from rupture of the corky tissues.  The shape , size and colour of lesions depends on the citrus 
species and variet y (EFSA 2017).  
• It can be difficult to detect E. australis in the early stages of infection , but the incubation 
period for symptoms to develop on fruit is approximately 10 days (Bitancourt and Jenkins 
1937). Immature young fruit up to 6 to 8 weeks after pet al fall are highly vulnerable to 
infection (CDFA 2020) , but only young tissues are attacked (Sivanesan and Critchett 19 74) 
when fruit are less than 20mm diameter ( MAF 2008 ). Young fruits may become distorted and 
may drop prematurely (Sivanesan and Critchet t 1974; CDFA 20 20). 
• Because t he latent period for symptoms of E. australis is short , symptoms are likely to be 
visible by the time fruit are mature enough to harvest and export. Mature fruit are not 
susceptible to the fungus, so it will not continue to spr ead through the consignment.  
 
Figure 6.1.1  Top left and top centre: Sweet orange scab lesions on green fruit40; Top right: Sweet orange 
scab lesion on a satsuma ( C. unshiu )41; Bottom: Oranges with sweet orange scab symptoms42 
 
    
                                                      
40 Cesar Calderon, Cesar Calderon Pathology Collection, USDA APHIS PPQ, Bugwood.org. 
https://www.ipmimages.org/browse/detail.cfm?imgnum=5499766 https://www.invasive.org/browse/detail.cfm?imgnum=5499770  
41 Don Ferrin, Louisiana State University Agricultural Center, Bugwood.org.  
https://www.invasive.org/browse/detail.cfm?imgnum=5473708  
42 Florida Division of Plant Industry, Florida Department of Agric ulture and Consumer Services, Bugwood.org.  
https://www.ipmimages.org/browse/detail.cfm?imgnum=5372451  
 
51 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
 
However, the evidence suggests that some infected fruit will not be detected. Symptoms of E. 
australis can be minor and can be missed or not recognised as disease symptoms during production 
or phytosanitary inspection . 
 
• Fruit infected with E. australis  has been frequently intercepted in quarantine inspections in 
Europe and the USA (see entry section), suggesting that symptoms were missed or 
misidentified. Likewise, the closely related (but non -regulated) E. fawcettii , which produces 
similar scab symptoms, was intercepted in 2016 on a commercial consignment of limes from 
USA ( C. aurantiifolia and C. latifolia ). Elsinoe fawcetti  has been recorded at the border on 
limes from Samoa (LIMS 2020).  
• In Texas, E. australis  was commonly isolated from wounds referred to as “late-season 
windscar ” that were not always recognisable as symptoms of disease (Kunta et al. 2013) . 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of the E. australis  to move from 
imported fruit onto a host plant  to allow establishment  is rated as low , with moderate 
uncertainty . 
 
Elsinoe australis  is likely to survive and develop on waste of citrus  fruit (whole fruit  or fruit pieces).   
 
• Elsinoe  australis can survive and produce spores in old lesions on fruit (Bitancourt and 
Jenkins 1937 ; Sivanesan and Critchett 1974 ).  
 
Most  waste  from imported citrus  in New Zealand will be disposed of using low -risk methods , so 
E. australis will be unable to spread from the citrus host.  
• Most kitchen  waste in New Zealand is disposed of in  bags in  landfills or in kitchen disposal 
units, and in these situations , E. australis is unlikely to reach a new host ( see w aste analysis 
in Chapter 2).  
 
Elsinoe australis can spread to citrus  trees if infected fruit or peels are discarded i n the New Zealand 
environment near citrus  trees , although the likelihood of this occurring is low .  
• Elsinoe  australis  is usually spread by asexual spores (conidia) , which  are produced in large 
quantities on lesions on old fruit ( Bitancourt and Jenkins 1937 ; CDFA 2020; Chung 2011 ). 
Spores are primarily distributed by rain splash between trees but can also spread short 
distances by air (Bitancourt and Jenkins 1937 ). The sexual stage (teleomorph) of E. australis 
has only been reported in Brazil , and there is very little information about its role ( Bitancourt 
and Jenkins 193 6; Chung 2011).  
 
Orange, mandarin, lemon and other citrus  hosts of E. australis  are widely available in New Zealand , 
and fruit is likely to be at a susceptible stage at times w hen citrus  fruit is imported.  
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 52 • In New Zealand, 783 ha are planted in commercial oranges, 556 ha in lemons, 257 ha in 
lemons ( Plant & Food Research  2019). Citrus trees are commonly grown in domestic 
gardens.  
• Most citrus fruit in New Zealand sets in November  (late spring/early summer) (Brown 2019), 
although some c itrus trees  in New Zealand produce  fruit through out the year.  
• Immature young fruit up to 6 to 8 weeks after petal fall are the most vulnerable to infection 
with E. australis (CDFA 2020; Sivanesan  and Critchett 19 74).  
• This means that young vulnerable fruit is likely to be present in early summer when domestic 
citrus supply is low and citrus fruit is likely to be imported to fill the gap in the domestic 
market.  
• However, young fruit would need to be  growing close enough to where citrus fruit or peel w as 
discarded for spores to spread to them via water splash or windblown rain.  
 
There is moderate uncertainty in this conclusion , because the  maximum distance of spore dispersal 
by natural means  is unknow n (EFSA 2017). Lesions that have been missed during production and 
phytosanitary inspection are likely to be small , and it is not known how much inoculum will be 
produced in small lesions.  
 
Sweet orange scab is spread by rain splash , and it is likely to s pread easily in New Zealand  once it 
infects a susceptible host : 
 
• Elsinoe  australis  can spread even if the previous crop has already been harvested and fruit 
waste is removed (Kunta et al. 2013). Old lesions on fruits, leaves and twigs are the probable 
source of infection at the start of each season  (Sivanesan and Critchett 1974 ). Although 
scabs on leaves are not severe, they may play an important role as a source of inoculum 
(Bitancourt and Jenkins 1937).  
 
Given the arguments and evidence below,  the N ew Zealand environment  is likely to 
be suitable for the establishment o f E. australis . 
 
Environmental conditions in New Zealand are likely to be suitable for E. australis to establish and 
spread, especially in the north of New Zealand where most commercial citru s is grown.  
 
• Elsinoe  australis  can grow at constant temperatures from 9.5°C to 35°C. The optimal 
temperature is near 26°C , with best growth between 24.5°C and 29°C (Bitancourt and 
Jenkins 1937; M AF 2008). Germination of conidia and infection is possible if there is moisture 
present from dew, fog or irrigation and does not require rainfall. A wet  period of 1 –2 hours will 
allow conidia to form and 2 –3 hours are needed for conidia to infect the fruit (Bitancourt and 
Jenkins 1937 ; MAF 2008).  
• As most commercial citrus fruit sets in November (Brown 2019), young susceptible fruit will be 
most abundant in December and early January , when temperatures are likely to be warm 
enough for the fungus to grow. For e xample, in Kerikeri, a citrus -growing region, summers are 
warm and humid , and daytime maximum air temperatures usually range from 22 °C to 26 °C 
(see the New Zealand climates section). These conditions are likely to favour infection of 
young fruit with E. au stralis.  
 
Elsinoe  australis  is commonly reported from areas with very similar climate conditions to the whole of 
New Zealand, indicated by a climate match index (CMI) of ≥0.7, modelled by Phillips et al. (2018).  
• The current global distribution of E. australis is shown in Figure 6.1.2.    
53 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   Figure 6.1.2   Distribution of E. australis (EPPO , 2020)  
 
• The sweet orange pathotype is reported in South America, including Argentina (CMI: 0.7 –
0.9), Uruguay (CMI: 0.7 –0.9) and Rio Grande do Sul in Brazil (CMI: 0.7 –0.9) (EPPO , 2020).  
• The natsudaidai pathotype has been reported from Jeju Island, Korea (CMI: 0.7) and Honshu, 
Japan (CMI: 0.6 –0.8) (Hyun et al. 2007; EPPO 2020). A closely related pathotype is recently 
invasive in some US states (Louisiana, Florida, Missi ssippi, Texas, Arizona and parts of 
California (Kunta et al. 2013). In general, these states have CMIs of 0.6 –0.8 with the whole of 
New Zealand.  
• Elsinoe  australis  is also reported from New South Wales, Australia and China ( Nanjing , 
Jiangsu  and Wuhu , Anhui  in southeastern China ), which have a CMI of 0.7 with New Zealand.  
• Elsinoe  australis is reported in areas with hotter and more tropical climates than New 
Zealand, including  Bolivia, other regions of Brazil  (Goias, Minas Gerais, Rio de Janeiro  and 
Sao Paolo) , Paraguay  and Queensland Australia.   
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below,  the level of impact caused by E. australis  
is likely to be low for New Zealand overall, but moderate for the citrus industry, with 
high uncertainty around the magnitude of impacts on citrus production.  
Elsinoe  australis can cause  moderate  economic impacts on the citrus industry through premature fruit 
drop, damage to fruit and impacts on overseas exports:  
• Elsinoe  australis  infects young fr uit, leading to raised and corky lesions (scab pustules)  
(Bitancourt and Jenki ns 1937 ; Kunta et al. 2013; Timmer et al. 2000 ). Fruit with scabs are 
misshapen and can drop early, resulting in significant quality and yield losses in epidemic 
regions (Timmer et al. 2000; CDFA 2020). The damage caused to the remaining fruit by scab 
(scarred and distorted fruit) does not affect the internal fruit quality but reduces its 
marketability as fresh fruit and for export (CDFA 2020; EFSA 2017).  
• Bitancourt and Jenkins ( 1937) reported that it was common for approximately one third of fruit 
produced in Sao Paolo , Brazil to be unfit for export due to sweet orange scab blemishes. In 
severely affected groves 50 –60% of fruit was damaged by the disease.  
• Elsinoe australis is hig hly likely to increase the impact of scab diseases on the citrus industry, 
since citrus scab  does not currently affect sweet oranges in New Zealand and satsuma 
mandarins are only mildly susceptible to the pathotypes of E. fawcettii that are currently 
present in New Zealand.  
o Oranges and mandarins ( clementine and satsuma ) are highly susceptible to E. 
australis  (Bitancourt and Jenkins 1937; Sivanesan and Critchett 1974). Oranges are 
not usually  susceptible to citrus scab caused by E. fawcettii  (EFSA 2017 ; Hyun et al. 
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 54 2009 ) and satsuma mandarins are only mildly susceptible to the citrus scab 
pathotype s currently present in New Zealand (Fullerton et al. 2019).  
o New Zealand  collections of E. fawcettii in the Landcare databases (NZ Fungi2) and 
PPIN are mainly fr om Auckland, Northland and Bay of Plenty but also Coromandel, 
mid-Canterbury, Wellington, Nelson, Taranaki and Wanganui from fruit , leaves and 
occasionally shoots of C. aurantiifolia , C. limon, C. reticulata, C. paradisi, C. grandis , 
and tangelo . Neither d atabase records E. fawcettii  from C. sinensis . 
• Therefore , E. australis would be likely to affect yields and marketability of oranges and 
satsumas, and impacts would not be mitigated by existing management of E. fawcettii . In 
2019 , export sales  of fresh oranges were worth NZ$1.75  million,  and the value of domestic 
orange sales was $18 m illion (Plant & Food Research 2019).  
• Establishment of E. australis  is likely to increase production costs for oranges and other 
susceptible fruit, because fungicide a pplications are typically required to manage the disease 
(EFSA 2017; Schultz et al. 2013; Olsen et al. 2011; UF/IFAS Citrus extension 2020). In 
Florida, two sprays (at ⅔ petal fall and 2 –3 weeks later) with azoxytrobin, trifloxystrobin, 
pyraclostrobin, fer bam, and /or copper fungicides are recommended to create a barrier on the 
fruit during its most susceptible growing period  (UF/IFAS Citrus extension 2020 ). Therefore , 
extra fungicide sprays  to control E. australis are likely to be an additional management cost 
for orange and satsuma production, although the disease is likely to be mitigated by existing 
measures for E. fawcettii in susceptible crops such as lemons, grapefruit and clementine 
mandarins .  
• However, i t is unlikely that E. australis will cause long -term damage to trees in citrus 
orchards. CDFA (2020) listed stunting of young trees (both nursery and field planted) as a 
potential impact of the pathogen. However, although E. fawcettii is reported to commonly 
cause lesions on shoots and leaves, E. austr alis does not usually affect the general health of 
sweet orange plants . Lesions on leaves and shoots are rare and do not contribute much to 
the impact of the fungus (Bitancourt and Jenkins 1937 ; Chung 2010 ). Although leaf lesions 
were reported in infection s of Citrus with E. australis in Texas (Kunta et al. 2013), recent 
information from agricultural extension services in Texas, Arizona, Florida and Louisiana 
confirm that E. australis mainly affects fruit in the USA (e.g. Schultz et al. 2013; Olsen et al. 
2011; UF/IFAS Citrus extension 2020;  LSU AgCentre (accessed 29  September 2020) and 
other articles on the LSU AgCentre website).  
 
Establishment of E. australis  may result in increased phytosanitary measures to maintain access 
to overseas markets in areas where the pest is absent.  
• For example, EPPO (2020) added it to their list as an A1 quarantine pest in 2019, and it is 
a quarantine pest in Australia , the USA and many other countries  (EPPO 2020; Plant 
Health Australia 2020; USDA -APHIS 2020).  
• An incursion of E. australis  in New Zealand could cause impacts from removal of 
productive plants, costs of surveillance and loss of income from sales of fresh citrus in 
domestic and export markets. For example, since sweet orange scab was first detected in 
Texas in 2010, it has sprea d to Louisiana, Florida, Mississippi, Texas, Arizona and parts 
of California , and there are quarantine zones and surveillance for E. australis  in all these 
states (USDA -APHIS 2020). There are strict requirements (e.g. packhouse procedures, 
fungicide treatm ents) for fresh citrus fruit and citrus nursery stock before it can be 
transported outside of the affected areas . 
 
There is high uncertainty about the magnitude of economic impacts of E. australis  on citrus 
production.  
• Effects on fruit quality and yield m ay differ depending on which pathotype of E. australis was 
to establish in New Zealand, and how that pathotype interacted with the New Zealand 
environment and citrus varieties. The difference in host range, symptoms and impacts of the 
natsudaidai pathotype  in Korea, Japan, USA and now possibly China show that impacts of 
this fungus can be difficult to predict.  
• Several citrus cultivars grown in New Zealand ( Yen Ben, Villafranca  and Meyer lemon s, 
Lemonade,  Clementine and Kara mandarins ) are highly susceptibl e to citrus scab caused by 
E. fawcettii , and S atsuma mandarins are mildly susceptible  (Fullerton et al. 2019) . It is 
therefore uncertain whether there will be additional yield losses in lemons or mandarins due 
to E. australis , and impacts of the disease ma y be mitigated by existing management 
measures for citrus scab in some of these crops .   
55 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Environmental impacts from E. australis  are likely to be low overall for New Zealand but may be 
moderate in citrus -producing areas due to increased use of fungicides to control the disease.  
• In states of the USA where E. australis is present, fungicide applications are recommended to 
manage the impacts of the pathogen  (Schultz et al. 2013; Olsen et al. 2011; UF/IFAS Citrus 
extension 2020;  LSU AgCentre (accessed 29  Septe mber 2020) and other articles on the LSU 
AgCentre website).  
• Since E. australis is mostly reported as a  citrus pathogen , and there are no native species of 
Citrus  (or Poncirus  or Fortunella ), it seems likely that environmental impacts would be low.  
However,  there is moderate uncertainty in this conclusion, given that there are recent reports 
of E. australis from unrelated genera such as Populus  and Simmondsia .  
 
Elsino e australis  is unlikely to cause any direct health impacts on human health:  
• Elsinoe australis is a plant pathogen and has not been reported to affect human or animal 
health.  
• However, there is moderate uncertainty in this conclusion , as there may be indirect impacts 
on human health if there is increased use of fungicides for pathogen contr ol. 
 
Social impacts of E. australis are likely to be low, with low uncertainty:  
• E. australis  can cause premature fruit  drop and is likely to affect the productivity of citrus trees 
in home gardens.  
• The production of homemade marmalade from citrus fruits m ay be affected if people consider 
the peel of diseased fruit to be unsuitable. However, such impacts have not been reported in 
the literature.  
• Damage to fruit from home gardens may make such fruit unattractive; although the damage is 
limited to the peel an d is not known to affect the quality or taste of the fruit itself.  
 
Risk assessment summary : 
 
Given the arguments and evidence below,  E. australis  may be considered  for 
additional measures . 
• Elsinoe australis has a strong association with Citrus fruit (most commercial citrus cultivars);  
• The evidence suggests that some fruit infected with E. australis  will not be detected , because  
symptoms can be minor and can be missed or not recognised as disease symptoms during 
production or phytosanitary inspe ction . Therefore, basic measures  reduce the likelihood of 
entry of E australis  to a moderate degree . Consequently, the likelihood of entry is considered 
to be  moderate , with low uncertainty.  
• Elsinoe australis has low ability (with moderate uncertainty) to move from imported fruit and 
into a suitable environment to allow establishment . 
• The New Zealand climate is likely to be suitable for the establishment of E. australis . 
• Hosts of the pest  (citrus ) are commercially grown in New Zealand and are common ly grown in 
home garden s. 
• Elsinoe australis has been recorded to cause severe damage to citrus fruit, and there are high 
costs of control in areas with similar climate to New Zealand. The closely related fungal citrus 
scab species E. fawcettii  is already p resent in New Zealand and affects some of the same 
hosts. Impacts of E. australis are likely to be high in oranges and satsuma mandarins but 
mitigated by existing management of citrus scab in other commercial citrus varieties. 
Therefore, it is likely to ca use moderate  impacts on the citrus industry in New Zealand and 
low impact s to the overall economy of New Zealand;  
• Elsinoe australis is present (although sometimes with restricted distribution or host range) in 
several countries in the scope of this IRA, in cluding  Australia, Brazil, China, USA and Korea.  
5.1.4 References  
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203–212. https://doi.org/10.1590/S1982 -56762013005000003  
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analysis -october -2008  Ministry of Agriculture and Forestry, Biosecurity New Zealand; NZ.  
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https://pierpestregiste r.mpi.govt.nz/  Accessed  August 2020 . 
Phillips , C B ; Kean , J M ; Vink , C J; Berry , J A (2018) Utility of the CLIMEX ‘match climates regional ’ 
algorithm for pest risk analysis: An evaluation with non -native ants in New Zealand.  Biological 
Invasions , 20(3): 777–791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) Fresh Facts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Resear ch Ltd ; Auckland , New Zealand.   
Plant Health Australia (2020) Sweet orange scab fact sheet. 
https://www.planthealthaustralia.com.au/wp -conten t/uploads/2013/01/Citrus -sweet -orange -scab-
FS.pdf  Accessed 12  October 2020 . 
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed August 2020 . 
Schultz, D; Rybak, M; French, R D (2013) Citrus scab and sweet orange scab. Texas A&M Agrilife 
extension PLPA -Cit013 -02. http://agrilife.org/amarillo/files/2010/11/CitrusScab2013 -1.pdf  Accessed 
29 September 2020 . 
Sivanesan, A; Critchett, C (19 74) Elsinoe australis . CMI Descriptions of Pathogenic Fungi and 
Bacteria , No. 440. CAB International ; Wallingford, UK . 
Timmer, L W (2000) Pink disease and thread blight / Scab diseases. In Timmer, L W;  Garnsey, S M; 
Graham, J H (eds) Compendium of Citrus Diseases , 2nd edition.  American Phytopathological Society . 
Timmer, L W; Priest, M; Broadbent, P; Tan, M -K. (1996) Morphological and pathological 
characteri zation of species of Elsinoe  causing  scab  diseas es of Citrus. Phytopathology , 86(10): 1032 –
1038.  
https://www.apsnet.org/publications/phytopathology/backissues/Documents/1996Articles/P hyto86n10
_1032.PDF   
UF/IFAS citrus extension (2020) Sweet Orange Scab. University of Florida. 
https://crec.ifas.ufl.edu/extension/plant_pathology/sweet_orange_scab. shtml  Accessed 30  September 
2020 . 
USDA (1952) List of intercepted plant pests, 1951. S.R.A., B.E.P.Q., United States Department of 
Agriculture . [Abstract only .] Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 58 http://ovidsp.ovid.com/ovidweb.cgi?T=JS&PAGE=reference&D=caba0&NEWS=N&AN=19531101316.  
Accessed 16 September 2020.  
USDA -APHIS (2020)  Sweet Orange Scab . Last modified 02 June 2020. 
https://www.aphis.usda.gov/aphis/ourfocus/planthealth/plant -pest-and-disease -program s/pests -and-
diseases/citrus/sweet -orange -scab  Accessed 29  September 2020 . 
Zhou, L; Xiao, H; Ma, X; Cheng, Q (2020) Elsino ë australis causing spot anthracnose on poplar in 
China. Plant Disease , 104(8):  2202 –2209. https://apsjournals.apsnet.org/doi/10.1094/PDIS -11-19-
2349 -RE  
   
59 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  5.2 Phyllosticta  citricarpa  (citrus black spot)  
 
Phyllosticta citricarpa (citrus black spot) causes severe spots and lesions affecting the rinds of fruit 
and sometimes leaves. Although the juice quality is unaffected, the blemished fruit is unappealing and 
unsuitable for marketing as fresh fruit. Most commercial citrus species are affected, and severe losses 
have been reported in lemons, sweet oranges and grapefruit.  
 
Scientific name: Phyllosticta citricarpa (McAlpine) Aa (1973)  
Order/Family: Botryosphaeriales/Botryosphaeriaceae   
Other names include: Guignardia citricarpa Kiely  (1949),  Phoma citricarpa McAlpine (1899)  
 
Taxonomic notes: Citrus  is host to several other Phyllosticta and Guignardia species , and 
historically , these species were sometimes identified as P. citricarpa (Glienke et al. 2011; Wang et al. 
2012) , which can lead to uncertainty in distribution records (see Appendix 1). For example, 
P. capitalensis  and G. mangiferae are widespread geographically, have broader host ranges than 
P. citricarpa , are present in New Zealand (NZ Fungi2 2020) and non -regulated  (BRAD 2020 ; ONZPR  
2020).  
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Phyllosticta citricarpa meets the criteria to be a quarantine pest for New Zealand.  
• Phyllosticta citricarpa has a strong association with citrus fruit  with low uncertainty . 
• Basic measures  for importing citrus fruit reduce the likelihood of entry of P. citricarpa  by a low 
degree  with low uncertainty . Consequently, the likelihood of entry is considered high , with low 
uncertainty . 
• Phyllosticta citricarpa  has low ability to move from most imported citrus fruit and into a 
suitable environment to allow establishment, that is, onto a host plant  with moderate 
uncertainty . However, it is very uncertain whether P. citricarpa  can move from imported C. 
latifolia  or C. aurantium  fruit onto a host plant to allow establishment.  
• The suitability of the New Zealand environment for P. citricarpa to establish is considered 
high, with low uncertainty . 
• The level of impact caused by  P. citricarpa is likely to be moderate for New Zealand overall 
with low uncertainty but high for the citrus industry.  
• Phyllosticta citricarpa  may be considered for additional measures on most citrus fruit 
commodities.  
 
Summary of risk assessment against criteria  
Criter ia Rating Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  High Low 
The ability to move from the imported commodity onto a suitable host  Low Moderate  
Suitability of the N ew Zealand  environment  High Low 
Impacts on the New Zealand economy, environment, health and society  Moderate  Low 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 60 5.2.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below, Phyllosticta citricarpa meets the criteria to 
be a quarantine pest for New Zealand  
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause harm43). 
 
Phyllosticta citricarpa is not known to be present in New Zealand:  
• Phyllosticta citricarpa  is recorded as ‘recorded in error’ in NZ Fungi2 (2020) and NZOR (2020), 
although it is recorded as present in PPIN (2020). It is listed as ‘Regulated’ in BRAD (2020) 
and ONZPR  (2020).  
 
Phyllos ticta citricarpa has the potential to establish and spread in New Zealand:  
• Phyllosticta citricarpa is reported from many areas with a very similar climate to the whole of 
New Zealand, indicated by a climate match index (CMI) of ≥0.7 (Phillips et al.  2018) , 
including parts of Argentina, Australia (New South Wales and Queensland), Uruguay and 
South Africa ( EFSA 2014;  EPPO 2020a)  
• The host range is Citrus and species in related genera in the Rutaceae such as Poncirus and 
Fortunella  (Baayen et al. 2002; EFSA 201 4; Farr and Rossman 2020).  
• Citrus is commercially grown in New Zealand and  commonly grown in home gardens (see 
section 2.5).  
 
Phyllosticta citricarpa has the potential to cause economic, social and environmental impacts to 
New Zealand:  
• Phyllosticta citricarpa has the potential to harm Citrus  that is of economic importance to 
New Zealand.  
• Phyllosticta citricarpa has the potential to have soci ocultural impacts: Citrus  is commonly 
planted in home gardens.  
• Given that the reported hosts of P. citricarpa are the Citrus, Poncirus and Fortunella  species 
and that there are no native species in these genera (see Chapter  2), impacts on native 
plants are likely to be low.  
• However, it is highly likely that increased applications of fungicides would be required to  
manage the pathogen in commercial production areas, and this would have environmental 
impacts.  
 
5.2.2 Hazard identification: commodity association  
 
Phyllosticta citricarpa is associated with citrus fruit  
Phyllosticta citricarpa is reported from citrus fruit:  
• Phyllosticta citricarpa causes lesions on citrus fruit , and most commercial varieties of citrus 
are hosts of P. citricarpa, including lemons, sweet oranges, grapefruit and mandarins (EFSA 
2014; Kotz é 1981; Miles and Smith  2019).  
5.2.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below, Phyllosticta citricarpa has a strong 
association with citrus fruit (with low uncertainty) and can be associated with 
                                                      
43 Refer to ISPM 5  for the definition of a quarantine pest under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.   
61 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  commercially traded (export) citrus fruit of most commercial varieties (with low 
uncerta inty):  
Phyllosticta citricarpa  has been reported from citrus fruit.  
• Phyllosticta citricarpa  has been isolated from disease lesions on symptomatic citrus fruit of 
most commercial citrus varieties, including sweet orange, mandarin, grapefruit and lemon. 
Species susceptible to P. citricarpa are listed in Table 6.2.1.  
• P. citricarpa  can be present as latent mycelia in susceptible hosts and as an endophyte in 
citrus fruit without symptoms (Baldassari et al. 2006, 2008; EFSA 2014; Wang et al. 2016).  
• Tahitian lim e (C. latifolia ) fruit does not show symptoms in natural infection, even in areas with 
high levels of inoculum (Baldassari et al. 2008; Wang et al. 2016). However, P. citricarpa was 
isolated from asymptomatic Tahitian lime fruit peel,  suggesting the fungus  can be present in 
fruit as an endophyte ( Baldassari et al. 2008).  
• Sour orange ( C. aurantium ) and its hybrids are often reported as not susceptible to the 
pathogen ( Baldassari et al. 2008; EFSA 2014; Kotz é 1981 ), but the fungus has been isolated 
from lesions on fruit of this species (Baldassari et al. 2008; Baayen et al. 2002; Glienke et al. 
2011; Wulandari et al. 2009).  
 
 
Table 6.2.1 Citrus species susceptible to citrus black spot caused by P. citricarpa (EFSA 2 020) 
Scientific name  Common name  
C. limon  (L.) Burm.f.  Lemon  
C. sinensis  (L.) Osbeck  Sweet orange  
C. reticulata  Blanco  Mandarin , Satsuma mandarin  
C. paradisi  Macfad.  Grapefruit  
C. medica  L.  Citron  
C. auranti ifolia (Christm.) Swingle  Key lime , Sweet lime  
C. hystrix  DC  Kaffir lime  
 
 
There is low uncertainty in this conclusion for most commercial citrus fruit varieties, because 
P. citricarpa has been frequently reported from these species.  
 
However, there is moderate uncertainty about the hos t status of pomelo ( C. maxima ). Wulandari et al. 
(2009) classified all Phyllosticta isolates in their study that came from pomelo ( C. maxima ) as 
P. citriasiana, although most had previously been classified as P. citricarpa . These isolates came from 
China, Thailand and Viet  Nam. In a later study, several Phyllosticta isolates from pomelo in 
Guangdong, Guangxi and Fujian were identified as P. citriasiana (Wang et al. 2012) . Phyllosticta 
citriasiana was not identified from other citrus species and P. citricarp a was not identified in pomelo in 
these studies.  However, Glienke et al. (2011) identified an isolate from C. maxima  in Brazil as 
P. citricarpa.  
 
Phyllosticta citricarpa can be associated with citrus fruit commodities.  
• Phyllosticta citricarpa  has a long latent period in fruit , and symptoms do not start to develop 
until fruit is fully grown and beginning to ripen (Kotzé 1981; Agostini et al. 2006). Infected fruit 
may appear healthy and might therefore be harvested and packaged for export.  
• Viabl e P. citricarpa  has been detected on imported citrus fruit from Brazil and China during 
border inspections in Europe (EFSA 2014; EPPO reporting service 2020; see Table 6.2.2 ). 
During 1999 –2012 there were 859 interceptions of P. citricarpa  on citrus fruit c onsignments 
entering Europe from countries outside the European Union (EFSA 2014). Most interceptions 
of P. citricarpa on fresh citrus fruit were on fruit originating in Brazil or South Africa (EFSA 
2014). Brazil is one of the countries included in the new  IHS. 
• However, P. citricarpa  has not been intercepted on citrus fruit at the New Zealand border 
(LIMS  2020 ). This is probably because  there are no IHSs for citrus from countries or areas of  
countries where the fungus is known to be present, except Australi a where there are targeted 
measures for P. citricarpa (as G. citricarpa ) on citrus imports. New Zealand has an existing 
IHS for citrus from  the USA, but citrus has not been imported from Florida since 2005 (MPI 
Quancargo database, checked 6  October 2020) , well before the current incursion of 
P. citricarpa  in that state . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 62  
Phyllosticta citricarpa is present in at least four of the countries in the scope of this pest risk 
assessment, with low uncertainty (see Table 6.2.2. ). There are reliable recent records of P. citricarpa  
causing citrus disease in some regions of Australia, China, Brazil and the USA. The Korean NPPO 
listed P. citricarpa on the pest list they provided to MPI. There are no recent reliable records of 
P. citricarpa in the Cook Islands, Egypt, Fiji, Japan, Mexico, Peru, Samoa, Spain, Vanuatu and Viet  
Nam. EPPO (2020a) reports P. citricarpa as absent from these countries , and it was not on the pest 
lists provided by the countr ies. Phyllosticta citricarpa is not  reported  in New Caledonia or Solomon 
Islands (see Table 6.2.2 ). 
 
Table 6.2.2 Distribution of P. citricarpa in countries in the scope of the pest risk assessment.  
Country  Information  Uncertainty  
Australia  Present in New South Wales, Northern Territories, 
Queensland and Victoria (Miles et al. 2013; EPPO 
2020a; Farr and Rossman 2020). Absent in Western 
Australia44 and South Australia, and the European 
Union recognise s these areas as pest-free areas for 
the dis ease.45 Low uncertainty .  
Brazil  Present, restricted distribution (Rio Grande do Sul, Rio 
de Janeiro, Sao Paolo) (EPPO 2020a; EFSA 2014 ; 
Farr and Rossman 2020 ). The EPPO reporting service 
(2020) record s numerous interceptions on citrus from 
Brazil, mostly on oranges ( C. sinensis ) but also 
mandarins ( C. reticulata ) and lemon ( C. limon ). 
 Low uncertainty .  
China  Present, restricted distribution (Fujian, Guangdong, 
Guangxi, Jiangsu, Sichuan, Hong Kong, Yunnan, 
Zhejiang) (EPPO 2020a; Wang et al. 2012). EPPO 
reporting service (2020): C. maxima, C . paradis i, 
Citrus  sp. Low uncertainty .  
Cook Islands  Absent, confirmed  by survey (EPPO 2020a). No 
reports found in s earches. Farr and Rossman (2020) 
have records on several species from a single 1981  
survey/technical report. A search of CAB Abstracts46 
found an abstract of 1990 distribution map for G. 
citricarpa  (same as Fiji, Samoa, Spain); CAB 
Abstracts, Farr and Rossman 2020)  Low uncertainty.  
Egypt  Absent, confirmed by survey (EPPO 2020a). Farr and 
Rossman (2020) have no record. A search of CAB 
Abstracts found several distribution maps for G. 
citricarpa (1966 ,1983, 1990).  Low uncertainty.  
Fiji Absent, confirmed by survey (EPPO 2020). Farr and 
Rossman (2020) have records on several species 
from a 1981  survey/technical report (same one as 
Cook Islands) and a 1972 list. A search of CAB 
Abstracts found an abstrac t of a 1990 distribution map 
for G. citricarpa.   Low uncertainty. 
Japan  Absent, confirmed by survey (EPPO 2020a), based on 
information dated 1992. EPPO consider historical 
records to be doubtful and presumably relating to G. 
mangiferae. Farr and Rossman (2020 ) have records 
on natsudaidai, unshiu and  Citrus  sp. from a 2007 
index of fungi inhabiting woody plants in Japan.  Low uncertainty. 
Korea  Absent, confirmed by survey (EPPO 2020a) EPPO 
note there are doubtful records presumably 
concerning G. mangiferae.  Farr and Rossman (2020) 
have a single record from a 2004 list of plant diseases 
in Korea.  Requires clarification. Korea included P. 
citricarpa on their list of diseases associated 
with unshiu mandarin , and the EPPO current 
pest situation is based on info rmation dated 
1992.  
Mexico  Absent unreliable record (EPPO 2020a). Farr and 
Rossman (2020) have no record . Moderate  uncertainty . Stringari et al. (2009) 
report a single isolate in a molecular 
phylogeny as G. citricarpa  from citrus black 
spot lesions in Mex ico. A search of CAB 
Abstracts found no other relevant records. 
EPPO reporting service (2020) record s a 
single interception  from Mexico  of P. citricarpa 
                                                      
44 Western Australia Department of Primary Industries and Regional Development, Citrus black spot: pest data sheet. 
https://www.agric.wa.gov.au/plant -biosecurity/citrus -black -spot-pest-data-sheet  Accessed 5 October 2020.  
45 MICoR (Australian Government Department of Agriculture , Water and the Environment Manual of Importing Country 
Requirements, Lemons – European  Union): “The European Union formally recognises the states of South Australia , and 
Western Australia as free from Black spot” ( Phyllosticta citricarpa ). 
46 Search terms used for all CAB Abstracts searches in this table were ‘citricarpa’ and the country name.   
63 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Country  Information  Uncertainty  
from C. paradisi  in 2016 with an asteri sk, 
indicating it is not known in the country of 
origin . Since these interception reports include 
passenger pathway interceptions, the fruit 
may not have been grown in Mexico.  
New Caledonia  No report found in CAB Abstracts searches . No record 
in EPPO (2020a) or Farr and Rossman (2020).  Low uncertainty.  
Peru  Absent, confirmed by survey (EPPO 2020a). Farr and 
Rossman (2020) have no record. A CAB Abstracts 
search found abstracts for 1990, 1983 and 1966 
distribution maps for G. citricarpa  and a 1942 Peruvian 
flora that records Phoma citricarpa  on citrus.  Low uncertainty.  
Samoa  Absent, confirmed by survey (EPPO 2020a). Farr and 
Rossman (2020) have records on several species 
from a 1981 survey/technical report (same one as 
Cook Islands, Peru, Spain and Fiji). A CAB Abstracts 
search found an abstract for the 1990 distribution map 
for G. citricarpa . Low uncertainty.  
Spain  Absent, confirmed by survey (EPPO 2020a). Farr and 
Rossman (2020) have no record. A CAB Abstracts 
search found abstracts for 1990, 1983 and 1966 
distribution maps for G. citricarpa.  Low uncertainty.  
Solomon Islands  No record in EPPO (2020a) or ( CABI 2020) . Farr and 
Rossman (2020) have no record. A CAB Abstracts 
search found no records.  Low uncertainty.  
USA  Present, restricted distribution (southern Florida) 
(EPPO 2020a; USDA -APHIS 2020)  Low uncertainty.  
Vanuatu  Absent, unreliable record ( CABI 2020; EPPO 2020a). 
Farr and Rossman (2020) have no record. A CAB 
Abstracts search found several distribution maps  
(under the name  New Hebrides)  for G. citricarpa  from 
1966,1983 and 1990.  Moderate  uncertainty . The IHS for citrus from 
Vanuatu currently has additional measures for 
P.citricarpa (as Guignardia citricarpa ) (MAF 
Biosecurity New Zealand  2006)  
 
Viet Nam  Absent, confirmed by survey (EPPO 2020a). No 
record in Farr and Rossman (2020) . A CAB Abstracts 
search found several distribution maps for G. 
citricarpa  (e.g.1966,1983, 1990).  Moderate  uncertainty . EPPO reporting service 
(2020)  records two past detections on C. 
maxima  and one on C. limon .  
 
 
Given the arguments and evidence below, basic measures  only reduce the likelihood 
of entry of P. citricarpa  by a low degree . Consequently, the likelihood of entry  is 
considered high, with low uncertainty.  
 
Infected fruits can show symptoms late in production and at the time of phytosanitary inspection , and 
symptomatic fruit are likely to be detected and removed.  
• Symptoms of P. citricarpa on fruit can start to develop once the fruit i s fully grown and starts 
to ripen (Kotz é 1981).  
• Examples of lesions on fruit caused by P. citricarpa are shown in Figure 6.2.1 . Obvious 
symptoms of infection such as these would be extremely unlikely to escape detection.  
 
  
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 64 Figure 6.2.1 Lesions on citr us fruit caused by P. citricarpa.  From left to right: Citrus black spot lesions47; 
Hard spot on orange, with pycnidia visible in the middle of the lesions48; Cracked spot lesions on 
Valencia orange49. 
 
However, the evidence suggests that some infected fruit is not detected and removed during 
production or phytosanitary inspection:  
• Symptoms of P. citricarpa appear at fruit maturity or post -harvest (Agostini et al. 2006; Kotz é 
1981). The latent period before symptoms develop can last for up to 24 weeks after t he fruit is 
infected (Tran et al. 2020). Infected fruit can be symptomless at the time of harvest and 
packaging for export and can subsequently develop symptoms in transit or storage (Agostini 
et al. 2006; Er et al. 2013; Tran et al. 2020).  
• During this pe riod, latent mycelium can be present in asymptomatic fruit (EFSA 2014).  
• The volume of the commodities can also affect efficiency of detection. Low levels of 
infestation may not be easily detected, especially if the volume of commodities is large.  
 
General handling after harvesting is not likely to remove fruit with latent infections.  
• General handling after harvesting (e.g. washing and brushing) only treats the surface of fruit , 
so it will not remove latent mycelium in the rind.  
• Waxing and some post -harvest fungicide treatments slow s postharvest development of 
P. citricarpa but does  not prevent it altogether (Agostini et al. 2006).  
• Packhouse treatments that reduce the recovery of viable P. citricarpa from existing lesions  
include a warm water bath (4 3–47°C for three minutes), chemical tank (1 ,000 µg/ml 
guazatine, 503 µg/ml imazalil sulphate, 500 µg/ml  2,4-D sodium salt) or polyethylene wax 
application (Korf et al. 2001). The warm water bath, chemical tank or a chlorine bath reduce 
the viability of con idia in existing lesions to zero. However, none of the treatments eliminate d 
the pathogen completely , and the Korf et al. (2001)  study examined fruit with visible lesions, 
so it is of limited relevance.  
 
Phyllosticta citricarpa is likely to survive transit  and storage in citrus commodities.  
• EFSA (2014) considered that P. citricarpa  is very likely to survive transport and storage either 
as conidia within pycnidia in fruit lesions or as latent mycelium present in asymptomatic fruit.  
• Storing the fruit at 8 °C slowed symptom development, compared with storage at ambient 
temperatures , but did not prevent it (Agostini et al. 2006). Live P. citricarpa was still detected 
in symptomatic peel and fruit after 40 days of storage at different combinations of temperature 
(8°C or ambient temperature: 18 –25°C) and humidity (saturated, moist or dry) (Agostini et al. 
2006).  
• Viable P. citricarpa could be isolated from lesions on untreated fruit, and fruit exposed to 
various packhouse treatment s, after 3 weeks  of storage at 4.5 °C (Korf et al. 2001).  
• Lesions and pycnidia of P. citricarpa  developed in asymptomatic, latently infected fruit 
maintained at 4°C, 12°C or 22°C over a period of 11 weeks, although development was 
slower at lower temperatures (Er et al. 2013). New lesions de veloped between weeks 9 –11 at 
4°C, indicating that the fungus was still viable after at least 9 weeks of cold  storage.  
• Post-harvest symptom development is influenced by the temperature in the packhouse and 
during transport to market, with more lesions deve loping at 27 °C than 20 °C (Kotz é 1981). 
More lesions develop on fruit kept at high light intensities than on  fruit stored in darkness 
(Kotz é 1981).  
• New P. citricarpa  lesions were observed on  citrus  fruit after cold storage for 5 weeks, followed 
by incubation for 2 weeks  under optimum conditions for symptom expression (25 –27 °C 
under constant light and > 80% humidity ) (Moyo et al. 2020).  In orange fruit 4.4 % of  lesions  
formed pycnidia , and in lemon fruit 6.6 % of lesions formed pycnidia (Moyo et al. 2020).   
• From a risk management perspective, it is worth noting that most commercial citrus fruit 
transported to New Zealand in cold storage, would not be exposed  to the prolonged periods 
                                                      
47 Florida Division of Plant Industry Archive / CC BY -SA (https://creativecommons.org/lic enses/by -sa/3.0 ). 
https://commons.wikimedia.org/wiki/File:Citrus_Black_Spot_lesions.jpg   
48 Cesar Calderon – USDA APHIS PPQ, Bugwood.org / CC BY -SA (https://creativecommons.org/licenses/by -sa/3.0 ). 
https://commons.wikimedia.org/wiki/File:Citrus_Black_Spot.jpg   
49 P. Barkley – Biological  and Chemical Research Institute, Bugwood.org / CC BY -SA (https://creativecommons.org/licenses/by -
sa/3.0 ). https://commons.wikimedia.org/wiki/File:Citrus_Black_Spot_on_Valencia_orange.jpg    
65 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  of light and warmer temperatures that promote symptom development until after they have 
entered New Zealand  
 
However, it is very unlikely the pathogen will spread further through the consignment.  
• Undamaged mature fruit are not susceptible to infection by P. citricarpa  conidia (spores) 
at temperatures of either -0.5 or 20 °C (Korf et al. 2001).  
• EFSA (2014) concluded that it is very unlikely (with low uncertainty) that the pathogen will 
multiply or increase in prevalence during transport or storage of infected citrus fru it, since:  
o the optimal temperature for hyphal growth of P. citricarpa  in synthetic medium is 
approximately 25°C;  
o the pathogen is largely inactive at temperatures below 15°C; and 
o citrus fruit is usually stored and transported at low temperatures  (EFSA 2014 ). 
 
There is low uncertainty in this conclusion. Without additional measures, it is highly likely that fruit 
containing latent P. citricarpa or small fungal lesions  will escape detection during production and 
phytosanitary inspection. It is also highly likely that P. citricarpa in citrus fruit can survive packhouse 
procedures, storage and transit to New Zealand. In addition, since citrus fruit is often transported at 
cold temperatures and in the dark, lesions may be slow to develop and may not yet be visible at the 
time of verification inspection at the New Zealand border.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below, the ability of the P. citrica rpa to move 
from imported citrus fruit (apart from C. latifolia or C. aurantium ) onto a host plant to 
allow establishment is rated as  low, with moderate uncertainty . 
 
Phyllosticta citricarpa is likely to survive and develop on the waste of citrus fruit (whole fruit, pieces 
and peel).  
• Live P. citricarpa was still detected in symptomatic peel and fruit after 40 days of storage at 
different combinations of temperature (8 °C or ambient temperature: 18 –25°C) and humidity 
(saturated, moist  or dry) (Agostini et al. 2006). Lesions and pycnidia of P. citricarpa  developed 
in asymptomatic, latently infected fruit after 9 –11 weeks at 4°C, 12°C or 22°C (Er et al. 2013).  
 
Most  waste from imported citrus in New Zealand will be disposed of using low -risk methods , so 
P. citricarpa  will be unable to spread from the citrus host.  
• The majority of kitchen  waste in New Zealand is disposed of in bags in landfills or in kitchen 
disposal units, and in these situations, P. citricarpa  is unlikely to reach a new host (see  the 
waste analysis in Chapter 2).  
 
Orange, mandarin, lemon, grapefruit and other citrus hosts of P. citricarpa  are extensively grown  in 
New Zealand , and fruit is likely to be at a susceptible stage at times when citrus fruit is imported and 
at times of the year when seasonal weather conditions are likely to favour development and spread of 
the pathogen.  
• Most commercial citrus species are susceptible, especially lemons and Valencia oranges 
(Kotz é 1981) . 
• In New Zealand, 783 hectares (ha)  are plante d in commercial oranges, 556 ha in mandarins, 
257 ha in lemons and 15 ha in grapefruit (FreshFacts 2019). Citrus trees are commonly 
grown in domestic gardens.  
 
Phyllosticta citricarpa can spread to nearby citrus trees if infected fruit or peels are discard ed in the 
New Zealand environment near citrus trees, although the likelihood is low.  
• Ascospores (sexual spores) produced in leaf  litter have historically been considered the most 
important means for dispersal of P. citricarpa (e.g. Fourie et al. 2013; Kot zé 1981).  
Ascospores require two mating types to be present and are not produced on fruit. However, in 
Brazil, Zimbabwe and Queensland, Australia, conidia (asexual spores) are now recognised as 
a significant source of inoculum for spreading the pathogen , even though ascospores are 
present (Spósito et al. 2011; Wang and Dewdney 2019).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 66 • Although there are recent studies that indicate that fresh citrus fruit is not an epidemiologically 
significant pathway for the entry, establishment and spread of citrus black spot , these studies  
assess the likelihood based on treatments being applied.  
o For example, Gottwald et al. (2021) developed a probabilistic model using a Monte 
Carlo simulation to investigate the overall probability of P. citricarpa  infecting 
commerci ally produced fresh citrus at several different production areas, remaining 
viable throughout production and transport, and establishing at various endpoint 
locations. The inputs integral to this model included estimates for the efficacy of pre -
harvest con trol measures (e.g. in -field fungicide treatments) and packinghouse 
treatments (e.g. disinfectant washes, fungicide dips/drenches, drying and waxing) to 
mitigate P. citricarpa .  
o Likewise, Moyo et al. (2020) studied the viability of P. citricarpa  in natural ly infected 
orange and lemon fruit. Despite the fact that these authors concluded that fruit was 
not a n epidemiologically significant pathway for the fungus, they observed that new 
fungal lesions developed on both treated and untreated orange and lemon fru it after a 
period in cold storage, and that pycnidia (asexual fruiting bodies) in lesions on 
untreated fruit produced viable spores.  
• Conidia of P. citricarpa are produced in lesions on infected fruits (as well as on leaves and 
branches) and can be spread b y water  splash and windblown rain (Tran et al. 2017; EFSA 
2014). EFSA (2014) considered that if citrus fruit, peel or other citrus by -products with 
pycnidia of P. citricarpa  are discarded underneath or in close proximity to susceptible citrus 
trees, the pa thogen can be dispersed by natural means and can  infect susceptible plant 
tissues.  
• Phyllosticta citricarpa is recently invasive in Florida , where the disease originate d from a 
single clonal lineage. Only one mating type is present , and P. citricarpa reprod uces asexually , 
so only conidia (asexual spores) are produced (Wang et al. 2016; Hendricks et al. 2020). 
Despite this, P. citricarpa  has been able to spread in Florida. The fungus was first reported in 
Florida in 2010 (Schubert et al. 2012), and by July 20 19 the quarantine zone had been 
extended to encompass 1160.32 km2 in Lee, Charlotte, Collier, Hendry and Polk counties 
(Hendricks et al. 2020).  
• Recent studies of P. citricarpa in Florida, USA, where the fungus does not produce wind -
dispersed ascospores, suggest that conidia can be spread by windblown rain over much 
greater distances than previously reported, within rows of trees in an orchard (3.36 m 
spacing), across rows (6.70  m spacing) and upwards into the topmost parts of a canopy 
(reaching heights of > 3 metres) (Hendricks et al. 2017; 2020). The incursion in Florida 
indicates that P. citricarpa  can spread widely, even when only conidia, such as those 
produced on fresh fruit, are present.  
• The temperature range for conidia to germinate and form appressoria (infective structures) in 
vitro (in medium containing citrus juice) was between 12 –32°C with  an optimum of 24 °C 
(Wang and Dewdney 2019). Mean daily maximum temperatures of between 12 and 24 °C are 
common across most of New Zealand through most of the  year (see the climate section in 
Chapter 2, section 4), meaning that conditions for appressoria fo rmation are widely available 
in New Zealand.  
• The majority of citrus fruit in New Zealand sets in November (late spring/early summer) 
(Brown 2019), although some citrus trees in New Zealand produce fruit through out the year.  
• Fruit are reported to be suscept ible to infection by P. citricarpa  for up to 30 weeks from fruit 
set, but the susceptible period may be shorter or longer depending on local weather 
conditions, Citrus variety and inoculum  pressure (EFSA 2014; Lanza et al. 2018; Tran et al. 
2020). Leaves d o not usually develop symptoms (except in lemon) but are reported to be 
susceptible for 10 months post formation (EFSA 2014).  
• Susceptible fruit is likely to be present throughout the summer when temperatures are more 
likely to favour germination of conidia , and susceptible leaves are likely to be present for most 
of the year. In summer, domestic citrus supply is low , and citrus fruit is likely to be imported to 
fill the gap in the domestic market. Susceptible leaves are likely to be present all year round.  
• However, citrus trees would need to be growing close enough to where citrus fruit or peel 
were discarded for conidia to be spread to them via water splash or windblown rain.  
 
There is moderate uncertainty in this conclusion , because there are no current data on the proportion 
of waste from imported citrus  that is discarded in and around citrus orchards or composted in home 
gardens. Although Hogg et al. (2010) reported that New Zealanders discard around 400,000 tonnes of  
67 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  kitchen waste each year  and about 12.5% is composted , there are no data on the proportion of 
composted waste that is imported Citrus (see section  2.4). Also, the distance of compost heaps from 
Citrus hosts in home gardens is likely to be highly variable.   
 
Given the arguments an d evidence below, i t is uncertain  whether P. citricarpa  can 
move from imported C. latifolia  or C. aurantium  fruit onto a host plant to allow 
establishment.  
 
There is no evidence that P. citricarpa can produce conidia to allow it to spread from C. latifolia  or 
C. aurantium  fruit to nearby citrus fruit or leaves.  
• Tahitian lime ( C. latifolia ) fruit does not show symptoms in natural infection, even in areas with 
high levels of inoculum (Baldassari et al. 2008; Wang et al. 2016). However, P. citricarpa has 
been isolated from asymptomatic fruit peel  and can colonise and fo rm viable ascospores in  
leaves of Tahitian lime  (Baldassari et al. 2008).  
• Sour orange ( C. aurantium ) and its hybrids are often reported as not susceptible to the 
pathogen ( Baldassari et al. 2008 ; EFSA 2014; Kotz é 1981 ), but the fungus has been isolated 
from lesions on fruit of this species (Baldassari et al. 2008; Baayen et al. 2002; Glienke et al. 
2011; Wulandari et al. 2009).  
• EFSA (2014), EPPO (2020b) found no evidence of reproduction and no r eference to 
production of conidia on either of these species.   
 
Given the arguments and evidence below, t he suitability of the New Zealand 
environment for Phyllosticta citricarpa to establish is considered high.  
Phyllosticta citricarpa  is commonly report ed from subtropical citrus -growing areas with summer 
rainfall. Many of these areas have  very similar climate conditions to the whole of New Zealand, 
indicated by a climate match index  (CMI) of ≥0.7, modelled by Phillips et al. (2018).  
 
• The current global distribution of P. citricarpa is shown in Figure 6.2.2 , and the CMI for each 
country/state is given in Table 6.2.3.  Climate is highly unlikely to limit the establishment of 
P. citricarpa , because it is reported from many areas with very similar climates to New 
Zealand including Argentina, Uruguay, some regions of Brazil, Australia (New South Wales, 
Queensland and Victoria), some provinces of China and the eastern provinces of South 
Africa.  
 
Figure 6.2.2  Distribution of P. citricarpa (EPPO 2020)    
 
Table 6.2.3  Distribution of P. citricarpa  (EPPO 2020)  
CMI values of ≥0.7 have very similar climate conditions to the whole of New Zealand (Phillips et al.  2018)  
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 68 Region  Country  State/Province (if 
recorded)  CMI range 
(Phil lips et al. 
2018)  
Africa  Angola (restricted 
distribution)   0.5–0.7 
Ghana (restricted 
distribution)   ≤0.6 
Kenya   0.4–0.8 
Mozambique   ≤0.6 
Namibia (few occur rences)   0.5–0.7 
South Africa (restricted 
distribution ; not present in 
Western Cape, Northern 
Cape, Free State)  Eastern Cape  0.7–0.9 
Gauteng  0.6–0.8 
KwaZulu -Natal  0.7–0.8 
Limpopo  0.6–0.7 
Mpumalanga  0.7–0.8 
North West Province  0.6–0.7 
Tunisia (restricted 
distribution)   0.5–0.8 
Uganda   0.5–0.8 
Zambia   ≤0.6 
Zimbabwe   0.5–0.7 
Asia Bhutan   0.4–0.7 
China (restricted 
distribution)  Fujian  0.6–0.7 
Guangdong  0.4–0.7 
Guangxi  0.5–0.7 
Jiangsu  0.7 
Sichuan  0.6–0.8 
Yunnan  0.6–0.8 
Zhejiang  0.7 
India (restricted 
distribution)  Maharashtra  ≤0.6 
Indonesia   ≤0.6 
Philippines   ≤0.6 
Taiwan   0.4–0.8 
North America  USA Florida ( Lee, Charlotte, 
Collier, Hendry and Polk 
counties)  0.5–0.6 
Cuba   ≤0.6 
South America  Argentina   0.6–0.9 
Brazil  Amazonas  ≤0.6 
Espírito Santo  ≤0.6 
Minas Gerais  ≤0.6 
Paraná  0.6–0.8 
Rio de Janeiro  0.5–0.7 
Rio Grande do Sul  0.7–0.9 
Santa Catarina  0.7–0.9 
São Paulo  0.5–0.7 
Uruguay   0.7–0.9 
Oceania  Australia  New South Wales  0.6–0.9 
Queensland  0.4–0.8 
Victoria  0.7 –0.9 
 
Host availability is unlikely to be a limiting factor for P. citricarpa  to establish in New Zealand . 
• Most commercial citrus cultivars are susceptible to P. citricarpa  to some degree (see Table 
6.2.1 ) especially lemons and sweet oranges , which are commonly grown in New Zealand, 
both in commercial production and in home gardens . Citrus is commercially produced in both 
the North Island and the South Island, with most commercial production taking place in the 
North Island (see section 4.2 in  Chapter 2).   
69 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Phyllosticta citricarpa  can spread once it becomes established in a new area.  
• In Nabeul,  Tunisia (an area with a CMI of 0.7 with the whole of New Zealand ), 339 orchards in 
the area were surveyed after symptoms were first observed , and some p lants in 69 lemon 
and orange orchards already showed symptoms (Boughalleb -M’Hamdi et al. 2020).  
• Phyllosticta citricarpa  was first reported in Florida, USA in 2010 (Schubert et al. 2012), and by 
July 2019 , the quarantine zone had been extended to encompass 1,160.32 km ² in Lee, 
Charlotte, Collier, Hendry and Polk counties as of July 2019 (Hendricks et al. 2020) . 
• In South Africa , disease symptoms were observed for 30 years before the disease reached 
epidemic levels and fungicidal control became necessary (Kotz é 1981).  
 
Phyllosticta citricarpa  is spread by rain splash and wind , and it is likely to spread easily in New 
Zealand once it infects a susceptible host . 
• Recent evidence suggests that P. citricarpa is commonly spread by conidia (asexual spores) 
produced in lesions on infected fruits, leaves and branches and dispersed by water  splash or 
windblown rain (Tran et al. 2017, 2020; Hendricks et al. 2020) (see above). This means that 
the pathogen can establish in an area even if only one mating type is present, as has 
apparently happened in Florida.  
• In Australia, South Africa and South America (Argentina, Brazil) ascospores (sexual spores) 
formed in pseudothecia in leaf litter from citrus trees are also a major source of inoculum to 
spread the disease (Reis et al.  2006; Tran et al. 2017).  
o Release of ascospores requires moisture from rainfall, irrigation or possibly heavy 
dew (EFSA 2014; Reis et al. 2006). Even a small amount of rain can trigger 
ascospore release (Reis et al. 2006).   
o Ascospore release in Argentina  and South Africa peaks in December –January , and in 
Brazil , the peak is January –February (Reis et al. 2006). Ascospores are infectious at 
temperatures between 15 and 29.5°C and require 15 to 38 hours of wetness (Reis et 
al. 2006; EPPO 2020b).  
o Once release d, ascospores are spread by wind currents to leaves, twigs and young 
fruit of citrus (Kotz é 1981).  
o The fruit of m ost citrus plants in New Zealand set s in November (late spring/early 
summer) (Brown 2019), although some citrus trees in New Zealand produce f ruit 
through out the year.  
o Fruit are susceptible to infection by P. citricarpa  for at least 4 –5 months after petal fall 
(Reis et al. 2006) , and leaves are susceptible for 10 months post formation (EFSA 
2014). Therefore, susceptible fruit and leaves will al most certainly be present at times 
when ascospores are released.  
• As most commercial citrus fruit sets in November (Brown 2019), young susceptible fruit will be 
most abundant in December and early January when temperatures are likely to be warm 
enough for the fungus to release spores and infect fruit. For example, in Kerikeri, a citrus -
growing region, summers are warm and humid , and daytime maximum air temperatures 
usually range from 22 °C to 26 °C (see the New Zealand climates section). These conditions 
are likely to favour the infection of young fruit with P. citricarpa ascospores . 
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, t he level of impact caused by P. citricarpa  
is likely to be moderate , with low uncertainty . 
Damage and symptoms caused by P. citricarpa  can reduce fruit quality.  
• The most commonly observed fruit symptom is hard spots (see Figure 6.2.1  above) , which 
are shallow lesions, 3 –10 mm in diameter, with a grey to tan centre and a dark brown to black 
margi n (FAO 2014). Pycnidia commonly form in the centre of hard spots (Miles et al. 2019). 
Other common lesion types include:  
o freckle spots (small (1 –2 mm diameter) grey, tan or colourless spots with no halo, 
which seldom produce conidia) ( FAO 2014 ); 
o virulent spots (sunken irregular red to brown or colourless lesions that form late in the 
season on heavily affected mature fruit ; these grow rapidly , can cover two thirds of 
the fruit within 4 –5 days and can cause premature fruit drop ) (FAO 2014 ); Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 70 o false melanoses (small raised dark brown to black lesions with no conidia that 
develop on green fruit, are often surrounded by dark specks and may coalesce as the 
season progresses) ( FAO 2014 ); and  
o cracked spots (see Figure 6.2.1  above ; cracked spots form when spider mites interact 
with the fruit lesions and have been observed in Brazil and Florida ) (Miles et al. 
2019).  
• Infections near the pedicel (stem) of the developing fruit may lead to premature fruit drop 
(Baayen et al. 2002). Yield losses due to prem ature fruit drop have been reported in Brazil 
(Reis et al. 2006). Hendricks et al. (2020) discuss use of fungicides to reduce crop losses due 
to premature fruit drop, suggesting that such losses are also a concern in Florida.  
• Except for C. aurantium  and it s hybrids and  C. latifolia , all commercially grown citrus species 
are susceptible to black spot disease caused by P. citricarpa  (Kotz é 1981). In particular, 
heavy losses of lemon, sweet orange and grapefruit crops are reported. Although the lesions 
do not usually affect the internal fruit or juice quality, i nfected fruit are unmarketable as fresh 
fruit ( Kotzé 1981; Zavala et al. 2014).  
 
Phyllosticta  citricarpa has been reported to cause severe damage and production loss of citrus in 
areas with similar clim ate to New Zealand . 
• In 1895 in New South Wales, P. citricarpa  caused serious losses to late Valencia oranges 
from blemished fruit from infections in the field and from latent infections that developed on 
fruit in transit (Sutton and Waterston 196 6).  
• In 1945, more than 90% of fruit from unprotected trees in some areas of East and North 
Transvaal (now Limpopo and Mpumalanga)  was unfit for export (Sutton and Waterston 1966).  
• Phyllosticta citricarpa has also been reported to cause crop losses of lemons i n Sichuan, 
Valencia oranges in Chongqing and some mandarin varieties in Zhejiang and Jiangxi (Wang 
et al. 2012).  
• Damage from P. citricarpa is most severe when mean maximum temperatures are between 
2–25°C while the fruit is maturing or when the temperature is 30°C when the fruit is mature 
(Sutton and Waterston 196 6). Therefore, at the times when fruit is maturing in commercial 
citrus -growing areas,  climate  conditions are likely to favour severe damage from the disease. 
However, in New Zealand , average temper atures at harvest are likely to be  lower than 30 °C. 
• Depending on the suitability of the climate and the susceptibility of hosts , it can take 5 –30 
years from the time citrus black spot symptoms  are first noticed in an area for the disease to 
reach epidemic proportions (Kotz é 1981). However, if P. citricarpa established, New Zealand 
is likely to be at the shorter end of that timeframe , given that the New Zealand climate is likely 
to favour spread of the fungus and susceptible citrus varieties such as sweet or anges and 
lemons are commonly produced.  
 
If P. citricarpa  becomes established, there are likely to be increased costs to citrus producers from in -
field fungicide applications during fruit development to prevent high levels of infection and damage to 
the crop.  
• For example, in an experimental plot  that was not tr eated with fungicide during the 
susceptible period of fruit development, the mature fruit showed 100% incidence of citrus 
black spot  (Baldarassi et al. 2006).  
• In Queensland, São Paulo and Florida, regular applications of fungicide are necessary 
throughout  the period when fruit are susceptible to prevent fruit from being infected 
(Hendricks et al. 2020; Lanza et al. 2018; Tran et al. 2020).  
• Furthermore,  because of the long latent period,  it is not possible to know if the fungicide 
applications have been su ccessful until the end of the season  when the visible citrus black 
spot symptoms  develop on the fruit ( Tran et al. 2020 ).  
• It is likely that there would be additional costs and delay in implementing effective fungicide 
treatments because research would be required to adapt spray regimes for New Zealand 
conditions. In Brazil, field trials were required because spray regimes from South Africa were 
not as effective at controlling P. citricarpa in São Paulo (Lanza et al. 2018). Field trials to 
evaluate fungicid e regimes  were also carried out in Florida (Hendricks et al. 2020).  
• Managing the disease with fungicides is costly , and it can be difficult to control the disease 
sufficiently to produce fresh fruit that is acceptable to consumers (Tran et al. 2017). Citru s 
black spot disease, caused by the fungus P. citricarpa , is estimated to cost Australian citrus  
71 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  growers approximately AU$80 million  per year through export restrictions, fungicide 
applications and fruit damage (Hort Innovation 2018).  
 
Citrus  is economica lly important in New Zealand ( for the value of Citrus in New Zealand , see Section 
5.2 in Chapter 2).  
• Phyllosticta citricarpa would be like ly to affect yields and marketability of most commercial 
citrus crops in New Zealand, including oranges, lemons, mand arins, grapefruit and some 
limes.  
• In 2019 , export sales  of fresh citrus fruit were worth NZ$12 million, and the value of domestic 
orange sales was $ 58.5 million (Plant & Food Research 2019).  
 
There is low uncertainty in this conclusion. Economically significant disease has been recorded in 
areas with similar climate to New Zealand, so the impact of P. citricarpa  on the New Zealand citrus 
industry is likely to be high. However, there is some unc ertainty about how long it would take for 
impacts to become severe. Impacts are likely to increase over time as inoculum levels increase and 
the disease spreads to new areas of New Zealand.  
 
Establishment of P. citricarpa  is likely to increase phytosanita ry measures required for export to 
countries where the pest is absent or regulated.  
• Phyllosticta citricarpa is an A1 pest for the European Union (EPPO 2020a).  It is still regulated 
by the USA and under eradication in parts of Florida (USDA -APHIS 2020). Pa rts of Australia 
are maintained as pest-free areas for P. citricarpa . Infected citrus fruit would not be 
acceptable for export to these areas.  
• An incursion of P. citricarpa in New Zealand could cause impacts from removal of productive 
plants, costs of sur veillance and loss of income from sales of fresh citrus in domestic and 
export markets. For example, Florida has maintained its quarantine zones for P. citricarpa 
since 2010 , and fresh citrus fruit cannot be transported outside of these areas (USDA -APHIS 
2020).  
 
Environmental impacts from P. citricarpa are likely to be low overall for New Zealand but may be 
moderate in citrus -producing areas due to increased use of fungicides to control the disease.  
• Developing fruit are susceptible to P. citricarpa for several months, and regular spraying with 
fungicide is current practice in areas with the disease:  
o For example, in Florida, the recommended fungicide regime for control of P. citricarpa  
is to apply fungicides on a 21 - to 28-day cycle from early May (late spring) to mid -
September (early autumn) (Hendricks et al. 2020). Recent research suggests that 
fungicide applications over an even longer period of 180 or 220 days would more 
effectively protect the fruit.  
o Recommended fungic ides for control of P. citricarpa in Florida  are copper, 
strobilurins, fenbuconazole , and premix combinations, such as 
azoxystrobin/difenoconazole and pyraclostrobin/boscalid  (Hendricks et al. 2020).   
o In São Paulo, two copper sprays after petal fall are us ed to control P. citricarpa and 
other fungal pathogens (e.g.  Elsino e spp. and Diaporthe citri ), and this is followed by 
different numbers of strobilurin (quinone  outside inhibitor) sprays to prevent infection 
of fruit with P. citricarpa (Lanza et al. 2018) . 
• Since P. citricarpa is mostly reported as a citrus pathogen , and there are no native species of 
Citrus  (or Poncirus  or Fortunella ), it seems likely that environmental  impacts would be low. 
There are historic reports of a non -pathogenic form of P. citricarpa from other plant families  
(Anacardiaceae, Aquifoliaceae, Bignoniaceae, Burseraceae, Cunoniaceae, Dioscoreaceae, 
Gramineae, Lauraceae, Leguminosae, Liliaceae, Lythraceae, Magnoliaceae, Myrtaceae, 
Orchidaceae, Passifloraceae, Proteaceae, Rosaceae , Rutaceae, Solanaceae, Sterculiaceae, 
Theaceae) (Sutton and Waterston 196 6). However, records on hosts outside the Rutaceae 
are doubtful and presumably refer to Phyllosticta  capitalensis  or Guignardia  mangiferae  (Farr 
and Rossman 2020; Glienke et al. 2011 )  
 
Phyllosticta citricarpa is unlikely to cause any direct health impacts on human health:  
• Phyllosticta citricarpa is a plant pathogen and has not been reported to affect human or 
animal health.  
• However, there may be indirect impacts on human health if th ere is increased use of 
fungicides for pathogen control.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 72  
Social impacts of P. citricarpa are likely to be low, with low uncertainty:  
• Phyllosticta citricarpa can sometimes cause premature fruit  drop, which would affect the 
productivity of citrus trees in h ome gardens.  
• Damage to fruit from home gardens may make such fruit unattractive; although the damage is 
limited to the peel and is not known to affect the quality or taste of the fruit itself.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence b elow,  Phyllosticta citricarpa may be considered  
for additional measure s. 
• Phyllosticta citricarpa has a strong association with citrus fruit (most commercial citrus 
cultivars) . 
• Fruit can have latent infections that are not apparent at the time of production and 
phytosanitary inspection but develop later during transit and storage.  Therefore, basic 
measures  do very little to reduce the likelihood of entry of P. citricarpa . Consequently, the 
likelihood of entry is con sidered high, with low uncertainty.  
• Phyllosticta citricarpa has low ability (with moderate uncertainty) to move from imported fruit 
and into a suitable environment to allow establishment . 
• The New Zealand climate is likely to be suitable for the establishme nt of P. citricarpa . 
• Hosts of the pest  (e.g. Citrus) are commercially grown in New Zealand and are common ly 
grown in home garden s. 
• Phyllosticta citricarpa has been recorded to cause severe damage to citrus fruit, and there are 
high costs of control in areas with similar climate to New Zealand. Therefore, it is likely to 
cause high impacts on the citrus industry in New Zealand and moderate impact to the overall 
economy of New Zealand . 
• Phyllosticta citricarpa is present (although with restricted distribution) in several countries in 
the scope of this IRA, including  Australia, Brazil, China, the USA and possibly Korea.  
 
5.2.4 References  
Agostini, J P; Peres, N A; Mackenzie, S J; Adaskaveg, J E; Timmer, L W (2006) Effect of fung icides 
and storage conditions on postharvest development of citrus black spot and survival of Guignardia 
citricarpa  in fruit tissues. Plant Disease , 90(11): 1419 –1424. 
https://ap sjournals.apsnet.org/doi/pdfplus/10.1094/PD -90-1419   
Baayen, R P; Bonants, P J M; Verkley, G; Carroll, G C; van der Aa, H A; de Weerdt, M; van 
Brouwershaven, I R; Schutte, G C; Maccheroni, W Jr.; Glienke de Blanco, C; Azevedo, J L (2002) 
Nonpathogenic isol ates of the citrus black spot fungus, Guignardia citricarpa , identified as a 
cosmopolitan endophyte of woody plants, G. mangiferae  (Phyllosticta capitalensis ). Phytopathology , 
92(5): 464 –477. https://apsjournals.apsnet.org/doi/pdf/10.1094/PHYTO.2002.92.5.464   
Baldassari, R B; Reis, R F; de Goes, A (2006) Susceptibility of fruits of the ‘Valência ’ and ‘Natal ’ 
sweet orange varieties to Guignardia citricarpa  and the influence of the coexistence of healthy and 
symptomatic fruits. Fitopatologia Brasileira , 31(4): 337 –341. 
https://www.scielo.br/scielo.php?pid=S0100 -41582006000400002&script=sci_arttext   
Baldassari, R B; Wickert, E; Goes, A de (2008) Pathogenicity, colony morphology and diversity of 
isolates of Guignardia citricarpa  and G. mangiferae  isolated from Citrus spp. European Journal of 
Plant Pathology , 120: 103 –110. https://link.springer.com/article/10.1007/s10658 -007-9182 -0  
Boughalleb -M’Hamdi, N; Fathallah, A; Benfradj, N; Ben Mahmoud, S; Bel Hadj Ali, A; Medhioub, A;  
Jaouadi, I; Hube r, J; Jeandel, C; Ioos, R (2020) First report of citrus black spot disease caused by 
Phyllosticta citricarpa  on Citrus limon  and C. sinensis in Tunisia. New Disease Reports , 41: 8. 
http://d x.doi.org/10.5197/j.2044 -0588.2020.041.008    
73 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  BRAD (2020) Biosecurity Risk Analysis Database. Ministry for Primary Industries internal database. 
Accessed October 2020.  
Brown, N (2019) Calendar of operations . In Mooney, P (ed)  Growing Citrus in New Zealand : A 
practical guide. HortResearch and the New Zealand Citrus Growers Inc. 
https://www.zeafruit.co.nz/wp -content/uploads/2019/01/NZCGI -Grow ing-Citrus -in-NZ-A-Practical -
Guide.pdf  Accessed 29  September 2020 . 
CABI (2020 ) Guignardia citricarpa  (citrus black spot) . In Invasive Species Compendium . CAB 
International ; Wallingford, UK . www.cabi.org/isc  Accessed October  2020 . 
EFSA (2014) EFSA Panel on Plant Health, 2014. Scientific Opinion on the risk of Phyllosticta 
citricarpa (Guignardia citricarpa ) for the EU territory with identification and evaluation of risk reduction 
options.  EFSA Journal , 12(2): 3557, 243 pp. DOI :10.2903/j.efsa.2014.3557 
https://efsa.onlinelibrary.wiley.com/doi/pdf/10.2903/j.efsa.2014.3557   
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77 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  6. Pest risk assessments: Bacteria  
6.1 Xanthomonas citri pv. citri and Xanthomonas citri  pv. aurantifolii  
(citrus canker ) 
 
Xanthomonas  citri pv. citri caus es citrus canker, a serious disease of citrus worldwide. The bacteri um 
produce s raised necrotic lesions on leaves, stems and fruit. Severe infections can result in defoliation, 
twig dieback, blemishes on fruit, premature fruit drop and tree decline ( Gottwald and Graham 2000 ; 
Graham et al. 2004). Xanthomonas citri pv. aurantifolii  strains cause less common forms of the 
disease.  
 
Scientific name: Xanthomonas  citri pv. citri (Hasse) Constantin, Cleenwerck, Maes, Baeyen, Van 
Malderghem, De Vos, Cottyn  
Order/Family: Xanthomonadales/Xanthomonadaceae  
Other relevant scientific names: Pseudomonas citri , Xanthomonas campestris  pv. citri, 
Xanthomonas citri , Xanthomonas axonopodis  pv. citri, Xanthomonas smithii  subsp. citri, 
Xanthomonas citri  subsp. citri 
Common n ames:  canker, Oriental canker, Asiatic canker, Asiatic citrus canker, canker A, cancrosis 
A, pv. citri “Group A ” strains, citrus canker type A, citrus bacterial canker type A, citrus bacterial 
canker  
Acronyms:  CBC, Xcc, XCC  
Note:  The most common and widesp read form of the disease is Asiatic citrus canker (also referred to 
as canker A, cancrosis A ). The bacteria that cause this form of the disease were known as group A 
strains of Xanthomonas axonopodis  pv. citri. This pathovar is now known as Xanthomonas cit ri pv. 
citri (syn. X. citri  subsp. citri, X. campestris  pv. citri). Isolates thought to be distinct variants of strain A 
(such as A* and Aw) have also been reported (Graham et al. 2004).  
 
Scientific name:  Xanthomonas citri pv. aurantifolii (Schaad et al.) Constantin et al.  
Order/Family:  Xanthomonadales/Xanthomonadaceae  
Other relevant scientific names:  Xanthomonas axonopodis  pv. aurantifolii , Xanthomonas 
campestris pv. aurantifolii , Xanthomonas citri  f. sp. aurantifolia , Xanthomonas fuscans  subsp. 
aurantifol ii 
Common names:  cancrosis B (B strains), citrus canker, false canker (B strains), Mexican lime 
cancrosis (C strains), South American canker  
Note:  Less common forms of the disease are caused by strains of another pathovar, Xanthomonas 
citri pv. aurantifoli i (syn. X. fuscans  subsp. aurantifolii , X. axonopodis  pv. aurantifolii , X. campestris  pv. 
aurantifolii ). Cancrosis B (false canker) caused by group B strains and cancrosis C (Mexican lime 
cancrosis) caused by group C strains appear to be restricted to Sout h America (Carrera 1933 ; 
Namekata 1971). Their known hosts are limited compared with the Asiatic form.  
 
The disease citrus canker has different forms with varying distributions and host ranges. These are 
caused by different strains and variants of the same, or closely related, bacterial species. Changes in 
taxonomy and nomenclature have resulted in multiple names used for some organisms in the 
literature and in MAF/MPI documents and databases.  
 
Other pathogens have been considered in the past to cause forms of citrus canker:  
• Alternaria limicola : A form of citrus canker from Mexico known as canker D, or citru s 
bacteriosis (Rodriguez et al. 1985), was thought to be caused by group D strains. However, 
this leaf and twig spot disease of Mexican lime was later found to be caused by Alternaria 
limicola  (Das 2003 ; EFSA 2 014). 
• Xanthomonas euvesicatoria  pv. citrumelonis  (syn. X. alfalfae  subsp. citrumelonis , X. 
axonopodis  pv. citrumelo , X. campestris  pv. citrumelo ) which causes citrus bacterial leaf spot, 
was originally confused with citrus canker and named strain E (Schoulties et al. 1987 ; 
Graham et al. 2004 ). This pathogen, most often seen on citrumelo rootstock ( Citrus paradisi  × 
Poncirus trifoliata ) and its parents, has been found in nursery conditions in Florida and is 
considered to be a minor pathogen with low impact in the citrus industry (EFSA 2014).  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 78 In addition, Xanthomonas citri  pv. bilvae  has been reported to cause a bacterial spot of rutaceous 
species, including Citrus aurantifolia . However, this has been reported only from India (EFSA 2014) 
and is out of scope for this import risk a nalysis . 
 
This assessment focuses on X. citri  pv. citri and X. citri  pv. aurantifolii , which are considered to be the 
two bacteria responsible for citrus bacterial canker disease. Most of the biological information in the 
literature refers to X. citri  pv. citri, which c auses the Asiatic form of citrus canker. However, the life 
cycle of X. citri  pv. aurantifolii  is expected to be similar.  
 
Summary of conclusions:  
 
Given the arguments and evidence presented : 
 
• Xanthomonas citri  pv. citri and X. citri  pv. aurantifolii  meet the criteria to be quarantine pest s 
for New Zealand.  
• Xanthomonas citri  pv. citri and X. citri  pv. aurantifolii  have a strong association with citrus fruit  
(with low uncertainty).  
• Basic measures  are likely to reduce the entry on citrus fruit by a high  degree  (with low 
uncertainty);  consequently, the likelihood of entry is considered to be low (with moderate 
uncertainty).  
• The ability of X. citri  pv. citri or X. citri  pv. aurantifolii  to transfer from imported fruit to suitable 
host plants is low (with h igh uncertainty).  
• The suitability of the New Zealand environment for X. citri  pv. citri and X. citri  pv. aurantifolii  to 
establish is considered high  (with low uncertainty) . 
• Xanthomonas citri  pv. citri and X. citri  pv. aurantifolii  are likely to cause moderate impacts 
overall for New Zealand, but high  impacts  for the citrus industry.  
• Xanthomonas citri  pv. citri and X. citri  pv. aurantifolii  may be considered  for additional 
measures . 
 
Summary of risk assessment against criteria:  
 
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Moderate  
The ability to move from the imported commodity onto a suitable host Low High 
Suitability of the N ew Zealand  environment  High  Low 
Impacts on the New Zealand economy, environment, health and society  Moderate  Low 
 
6.1.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Xanthomonas citri pv. citri meets the 
criteria to be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause har m). 
 
Xanthomonas citri pv. citri is not known  to be present in New Zealand.  
• Xanthomonas citri  is recorded as absent from the New Zealand region in NZ Fungi2 (2020) 
and NZOR (2020).  
• Xanthomonas  c. pv. citri is recorded as eradicated from the New Zealand region in NZ Fungi2 
(2020) [listed as X. citri  subsp. citri], as eradicated/destroyed in New Zealand in NZOR (2020) 
[listed as X. citri  subsp. citri], and as eradicated in New Zealand in PPIN (2020) [listed as X. 
campestris  pv. citri and also as X. axonopodis  pv. citri].  
79 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • The disease citrus canker was first observed in New Zealand in 1937 when a campaign for its 
eradication was begun. Neither the disease nor the bacteria (referred to by Pennycook as X. 
campestris  pv. citri) have been detected in New Zealand since 1972 (Pennyc ook 1989). 
Surveys and other evidence (noted in PPIN 2020) have resulted in international acceptance 
that it has been eradicated (e.g. Smith et al. 1997).  
• New Zealand has country freedom status for X. citri  pv. citri (syn. X. campestris  citri, X. 
axonopodis  pv. citri) in the MPI country freedom status database50. 
• X. citri  pv. citri is a regulated organism in New Zealand ( ONZPR  2020).  
• X. citri  pv. citri was determined a notifiable organism in May 2002  and a regulated pest in 
June 2002 . Its status is unwanted ( ONZPR  2020).  
 
Xanthomonas citri pv. citri has the potential to establish and spread in New Zealand.  
 
Some of the countries/states where X. citri  pv. citri has been recorded (Table 7.1.3) have areas with 
similar climates to New Zealand, as indicated by climate match ind ex (CMI)  values  of >7 (Phillips et 
al. 2018), for example: China, Korea, Uruguay, Brazil, Japan.  
• Known plant hosts of X. citri  pv. citri, Citrus  species, are widely grown in a number of regions 
of New Zealand, both commerciall y and in domestic gardens . 
• The pathogen was once present in New Zealand (Pennycook 1989) but has been eradicated 
(PPIN 2020).  
 
Xanthomonas citri  pv. citri has the potential to cause economic impacts to New Zealand.  
• X. citri  pv. citri can cause economically  significant disease in citrus , which is of economic 
importance to New Zealand . 
 
Given the arguments and evidence below,  Xanthomonas citri pv. aurantifolii  meets 
the criteria to be a quarantine pest for New Zealand .  
Xanthomonas citri pv. aurantifolii  is not known  to be present in New Zealand.  
• X. citri pv. aurantifolii  is recorded as absent from the New Zealand region in NZFungi2 (2020) 
and NZOR (2020).  
• X. citri  pv. aurantifolii  is recorded as absent from the New Zealand region in NZFungi2 (2020) 
and NZOR (2020) [listed as Xanthomonas fuscans  subsp. aurantifolii  in both].  
• New Zealand has country freedom status for X. citri pv. aurantifolii  (syn. X. campestris  pv. 
aurantifolii ) in the MPI country freedom status database50. 
• X. citri  pv. aurantifolii  is a regulated organism in New Zealand and is an unwanted organism 
(ONZPR  2020) [listed as X. fuscans  subsp. aurantifolii  (syn.  X. axonopodis  pv. aurantifolia , X. 
campestris  pv. aurantifolii ) in these databases] . 
 
Xanthomonas citri pv. aurantifolii  has th e potential to establish and spread in New Zealand.  
• Some of the countries where X. citri  pv. aurantifolii  has been recorded have areas with similar 
climates to New Zealand, as indicated by climate match ind ex (CMI)  values  of >7 (Phillips et 
al. 2018), for example: Argentina, Uruguay, Brazil.  
• Known plant hosts of X. citri pv. aurantifolii , Citrus  species, are widely grown in a number of 
regions of New Zealand, both commercially and in domestic gardens . 
 
Xanthomonas citri  pv. aurantifolii  has the potential to  cause economic impacts to New Zealand.  
• X. citri  pv. aurantifolii can cause economically significant disease in citrus , which is of 
economic importance to New Zealand . 
 
                                                      
50 MPI country freedom status database: https://www .mpi.govt.nz/news -and-resources/resources/registers -and-lists/country -
freedom -status/  Accessed September 2020.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 80 6.1.2 Hazard identification: commodity association  
Xanthomonas citri pv. citri and X. citri pv. aurantifolii are associated with citrus fruit . 
 
Xanthomonas citri pv. citri is reported from citrus fruit.  
• X. citri  pv. citri is a bacterial pathogen that causes distinctive necrotic raised lesions on 
leaves, stems and fruit of citrus (Schubert et al. 2 001).  
 
Xanthomonas citri  pv. aurantifolii  is reported from citrus fruit.  
• Cancrosis B (caused by X. citri  pv. aurantifolii ) produces canker -type lesions on fruit, leaves 
and twigs that are similar to  but smaller than those caused by the A form (Gottwald and 
Graham 2000).  
• Symptoms for Cancrosis C are the same as for those of canker A [ X. citri  pv. citri] (Graham 
and Gottwald 2000).  
6.1.3 Risk assessment  
Most biological information in the literature is in rel ation to X. citri  pv. citri. For this assessment, it is 
assumed that X. citri  pv. citri and X. citri  pv. aurantifolii hav e similar life cycles. Information specific to 
X. citri  pv. aurantifolii  is given for citrus hosts, geographic distribution, climate si milarities and impacts ; 
otherwise , it is assumed that biological information for X. citri  pv. citri is applicable to both.  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  X. citri pv. citri and X. citri  pv.aurantifolii  
have a strong association with citrus fruit , with low uncertainty . 
• Occurrence of X. citri  pv. citri on fruit may be associated with lesions, injuries or blemishes, or 
may be epiphytic on the fruit surface (contamination).  
• Lesions start as pinpoint spots t hat enlarge over time to become corky eruptions with raised 
margins and sunken centres. The area around the lesion may have an oily or water -soaked 
appearance, and lesions become surrounded by characteristic yellow halos. Lesions on fruit 
can vary in size due to both age and fruit susceptibility and are up to 1mm deep in the fruit 
rind (Gottwald and Graham 2000 ; Gottwald et al. 2002).  
• The multiplication of X. citri  pv. citri bacteria occurs at the lesion margin and occurs mostly as 
the lesion is still expan ding (Gottwald and Graham 2000). The bacteria remain alive in the 
margins of lesions on the fruit until they fall and begin to decompose (Gottwald and Graham 
2000 ; Gottwald et al. 2002).  
• Cancrosis B (caused by X. citri  pv. aurantifolii ) produces canker -type lesions on fruit, leaves 
and twigs that are similar to but smaller than those caused by the A form (Gottwald and 
Graham 2000). Symptoms for cancrosis C are the same as for those of canker A [ X. citri  pv. 
citri] (Graham and Gottwald 2000).  
 
Plant hosts for X. citri  pv. citri and X. citri  pv. aurantifolii  include Citrus  spp. and close relatives.  
• Hosts of X. citri  pv. citri belong primarily to the plant family Rutaceae. They include most 
Citrus  species and hybrids between citrus species and tri foliate orange Poncirus trifoliata  
(Graham et al. 2004) (Table  7.1.1 and Table 7.1.2).  
• The host range of the X. citri  pv. citri pathotype A strain includes (but is not confined to) sweet 
orange ( Citrus sinensis ), grapefruit ( C. paradisi ), lemon ( C. limon ) and Mexican (key) lime ( C. 
aurantiifolia ) (EFSA 2014 ; Brunings and Gabriel 2003).  
• Variants of the bacterium  that are phylogenetically close but appear to be pathologically 
distinct in host range  have  also been reported, but from fewer hosts: the A* strai n has been 
found primarily on Mexican lime (Verniere et al. 1998) , and the Aw strain (also known as the 
Wellington strain)  has been found  on Mexican lime and alemow plants ( C. macrophylla ) (Sun 
et al. 2004 ; Rybak 2005 ; da Graca et al. 2017).  
• Citrus  species  vary in their level of susceptibility (Gottwald and Graham 2000):  
o Grapefruit ( C. paradisi ), lime ( C. aurantifolia ) and trifoliate orange ( Poncirus trifoliata ) 
are highly susceptible .  
81 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  o Sour orange ( C. aurantium ) and sweet orange ( C. sinensis ) are moderately  
susceptible . 
o Most mandarin cultivars ( C. reticulata ) are moderately resistant.  
• The re lative susceptibility/resistance of commercial citrus cultivars and species to citrus 
canker is presented in Table 7.1.2. 
• The known host range for X. citri  pv. aurantifol ii is much more restricted than for X. citri  pv. 
citri (Table 7.1.1). 
 
Table 7.1.1 Pathovar, pathotype classification and host range of xanthomonads causing citrus canker  
(based on Table 2, EFSA 2014)  
Species  Xanthomonas citri  
Pathovar (a) citri aurantifolii  
pathotype  A A* (Aw) B C 
Disease  Asiatic canker  South American canker  
Host range  Citrus  spp. (b) 
Several other 
rutaceous genera, 
e.g. Ponciru s, 
Fortunella  C. aurantiifolia  
C. macrophylla  
(C. latifolia)  
(C. sinensis, C. 
paradisi)  (c) C. aurantiifolia  
C. limon  
C. aurantium  
(C. sinensis)  C. aurantiifolia  
(P. trifoliata × C. 
paradisi)   
In bold: main host species in field conditions; in brackets: host species rarely infected in the field.  
(a): A pathovar is an infraspecies taxon. “The term pathovar is used to refer to a strain or set of strains with the same or 
similar characteristics, differentiated at infrasubspecific level from other strains of the same species or subspecies on the  
basis of distinctive pathogenicity to one or mor e plant hosts .” (Young et al. 1991 ; Young et al. 2001)  
(b): With differential host susceptibility among species and/or cultivars. Many commercial cultivars range from susceptible 
to very susceptible (Gottwald et al. 2002) (Table 7.1.2 ). 
(c): Reported for s trains originating from Iran (Escalon et al. 2013).  
 
Table 7.1.2 Relative susceptibility/resistance to citrus canker of commercial citrus cultivars and species  
(from Gottwald et al. 2002)  
Rating  Citrus  cultivars  
Highly resistant  Calamondin ( C. reticulata ); Kumquats ( Fortunella  spp.)  
Resistant  Mandarins ( C. reticulata ) – Ponkan, Satsuma, Tankan, Satsuma, Cleopatra, Sunki, Sun Chu 
Sha 
Less susceptible  Tangerines, Tangors, Tangelos ( C. reticulata  hybrids);  
Cravo, Dancy, Emperor, Fallglo Fairchild , Fremont, Clementina, Kara, King Lee, Murcott, 
Nova, Minneola, Osceola, Ortanique, Page, Robinson, Sunburst, Temple, Umatilla, Willowleaf 
(all selections);  
Sweet oranges ( C. sinenesis ) – Berna, Cadenera, Coco, Folha Murcha, IAPAR  
73, Jaffa, Moro, Lima, M idsweet, Sunstar, Gardner, Natal, Navelina, Pera, Ruby Blood, 
Sanguinello, Salustiana, Shamouti, Temprana and Valencia;  
Sour oranges ( C. aurantium ) 
Susceptible  Sweet oranges – Hamlin, Marrs, Navels (all selections), Parson Brown, Pineapple, Piralima , 
Ruby, Seleta Vermelha (Earlygold), Tarocco, Westin;  
Tangerines, Tangelos – Clementine, Orlando, Natsudaidai, Pummelo ( C. maxima ); 
Limes ( C. latifolia ) – Tahiti lime, Palestine sweet lime;  
Trifoliate orange ( Poncirus trifoliata );  
Citranges/Citrumelos ( P. trifoliata  hybrids)  
Highly susceptible  Grapefruit ( C. paradisi );  
Mexican/Key lime ( C. aurantiifolia ); 
Lemons ( C. limon );  
Pointed leaf Hystrix ( C. hystrix ) 
 
Xanthomonas citri  pv. citri and X. citri  pv. aurantifolii  are present in some citrus export c ountries that 
are considered in this import risk analysis . 
• Citrus canker is endemic in India, Japan and other South east Asian countries from where it 
has spread to all other citrus -producing continents except Europe (Das 2003).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 82 • The known geographic distri bution of X. citri  pv. citri is listed in Table 7.1.3  (EPPO 2020 and 
references)51. 
• X. citri  pv. citri is present in the following citrus export countries that are under consideration:  
o Brazil, China, Korea, Japan, Viet  Nam, Australia, Fiji, Solomon Islands,  USA 
o Mexico: transient, actionable and under eradication  
• X. citri  pv. aurantifolii  has been reported only from South America (Gottwald and Graham 
2000):  
o The B strain has been reported from Argentina, Paraguay  and Uruguay. This strain 
appears to have disappeared in Argentina since the introduction of the more 
aggressive A strains ( X. citri  pv. citri) (Canteros et al. 2017 ; Fonseca et al. 2019).  
o The C strain has been reported from Brazil (Jaciani et al. 2009).  
o Brazil is one of the citrus export countries under consideration . 
 
Table 7.1.3. Known geographic distribution of citrus canker . Information compiled in September 2020 from 
EPPO 2020. Countries in bold  are included in the scope of this risk assessment.  Countries underlined  have 
records for both X. citri  pv. citri and X. citri  pv. aurantifolii . 
Continent/Region  Country (province/state)  
Africa  Burkina Faso, Comoros, Congo (Democratic Republic), Ethiopia, Gabon, Ivory 
Coast, Madagascar, Mali, Mauritius, Mayotte, Réunion, Senegal, Seychelles, 
Somalia, Sudan, Tanzania  
North America  USA , Mexico  (transient, actionable and under eradication)  
Central America 
and Caribbean  British Virgin Islands, Martinique (transient, under eradication)  
South America  Argentina , Bolivia,  Brazil , Paraguay , Uruguay  
Asia Afghanistan, Bangladesh, Cambodia, China , Christmas Island, Cocos Islands, 
East Timor, India, Indonesia, Iran, Iraq, Japan , Korea (Democratic People's 
Republic), Korea (Republic of),  Laos, Malaysia, Maldi ves, Myanmar, Nepal, 
Oman, Pakistan, Philippines, Saudi Arabia, Singapore, Sri Lanka, Taiwan, 
Thailand, United Arab Emirates, Viet Nam, Yemen.  
Oceania  Australia, Fiji,  Guam, Marshall Islands, Micronesia, Northern Mariana Islands, 
Palau, Papua New Guinea, Solomon Islands  
 
Given the arguments and evidence below, the basic measures  are likely to reduce 
the entry of X. citri  pv. citri and X. citri pv. aurantifolii  on citrus fruit by a high degree; 
consequently, the likelihood of entry is considered to be  low (with moderate 
uncertainty).  
Some degree of disease management is likely to take place in the field for commercial production of 
citrus.  
• The disease citrus canker can reduce both the quality of the citrus fruit itself and the quantity 
that is produced . Therefore, some degree of disease management is likely to occur where 
citrus is grown commercially.  
• The prevalence of X. citri  pv. citri in citrus groves depends upon environmental conditions and 
management practices. Management practices to reduce the amount of disease, such as 
cultural practices and copper sprays (Gottwald and Graham 2000), result in fewer disease 
symptoms on fresh fruit for consumption. However, the specific activities that take place 
cannot be assumed and are unlikely to eliminate th e pathogen.   
 
Symptomatic fruit are likely to be detected and removed from consignments.  
• Occurrence of X. citri  pv. citri on fruit may be associated with lesions, injuries or blemished. 
Lesions on symptomatic fruit are obvious with a characteristic appearance and can be readily 
detected visually.  
                                                      
51 EPPO notes that the taxonomy of bacteria associated with citrus canker has been subject to many changes and that because 
their di stribution list was established over a long period of time, it might cover taxa that are now considered to be separate (i.e. 
X. citri  subsp. citri and X. fuscans  subsp. aurantifolii ).  
83 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • For commercial reasons, blemish -free fruit will be preferred over fruit that a ppears damaged 
when harvested as fresh fruit for consumption. It is likely that a certain amount of culling to 
remove symptomatic and other blemished, damaged or misshapen fruit will take place in the 
field at harvest. This can be highly effective in remov ing symptomatic fruit before reaching the 
packing house. Inspections at the packing house further reduce the likelihood of symptomatic 
fruit being packed. Ploper et al. (2004, in USDA 2007) reported that culling procedures in 
Argentina resulted in very low  numbers (near zero) of symptomatic fruit reaching the packing 
bench and zero symptomatic fruit packed in boxes during their study.  
 
However, some symptomatic fruit may go unnoticed during the export production process.  
• During visual inspection, small lesi ons may escape detection or be attributed to other causes 
that produce similar symptoms (EFSA 2014).  
• Importation of citrus to the EU requires that the fruit be free of symptoms of citrus canker 
disease. Despite this requirement, canker -like symptoms have b een detected on commercial 
citrus fruit imported from countries outside the EU by Spanish inspection services at ports of 
entrance and packing houses. Subsequent diagnostic tests (isolation and PCR -based 
methods) detected viable X. citri  pv. citri bacteria  in the lesions (Golmohammadi et al. 2007).  
 
General handling and processing after harvesting are likely to reduce the number of viable X. citri  pv. 
citri and X. citri  pv. aurantifolii  bacterial cells by a high degree but are unlikely to remove all  X. citr i pv. 
citri and X. citri  pv. aurantifolii  from citrus fruit.  
• Occurrence of X. citri  pv. citri on fruit may be associated with lesions, injuries or blemishes, or 
it may be epiphytic on the surface (contamination) of fruit that otherwise appears healthy 
(Gottwald et al. 2009).  
• The viability of  X. citri  pv. citri bacteria on fruit reduces after harvest whether in lesions or on 
the fruit surface (Gottwald et al. 2009). Epiphytic bacteria appear to be short -lived after fruit 
harvest , with experiments on satsuma mandarin s under natural conditions showing survival 
on the fruit surface decreasing significantly after three days (Shiotani et al. 2009). 
Consequently, development of citrus canker disease on the fruit between harvest and packing  
house is unlikely.  
• Packing  house processes for cleaning fruit, such as brushing, washing with detergents and 
disinfectants, and drying, all act to reduce the epiphytic X. citri  pv. citri populations (USDA 
2009). Brushing increases the exposure of citrus canker to toxicants. Disinfectants such as 
chlorine and sodium  ortho -phenylphenate (SOPP) further reduce inoculum levels. Washing 
before disinfecting removes organic matter and increases the effectiveness of disinfection 
treatments. Experimental work has shown that processing that includes pre -washing fruit with 
detergent over brushes followed by a disinfectant treatment further reduces amounts of X. citri  
pv. citri inoculum on infected or contaminated fruit (Gottwald et al. 2009 ; USDA 2009). Drying 
the fruit contributes to the reduc tion of  epiphytic bacteria populations (Schubert et al. 2001). 
The cumulative effect of these treatments reduces the prevalence of viable X. citri  pv. citri 
and, therefore, the inoculum associated with commercially packed and disinfected fruit (USDA 
2009).  
• However, disinfectant treatments such as chlorine and SOPP do not fully eliminate viable 
bacteria from fruit (Gottwald et al. 2009 ; Golmohammadi et al. 2007).  
• In addition, a viable but not culturable (VBNC) state has been proposed for X. citri  pv. citri in 
response to copper ions and other environmental stresses (Golmohammadi et al. 2013). 
Bacterial cells in this state would not be detected in by plating samples on agar media , which 
means that experimental work using such methods may underestimate th e number of viable 
bacteria present.  
• The specific post -harvest activities that take place in the packhouse cannot be assumed or 
guaranteed and are unlikely to eliminate the pathogen from the citrus commodity 
(Golmohammadi et al. 2007).  
 
Xanthomonas citri  pv. citri and X. citri  pv. aurantifolii  are likely to survive transit of citrus commodities.  
• Storage and transport of citrus consignments from exporting countries to New Zealand are 
likely to occur at cool temperatures, with the length of time for shipment depending on the 
exporting country. For example, transport of fruit by sea from Korea may take up to three 
weeks and more than three weeks from Brazil. Storage temperatures may vary depending on 
the citrus variety (EFSA 2014).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 84 • Low temperatures are not expe cted to have a n impact on the survival of X. citri  pv. citri (Goto 
1962, in EFSA 2014). However, the amount of viable X. citri  pv. citri bacteria decreases over 
time, both for fruit that ages on the tree and for fruit in cold storage (Gottwald et al. 2009) .  
• Commercial packing  house procedures that include antimicrobial treatments can reduce 
populations of X. citri  pv. citri on the surfaces of harvested fruit to a very low level (Gottwald et 
al. 2009). The bacteria have a limited ability to survive epiphyti cally, so surface populations 
are likely to decline further over the transit period.  
• Gottwald et al. (2009) found that packhouse processes can reduce canker lesion activity by 
as much as 50% compared with unprocessed citrus fruit.  
• Therefore, the condition s under which commercial citrus fruit consignments are processed, 
disinfected and packed, and the duration of time between harvest and market reduce the 
likelihood that viable pathogenic X. citri  pv. citri bacteria will survive the journey.  
• However, viable  X. citri  pv. citri bacteria in lesions have been demonstrated to survive transit 
on imported fresh citrus fruit even when fruit has been treated with officially approved 
chemicals (Golmohammadi et al. 2007 ; EFSA 2014).  
 
The level of uncertainty in relation to entry is rated as moderate because the prevalence of citrus 
canker in areas of production may vary, along with details of in -field pest management activities, post -
harvest activities and duration of transit.  
 
Likelihood of establishment:  
 
Given  the arguments and evidence below,  Xanthomonas citri  pv. citri and X. citri  pv. 
aurantifolii  have a low ability (with high uncertainty) to move from imported fruit and 
into a suitable environment to allow establishment, that is, onto a host plant .  
Xanthom onas citri  pv. citri and X. citri  pv. aurantifolii  can survive on the skin of discarded citrus fruit 
and fruit pieces.  
• The imported fresh citrus fruit is intended for human consumption , and waste material would 
be generated, including the fruit skin or pee l, even for fruit that is consumed.  
• X. citri  pv. citri bacteria in lesions on the fruit surface have been demonstrated to survive 
transit on imported fresh citrus fruit even when fruit has been treated with officially approved 
chemicals (Golmohammadi et al . 2007 ; EFSA 2014).  
 
Most citrus fruit waste in New Zealand is likely to be disposed of using low -risk methods , so X. citri  pv. 
citri and X. citri  pv. aurantifolii  would be unable to spread from the infected fruit.  
• Most kitchen  waste in New Zealand is either bagged and sent to landfill or run through kitchen 
disposal units (see section  2.4.1, waste analysis). X. citri  pv. citri or X. citri  pv. aurantifolii  in 
infected or contaminated fruit is unlikely to reach a new host in these  circumstances.  
 
However, some waste is likely to be disposed of using high -risk methods, including composting in 
gardens, use as animal feed, cull piles or discard ing directly into the environment.  
• A small proportion of infected or contaminated fruit or p eel is likely to be discarded in a home 
compost bin or open compost heap, or directly into the environment in gardens, roadsides, 
parks and public areas (see section 2.4.1, waste analysis). Cull piles may occur when large 
amounts of fruit are sorted and ma y be used for animal feed in outdoor environments.  
 
The likelihood of X. citri  pv. citri or X. citri  pv. aurantifolii  reaching citrus hosts if infected fruit or peels 
are discarded nearby is very low . 
• Bacteria on plant surfaces die within hours from desicc ation and exposure to direct sunlight 
(Graham et al. 2000, in Graham et al. 2004).  
• When diseased fruit and leaves drop to the ground, bacterial populations decline to non -
detectable levels in 1 –2 months because of antagonism and competition with saprophyti c 
microorganisms (Graham et al. 1989). Bacteria survive only a few days in soil, although they 
may last a few months in plant refuse in soil (Graham et al. 1989).  
• Goto et al. (1978) observed canker leaf lesions on C. natsudaidai  from splash dispersal 
(prod uced by a rainfall simulator) of rice straw contaminated with low concentrations of X. citri   
85 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  pv. citri. They concluded that infected plant tissues on soil can provide inoculum for the 
infection of wounded susceptible seedlings by splash dispersal (EFSA 201 4). 
• There has been little research into the probability of transfer of X. citri  pv. citri from infected 
fruit to citrus trees. Gottwald et al. (2009) performed a series of experiments to investigate the 
possibility of transmission of X. citri  pv. citri from discarded cull piles of symptomatic fruit. 
Transmission did not occur under natural conditions in their study. However, in one instance 
in highly contrived conditions, a single lesion was formed on a trap plant at 0 metres from the 
cull pile (Gottwald et  al. 2009). EFSA (2014) concluded that it is difficult to extrapolate their 
results to a situation where symptomatic fruit or peel ha s been discarded underneath or very 
close to susceptible mature citrus trees. The lower branches of citrus trees can be ver y close 
to the soil level , and these conditions can be very similar to the zero -metre situation for which 
an infection was observed by Gottwald et al. (2009) from fruit.  
• Citrus  that is discarded using high -risk methods ha s the  potential to end up in close proximity 
to low -hanging citrus branches, as described above, especially in domestic gardens. 
However, there is a low likelihood of the combination of factors required for successful 
transfer of citrus canker inoculum to new host plants taking place.  
 
There is potential for human touch  to transfer the pathogens to citrus after handling infected fruit.  
• Nursery workers can carry bacteria from one nursery to another on hands, clothes and 
equipment, and spread can also result from movement of contaminated p runing, hedging and 
spray equipment (Das 2003). Therefore, there is potential for bacteria to be transferred to a 
host plant by people handling infected fruit, although this is not likely to be a frequent 
situation.  
 
The level of uncertainty associated wi th this conclusion is high. Waste data may not be very accurate 
or up to date (see section  2.4.1, waste analysis). It is uncertain what proportion of composting sites 
are exposed or uncovered (e.g. in a compost bin). The role of infected citrus fruit or pe el as a source 
of primary inoculum allowing the transfer to susceptible host plants nearby is not well understood.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for X. citri  pv. citri and X. citri  pv. aurantifolii  to establish is considered  
high.  
Climatic conditions in New Zealand are favourable for X. citri  pv. citri and X. citri  pv. aurantifolii  to 
establish, especially in the north of New Zealand where most commercial Citrus is grown.  
• Citrus canker occurs in areas of the world where high rainfall and high temperatures co -exist 
(CABI 2020). Establishment and spread is favoured by warm (20 –32°C), wet conditions (Miles 
et al. 2009). During wet weather, bacteria ooze out of lesions and are spread by windblown 
rain to form new infections. Bacterial cells enter the plant tissue though natural openings such 
as stomata or wounds from insect feeding or physical damage. Entry through stomata is most 
effective before leaf tissues have fully expande d and cuticle and waxes have formed on the 
tissue surface (Miles et al. 2009). The disease occurs in severe form in seasons and/or areas 
characterised by warm and humid weather conditions (Das 2003).  
• Some of the areas where X. citri  pv. citri has been reco rded (see Table 7.1.3 ) have a similar 
climate to New Zealand, as indicated by climate match ind ex (CMI)  values  >7 (Phillips et al. 
2018), for example:  
o All New Zealand climate match: Argentina (CMI 0.7 –0.9); Uruguay (mostly 0.8 –0.9 
CMI); Brazil (parts of Paraná with 0.7 –0.8 CMI, Rio Grande do Sul: 0.7 –0.9 CMI, 
Santa Cat arina: 0.7 –0.9 CMI, parts of S ão Paulo with 0.7 –0.8 CMI; Bolivia (parts with 
0.7–0.8 CMI); USA (parts of Florida with 0.7 CMI ; parts of Texas with 0.7 –0.8 CMI); 
Japan (parts of Shikoku with 0 .7 CMI ; most of Honshu with 0.7 –0.8 CMI); China 
(parts of Chongqing, Fujian, Guizhou, Hubei, and Hunan with CMI 0.7; parts of Gansu 
and Yunnan with 0.7 –0.8 CMI; parts of Sichuan with 0.8 CMI), Republic of Korea 
(parts with 0.7 CMI)  
• X. citri  pv. citri has been previously established in New Zealand (recorded in Northland, 
Coromandel, Bay of Plenty  and Taranaki (PPIN 2020 ; Pennycook 1989) but has been 
eradicated (PPIN 2020).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 86 • Some of the areas where X. citri  pv. aurantifolii  have been recorded have a similar climate to 
New Zealand: northeastern Argentina (0.8 –0.9 CMI), Uruguay (0.8 –0.9 CMI) and the state of 
São Paulo Brazil (parts of S ão Paulo with 0.7 –0.8 CMI).  
 
Once established , Xanthomonas citri  pv. citri and X. citri  pv. aurantifolii  can spread to new host plants.  
• X. citri  pv. citri bacteria that multiply in lesions rely on free water for dispersal (Gottwald et al. 
2002). Free moisture on the lesion surface allows bacteria to be released in a polysaccharide 
matrix that prevents bacteria from drying out. Bacteria exude from lesions during wet weather 
and are disseminated by splash dispersal at short range, windblown rain at medium to long 
range and human -assisted movement at all ranges (Graham et al. 2004).  
• Windblown inoculum of X. citri  pv. citri was detected 32 m from  infected trees in Argentina 
(Stall et al. 1980, in EFSA 2014). Wind speeds of at least 8 m/s help bacteria to penetrate the 
stomata and other openings such as wounds (Graham et al. 1992). Water congestion of leaf 
tissues can be seen during rainstorms. Wat er congestion during inoculation with as few as 1 –
2 bacterial cells, forced through stomatal openings, can lead to infection and lesion formation 
(Gottwald and Graham 1992, Graham et al. 1992). Dispersal over longer distances has been 
observed after weathe r events such as thunderstorms, typhoons and hurricanes. For 
example, in Florida, dispersal over distances of 10 –15 km has been attributed to storm events 
(Gottwald et al. 1997).  
• Contaminated equipment and persons can also transmit inoculum. Long -distance spread 
normally occurs by human movement of diseased or exposed citrus plant material or by use 
of equipment contaminated by diseased citrus (S chubert et al. 2001) . 
• All aboveground plant parts are susceptible to infection (Leite and Mohan 1990). Bacteria 
enter plant tissues though openings such as stomata, lenticels or wounds (Gottwald and 
Graham 1992; Graham et al. 2004). The most susceptible plant tissues are young tissues that 
are expanding. Vigorously growing trees are most susceptible to infection by X. citri  pv. citri. 
Citrus  trees that have several growth flushes each growing season will have corresponding 
periods of increased susceptibility (Graham et al. 2004). Trees are most susceptible to 
disease when growth flushes coincide with warm temperatures  (20–32°C), high rainfall and 
wind.  
 
Known plant hosts of X. citri  pv. citri and X. citri  pv. aurantifolii  are available in New Zealand.  
• Host species for X. citri  pv. citri are found within the plant family Rutaceae. They include many 
Citrus  species and hybrids between citrus species and trifoliate orange ( Poncirus trifolata ) 
(Graham et al. 2004) (Table 7.1.1 and Table 7.1.2).  
• Host records in New Zealand prior to the pathogen being eradicated include Citrus limon , 
C. reticulata , C. sinensis , Citrus  sp. (citronelle) and Citrus  sp. (grapefruit ) (Pennycook 1989).  
• There are fewer recorded hosts for X. citri  pv. aurantifolii : both strains B and C occur on 
C. aurantifolii , and strain C has been recorded on several other citrus varieties, including  
lemon ( C. limon ) (Table 7.1.1).  
• Citrus  species are widely grown in a number of regions of New Zealand, both commercially 
and in domestic gardens. Commercial production takes place in both the North and South 
Islands, with the main areas being Northland, Auckland, Bay of Plenty, Hawke’s Bay and 
Gisborne ( Plant & Food Research 2019) (see section 2.4.2 ). Commercial crops include 
oranges, mandarins, lemons, tangelos, limes and grapefruit ( Plant & Food Research 2019). 
(see section 2.5.2 ). Lemons are grown in d omestic gardens through much of the country.  
• Given that citrus is grown widely in New Zealand, especially in the North Island, and given 
that citrus canker has previously established in several citrus production areas in New 
Zealand, potential host plants are likely to occur in climatically suitable areas for 
establishment.  
 
Given the arguments and evidence below, the level of impact caused by  X. citri  pv. 
citri and X. citri  pv. aurantifolii  is likely to be moderate for New Zealand overall  (with 
low uncertainty) . 
 
Damage and symptoms of X. citri  pv. citri and X. citri  pv. aurantifolii  can reduce citrus fruit quantity 
and quality.   
87 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • The disease citrus canker is considered devastating to citrus , causing extensive damage to 
crops (Das 2003). Severe infecti on of the foliage can cause defoliation of trees. Severely 
blemished fruit can drop prematurely, leading to reduced yield and marketability as fresh fruit , 
although the internal quality of mature fruit with lesions is unaffected and is still edible and 
usable for juice.  
 
Xanthomonas citri  pv. citri and X. citri  pv. aurantifolii  cause disease on  citrus , with impacts on 
commercial production, including in areas with similar climates to New Zealand.  
• In Argentina, 83 –97% of the fruit of grapefruit trees were diseased in unsprayed plots during 
1979 –1980 , and, in the same plots, up to 88% of the leaves of summer growth flushes were 
infected. Up to 15% of fruit from unsprayed grapefruit plots fell prematurely to the ground 
(Stall and Seymour 1983). Premature frui t drop of up to 50% was reported for sweet orange 
cv. Hamlin and other cultivars.  
o Argentina has a similar climate to New Zealand, as indicated by CMI values of 0.7 –
0.9 (Phillips et al. 2018) , especially in the northeastern part of the country where 
much ci trus is grown and where X. citri  pv. citri has had severe impacts on the 
industry (Canteros et al. 2017).  
• The cost for living with citrus canker in Florida, USA was estimated to be US$342 million per 
year in 2001 (Gottwald et al. 2002). The estimates were for commercial disease management 
costs and crop losses only.  
• The total cost of a major national outbreak of citrus canker in Australia has been assessed at  
$410  million  (Alam and Rolfe 2006). If the citrus industry were closed down in Australia for 
five years, it has been estimated that over $2 billion in direct revenue would be taken out of 
mainly rural communities (Alam and Rolfe 2006).  
• An indirect consequence of the disease is the loss of fruit export markets (e.g. the European 
Union, Chile, Israel, Ne w Zealand ) for countries or areas where satisfactory control of the 
disease cannot be achieved ( EPPO 2020 ; EFSA 2014).  Countries and areas that have citrus 
canker as a quarantine pest are listed in the EPPO Global Database (EPPO 2020).  
• Host species for X. citri pv. citri include many commercially grown Citrus  species and hybrids 
between citrus species and trifoliate orange Poncirus trifolata  (Graham et al. 2004). Some 
species and cultivars, such as grapefruit ( C. paradisi ), Mexican lime ( C. aurantiifolia ) and 
hybrids of trifoliate orange used for rootstock, are more susceptible than others. Therefore, all 
citrus grown commercially in New Zealand could potentially be affected by the disease to 
some degree.  
• X. citri  pv. aurantifolii  has a more restricted host  range; nevertheless, commercially grown 
citrus crops would be directly affected by the disease, particularly lemon s and Mexican limes, 
and indirect effects from its presence would still occur.  
• If X. citri  pv. citri or X. citri  pv. aurantifolii  established, then a considerable long -term effect on 
the citrus industry would be expected through lowered production, increased management 
activities and reduced access to or increased requirements for overseas markets where the 
disease is absent.  
• Citrus  canker occurs in areas of the world where high rainfall and high temperatures co -exist 
(CABI 2020). Should it establish again in New Zealand, the disease itself is likely to have the 
greatest impact on citrus production in warmer and wetter regions, such as Northland , which 
is one of the main commercial production areas for citrus in the country.  
 
Establishment or an incursion of X. citri  pv. citri or X. citri  pv. aurantifolii  is highly likely to cause trade 
impacts.  
• The discovery of the presence of X. cit ri pv. citri or X. citri  pv. aurantifolii  in New Zealand is 
likely to have an immediate impact on exports of citrus because of the quarantine status of 
the pathogen in some countries that are markets (e.g. European Union). An MPI Organism 
Ranking System evaluation of X. citri  pv. citri in 2014 es timated that the immediate impact on 
trade would be moderate.  
 
If X. citri  pv. citri or X. citri  pv. aurantifolii  were detected in New Zealand, the cost incurred by a 
response would be high.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 88 • As X. citri  pv. citri is one of the priority species for the Cit rus industry’s Government Industry 
Agreement (GIA), an eradication programme is likely to be undertaken , which would probably 
result in the large -scale removal of citrus plants.  
• Eradication of past citrus outbreaks in Australia have cost growers and govern ments 
hundreds of millions of dollars and resulted in destruction of large areas of host trees (Miles et 
al. 2009). An eradication campaign for citrus canker in Emerald, Australia, completed in early 
2009, was estimated to cost AU$17.6 million and required  in excess of 200 ,000 staff hours to 
complete (Gambley et al. 2009).  
• Similarly, it is likely that a response programme would be undertaken for X. citri  pv. aurantifolii  
if detected in New Zealand.  
• Around 1,660 ha is planted in Citrus  for commercial product ion in New Zealand , with 316 
growers producing 34,096 tonnes. Domestic consumers spend approximately NZ$18 million 
on oranges and $40.5 million on other citrus fruits. Citrus has an export value of $12 million 
(Plant & Food Research 2019).  
 
It is likely th at X. citri  pv. citri and X. citri  pv. aurantifolii  will cause a low level of sociocultural impacts 
in New Zealand.  
• The main hosts of X. citri  pv. citri are Citrus  spp., which are commonly grown in domestic 
gardens in New Zealand, particularly in warmer regions in the north . Lemons occur widely 
through out the country domestically. X. citri  pv. aurantifolii  has a more restricted host range ; 
however , strain C affects lemons .  
• The disease would affect both appearance and productivity, although blemished fruit would 
still be suitable for consumption, and some varieties and cultivars are more resistant than 
others. Plants may require additional management such as copper sprays to ensure quality 
and quantity of fruit.  
 
It is likely that X. citri  pv. citri and X. citri  pv. aurantifolii  will have a very low level of impact on the 
environment.  
• Citrus species, which are the primary hosts of X. citri  pv. citri and X. citri  pv. auranti folii, are 
members of the Rutaceae family. There are two genera within Rutaceae endemic to 
New Zealand: Melicope  and Leionema . Neither Leionema  nor Melicope  species are 
considered threatened (NZPCN 2020).  
 
Xanthomonas citri  pv. citri and X. citri  pv. auran tifolii are not known to have any unwanted impacts on 
human health.  
 
Risk assessment summary : 
 
Given the arguments and evidence below,  Xanthomonas citri  pv. citri and X. citri  pv. 
aurantifolii  may be considered for additional measure s. 
• X. citri  pv. citri and X. citri  pv. aurantifolii  have a strong association with citrus fruit.  
• The basic measures  are likely to reduce the entry of X. citri  pv. citri and X. citri  pv. aurantifolii  
on citrus fruit by a high degree. However, some infested fruit will not be detected, especially 
when the volume of commodities is large, and general handling (e.g., washing and brushing) 
does not completely eliminate viable bacteria from fruit. Consequent ly, the likelihood of entry 
is considered to be low (with moderate uncertainty).  
• X. citri  pv. citri and X. citri  pv. aurantifolii  have a low ability (with high uncertainty) to move 
from imported fruit and into a suitable environment to allow establishment,  that is, onto a host 
plant.  
• The suitability of the New Zealand environment for X. citri  pv. citri and X. citri  pv. aurantifolii  to 
establish is considered high.  
• Citrus hosts of X. citri  pv. citri and X. citri  pv. aurantifolii  are grown commercially in 
New Zealand and are common garden plants.  
• The level of impact caused by X. citri  pv. citri and X. citri  pv. aurantifolii  is likely to be 
moderate for New Zealand overall, but high for the citrus industry.  
• X. citri  pv. citri is present in several citrus export ing countries considered in this import risk 
analysis : Brazil, China, Korea, Japan, Viet  Nam, Australia, Fiji, Solomon Islands, USA and 
Mexico.   
89 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • X. citri  pv. aurantifolii  is present in one citrus -exporting country considered in this import risk 
analysis : Brazil.  
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93 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  7.  Pest risk assessments: Oomycetes  
7.1 Phytophthora palmivora  (brown rot, gummosis of citrus)  
 
Phytophthora palmivora  is an oomycete (or water mould)  that causes brown rot of citrus fruit. It also 
causes other diseases such as root rot and dieback in citrus and many other host plants.  
 
Scientific name: Phytophthora palmivora  (E.J. Butler) E.J. Butler  
Class/Order/Family : Oomycetes/Peronosporales/Perono sporaceae  
Other names include: Phytophthora arecae, Phytophthora cactorum var. arecae, Phytophthora 
faberi, Phytophthora hevae, Phytophthora omnivora var. arecae, Phytophthora palmivora var. heveae, 
Phytophthora palmivora var. theobromae, Phytophthora theobromae , Pythium palmivorum  (CPC 
2020)  
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Phytophthora palmivora  meets the criteria to be a quarantine pest for New Zealand.  
• Phytophthora palmivora  has a moderate association with most citrus fruit types, with 
moderate to high uncertainty.  
• Basic measures  are likely to reduce the likelihood of entry of P. palmivora  on th e commodity  
by a moderate  to high degree , with low uncertainty . Consequently, the likelihood of entry on 
the commodity is considered to be low , with low uncertainty . 
• The ability of P. palmivora  to move from imported citrus fruit and into a suitable environment 
to allow establishment, that is, onto a nother  suitable host plant , is considered to be very low, 
with moderate uncertainty . 
• The suitability of the New Zealand environment for P. palmivora  to establish is considered to 
be low to moderate , with low uncertainty .  
• The level of impact caused by P. palmivora  is likely to be low to  moderate , with low 
uncertainty . Its spread and disease expression are  very likely to be limited by climate, though 
it may be more damaging  in sheltered or protected environments.  
• Phytophthora palmivora  may be considered for additional measures . 
 
Summary o f risk assessment against criteria:  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Moderate  Moderate –high 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from  the imported commodity onto a suitable host  Very l ow Moderate  
Suitability of the New Zealand  environment  Low–moderate  Low 
Impacts on the New Zealand economy, environment, health and society  Low–moderate  Low 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 94 7.1.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below, Phytophthora palmivora  meets the criteria 
to be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: that the pest is  not present in 
New Zealand, and it is of pote ntial importance ( it is able to establish and cause harm).  
 
Phytophthora palmivora is not known to be present in New Zealand:  
• NZFungi (2020) and PPIN (2020) report P. palmivora  as absent . 
• Phytophthora palmivora is an unwanted organism and a regulated pest  (ONZPR  2020 , as 
P. palmivora  and P. palmivora var. palmivora ). 
 
Phytophthora palmivora has the potential to establish and spread within the warmer parts of New 
Zealand:  
• Phytopht hora palmivora  has a very wide host range , and k nown plant hosts, including Citrus  
species, are widely grown in New Zealand, both commercially and in domestic gardens.  
• Phytophthora palmivora  is typically found in tropical and subtropical countries with high 
rainfall. Climate matching and climate modelling suggest that it is likel y to have the ability to 
infect plants and spread  in northern New Zealand, especially in the summer months of 
December to March. Phytophthora palmivora  may be able to persist in the environment over 
other months as resistant spore stages.  
• However, disease expression and spread are very likely to be limited by climate, particularly 
in the south of New Zealand . 
 
The establishment of  P. palmivora in New Zealand has the potential to cause unwanted impacts:  
• P. palmivora  infects more than 200 species of crop, orn amental, shade and hedge plants, 
including tomato, avocado, macadamia, potatoes and orchids.  
• It causes brown rot epidemics on citrus in Florida , pre-harvest and post -harvest  fruit rots  in 
other crops and many other diseases on a wide range of hosts in other humid subtropical and 
tropical areas of the world. It has been reported killing kiwifruit plants in Turkey and is 
relatively common as the causal agent of black rot of economically important orchids in 
Taiwan .  
7.1.2 Hazard identification: commodity associ ation  
Phytophthora palmivora  is associated with citrus fruit  
• Phytophthora species are able to infect many different tissues, including fruit (Graham et al. 
1998 ; CPC 2020 ; Farr and Rossman 2020). Phytophthora palmivora  causes fruit rots of 
numerous plant s pecies, including species of citrus, e.g. C. unshiu  in Japan (Tashiro et al. 
2012); C. sinensis  in the USA (Graham 2011 ; Dewdney and Johnson 2020 ).  
7.1.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Phytophthora palmivora  has a moderate 
association with citrus fruit commodities , with moderate to high uncertainty:  
 
Many citrus cultivars are reported to be affected by P. palmivora.  
• Phytop hthora palmivora  has been reported from many Citrus  species  (Table 8.1.1) . 
• Phytophthora palmivora  infections cause severe brown rot on citrus fruit under wet and warm 
conditions (Drenth and Sendall 2004).  All citrus cultivars are affected by brown rots caused by 
Phytophthora  species (Graham and Menge 2000 , Brown and Eckert 2000), particularly  by 
Phytophthora nicotianae or P. palmivora  (Dewdney and Johnson 2020). In New Zealand,  
95 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  brown rot of citrus is caused by P. citrophthora and P. citricola at moderate temperatures and  
P. syringae  and P. hibernalis  at cool temperatures (Mooney 2001). These pathogens also 
cause other diseases. Graham and Menge (2000)  report th at brown rot is particularly severe 
on winter crops of lemons in California and early -season oranges in Florida , while Dewdney 
and Johnson (202 0) state it is usually most severe on Hamlin, Navel and other early -maturing 
sweet orange cultivars. The pathogens can survive and sporulate on the surface of pods or 
fruit under certain conditions (Brassier and Griffin 1979 ; Graham and Menge 2000 ; Graham 
and Timmer 2003).  
• However, different species of brown rot -causing Phytophthora  are prevalent in different areas, 
and in the same area at different times (Hao et al. 2018) , and it is often unclear which 
Phytophthora  species is responsible for brown rot  in citrus (see  the uncertainty section 
below).  
  
Table 8.1.1  Records of Phytophthora palmivora  from Citrus  species in the scope of this pest risk 
assessment  
Scientific name  Common name  
(from source)  Country (with host name given in 
source)  Source  
Citrus aurantiifolia   Philippines  (as C. aurantiifolia ) Farr and Rossman 2020  
Citrus aurantium   India, Philippines, Trinidad and Tobago, 
United States  (as C. aurantium ) Farr and Rossman 2020  
Citrus latifolia  Persian lemon  Guatemala (as C. latifolia ) Abad -Campos  et al. 2008  
Citrus limon   India, Philippines  (as C. limon ), Egypt  
(as Citrus volkameriana ) Farr and Rossman 2020 ; CPC 
2020 ; Farr and Rossman 2020  
Citrus maxima   Philippines , Thailand (as C. grandis ) Farr and Rossman 2020  
Citrus medica   India, Philippines, United States  Farr and Rossman 2020  
Citrus reticulata  mandarin  India, Malaysia, Puerto Rico, United 
States  (as C. reticulata ) CPC 2020 ; Farr and Rossman 
2020  
Citrus sinensis   China, India, Tanzania, United States  
(as C. sinensis ) Farr and Rossman 2020 ; Graham 
2011 ; Dewdney and Johnson 2020  
Citrus paradisi  grapefruit  Puerto Rico, Virgin Islands, Trinidad 
and Tobago  CPC 2020 ; Farr and Rossman 
2020  
NOTES  
1. The records are from all plant parts, not specifically from fruit . 
2. All citrus disease  record s are included, not specifically brown rot of citrus.  
3. The country records are not exhaustive, only indicative (i.e enough to establish that the Citrus  species has 
been reported as a host of P. palmivora  in some part of the world).  
4. Other Citrus  speci es that have been reported as hosts of P. palmivora  are: C. nobilis  and C. nobilis  var. 
deliciosa  (India; Farr & Rossman 2020); C. suhuiensis  (Malaysia ; Farr & Rossman 2020)  and C. unshiu  (Japan ; 
Tashiro et al. 2012)  (all considered Citrus reticulata ) 
 
Phytophthora palmivora  is widely distributed globally and is reported from all of the countries included 
in this IRA (Table 8.1.2 ), though it may not be reported from citrus or as causing brown rot in those 
countries:  
• Phytophthora palmivora  is present in Australia, Brazil, China,  the Cook Islands , Egypt, Fiji, 
Japan, Korea, Mexico, New Caledonia, Samoa, Solomon Islands, Spain, Peru, the United 
States, Vanuatu , Viet Nam and other countries  listed in  Table 8.1.2. 
 
Uncertainty  
The association o f citrus fruit commodities with P. palmivora  is considered to be moderate , with 
moderate to high uncertainty :  
• It is important to note that it is often unclear which Phytophthora  species is responsible for 
brown rot . This is  because  many publications refer only to “Phytophthora brown rot”  and do 
not further identify the causal agent, although  P. palmivora  is one of the species that is most 
commonly reported as a causal agent of brown rot on citrus fruit , along with P. citrophthora  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 96 and P. nicotianae (Graham and Menge 2000 ; Dewdney and Johnson 2020). Both these latter 
species are present in New Zealand (NZF ungi 2020)  and are reported to cause post -harvest 
brown rots on citrus here (Mooney 2001) .  
• Similarly, it  is also often unclear whic h citrus species are affected by Phytophthora -induced 
brown rot, since many publications refer to  the host only as “citrus”.  
 
 
Given the arguments and evidence below, b asic measures  are likely to reduce the 
likelihood of entry of P. palmivora  by a moderate to high degree.  
Brown rot epidemics are only prevalent under certain conditions and can be managed in -field.  
• Phytophthora palmivora  infections cause severe brown rot on citrus fruit under wet and warm 
conditions (Drenth and Sendall 2004), an d epidemics are prevalent during prolonged rains in 
late summer and autumn (Graham and Menge 2000).  
• Post-harvest fungicides applied in the packhouse against brown rot caused by P. palmivora  
may not be effective, but in -field treatments applied to the canopy can provide effective 
control (Graham and Menge 2000) . 
• For general control of Phytophthora diseases , the most effective chemical s are based on 
phosphonate  (Woodward and Boa 2019).  
 
Phytophthora  infec tions often cause fruit to fall to the orchard floor.  
• Most fruit with brown rot caused by Phytophthora  infections abscise (Graham and Menge 
2000, Graham and Timmer 2003) and are unlikely to be harvested for export.  
 
Brown rot -causing Phytophthora  infection s induce visible symptoms on the fruit surface that are 
usually easily detectable , leading to the removal of infected produce.  
• Phytophthora  infection of fruit produces a decay in which the affected area is light brown, 
leathery, and not sunken compared to the adjacent rind. White mycelium forms on the rind 
surface under humid conditions (Graham and Timmer 2003).  
• Fruit with symptoms of brown rot would be rejected during routine harvesting and grading 
operations.  
• If infected fruit is packed, brown rot may spr ead to adjacent fruit in the container. In storage, 
infected fruit have a characteristic pungent, rancid odour (Graham and Timmer 2003).  
 
However, some infected fruit are likely to remain undetected.  
• Fruit that are infected shortly before harvest may not s how symptoms until after they have 
been held in storage a few days (Graham and Timmer 2003). These fruit may therefore be 
overlooked and may be exported.  
• Transport of fruit is likely to be by sea and may take a number of weeks. The optimum 
carrying tempera ture is variable depending on the fruit type but is generally cool52 (between 8 
and 14°C  for grapefruit, lemons and limes , and between 2 and 7 °C for oranges (BMT 2020 )). 
Disease development is unlikely to occur at or below 22°C (the optimum temperature range 
for fruit infection and brown rot development is 27 –30°C (Timmer et al. 2000 )), and storage of 
fruit at 5°C significantly delays the development of brown rot (Brown and Eckert 2000). The 
carrying conditions during shipment and storage conditions may allow for pathogen survival 
but are not expected to be conducive for disease development. Under such conditions, it is 
likely that infection of citrus fruit by P. palmivor a would not be detected on arrival into 
New Zealand.  
 
Phytophthora palmivora  has been identified at the New Zealand border, but not on fruit.  
• Phytophthora palmivora  has not been detected on fresh produce (of any type) at the 
New Zealand or European Union b orders (EPPO 2020 ; LIMS 2020 ; Quancargo 2020). In 
New Zealand, it has been identified at the border around 14 times, all either on nursery stock 
(Dracaena, Epipremnum ) or on unknown pathways (LIMS 2020). It has also been detected 
post border in 2018, in association with ornamental plants imported from Malaysia . The 
affected plants Epipremnum , Philodendron  and Ficus ) were destroyed in post -entry 
quarantine (MPI internal report).  
                                                      
52 Note that cool storage is not equivalent to cool treatment, which is closely monitored and expected to remain within a very 
narrow range. The effect of cool storage on an organism should only be used as a broad generalization.   
97 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
The overall likelihood of entry is considered to be low , with low uncertainty . Conditions for high levels 
of infection of citrus fruit with P. palmivora  in fruit are apparently infrequent and can be managed. Fruit 
infection is usually conspicuous. However late infection combined with arrested development due to 
transit conditions m ay delay disease expression , and consequently infection may not be detectable.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below, t he ability of Phytophthora palmivora  to 
move  from imported citrus fruit onto a host plant to a llow establishment is considered 
to be very low, with mo derate  uncertainty.  
 
 
Phytophthora palmivora  has the potential to spread to new hosts from infected fruit or peels if they are 
discarded in the New Zealand environment near citrus trees, or any of man y other suitable host s, but 
the likelihood of this occurring is considered to be very low: 
• Fruit that is visibly i nfected with brown rot is likely to be discarded.  The majority of  organic 
waste in New Zealand is likely to be disposed of using low risk meth ods, meaning that 
infected fruit is unlikely to come into contact with suitable host s for P. palmivora . The majority 
of waste in New Zealand is bagged and disposed of in landfills and into kitchen disposal units. 
In these situations, spores are unlikely to be released into the environment (see section  
2.4.1). 
• However, some  waste is likely to be disposed of using high -risk methods, including 
composting in gardens, discarding into the environment (e.g. roadsides, parks) and use as 
animal  feed.  
• Mycelium on infected citrus fruit surfaces can survive and can produce sporangia ( Graham 
and Menge 2000, Graham and Timmer 2003). The optimum temperature for sporangium 
production by P. palmivora  (in vitro ) is 24°C , and wet conditions are necessary for 18 to 72 
hours (Timmer et al. 2000). Under these conditions , which may not be commonly met in New 
Zealand, sporulation is profuse.  
• Sporangia can germinate and infect host tissues directly, or they can release large numbers 
of zoospores. Sporangia are s pread by windblown rain through the air and are carried with 
water movement in soil. Phytophthora palmivora  sporangia are caducous53 (Martin et al. 
2012) and can be dispersed at least 0.5  m by rain splash. Zoospores are released in water 
and are dispersed by irrigation or surface water. Zoospores are able to swim for several hours 
and can directly infect plant tissues (Babadoost 2004 ; Lamour and Hausbeck 2003) ; however 
a large amount of surface moisture is required for their movement (Roberts and Kucharek 
2018).  
• Phytophthora grows and reproduces on both living and dead tissue in soil. Because it 
requires water for spore production and infection, root and trunk rots are most frequent in 
sites with poor drainage and frequent waterlogging. Fruit infection can be initiated during wet 
conditions when spores are splashed from the soil onto fruit that are touching, or near, the 
ground. According to Timmer et al. (2000), raindrops would be sufficient to propel small 
sporangium -filled droplets into the  air where they  could be carried some distance by wind, but 
sporangia of P. palmivora  are not dispersed by wind currents alone (unlike sporangia of some 
Phytophthora  species, e.g. P. infestans ). If wet weather persists, secondary infections are 
caused by spores produced on those fruit being splashed or blown onto fruit higher on the 
tree and, less commonly , invertebrates such as snails and ants (Taylor and Griffin 1981 ; 
Graham and Menge 2000 ; Mooney 2001).   
• Other Phytophthora  species have been transmitted from experimenta lly infected detached 
fruit on the soil surface to growing plants. Phytophthora ramorum  was transmitted from 
infected Pyracantha  fruit to the roots of Viburnum plants (Tooley et al. 2016). Tooley et al. 
(2016) commented that “Regulators will have to consid er fruit transmission [of  P. ramorum ] as 
a possibility allowing for spread of the disease”.  
• The spread of P. palmivora  is unlikely to be limited by host availability. The pathogen has 
been reported from over 130 species of crop, ornamental, shade and hedge  plants54, 
                                                      
53 They become dislodged read ily and separated from the sporangiophore and therefore are readily dispersed.  
54 not necessarily from fruit  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 98 including many that are common in the New Zealand environment, e.g. Capsicum annuum 
(peppers) , Citrus species,  Colocasia species (taro),  Dianthus species,  Ficus carica (fig), 
Fuchsia species , Grevillea species,  Hedera helix (English ivy),  Hibiscus species,  
Lycopersicon esculentum (tomato) , Persea americana (avocado),  Phaseolus species  (green 
and dried beans) , Philodendron species,  Solanum tuberosum (potato)  and Syzygium species 
(Ho 1990 ; Graham and Menge 2000 ; Farr and Rossman 2017 ; CPC 20 20). 
 
There is a moderate level of uncertainty associated with the assessment that Phytophthora palmivora  
has a very low likelihood of moving from imported citrus fruit onto a new host. The amount of infected 
imported material that is disposed of in a high  risk manner is likely to be extremely low and the 
optimal conditions for sporulation  are not likely to be commonly met. However, it  is not known what 
level of inoculum would be required to successfully infect a new host. Climate conditions in New 
Zealand are very likely to inhibit successful exposure of the pathogen , but it is not known how long the 
pathogen is able to  survive unfavou rable conditions.   
 
Given the arguments and evidence below, t he suitability of New Zealand’s 
environment for the establishment of Phytophthora palmivora is considered to be low 
to moderate, with low uncertainty.  
 
Phytophthora palmivora is a warm -climate sp ecies , historically restricted in distribution to tropical or 
subtropical regions (Table 8.1.2). Although the New Zealand climate is temperate and therefore not 
optimal for this species:  
• Major impacts were reported on kiwifruit in  Elazığ Province, Turkey ( 38°29ʹ01ʺ N; 38°34ʹ44ʺ E; 
Çiftçi et al. 2016). Most of this region has a 0.7 climate match index (CMI) with all of New 
Zealand (Phillips et al. 2018), indicating that at least some parts of New Zealand are 
climatically suitable for establishment  and diseas e expression .  
• Climate match assessments conducted by MPI (Fig. 8.1.1) indicate that this species is likely 
to be capable of infecting susceptible hosts and spreading in northern New Zealand, 
especially in the summer months of December to March. Phytophthora palmivora  can also 
persist in the environment as dormant forms such as oospores55 and chlamydospores, which 
are resistant to unfavourable conditions. Chlamydospores may form when soil moisture is 
limiting, conditions are cool or where the host roots are not actively growing and producing 
susceptible tissues for infection. Chlamydospores of some Phytophthora  species can remain 
in the soil for several years (Kunta et al. 2020) and can serve as an inoculum source until the 
environmental conditions are optimal. However it is uncertain how long chlamydospores of 
P. palmivora  can survive and how long they would survive under conditions in New Zealand.  
• Therefore, it is likely that P. palmivora  would be able to infect plants and be able to spread in 
northern New Zealand, especially in the summer months of December to March. Disease 
expression and spread are very likely to be limited by climate, even in northern New Zealand , 
and the pathogen is unlikely to establish in southern regions.  
 
Table 8.1.2  Geographic distribution of Phytophthora palmivora  
• Records are from all hosts, not only from Citrus  
• Areas in bold are included in the Citrus IHS project  
Continent/Region  Country/ Area (source CPC (2020), unless otherwise noted ) 
Africa  Angola , Cameroon, Central African Republic, Democratic Republic of the 
Congo, Republic of the Congo, Côte d'Ivoire, Egypt [Note 1], Equatorial 
Guinea, Gabon, Ghana, Liberia, Madagascar, Malawi, Maurit ius, Morocco, 
Nigeria, Réunion, São Tomé and Príncipe, Senegal, Seychelles, Sierra 
Leone, Somalia,  Tanzania, Togo, Uganda, Zimbabwe  
Asia Afghanistan , Brunei, Cambodia, China (Beijing, Fujian, Guangdong, 
Hainan, Jiangsu, Yunnan, Zhejiang), India, Indonesia, Iran, Japan 
(Kyushu, Shikoku),  Jordan, Korea [Note 2],  Lebanon, Malaysia, 
Myanmar, Pakistan, Philippines, Singapore, Sri Lanka, Taiwan,  Thailand, 
Turkey,  Viet Nam 
                                                      
55 Oospores are formed when two different mating types are present. The likelihood of this occurring in New Zealand as the 
result of an incursion is considered to be very low.   
99 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Continent/Region  Country/ Area (source CPC (2020), unless otherwise noted ) 
Europe  France , Greece, Italy, Norway, Poland, Spain (incl. Canary Islands)  
North America  Belize , Cayman Islands, Costa Rica, Cuba, Dominica, Dominican Republic, 
El Salvador, Grenada, Guatemala, Haiti, Honduras, Jamaica, Mexico , 
Nicaragua, Panama, Puerto Rico, Saint Kitts and Nevis, Saint Lucia, Saint 
Vincent and the Grenadines, Trinidad and Tobago, United States 
(Arizona, California, Florida, Hawaii, North Carolina, Tennessee, 
Virginia)  
Oceania  American Samoa , Australia [Note 3], Cook Islands [Note 4], Fiji,  French 
Polynesia, New Caledonia , Northern Mariana Islands, Papua New Guinea, 
Samoa, Solomon Islands  [Note 5] , Tonga, Vanuatu  
South America  Argentina, Bolivia , Brazil (Alagoas, Bahia, Esp írito Santo, Maranh ão, 
Pará, Paran á, São Paulo) , Colombia, Ecuador, Guyana, Peru , Suriname, 
Venezuela  
Note 1 . Regarded as a regulated non -quarantine pest by Egypt (EPPO)  
Note 2.  Phytophthora palmivora  is present in Australia, including Western Australia (Barber et al. 
2013); where it was previously considered to be absent and was treated as a quarantine pest 
(e.g. Biosecurity Australia 2005)  
Note 3.  Reported from the Cook Islands by Dingley et al. (198 1) 
Note 4.  Reported from Soloman Island s by Newhook and Jackson (1977)  
 
 
Figure 8.1.1  The potential distribution of P. palmivora  in New Zealand,  as predicted by CLIMEX 
modelling1. 
1The Eco -climate index shows the potential long -term establishment of the species and ranges from low (white) through 
increasing suitability (green through to red) . The index for P. palmivora  is around 40 (out of 100) in suitable area s in New 
Zealand. This index for tropical areas is above 90. This indicates  that although New Zealand is less suitable compared to 
tropical and subtropical areas, the environment may still facilitate establishment.  
 
Impacts in New Zealand:  
 
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 100 Given the arguments and evidence below, t he level of impact caused by 
P. palmivora  is likely to be low to moderate, with low uncertainty.  
 
Phytophthora palmivora  can cause severe damage, but the economic impacts of this pathogen are 
largely limited to tropical fruit crops in warm regions.  
• Phytophthora palmivora  has an extremely wide host range and can cause significant to 
severe losses to many tropical crops, for example , cocoa, durian, rubber, coconut, pineapple 
and oil palm. Symptoms include root rots, collar rots, stem cankers, leaf bli ghts and pre -
harvest and post -harvest fruit rots (CABI 2020 ; Drenth and Sendall 2004).  
• Phytophthora  species, and P. palmivora  in particular, are able to cause multiple diseases on 
the same host. On cocoa , P. palmivora  causes seedling dieback, root rot, st em canker, 
chupon wilt, leaf blight, cherelle wilt and black pod rot. Thus, both inoculum and susceptible 
host tissue are continuously available, and the disease potential is always present (Drenth 
and Guest 2004a).  
• Hosts that are economically important to  New Zealand include citrus, kiwifruit (Actinidia  spp.) 
and cut flowers:  
o Phytophthora palmivora  causes brown rot epidemics on citrus in Florida and 
California, and probably brown rot and foliage blights in other humid subtropical and 
tropical areas of the world (Graham and Menge 2000). Epidemics are prevalent 
during prolonged rains  and high temperatures in late summer and early autumn 
(Graham and Menge 2000 , Timmer et al. 2000 ). In southeast Asia, P. palmivora  is 
one of the most common species causing Phyto phthora disease in citrus (Drenth and 
Sendall 2004).  
o Phytophthora palmivora  has been isolated from the roots and crowns of infected 
Actinidia chinensis var. deliciosa  (cv. Hayward)  plants in Turkey, causing crown and 
root rot symptoms on approximately 10% of plants in an experimental orchard (Çiftçi 
et al. 2016). Within two years, all the kiwifruit vines in the experimental orchard had 
died. Çiftçi et al. (2016) considered this to b e a new host record , and considered that 
P. palmivora  had the potential to be a major limiting factor in kiwifruit production, 
However, the host range and cultivar susceptibility within  Actinidia  is unknown. 
Further, it is not known whether kiwifruit in Ne w Zealand would be impacted since this 
appears to be as yet the only report of infection of kiwifruit by P. palmivora . 
o In Taiwan, P. palmivora  is known to cause severe black rot in economically important 
orchids, including Cattleya, Cymbidium, Dendrobium, Oncidium and Phalaenopsis  
(Tsai et al. 2006). Many of these species are grown in New Zealand.  
However:  
o Although damage can be severe, the economic impacts of this pathogen are largely 
limited to tropical fruit crops in warm regions (Biosecurity Australia 2005 ; Daniel and 
Guest 2008). In New Zealand, the severity of symptoms, spread and consequently 
the impact is very likely to be limited by the climate. Impacts in protected 
environments such as nurseries and glasshouses are likely to be more severe than in  
unprotected environments ; for example, heavy losses in nurseries (hosts not 
specified) are reported due to seedling blight (Daniel and Guest 2008).  
o An Australian risk assessment (Biosecurity Australia 2005) concluded that 
program mes to minimise the impac t of P. palmivora  on host plants are not likely to be 
more costly than existing management programs for other Phytophthora  species ; 
however this may depend on the crop and the country.  For example, Zito and Timmer 
(1994) report that P. palmivora  is a more aggressive and competitive pathogen of 
citrus roots, stems and fruit tissues than P. nicotianae . Therefore, even if P. 
nicotianae  (for example) is being managed, the establishment of P. palmivora  may 
result in extra costs and damage.  
 
The establishment of P. palmivora  is unlikely to cause serious trade impacts.  
• Phytophthora palmivora  is widely distributed globally. However, some trading partners may 
impose trade restrictions in the event of an incursion, e.g.:  
o EPPO56 reports that several countries regard P. palmivora  as a quarantine pest 
(Morocco, Bahrain and Chile), and Egypt regards it as a regulated non -quarantine pest.  
                                                      
56 https://gd.eppo.int/taxon/PHYTPL/categorization   
101 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  o In 2014 China closed the Californian fresh citrus fruit market (wor th approximately 
US$140 million), based on detections of two other Phytophthora species ( P. syringae  
and P. hibernalis , claimed to be absent from China ) on Californian fruit. The Chinese 
market is open again to Californian growers, but strict export protocols have been 
implemented to manage the pathogens (H ao et al. 2 018). 
 
The establishment of P. palmivora may cause environmental impacts , but these are likely to be limited 
by climatic unsuitability:  
• Phytophthora palmivora  is a highly polyphagous pathogen and has been recorded on several 
species represented by genera in the native flora including Hibiscus, Solanum and Syzygium  
species (Farr and Rossman 2020).  
• It is most likely to establish in warmer, more humid regions of New Zealand . Amenity plants 
grown in sheltered conditions, such as tropical plant collections in botanic gardens, could be 
affected by this species. Although there are no native orchid species in the genera known to 
be affected by P. palmivora , Northland is the centre of diversity of native orchids in New 
Zealand , and this overlaps with the most likely area of establishment.  
• Phytophthora agathidicida  (previously known as PTA, the causal agent of kauri dieback) has 
been found in northern parts of New Zealand attacking kauri ( Agathis australis ), an iconic 
New Zealand  tree species (Beever et al. 2009). Its biostatus (whether native or introduced) is 
not fully resolved , but it is reported to kill t rees of all ages in natural forest remnants, amenity 
stands and silvicultural plantations  (Bellgard  et al. 20 15). This indic ates the potential for 
Phytophthora  species to negatively impact on the natural environment and on socio -cultural 
values.  
 
Phytophthora palmivora is unlikely to cause unwanted impacts on human health.  
• No evidence of such impacts has been found.  
 
Risk asses sment summary : 
 
Given the arguments and evidence below,  Phytophthora palmivora  may be 
considered for additional measures . 
• Many citrus species are hosts . 
• Infection of fruit that occurs close to harvest time may not be detected during general 
handling, especially when the volume of commodities is large . 
• Cool storage in transit is likely to delay disease development, re ducing the likelihood of 
detection during phytosanitary inspection . 
• Hosts are widely available . 
 
However : 
• There is a very low likelihood o f P. palmivora moving  from imported fruit into a suitable 
environment to allow establishment . 
• Only limited areas  of New Zealand are likely to be suitable for the establishment of P. 
palmivora . 
7.1.4 References  
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Phytophthora  species associated to branch cankers on Persian lemon trees in Guatemala . 
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Babadoost, M (2004) Phytophthora blight: a serious threat to cucurbit industries. The American 
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Barber, P A; Paap, T; Burgess, T I; Dunstan, W; Hardy, G E St J (2013) A diverse range of 
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under threat from Phytophthora ? In Goheen, E M; Frankel, S J (coords.) Phytophthoras in Forests 
and Natural Ecosystems . Proceedings of the Fourth Meeting of IUFRO Working Party S07.02.09, 
General Technical report PSW -GTR -221. USDA Forest Service ; Albany, CA, USA ; pp 74–85. 
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Brassier, C M; Griffin, M J (1979) Taxonomy of Phytopht hora palmivora  on cocoa. Transactions of the 
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Çiftçi, O; Serçe, Ç U; Türkölmez, Ş; Derviş, S (2016) Disease Notes: First Report of Phytophthora 
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Drenth, A; Guest, D I (2004b) Phytophthora  in the tropics. In Drenth, A; Guest, D I (eds) Diversity and 
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occurrence and niche preferences of Phytophthora  spp. causing brown rot of Citrus in the central 
valley of California. Phytopathology , 108(3): 384 –391.  
Ho, H H (1990) Taiwan Phytophth ora. Botanical Bulletin of Academia  Sinica , 31(2): 89 –106. 
Hong, S Y; Jee, H J; Hyun, S W (1998) First report of Phytophthora palmivora  in Cheju Island as the 
causal pathogen of Phytophthora  crown rot of Cymbidium . Korean Journal of Plant Pathology , 14(6): 
725–728. 
Kunta, M ; Chavez, S ; Viloria, Z ; del Rio, H S ; Devanaboina, M ; Yanev, G ; Park, J ; Louzada, E S  
(2020) Screening potential citrus rootstocks for Phytophthora nicotianae  tolerance . HortScience  55(7) : 
1038 –1044. https://journals.ashs.org/hortsci/view/journals/hortsci/55/7/article -p1038.xml . 
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internal database . Accessed 28 September 2020.  
Martin, F N; Abad, Z G; Balci, Y; Ivors, K (2012) Identification and detection of Phytophthora:  
reviewing our progress, identifying our needs. Plant Disease , 96(8): 1080 –1103.  
Mooney, P ( ed) (2001) Growing Citrus in New Zealand: A practical guide.  New Zealand Citrus 
Growers Inc. and HortR esearch. https://www.zeafruit.co.nz/wp -content/uploads/2019/01/NZCGI -
Growing -Citrus -in-NZ-A-Practical -Guide.pdf  
Newhook, F J; Jackson, G V H (1977) Phytophthora palmivora  in cocoa plantation soils in the 
Solomon Islands . Transactions of the British Mycological Society , 69(1): 31–38. 
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Quancargo  (2020) MPI internal database. Accessed 28 September 2020.  
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Tashiro, N; Uematsu, S; Ide, Y; Matsuzaki, M (2012) First report of Phytophthora palmivora  as a 
causal pathogen of citrus brown rot in Japan . Journal of General Plant Pathology , 78(3): 233 –236. 
https://link.springer.com/article/10.1007/s10327 -012-0378 -6 
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temperature  and moisture effects on infection, sporangium production, and dispersal. Plant Disease , 
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palmivora  on ﬁbrous roots of citrus. Phytopathology , 84(10): 1000 –1004 . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 104    
105 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8. Insects: Diptera, Tephritidae (fruit flies)  
 
8.1 Anastrepha fraterculus  (South American fruit fly ) 
 
Anastrepha fraterculus  is native to the Americas and may represent a complex of cryptic species 
through its range. It attacks a wide range of fruits. The eggs and larvae are found inside the fruit , 
causing  it to rot and become unmarketable.  
 
Scientific name: Anastrepha fraterculus  (Wiedemann , 1830 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Acrotoxa fraterculus , Anastrepha braziliensis , Anastrepha costarukmanii , 
Anastrepha fraterculus  var. solut a, Anastrepha lambayecae , Anastrepha peruviana , Anastrepha 
pseudofraterculus , Anastrepha scholae , Anastrepha soluta , Anthomyia frutalis , Dacus fraterculus , 
Tephritis mellea , Trypeta fraterculus , Trypeta unicolor  
 
Taxonomic comments:  
Anastrepha fraterculus  is variable through out its geographic range (South, Central and North America 
as far north as the south of Texas). The overwhelming evidence suggests that ‘ A. fraterculus ’ is not a 
single species, but rather a species complex , with the taxa comprising it not yet formally described.  
So far , eight morphotypes have been characterised: Mexican, Venezuelan, Andean, Ecuadorean, 
Brazilian -1, Brazilian -2 and Brazilian -3 (Hernández -Ortiz et al. 2012 ; Hernández -Ortiz et al. 2015 ; 
Prezotto et al. 2019 ). This could ha ve implications for biosecurity , as there could be changes in 
geographic distributions and recorded hosts attributed to each species.  
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Anastrepha fraterculus  meets the criteria to be a quarantine pest for New Zealand . 
• Anastrepha fraterculus  has a strong association with citrus fruit . 
• Basic measures  are likely to reduce the entry of A. fraterculus  on citrus fruit by a moderate 
degree (with moderate uncertainty) ; consequently, the likelihood of entry is considered to be 
low (with moderate uncertainty) . 
• Anastrepha fraterculus  has a moderate ability (with low to moderate uncertainty) to move from 
imported fruit and into a suitable environment to allow establishment , that is, onto a host 
plant.  
• The suitability of the New Zealand environment for A. fraterculus  to establish is considered 
moderate (with low to moderate uncertainty) .  
• The level of impacts caused to New Zealand by A. fraterculus  is likely to be high, main ly due 
to stricter phytosanitary requirements for citrus and other horticultural crops.  
• Anastrepha fraterculus  may be considered for requiring additional measures.  
 
Summary of risk assessment against criteria:  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low  Moderate  
The ability to move from the imported commodity onto a suitable host  Moderate  Low–moderate  
Suitability of the N ew Zealand  environment  Moderate  Low–moderate  
Impacts on the New Zealand economy, environment, health and society  High Low 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 106 8.1.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Anastrepha fraterculus meets the criteria 
to be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause har m). 
 
Anastrepha fraterculus is not known to be present in New Zealand.  
• Anastrepha fraterculus  is not recorded in NZInverts (2020), NZOR (2020) or PPIN (2020).  
• The quarantine status of A. fraterculus  in New Zealand is ‘regulated’ , and it is a notifiable 
organism and unwanted organism ( ONZPR  2020).  
 
Anastrepha frat erculus has the potential to establish and spread in New Zealand.  
• The Anastrepha fraterculus  complex occurs from Mexico to Northern Argentina. Some of the 
locations where it occurs have climatic similarities to parts of New Zealand. For example, 
A. fraterc ulus is widespread in Uruguay , which , over most of its area , has a climate  match 
index  (CMI)  of 0.8 –0.9 with New Zealand (Phillips et al. 2018), indicating the potential for A. 
fraterculus  to establish in parts of New Zealand. Similarly, the Brazilian states of Santa 
Catarina (0.7 –0.9 CMI), Rio Grande do Sul (0.7 –0.9 CMI) and Paraná  (mostly 0.7 –0.8 CMI), 
and parts of northern Argentina (0.7 -0.9 CMI) have areas with high climatic similarity to parts 
of New Zealand.  
• Anastrepha fraterculus  is a polyphagous species with a broad host range (CPC 2020 ; Liquido 
et al. 2018). Currently, 143 plant species/taxa, belonging to 63 genera in 32 families, are 
considered host plants for the A. fraterculus  species complex under natural field conditions 
(Liquido et al. 2018) and another 124 plant taxa have “undetermined host status”. Hosts 
include cultivated crops such as Citrus  spp.,  Psidium guajava  (guava), Malus domestica  
(apple), Passiflora edulis  (passionf ruit), Persea americana  (avocado), Prunus persica  
(peach), Vitis vinifera  (grape) and Pyrus communis  (European pear) (Weems 2015 ; CPC 
2020 ; Liquido et al. 2018).  
• Host species are present in climatically suitable areas of New Zealand , indicating the potenti al 
for establishment.  
 
Anastrepha fraterculus has the potential to cause economic impacts on Citrus  and other horticultural 
species in New Zealand.  
• Host species, such as Citrus  spp., Malus domestica  (apple), Passiflora edulis  (passionfruit), 
Persea americ ana (avocado), Prunus persica  (peach), and Pyrus communis  (European pear) 
are grown commercially in New Zealand and establishment could cause economic loss 
primarily due to a potential loss of pest free status and subsequent restrictions on trade.  
 
8.1.2 Hazard  identification: commodity association  
Anastrepha fraterculus  is associated with citrus fruit . 
 
Anastrepha fraterculus is reported from citrus fruit.  
• Larvae of A. fraterculus  develop in the fruit of Citrus , including , but not limited to , C. aurantium  
(sour orange), C. lim on (sweet lime), C. maxima  (pomelo), Citrus  paradisi  (grapefruit), 
C. reticulata  (tangerine) and C. sinensis  (sweet orange) (White and Elson -Harris ; 1994).  
 
8.1.3 Risk assessment  
 
Likelihood of entry:  
  
107 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Given the arguments and evidence below , Anastrepha fraterculus  has a strong 
association with citrus fruit . 
 
Eggs and larvae of A. fraterculus  can be associated with citrus fruit commodities.  
• Anastrepha fraterculus  is multivoltine. Eggs are deposited into ripening fruit , and, once 
hatched, larvae tunnel inside the fruit , feeding on pulp (Aluja 1994 ; Weems 2015 ; CPC 2020) . 
The egg stage lasts 3 days in summer and 6 days in winter; the larval stage lasts 15 –20 days 
in summer and 20 –25 days in winter (Christenson and Foote 1 960). There may be as many 
as 50 eggs in a single fruit (Christenson and Foote 1960). Larvae leave the fruit to pupate in 
the soil under the host plant (Weems 2015).  
• Larvae have been recorded developing in the fruit of Citrus , for example: C. aurantium  (sour 
orange), C. lim on (sweet lime), C. maxima  (pomelo), Citrus  x paradisi  (grapefruit), C. 
reticulata  (tangerine) and C. sinensis  (sweet orange) (White and Elson -Harris ; 1994).  
 
Anastrapha fraterculus  infests many Citrus species and varieties , although this  may vary depending 
on morphotype . 
• Anastrepha fraterculus  has been recorded as infesting many citrus species and varieties. 
Table 9.1.1 lists Citrus  species/taxa that have validated host records for plants for the A. 
fraterculus  species complex under natural field conditions (Liquido et al. 2018) and others that 
have “undetermined host status” (i.e. no validated record of infestation under natural field 
condit ions (Liquido et al. 2018) ). 
• Citrus  may not be a host for all morphotyp es, for example:  
o In Mexico, A. fraterculus  has not been reported attacking citrus under natural 
conditions (Aluja et al. 2003). Mexican A. fraterculus  collected in the state of Veracruz 
were unable to develop successfully on C. sinensis  cultivar Valencia ( oranges) and C. 
paradisi  cultivar Ruby Red (grapefruit) under laboratory and seminatural conditions 
(Aluja et al. 2003).  
• Morphotypes that use some Citrus  types as hosts may not use other Citrus  types, for 
example:  
o According to Ruiz et al. (2015), lemons ( C. limon  var. Eureka) and sweet oranges ( C. 
sinensis  var. Valencia) are not hosts for the Brazilian -1 morphotype. In their study, 
eggs were laid, but there was poor egg hatch and zero survival of larvae to the pupal 
stage. No oviposition by A. fraterculus  (likely Brazilian -1 morphotype based on the 
location of collection and with reference to Prezotto et al. 2019) occurred in lemons 
(var. Siciliano) (Dias et al. 2017). On the other hand, some Citrus  types are hosts for 
the Brazilian -1 morphotype (e.g. grape fruit, sweet orange, tangerine in Dias et al. 
2017, Ruiz et al. 2015).  
 
Table 9.1.1: Citrus  host plant records for Anastrepha fraterculus  species complex (Liquido et al. 2018). 
The closely related genera, Poncirus  and Fortunella , are included.  Validated natural infestation = validated 
documentation of field infestation by A. fraterculus ; “undetermined host status” = no validated record of 
infestation under natural field conditions, and its host association is based on reported interception at a  port of 
entry, laboratory infestation, or a mere listing as a host without any accompanying verifiable data (Liquido et al. 
2018).  
Botanical name  Common name  
Validated natural infestations:   
Citrus  aurantium  L. Bigarade, bitter orange, Seville orange, sour orange, bigaradier, naranja agria, 
naranja amarga, naranja mateca, oranger amer , Myrtle -leaf orange, chinois, 
naranja mirtifolia  
Citrus lim on (L.) Burm.f.  Limetta of the Mediterranean, lumia of the Mediterranean, sweet lemon, sweet 
lime, lima, lima -de-bico, limero dulce, limeta dulce de Túnez, limette d'Italie, 
limette, douce de Tunesie, limettier doux, limón dulce, limonero dulce, limonette  
Citrus maxima  (Burm.) Merr.  Pomelo, pummelo, shaddock, pamplemousse, pamplemoussier, toronja  
Citrus  paradisi  Macfad.  Grapefruit, pomelo, toronja  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 108 Botanical name  Common name  
Citrus reticulata  Blanco  Culate mandarin, mandarin, mandarin orange, mandarine orange, Swatow 
orange, tangerine, bergamota, mandarina, mandarinier, tangerine, King of 
Siam, king orange, tangor, mandarinier king, roi  de Siam  
Citrus  sinensis  (L.) Osbeck  Blood orange, navel orange, orange, sweet orange, Valencia orange, laranja -
doce, laranjeira, laranjeira -doce, laranja -amarga, laranja -azeda, laranja -
bigarade, laranja -da-terra, laranja -de-sevilha, naranja, naranjo dulce, navel, 
orange douce, oranger, oranger doux, sanguine  
Citrus reticulata  × Citrus paradisi  Tangelo, uglifruit  
Fortunella japonica  (Thunb.) Swingle  Marumi kumquat, round kumquat, round kumquat, kumquat marumi  
Poncirus trifoliata  (L.) Raf.  Hardy  orange, Japanese bitter  orange, trifoliate  orange, limoeiro -trifoliado, 
naranjo trébol, poncirus, oranger trifoliolé  
“Undetermined host status”:   
Citrus  aurantiifolia  (Christm.) Swingle  Egyptian lime, Indian lime, Key lime, lime, Mexican lime, sour lime, West Indian 
lime, citron vert, citronnier gallet, lima, lima -ácida, lima mejicana, limão, limão -
galego, limão -tahiti, lime acid, limeira, limero, limettier, limettier des Antilles, 
limett ier mexicain, limón agrio, limón ceutí , Indian sweet lime, Palestine sweet 
lemon, Palestine sweet lime, sweet lime, lima dulce de India, lima dulce de 
Palestina, limettier doux de Palestine  
Citrus  limon  (L.) Osbeck  Lemon, citronnier, limão, limão -eureka, limão -gênova, limão -siciliano, limão -
verdadeiro, limoeiro, limoeiro -azedo, limón, limonero, limonier , Indian sweet 
lime, Palestine sweet lemon, Palestine sweet lime, sweet lime, lima dulce de 
India, lima dulce de Palestina, limettier doux de Palestine  
Citrus medica  L. Citron, cédrat, cédratier, cidra, cidreira, cidro, toronja  
Citrus reticulata  Blanco  Dancy tangerine , tangerine  
 
Anastrepha fraterculus  is present in some citrus export countries considered in this import risk 
analysis . 
• The geographic ran ge of A. fraterculus is South, Central and North America as far as the 
south of Texas (Table 9.1.2). 
• Anastrepha fraterculus  is present in the following citrus export countries that are under 
consideration:  
o Brazil, Peru, Mexico (EPPO 2020 a) 
• Anastrepha fraterculus  is considered absent from the USA by their National Plant Protection 
Organisation (EPPO 2020 a) and is a quarantine pest for that country.  There are some old 
records from s outh Texas  that are considered unreliable as to species. USDA -APHIS has a n 
ongoing Mexican fruit fly (Anastrepha ludens ) trapping network in southern Texas, which 
includes traps capable of attracting A. fraterculus , which are present in Mexico (CPC 2020).  
• Anastrepha fraterculus  was eradicated in 1964 in Chile (an export country  under 
consideration) (EPPO 2020 a). 
• Although A. fraterculus  has a wide distribution, at least eight  morphotypes are known , and 
some of these are likely to be formally described as separate species at a later date. The 
morphotypes have different distributio ns through the overall geographic range for A. 
fraterculus , and it is likely that characteristics such as differences in climatic requirements and 
association with Citrus  will vary between morphotypes. Each of the countries under 
consideration in this asse ssment has a unique set of cryptic species or morphotypes:  
o Brazil has three clearly defined morphotypes (Brazilian -1, Brazilian -2, Brazilian -3), 
that have been well characterised by genetic, morphological and behavioural studies 
(e.g. Cáceres et al. 2009 ; Hernández -Ortiz et al. 2012 ; Prezotto et al. 2019 ; Passos 
Roriz et al. 2017 ; Passos Roriz et al. 2018).  
o Mexico has only one morphotype (Mexican) (Hernández -Ortiz et al. 2012, Prezotto et 
al. 2019).  
o The Peruvian coastal plain where citrus is increasingly grown commercially has the 
Peruvian morphotype, whereas the Peruvian highlands support the Ecuadorian 
morphotype , and the Brazilian lineage has been collected on the east side of the 
Andes (Hernández -Ortiz et al. 2015 ; Prezotto et al. 2019).   
109 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Table 9.1.2: Known geographic distribution of Anastrepha fraterculus  (EPPO 2020a, CPC 2020).  Countries 
in bold  are potential exporting countries under consideration in this import risk analysis . 
Continent/Region  Country [State]  
South America  Argentina, Bolivia, Brazil  [Alagoas, Amapa, Bahia, Cear á, Esp írito Santo, 
Goiás, Maranh ão, Mato Grosso do Sul, Minas Gerais, Para íba, Paraná , 
Pernambuco, Piau í, Rio de Janeiro, Rio Grande do Norte, Rio Grande do Sul, 
Santa Cat arina, S ão Paulo, Tocantins], Colombia, Ecuador, Guyana,  Paraguay, 
Peru , Suriname, Uruguay, Venezuela  
Eradicated from Chile  in 1964  
Central America and Caribbean  Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama, 
Trinidad and Tobago  
North America  Mexico  
USA: has been reported in south Texas but is considered absent by the US 
NPPO.  
 
Given the arguments and evidence below,  basic measures  are likely to reduce the 
entry of A. fraterculus  on citrus fruit by a moderate degree (with moderate 
uncertainty); consequently, the likelihood of entry  is considered to be low (with 
moderate uncertainty)  
Infested fruit may show signs of infestation and be removed from the consignment.  
• Eggs or larvae of A. fraterculus  are present inside the fruit. Infested fruit may show signs of 
oviposition punctures. La rvae tunnel through the interior of the fruit while feeding , and 
networks of tunnels may develop , accompanied by rotting. The internal damage may show as 
symptoms on the exterior of the fruit at later stages of infection. Sugary exudates may be 
produced in  very sweet fruits (CPC 2020). Fruit showing obvious signs of infestation by A. 
fraterculus , such as oviposition punctures and other symptoms on the exterior, are likely to be 
detected and removed from a line or consignment during packhouse activities and 
inspections.  
 
However, some infested fruit may go unnoticed during the export production process.  
• If eggs or larvae are present in the fruit at low density or at an early stage of infestation, the 
external signs such as oviposition punctures may not be vis ually obvious. Much damage can 
occur inside the fruit before exterior symptoms appear  (CPC 2020).  
• Therefore,  commercial processes and post -harvesting activities may reduce the presence of 
A. fraterculus to a low level, but not eliminate it . Low levels of fruit infestation are likely to go 
undetected , especially in high volumes of the fruit commodity.  
 
General handling and processing after harvesting is unlikely  to remove eggs and larvae of A. 
fraterculus  from citrus fruit.  
• Eggs and larvae are found inside the fruit and so would not be removed by routine activities in 
the packhouse such as washing and brushing , which only treat the fruit surface.  
 
Anastrepha fraterculus  may survive transit in some citrus commodities . 
• Storage and transport of citrus consignme nts from exporting countries to New Zealand are 
likely to occur at cool temperatures, with the length of time for shipment depending on the 
exporting country. For example, transport of fruit from Brazil by sea may take more than three 
weeks.  
• The larval sta ge of A. fraterculus  lasts 15 –20 days in summer and 20 –25 days in winter , with 
the rate of larval development influenced by temperature (Christenson and Foote 1960).  
• Machado et al. (1995, in Sequeira et al. 2001) reported lower -threshold temperatures for t he 
life stages of A. fraterculus : egg (9.25 °C), larva (10.27 °C), pupa (10.78 °C), and complete life 
cycle (10.72 °C). Salles (2000, in Poncio et al. 2016) reported the base temperature (below 
which no development occurs) for A. fraterculus  as 10.7 °C.  
• A recent study investigated the relative cold tolerance of five populations from three 
morphotypes of the A. fraterculus  complex (Andean, Peruvian and Brazilian -1) in relation to Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 110 phytosanitary cold treatment of fruit (Diaz et al. 2020). Differences in mort ality of third instars 
of the five A. fraterculus  populations reared on nectarines were observed only with short 
treatment durations at temperatures ranging from 1.38 ± 0.04°C to 1.51 ± 0.08°C (mean ± 
SEM). Using nectarines as a host, Diaz et al (2020) est ablished that cold treatments of 15 d 
at ≤ 1.11°C or 17 d at ≤ 1.67°C will kill immature stages of Brazilian -1, Andean and Peruvian 
morphotypes. If applied to Citrus , the temperatures given could ensure disinfestation without 
chilling injury in many cultiv ars (Grout et al. 2011 ; De Lima et al. 2007).  
• Therefore, some larvae may survive transit depending on transport temperatures and times , 
which are unspecified.  
 
The level of uncertainty in relation to survival during transit is moderate. There is no specifi c 
information on the conditions of transit, including temperature and duration. There is a lack of 
New Zealand interception data for Anastrepha  spp. in fresh produce , which would be informative if 
live specimens were detected. Species of Anastrepha have be en intercepted by EPPO (2020b) ; 
however , the data does not indicate if the specimens are alive or dead. There is also potential for 
variation among morphotypes in development times and ability to survive low temperatures.  There is 
potential for the host st atus of different types of Citrus  to vary , depending on the morphotype of A. 
fraterculus , and this may need to be determined in specific instances.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Anastrepha fraterculus  has a moderate 
ability (with low to moderate uncertainty) to move from imported fruit and into a 
suitable environment to allow establishment, that is, onto a host plant.  
Anastrepha fraterculus  can survive and develop on discarded citrus fruit and fruit pi eces.  
• Eggs are deposited into ripening fruit , and, once hatched, larvae tunnel inside the fruit , 
feeding on pulp (Aluja 1994 ; Weems 2015 ; CPC 2020) . The egg stage lasts 3 to 6 days , and 
the larval stage lasts for 15 to 25 days of development time , dependin g on temperature 
(Christenson and Foote 1960). Larvae leave the fruit to pupate in the soil under the host plant 
(Weems 2015) or other substrates such as packaging for fruit (CPC 2020).  
• If infested citrus fruit is discarded as whole fruit or fruit pieces, A. fraterculus  may complete 
larval development in the waste and find a suitable location to pupate.  
 
Most citrus fruit waste in New Zealand is likely to be disposed of using low -risk methods , so any 
A. fraterculus  present would either be killed or unable to escape from the citrus host . 
• In New Zealand, the majority of kitchen  waste is either bagged and sent to landfill or run 
through kitchen disposal units (see section  2.4.1, waste analysis). A. fraterculus  in infes ted 
fruit is unlikely to survive in these circumstances.  
 
However, some waste is likely to be disposed of using high -risk methods, including composting in 
gardens, use as animal feed or discard ing directly into the environment.  
• A small proportion of infested fruit is likely to be discarded in a home compost bin or open 
compost heap, or directly into the environment (see section 2.4.1, waste analysis).  
• Anastrepha fracterculus  larvae move from citrus fruit to pupate in the soil in  natural conditions 
but may also pupate in other sheltered situations such as in packaging (CPC 2020). 
Therefore, some larvae or pupae associated with discarded citrus may find suitable conditions 
to develop to adulthood. Adults emerge from pupae after 10 –15 days (43.2 days at 15 °C) 
(Salles 2000, in CPC 2020). The pupal stage lasts 15 –18 days in summer and 20 –25 days in 
winter , and in exceptional cases , adults have been known to emerge from pupae after 12, 14 
and 18 months (Christenson and Foote 1960).  
• Adults emerging from the soil are likely to be able to find food in the environment.  Before 
becoming sexually active, adult Anastrepha  go through a period during which they need to 
feed regularly on carbohydrates and water to survive and on protein sources to allow for 
gonad maturation (Aluja 1994). Nutrients can be found in liquids oozing from overripe or 
damaged fruit, bird faeces, leaf and fruit surfaces, and raindrops (Aluja 1994).  
• Anastrepha fraterculus  is polyphagous and can complete development on a wid e range of 
unrelated species. At least 143 species/taxa belong ing to 63 genera in 32 families are 
considered to be hosts under natural field conditions and another 24 plant taxa have  
111 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  “undetermined host status” (Liquido et al. 2018). Recorded hosts, such as  citrus, peach, 
persimmon, apple, avocado, passionfruit, grape, guava, fig, capsicum and mango, are 
available in many areas of New Zealand.  
• If suitable hosts are located near the site for citrus fruit waste, A. fraterculus  adults are likely 
to find them.  
 
Anastrepha fraterculus  can disperse to find a suitable host.  
• Adult A. fraterculus  that emerge from the soil disperse to find a suitable host plant. Dispersal 
is correlated with suitable environmental conditions. In a study on movement of adults from 
native  breeding sites into apple orchards in Southern Brazil, most adults  moved within 200 m 
from their release point in native forest; however, dispersal of up to 900 m to a nearby apple 
orchard was recorded (Kovaleski et al. 1999).  
• A recent study by Ramos et al. (2019) on temporal patterns of A. fraterculus  dispersion in 
apple orchards found that A. fraterculus  entered two apple orchards in Brazil during fruit 
periods. This reinforces the findings of Kovaleski et al. (1999) that A. fraterculus  can 
immigrate in to areas where host fruit is present. However, the distance A. fraterculus  is able 
to cover is not quantified due to the absence of a highly effective lure to improve sampling 
(Tan et al. 2014).  
 
The level of uncertainty associated with this conclusion is low to moderate. Firstly, waste data may 
not be very accurate or up to date (see section  2.4.1, waste analysis). Secondly, it is uncertain what 
proportion of composting sites are exposed or uncovered (e.g. in a compost bin).  
 
Given the arguments and eviden ce below,  the suitability of the New Zealand 
environment for A. fraterculus  to establish is considered moderate (with low to 
moderate uncertainty) . 
New Zealand’s climate in some fruit -growing regions is likely to be suitable for establishment of A. 
fraterc ulus. 
• Given the geographic distribution of A. fraterculus  (Table 9.1.2), it is likely that parts of 
New Zealand will be climatically suitable for establishment. Some of the countries and regions 
where it occurs have areas with a high climate match with New  Zealand, with climate  match 
index  (CMI) of 0.7 or greater (Phillips et al. 2018):  
o Argentina: the northeastern provinces of Corrientes and Entre Rios (Guillen and 
Sanchez 2007) are 0.7 and 0.7 –0.8 CMI, respectively;  
o Brazil: southern states, for example, Paraná  (mostly 0.7 –0.8 CMI), Rio Grande do Sul 
(0.7–0.9 CMI), Santa Catarina (0.7 –0.9 CMI) and S ão Paulo (areas in the south are 
0.7–0.8 CMI);  
o Peru: large areas with 0.7 –0.8 CMI;  
o Uruguay: 0.8 –0.9 CMI.  
• However, different taxa within the A. fraterculus  speci es complex may vary in their ability to 
establish in New Zealand. A study by Godefroid et al. (2015) predicted the potential 
distribution of A. fraterculus  in Europe, with it being climatically suited to parts of Europe 
particularly around the Mediterranea n. The three conspecific lineages considered showed 
some strong differences in potential distributions. Climatic suitability for Europe was greater 
for the Brazilian lineage than for the Mexican lineage, and the Andean lineage showed little 
climatic suitab ility. 
• The areas in Europe with highest climate suitability (Godefroid et al. 2015) are largely around 
the edge of the Mediterranean (Europe, Africa, Middle East), Portugal and the Atlantic coast 
(Spain, Portugal, France). These areas have a high climate m atch with New Zealand (0.8 –0.9 
CMI). However, very little of Europe overall showed climatic suitability for A. fraterculus . The 
findings from Godefroid et al . (2015) support the likelihood of establishment in at least some 
parts of New Zealand, particularl y in the northern regions.  
 
Anastrepha fraterculus  is likely to find mates and has a high reproductive rate.  
• Multiple larvae are contained within a single fruit, and after emergence , adults can disperse to 
find a suitable host. Surviving pupae from the larvae contained within a single fruit would be 
enough to establish a population if that fruit were discarded within range of a suitable host 
plant. Adults have been trapped on host pla nts as far as 900 m from their release point Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 112 (Kovaleski et al. 1999). Therefore, it would be likely that there would be enough emerging 
adults to establish a viable population.  
• Anastrepha fraterculus has sexual reproduction. As multiple larvae are containe d within a 
single fruit both males and females are likely to be present in the same location.  
• Males establish territories on the underside of leaves and emit pheromones to attract 
receptive females (Aluja 1994) enhancing the opportunity for mate finding a nd therefore 
increasing the likelihood of establishment.  
• Adults are long -lived (3 –5 months in laboratory studies (Fletcher 1989) and 8 months in cages 
(Christenson and Foote 1960) have been reported ). Salles (2000, in CPC 2020) reported that 
females can pr oduce 278 –437 eggs.  
 
Host availability is unlikely to be a barrier to establishment and spread of A. fraterculus . 
• Anastrepha fraterculus  is polyphagous on a range of other unrelated plants, as well as Citrus  
spp. (Table  9.1.1). Many plants for which there are verified natural infestations (Liquido et al. 
2018), are grown in home gardens, amenity areas and as commercial crops, or occur as 
environmental weeds in New Zealand, for example:  
o Acca sellowiana  (feijoa), Capsicum annuum  (pepper), Cydonia oblonga  (quince), 
Crataegus monogyna  (hawthorn), Diospyros kaki  (persimmon), Eriobotrya japonica  
(loquat), Ficus carica  (fig), Fragaria  × ananassa  (strawberry), Malus domestica  
(apple), Olea europaea  (olive), Passiflora caerulea  (blue passion flower), Passiflora 
edulis  (passionfruit), Passiflora tripartita  var. mollissima  (banana passionfruit), Persea 
americana  (avocado), Prunus armeniaca  (apricot), Prunus avium  (sweet cherry), 
Prunus domestica  (plum), Prunus persica  (peach), Psidium cattleianum  (purple 
guava), Psidium guajava  (guava), Punica granatum  (pomegranate), Pyrus communis  
(pear), Rubus fruticosus  (blackberry), Rubus idaeus  (raspberry), Vaccinium 
corymbosum  (blueberry), Vitis vinifera  (grape).  
• The main citrus -growing areas in New Zealand are Northland, Auck land, Bay of Plenty, 
Hawke’s Bay and Gisborne. Apples are grown throughout the country , including  in Hawke’s 
Bay, Gisborne, Waikato, Tasman -Nelson, Canterbury and Otago; and peaches are grown 
primarily in Otago and Hawke’s Bay. Avocados are grown primarily  in Northland, Auckland, 
Waikato and Bay of Plenty; wine grapes are grown throughout the country , including in 
Auckland, Gisborne, Hawke’s Bay, Wellington, Tasman -Nelson, Marlborough, Canterbury and 
Otago ( Plant & Food Research  2019)   
• Therefore, potential  hosts are likely to occur in climatically suitable areas for establishment.  
 
Anastrepha fraterculus  may not be detected until a population is established in New Zealand.  
• No male lures have yet been identified for Anastrepha  spp. (CPC 2020). Therefore, A. 
fraterculus  is unlikely to be picked up in New Zealand’s surveillance grid because it is not 
responsive to the lures used. As a result, there is unlikely to be early warning that A. 
fraterculus  is present in New Zealand , and it may not be detected until a population has 
established.  
 
There is uncertainty around the morphotypes and to what degree these vary in terms of plant hosts, 
geographic distribution, climatic requirements and tolerances. As a result, there is some uncertainty 
as to which taxa could est ablish, the extent that they could spread in New Zealand and what their host 
preferences would be.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below,  the level of impacts caused by A. 
fraterculus  is likely to be high.  
 
Damage and symptoms caused by A. fraterculus  can reduce fruit quality.  
• Attacked fruit can show signs of oviposition punctures , but much damage may occur inside 
the fruit before external symptoms are seen, often as networks of tunnels accompanied by 
rotting. Very sweet fruits may produce a sugary exudate (CPC 2020).  
  
113 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Anastrepha fraterculus is considered a serious pest of citrus an d other crops with impacts on 
commercial production, including in areas with similar climate to New Zealand.  
• Damage to crops through fruit loss can be considerable in areas where A. fraterculus  is 
present. The state of S ão Paulo, Brazil, is a significant a rea for citrus production. In 
unsprayed citrus orchards, fruit drop caused by fruit flies has been estimated at 25 –50% 
(Raga et al. 2004). These authors evaluated the natural infestations levels of fruit flies in 
different citrus varieties and hybrids coll ected across the state and found that about 78.1% of 
all adult Tephritoidea flies recovered from the fruit were Tephritidae (77.1% Anastrepha  sp. 
and 1.0% Ceratitis capitata ) and 21.9% were Lonchaeidae ( Neosilba  spp.). All females of 
Anastrepha  were identi fied as A. fraterculus . 
• The state of S ão Paulo, Brazil, is a significant producer of guava ( Psidium guajava ) (Raga et 
al. 2005). Raga et al. (2005) carried out a field survey across the state of unsprayed guava 
and other species of Myrtaceae. For guava, so me samples had infestations of up to 21.26 
fruit fly puparia per fruit, with an overall estimate of 2.69 puparia per fruit of guava. 
Anastrepha fraterculus  was the dominant fruit fly, reaching 87.74% of all Anastrepha  females 
and 76.62% of all female fruit  flies (Tephritoidea) from guavas (Raga et al. 2005).  
• In Brazil, A. fraterculus  is considered the main pest of temperate fruit trees and accounts for 
almost all pest species in orchards in southern Brazil (Poncio et al. 2016). Vacaria (0.9 CMI), 
located in  the state of Rio Grande do Sul, Brazil, produces about 55% of the total harvest of 
apples in the state and around  20% of th e apples  in Brazil. Kovaleski et al. (1999) report that 
losses caused by A. fraterculus  to the apple crop in Brazil are due primarily to ovipositing 
females rather than to larval development.  
• In the northeastern region of Argentin a, one of the main citrus -growing areas  of the country , 
the fruit flies A. fraterculus  and C. capitata  together c ause significant losses in orchards 
unless actively controlled by growers (Gullen and Sanchez 2007). The area most affected 
stretches from Monte Caseros (in Corrientes Province) to Colón (in Entre Ríos Province) 
where 954 ,000 tons of oranges, tangerines an d grapefruits are produced for commercial 
markets. Due to fruit fly pests, about 143 ,000 tons of produce are lost every year , with a gross 
value estimated at US $37 million (Gullen and Sanchez 2007). This area of Argentina has high 
climatic similarity to Ne w Zealand (0.7 –0.8 CMI) , indicating the potential for impact on citrus 
production in New Zealand should A. fraterculus  establish.  
• Anastrepha fraterculus  can infest many commercial crops including citrus, apple, stonefruit, 
berryfruit and grapevine. If A. fraterculus  established in New Zealand , the losses could be 
considerable. Citrus is of economic importance to New Zealand (see Chapter 2, section 2.6) , 
and apple exports alone were worth around NZ$82.8 million in 2019 ( Plant & Food Research  
2019). The combi ned export value for fresh fruit was NZ$3.39 billion in 2019 ( Plant & Food 
Research  2019).  
• Direct losses due to fruit fly damage on crops (citrus and other hosts, such as apples) would 
depend on how widely A. fraterculus  established, with establishment mo re likely in the 
northern regions of New Zealand.  
 
Establishment or an incursion of A. fraterculus  is highly likely to cause trade impacts.  
• The trade impact if A. fraterculus  is detected in New Zealand is likely to be high due to export 
restrictions and/o r extra phytosanitary measures being required by many trading partners.  
• Anastrepha fraterculus  is the subject of quarantine regulations in other countries , and 
detection in New Zealand could cause disruption of market access for any of its hosts, such 
as citrus, apple, pears, avocado, peach, passionfruit and persimmon, even if it did not 
establish. It is not present in existing or potential markets such as Europe, Australia, Asia and 
the USA. Anastrepha fraterculus  is a quarantine pest in the European Unio n, to which exports 
of apples from New Zealand were worth NZ$149  million in 2019 ( Plant & Food Research  
2019), for example. New Zealand currently has country freedom status from all fruit flies of 
economic importance , including A. fraterculus . 
• Because A. fraterculus  does not respond to lures used in New Zealand’s fruit fly surveillance 
grid, it is likely to have an established population once detected.  
 
If A. fraterculus  is detected in New Zealand, the cost incurred by a response would be high.  
• Anastrepha  fraterculus  is not responsive to current lures based on sex attractants. Therefore, 
once detected in New Zealand, eradication would be very difficult but is likely to be attempted. 
McPhail traps are usually used for the capture of Anastrepha  spp. (White a nd Elson -Harris Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 114 1994) with baits such as ammonium acetate, casein hydrolysate and torula yeast (CPC 
2020).  
• The typical cost of a response is millions of dollars. For example, the Queensland fruit fly 
response in 2019 cost approximately NZ$18 million (MPI 2020).  
 
It is likely that A. fraterculus  will cause a low to moderate level of sociocultural impacts within a limited 
area in New Zealand.  
• Many hosts of A. fraterculus  are common amenity and home garden species and occur in 
parks and gardens throughout the  country , for example , citrus, stonefruit, apple, pear, peach, 
avocado and blackberry. Anastrepha fraterculus  are fruit feeders , and infested fruit are 
rendered inedible and drop prematurely.  
• However, temperature is likely to restrict population grow th, and establishment is more likely 
in northern regions of the country . Therefore , direct impact on plants may be within a limited 
area of the country.  
 
It is likely that A. fraterculus  will have a low level of impact on the environment.  
• Citrus  species are members of the Rutaceae family. There are two genera within Rutaceae 
endemic to New Zealand . These are Melicope  and Leionema . Neither the Leionema  nor 
Melicope  species are considered threatened (NZPCN 2020).  
• There are several genera of hosts with representatives in the same genus in New Zealand, 
for example, Passiflora tetranda , Rubus  spp. and Syzygium maire . The latter has threatened 
(nationally critical) status (NZPCN 2020).  
• Anastrepha fraterculus  are fruit pulp feeders so may not impact on the reproductive potential 
of infested plants , particularly those plants bearing small fruit with limited flesh. Additionally, 
temperature is likely to restrict population growth , and establishment is likely to be limited to 
northern New Zealand.  
 
It is li kely that  A. fraterculus  will have negligible impacts on human health.  
• No evidence was found that A. fraterculus  has an impact on human health.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence below, Anastrepha fraterculus  may be 
considered for  additional measures . 
 
• Anastrepha fraterculus has a strong association with citrus fruit.  
• Some infested fruits will not be detected, especially when the volume of commodities is large.  
• As the larvae feed internally in the fruits, general handling (e.g., wa shing and brushing) 
cannot remove the larvae.  
• The basic measures  are likely to reduce the of entry of A. fraterculus  on citrus fruit, by a 
moderate degree (with moderate uncertainty); consequently, the likelihood of entry is 
considered to be low (with mode rate uncertainty)  
• Anastrepha fraterculus  has a moderate ability (with low to moderate uncertainty) to move from 
imported fruit and into a suitable environment to allow establishment, that is, onto a host 
plant.  
• The suitability of the New Zealand environment for A. fraterculus  to establish is considered 
moderate, within a limited area due to climate requirements.  
• Citrus, and other hosts of A. fraterculus, such as avocados, apples, pears and peaches, are 
grown comm ercially in New Zealand  and are common garden plants . Some are also 
environmental weeds.  
• The level of impact caused by A. fraterculus  is likely to be high to the overall economy of New 
Zealand, mainly due to stricter phytosanitary requirements for citrus a nd other horticultural 
crops.  
• Anastrepha fraterculus is present in three citrus -exporting countries considered in this import 
risk a nalysis , Brazil, Peru and Mexico.  
  
115 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.1.4 References  
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178. 
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Netherlands: Elsevier, 209 –219. 
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flies: intraspecific divergence matters. PLoS ONE , 10(08) e0135209 . DOI: 
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and Pacific Neotropical dominions (Diptera, Tephritidae). In De Meyer M, Clarke AR, Vera  MT, 
Hendrichs J ( eds) Resolution of Cryptic Species Complexes of Tephritid Pests to Enhance SIT 
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Liquido, N J; Santamaria, J; Lee, K L K; Tateno, A P K; Hanlin, M A; Ching., A J F; Marnell, S A 
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2019.pdf  
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Vera, M T (2015) Oviposition behaviour and larval development of Anastrepha fraterculus  from 
Argentina in citrus. Entomologia Experimentalis et Applicata  157(2): 198 –213. 
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Holos ; Riberão Preto, Brazil ; pp 81–86. 
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Weems, H V (2015) EENY 266. South American fruit fly (suggested common name), Anastrepha 
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117 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.2 Anastrepha ludens  (Mexican fruit fl y) 
 
Anastrepha ludens  is a polyphagous fruit fly. The larvae bore into and feed on fruit , and once infested , 
the fruit become s inedible. It is a very serious pest of various fruits, particularly citrus and mango, in 
Mexico and Central America (Weems et al.  2015).  
 
Scientific name: Anastrepha ludens  (Loew , 1873 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Trypeta ludens, Acrotoxa ludens, Anastrepha lathana  
 
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Anastrepha ludens  meets the criteria to be a quarantine pest for New Zealand.  
• Anastrepha ludens  has a strong association with citrus fruit . 
• Basic measures  are likely to reduce the entry  of A. ludens  on citrus fruit by a moderate 
degree; consequently, the likelihood of entry is considered to be low to moderate.  
• Anastrepha ludens  has a moderate ability to move from imported fruit and into a suitable 
environment to allow establishment, that is, onto a host plant.  
• The suitability of the New Zealand environment for A. ludens  to establish is considered 
moderate . 
• The level of impact by A. ludens  is likely to be high, mainly due to stricter phytosanitary 
requirements for citrus and other horticultural crops.  
• Anastrepha ludens  may be considered for requiring additional measures.  
 
Summary of risk assessment against criteria  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Low 
The ability to move from the imported commodity onto a suitable host  Moderate  Low–moderate  
Suitability of the N ew Zealand  environment  Moderate  Low 
Impacts on the New Zealand economy, environment, health  and society  High  Low 
 
8.2.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Anastrepha ludens meets the criteria to 
be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest, relevant to this assessment, are: not present in New Zealand, and 
of potential importance (able to establish and cause harm).  
 
Anastrepha ludens is not known to be present in New Zealand:  
• Anastrepha ludens  is not recorded in NZInverts (2020), NZOR (2020) or PPIN (2020) . 
• The quarantine status of A. ludens  in New Zealand is ‘regulated’ , and it is a notifiable 
organism and unwanted organism ( ONZPR  2020).  
 
Anastrepha ludens has the potential to establish and spread in New Zealand:  
• Anastrepha ludens  is native to Mexico, and po ssibly Nicaragua and Costa Rica, and occurs in 
other parts of North and Central America (Molina -Nery et al. 2014 ; CPC 2020). It is 
widespread in Mexico which has areas with a climate match index (CMI) of 0.7 or greater with Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 118 New Zealand , indicating the pote ntial for A. ludens  to establish in parts of New Zealand  
(Phillips et al. 2018).  
• Anastrepha ludens  is a polyphagous species with a broad host range (CPC 2020 , Liquido et 
al. 2017), including Citrus  spp., Malus domestica  (apple ), Passiflora edulis  (passion fruit), 
Persea americana  (avocado), Prunus persica (peach), Pyrus communis  (European pear) and 
Syzygium jambos  (rose apple) (Weems et al. 2009 ; CPC 2020 ; Liquido et al. 2017).  
• Host species are present in climatically suitable areas of New Zealand , indicati ng the potential 
for establishment.  
 
Anastrepha ludens has the potential to cause impacts on Citrus  and other horticultural crops in New 
Zealand:  
• Host species, such as citrus Citrus  spp., Malus domestica  (apple), Passiflora edulis 
(passionfruit), Persea a mericana  (avocado), Prunus persica  (peach), Pyrus communis  
(European pear) are grown commercially in New Zealand and establishment of A. ludens  
could cause economic loss primarily due to a potential loss of pest -free status and 
subsequent restrictions on trade.  
 
8.2.2 Hazard identification: commodity association  
 
Anastrepha ludens  is associated with citrus fruit . 
 
Anastrepha ludens is reported from citrus fruit:  
• Larvae of A. ludens  develop in the fruit of Citrus , for e xample, C. aurantiifolia , C. aurantium , 
C. limetta , C. maxima , C. medica , Citrus  x paradisi , C. reticulata , C. sinensis  and Citrus  x 
tangelo  (White and Elson -Harris 1994) . 
 
 
8.2.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Anastrepha ludens  has a strong 
association with citrus fruit:  
 
Eggs and larvae of A. ludens  can be associated with citrus fruit commodities.  
• Eggs of A. ludens  are deposited under the skin of ripening fruit and, once hatched, larvae 
tunnel inside the fruit feeding on pulp (Weems et al. 2015 ; CPC 2020).  
• Larvae have been recorded developing in the fruit of Citrus , for example, C. aurantiifolia , C. 
aurantium , C. lim on, C. maxima , C. medica , Citrus  paradisi , C. reticulata , C. sinensis  and 
Citrus reticulata × Citrus paradisi  (White and Elson -Harris 1994).  
• Females begin to oviposit in fruit at the time when fruit begins to show colour. As many as 40 
eggs are laid by each female at a time; however, eggs are usually laid in batches of 10 
(Weems et al. 2015). A sin gle female can produce over 1,000 eggs in her lifetime (Thomas et 
al. 2018). The egg stage lasts 6 –12 days (Weems et al. 2015). Larvae are white and maggot -
shaped , with the final instar about 9 –12 mm long (Weems et al. 2015). The larval stage lasts 
approxi mately 3 –4 weeks , with the rate of larval development determined by temperature and 
host fruit (Weems et al. 2015 ; Christenson and Foote 1960). Larvae go through three instars 
before leaving the fruit and burrowing into the ground, or other suitable substr ate, to pupate 
(Aluja 1994).  
 
Anastrapha ludens  infests many citrus species and varieties.  
• Anastrepha ludens  has been recorded as infesting many citrus species and varieties under 
natural conditions (White and Elson -Harris 1994; Liquido et al. 2017):   
119 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  o Citru s aurantiifolia , C. aurantium , C. lim on, C. maxima , C. medica , C. paradisi , C. 
reticulata  var. austera , C. reticulata , C. sinensis , Citrus  reticulata × Citrus paradisi . 
• According to Weems et al. (2015), all varieties of citrus except lemons and Mexican  limes are 
attacked, with grapefruit the most  preferred host and oranges the second.  
• Arredondo et al. (2015) report that the ‘Persian’ lime ( C. latifolia  Tanaka) is not a host for A. 
ludens , with their study showing no natural infestation in the field  or under forced infestation 
conditions on unharvested fruit. A very low rate of infestation of harvested fruit occurred under 
forced infestation conditions in the laboratory with very few immatures reaching adulthood. 
They conclude that because some adult flies emerged from the pupae obtained from 
harvested ‘Persian’ limes, after exposure to infestation, they should be considered a 
conditional host for A. ludens  flies. 
• According to Liquido et al. (2017), C. paradisi , C. limon  and C. reticulata  (as synonyms)  have 
undetermined host status, that is, no valid record of infestation under natural conditions.  
 
Anastrepha ludens  is present in one citrus export country (and transient in another country) 
considered in this import risk analysis : 
• Anastrepha ludens  is present in Mexico (EPPO 2020) , where it is widespread, being present 
in Aguascalientes, Baja California Sur, Campeche, Colima, Chiapas, Durango, Guanajuato, 
Guerrero, Hidalgo, Jalisco, México, Morelos, Nayarit, Nuevo León, Oaxaca, Puebla, 
Querétaro, Quintana  Roo, San Luis Potosí, Sinaloa, Sonora, Tabasco, Tamaulipas, Veracruz, 
Yucatan  and Zacatecas (EPPO 2020).  
• Anastrepha ludens  is currently considered “transient, under eradication ” in the US A, in 
California and Texas (EPPO, 2020). It is considered “absent, n o longer present ” in Arizona 
and Florida (EPPO 2020).  
• It is also found in the following Central American countries , which are not considered in this 
assessment: Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama 
(EPPO 2020).  
 
Given the arguments and evidence below,  basic measures  are likely to reduce the 
entry  of A. ludens  on citrus fruit  by a moderate degree . Consequently, the likelihood 
of entry is considered to be low to moderate, with low uncertainty.  
Infested fruit may show sign s of infestation and be removed from the consignment.  
• Any A. ludens  coming into New Zealand will likely be eggs or larvae inside infested fruit. 
Infested fruit may show signs of oviposition punctures , and these fruits would likely be culled. 
If fruit is at  the later stage of infestation, then it will likely be culled during routine packing 
processes , as extensive internal damage may start to show as external symptoms , and 
infested fruit rots prematurely. Sugary exudates may also be produced in very sweet fr uits 
(CPC 2010).  
 
However, some infested fruit may go unnoticed during the export production process.  
• If eggs and larvae are present inside fruit and are present at low density or at an early stage 
of infestation, the external signs such as oviposition punctures may not be visually obvious.  
• Therefore, low levels of infestation may go undetected , especially at high volumes of the fruit 
commodity.  
 
General h andling and processing after harvesting are not likely to remove eggs and larvae of A. 
ludens  from Citrus  fruit. 
• Eggs and larvae are found inside the fruit and so would not be removed by routine activities in 
the packhouse such as washing and brushing , which only treat the fruit ’s surface.  
• Post-harvest treatments can effectively kill eggs or larvae of A. ludens . For example, the 
USDA approves vapor or high -temperature forced air treatments for fruit disinfestation of 
Anastrepha  (pulp temperature of 44 °C for 100 minutes) (USDA 2016) for Citrus  types , 
including oranges, tangerines and grapefruit.  However, such treatments are beyond basic 
measures , and so their impact is not taken into account here.  
 
Larvae of A. ludens  are likely to survive transit in some  Citrus  commodities.  
• Transport of fruit from Mexico is likely to be by sea at low temperatures and may take up to 
three weeks. The larval stage lasts 21 –28 days under optimal temperatures. Development Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 120 continues to occur at temperatures as low as 10 °C. However, development will take 
considerably longer at low temperatures (Christenson and Foote 1960). Therefore, some 
larvae may survive under these conditions.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Anastrepha ludens  has a moderate ability 
(with low to moderate uncertainty) t o move from imported fruit into a suitable 
environment to allow establishment, that is, onto a host plant . 
Anastrepha ludens  can survive and develop on discarded Citrus  fruit and fruit pieces.  
• Infested fruit may contain many eggs , as females usually lay them in batches of about 10, and 
multiple ovipositions by different females can take place in a single fruit (Aluja 1994). Once 
these eggs hatch , the larvae feed within the fruit. Larvae move from t he fruit to pupate in the 
soil or other suitable substrates (Aluja 1994). Adult A. ludens  can emerge from buried fruit 
(Christenson and Foote 1960).  
• If infested Citrus  fruit is discarded as whole fruit or fruit pieces, A. ludens  may complete larval 
develop ment in the waste and find a suitable location to pupate.  
 
Most citrus fruit waste in New Zealand is likely to be disposed of using low -risk methods , so any A. 
ludens  present would either be killed or unable to escape from the Citrus  host. 
• In New Zealand, most waste is either bagged and sent to landfill or run through kitchen 
disposal units (see section 2.4.1 , waste analysis). Anastrepha ludens  in infested fruit is 
unlikely to survive in these circumstances.  
 
However, some waste is likely to  be disposed of using high risk methods, including composting in 
gardens, use as animal feed, or discard ing directly into the environment.  
• A small proportion of infested fruit is likely to be discarded in a home compost bin or open 
compost heap, or directly into the environment (see section 2.4.1 , waste analysis).  
• Anastrepha ludens  larvae move from fruit to pupate in soil or other suitable s ubstrate (Aluja 
1994). Adults have been known to emerge from fruit buried more than 45 cm below the 
ground (Christenson and Foote 1960). Therefore, some larvae or pupae associated with 
discarded citrus may find suitable conditions to develop to adulthood.  
• Before becoming sexually mature , adults go through a period where they need carbohydrates 
and water for survival and protein for gonad development (Aluja 1994). Adults emerging from 
the soil are likely to find suitable food in the environment, such as bir d droppings, nectar and 
plant sap (Christenson and Foote 1960).  
• Anastrepha ludens  is a polyphagous species and can complete development on many 
unrelated species. It is associated with a total of 96 plant species/taxa . Of these , 45 taxa 
belonging to 24 ge nera in 17 families have validated record of infestation under natural field 
conditions (Liquido et al. 2017). Known host species are present in New Zealand in modified 
habitats, for example, citrus, avocado, guava, peach, apple, pear, persimmon, passionfr uit, as 
are species within the same genus as known hosts, such as the native species Passiflora 
tetrandra  and Syzygium maire . Therefore, host plants are likely to be present in areas where 
waste fruit has been disposed of.  
 
Anastrepha ludens  can disperse t o find a suitable host . 
• Anastrepha ludens  adults emerging from pupae disperse to find a suitable host plant. The 
presence of host fruit (particularly Citrus ) for oviposition in the landscape is associated with 
increased abundance of female A. ludens  (Vanoy e-Eligio et al. 2019a, Vanoye -Eligio et al. 
2019b). This supports the potential for A. ludens  to locate suitable hosts to establish a 
population.  
• In climatically suitable locations where host plants are present , adults will not fly far from the  
site of emergence (the average dispersal distance is approximately  100 m (Hernández et al. 
2007)) . 
• However, A. ludens  is capable of long -distance dispersal if resources are scarce (Aluja 1994). 
The fruit fly regularly disperses up to 100 km from the site of emergence , and distances as far 
as 260  km ha ve been recorded (Christenson and Foote 1960).   
121 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
The level of uncertainty associated with this conclusion is low to moderate. Firstly, waste data may 
not be very accurate or up to date (see section 2.4.1 , waste  analysis). Secondly, it is uncertain what 
proportion of composting sites are exposed or uncovered (e.g. in a compost bin).  
 
Given the arguments and evidence below,  the suitability of the New Zealand 
environment for A. ludens  to establish is considered mod erate . 
New Zealand’s climate in some fruit -growing regions is likely to be suitable for A. ludens . 
• Given the current geographical range of A. ludens , which is widespread in Mexico, it is likely 
to establish in both the North and South Islands of New Zealand, especially in the warmer 
areas of northern New Zealand. Some of the  Mexican  states where it occurs have areas with 
a high climate match with New Zealand, with a climate match index  (CMI) of 0.7 or greater 
(Phillips et al. 2018) : 
o Aguascalientes (0.7 CMI), Durango (0.7 –0.8 CMI), Guanajuato (0.7 CMI), Oaxaca 
(0.7–0.8 CMI), Puebla (0.7 –0.8 CMI), San Luis Potos í (0.7–0.8 CMI), T laxcala (0.7 –
0.8 CMI), Zacatec as (0.7 –0.8 CMI)  
• Molin a-Nery et  al (2014) studied genetic diversity and structure of A. ludens  populations from 
seven Mexican states (Chiapas, Yucatán, Morelos, Veracruz, San Luis Potosí, Tamaulipas 
and Durango). Some of the sites were at higher elevations and had mean annual 
temperatur es below 20 °C. For example, the collection site in Morelos was at 1 ,920 metres 
above sea level ( masl ), with a mean annual temperature of 15 °C with warm humid climate; 
the site in Durango was at 2 ,500 masl, with a mean annual temperature of 14.6 °C with warm 
subhumid climate; and the site at Ch iapas was at 1 ,660 masl, with a mean annual 
temperature of 17.6 °C with warm temperate subhumid climate. Mean annual temperatures in 
the north of New Zealand are within this range (NIWA 2020) , and it is very li kely other areas 
in both the North and South Islands are climatically suitable also.  
• Vanoye -Eligio et al. (2017) studied A. ludens  in the neighbouring municipalities of Miquihuana 
and Bustamante in the state of Tamaulipas, between 99°22′33″W, 23°38′06″N an d 
99°48′50″W, 22°58′07″N. Their sites extended over the highlands of the Sierra Madre Oriental 
in the southwestern part of the state with altitude ranges from 1 ,800 to 1 ,950 m asl. Their 
study indicates that semi -arid ecosystems above 1 ,500 masl are native habitats of A. ludens  
populations in northeastern México. The authors note that A. ludens  can occur in semi -arid 
ecosystems and temperate environments.  
o Miquihuana and Bustamante have a high climate match (0.7 –0.8 CMI) with 
New Zealand . 
• Wild populations can  be self -sustaining under cool conditions although the rate of population 
growth is low (Thomas 2003). Anastrepha ludens  is the dominant fruit fly in higher altitude 
(1100 m above sea level) regions of Mexico (Aluja 1994) and is localised to higher elevati ons 
within Central America (CPC 2010).  
• A. ludens  is multivoltine and a highly polyphagous species that can infest uncommon fruits 
under unfavourable climatic conditions (Vanoye -Eligio et al . 2017). In addition, adults have a  
long life -span and high fecundi ty. Vanoye -Eligio et al. (2015) and Aluja et al. (2014) note that 
A. ludens  has a high degree of physiological and behavioural plasticity to adapt to varying 
environmental conditions.  Therefore, individuals arriving in New Zealand from Mexico may not 
find the change in seasons a barrier to establishment.  
 
Anastrepha ludens  is likely to find mates and has a high reproductive rate.  
• Multiple larvae are contained within a single fruit , and after emergence , adults can disperse to 
find a suitable host. Surviving pupae from the larvae contained within a single fruit would be 
enough to establish a population if that fruit were discarded within range of a suitable host 
plant. Therefore, it would be likely that t here would be enough emerging adults to establish a 
viable population.  
• Anastrepha ludens  reproduces sexually . As multiple larvae are contained within a single fruit , 
both males and females are likely to be present in the same location.  
• Males of A. ludens  establish territories on the underside of leaves and emit pheromones to 
attract receptive females (Aluja 1994) , enhancing the opportunity for mate -finding and 
therefore increasing the likelihood of establishment.  
• Adults are long -lived and may live for up to 12 months in the field (Aluja 1994). A single 
female can produce over 1,000 eggs in her lifetime (Thomas et al. 2018).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 122  
Host availability is unlikely to be a barrier to establishment and spread of A. ludens . 
• Anastrepha ludens  is polyphagous on fruit fr om many different hosts (Weems et al. 2015 ; 
Liquido et al. 2017 ; CPC 2010). Potential host plants are available throughout New Zealand in 
climatically suitable areas in both commercial groves and home gardens. The main citrus-
growing areas in New Zealand a re Northland, Auckland, Bay of Plenty, Hawke’s Bay and 
Gisborne. Apples are grown throughout the country , including  in Hawke’s Bay, Gisborne, 
Waikato, Tasman -Nelson, Canterbury and Otago; and peaches are grown primarily in Otago 
and Hawke’s Bay. Avocados a re grown primarily in Northland, Auckland, Waikato and Bay of 
Plenty ( Plant & Food Research  2019). Some of the  above  commercial growing areas may be  
climatically suitable for A. ludens . 
 
Anastrepha ludens  may not be detected until a population is establish ed in New Zealand.  
• No male lures have yet been identified for Anastrepha  spp. (CPC 2020). Therefore, A. ludens  
is unlikely to be detected  in New Zealand’s surveillance grid , because it is not responsive to 
the lures used  (Tan et al. 2014) . As a result, the re is unlikely to be early warning that A. 
ludens  is present in New Zealand , and it may not be detected until a population has 
established.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below,  the level of impact caused by A. ludens  is 
likely to be high . 
 
Damage and symptoms caused by A. ludens  reduces fruit quality.  
• Attacked fruit can show signs of oviposition punctures , but much damage may occur inside 
the fruit before external symptoms are seen, often as networks of tunnels accomp anied by 
rotting (CPC 2020).  
 
Anastrepha ludens  is considered a serious pest of citrus and other crops , with impacts on commercial 
production.  
• Damage to crops through fruit loss is considerable in areas where A. ludens  is present. In 
Mexico  (areas not give n) 20–40% of grapefruit is lost annually to damage by A. ludens  (Birke 
et al. 2006). Damage to greater than 37% of grapefruit by A. ludens  has been observed in 
Tamaulipas , which is one of the main citrus -growing regions (Vanoye -Eligio et al. 2015).  
• Anastr epha ludens  can infest many commercial crops , including Citrus  species , apple, 
avocado, European pear and peach. If A. ludens  became widespread in New Zealand , the 
losses could be considerable. Citrus  is of economic importance to New Zealand (see Chapter 
2, section 2.6), and apple exports alone were worth around NZ$82 0.8 million in 2019 ( Plant & 
Food Research  2019). The combined export value for fresh fruit was NZ$3.39 billion in 2019 
(Plant & Food Res earch  2019).  
• Direct losses due to fruit fly damage on crops (citrus and other hosts, such as apples) may 
vary throughout New Zealand depending on factors such as the local climate and fruiting 
phenology of suitable hosts (Vanoye -Eligio et al. 2019a) . 
 
Establishment or an incursion of Anastrepha  ludens  is highly likely to cause trade impacts.  
• The trade impact if A. ludens  is detected in New Zealand is likely to be high due to export 
restrictions and/or extra phytosanitary measures being required by many tra ding partners.  
• Anastrepha ludens  is the subject of quarantine regulations in other countries , and detection in 
New Zealand could cause disruption of market access for any of its hosts, such as citrus,  
apple , pear, avocado, peach, passionfruit and persimmon, even if it did not establish . It is not 
present in existing or potential markets such as Europe, Australia, Asia and the USA. 
Anastrepha ludens  is a quarantine pest in the European Union to which exports of apples 
from New Zealand were worth NZ$149 million in 2019 ( Plant & Food Research  2019), for 
example. New Zealand currently has country freedom status from all fruit flies of economic 
importance including A. ludens . 
• Because A. ludens  does not respond to lures used in New Zealand’s fruit fly surveillance grid, 
it is likely to have an established population once detected.   
123 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
If A. ludens  is detected in New Zealand, the cost incurred by a response would be high.  
• Anastrepha ludens  is not r esponsive to lures based on sex attractants  (Tan et al. 2014) . 
Therefore, once detected in New Zealand, eradication would be very difficult but is likely to be 
attempted. Existing detection systems for pest Anastrepha  species rely on the use of non -
specifi c wet, protein -baited McPhail traps , which act as general food attractants (Weems et al. 
2015).  
• The typical cost of a response is millions of dollars. For example, the Queensland fruit fly 
response in 2019 cost approximately NZ$18 million (MPI 2020).  
 
It is likely that A. ludens  will cause a low level of sociocultural impacts in New Zealand.  
• Many hosts of A. ludens  are common amenity species and occur in gardens and parks in 
New Zealand, for example Citrus  spp., peach, apple and pear. Anastrepha ludens  are fruit 
feeders , and infested fruit are rendered inedible and drop prematurely. However, temperature 
is likely to restrict population growth , and therefore , direct losses may be variable in where 
they occur in  the country.  
 
It is likely that A. ludens  will have a very low level of impact on the environment.  
• Citrus  are the primary hosts of A. ludens . Citrus  species are members of the Rutaceae family. 
There are two genera within Rutaceae endemic to New Zealand; these are Melicope  and 
Leionema . Neither the Leionema  nor Melicope  species are considered threatened (NZPCN 
2020).  
• New Zealand has one native species of Passiflora  (P. tetrandra ), which is not considered 
threatened , and one species of Syzygium  (S. maire ), which is considered threatened 
(nationally criti cal) (NZPCN 2020).  
• Anastrepha ludens  are fruit pulp feeders so may not impact on the reproductive potential of 
infested plants, particularly those plants bearing small fruit with limited flesh. Additionally, 
temperature is likely to restrict population gro wth and  impacts may be variable as to where 
they occur in the country . 
 
Anastrepha ludens  is not known to have any impacts on human health.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence below, Anastrepha ludens  may be considered for 
additional measures . 
 
• Anastrepha ludens  has a strong association with fruits of some citrus species.  
• Some infested fruits will not be detected, especially when the volume of commodities is large.  
• As the larvae feed internally in the fruits, general handling (e.g. washing and brushing) cannot 
remove the larvae.  
• Anastrepha ludens  has a moderate ability (with low  to moderate uncertainty) to move from 
imported fruit and into a suitable environment to allow establishment, that is, onto a h ost 
plant.  
• The suitability of the New Zealand environment for A. ludens  to establish is considered 
moderate . 
• Citrus, and other hosts of A. ludens, such as avocados, apples, pears and peaches, are 
grown commercially in New Zealand and are common garden plan ts. 
• The level of impact caused by A. ludens  is likely to be high to the overall economy of 
New Zealand, mainly due to stricter phytosanitary requirements for citrus and other 
horticultural crops.  
• Anastrepha ludens  is present in one citrus -exporting countr y considered in this import risk 
analysis , Mexico, and considered “transient, under eradication ” in the USA.  
 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 124 8.2.4 References  
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155–178. 
Aluja, M; Birke, A; Ceymann, M; Gui lléna, L; Arrigoni, E; Baumgartner, D; Pascacio -Villafána, C; 
Samietz, J (2014) Agroecosystem resilience to an invasive insect species that could expand its 
geographical range in response to global climate change. Agriculture, Ecosystems and Environment  
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economically important fruit flies (Diptera: Tephritidae) present in Chiapas and a few other fruit 
growing regions in Mexico. Florida Entomolog ist, 70(3): 320 –329. 
Arredondo, J; Ruiz, L; López, G; Díaz -Fleischer, F (2015) Determination of the host status of the 
‘Persian’ lime ( Citrus latifolia  Tanaka) for Anastrepha ludens  (Loew) (Diptera: Tephritidae). Journal of 
Economic Entomology , 108(1): 77–87. 
Christenson, L D; Foote, R H (1960) Biology of fruit flies. Annual Review of Entomology , 5: 171 –192. 
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Hernández, E; Orozco, D; Breceda, S F; Domínguez, J (2007) Dispersal and longevity of wild and 
mass -reared Anastrepha ludens  and Anastrepha obliqua  (Diptera: Tephritidae). Florida Entomologist , 
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populations of Anastrepha ludens  (Diptera: Tephritidae) in Mexico. Florida Entomologist , 97(4): 1648 –
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MPI (2020) Successful end to fruit fly operation in Auckland. https://www.mpi.govt.nz/news -and-
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training/ schools/resources/climate/overview  
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September 2020.  
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Accessed September 2020 . 
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Sivinski, J; Pi ñero, J; Aluja, M (2000) The distributions of parasitoids (Hymenoptera) of Anastrepha  
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fruit flies. In Shelly, T E; Epsky, N; Jang, E B; Reyes -Flores, J; Vargas, R I (eds) Trapping Tephritid 
Fruit Flies: Lures, Area -Wide Programs, and Trade Implications . Springer Netherlands; Dordrecht, 
Netherlands;  pp 15-74. 
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(Diptera: Tephritidae) in the Sierra Madre Oriental, Northern Mexico. Neotropical Entomology , 32(3): 
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(2015) Population dynamics of Anastrepha luden s (Loew) (Diptera: Tephritidae) on citrus areas in 
southern Tamaulipas, Mexico. Neotropical Entomology , 44(6): 565 –573.  
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Rocandio ‐Rodríguez , M (2019a) Analysis of temporal fluctuations in numbers of sexually mature 
Anastrepha ludens  females over an extensive citrus area in northeastern Mexico . Entomologia 
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Mexican fruit fly populations in the semi -arid highlands of the Sierra Madre Oriental in northeastern 
Mexico. Neotropical Entomology , 46(4): 380 –387. 
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(2019b) A spatio -temporal approach for the occurrence of traps capturing sexually mature Anastrepha 
ludens  females over an extensive citrus area in Mexico. Crop Protection , 124: 104858.  
Weems, H V; Heppner, J B; Steck, G J; Fasulo, T  R; Nation, J L (2015) EENY 201.Mexican Fruit Fly, 
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   Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 126 8.3 Bactrocera dorsalis  (Oriental fruit fly ) 
 
Bactrocera dorsalis  is one of the most destructive insect pests of tropical and subtropical fruits and 
vegetables. It is highly polyph agous and highly adaptable to various climates, which has allowed it to 
spread to temperate areas.  
 
Scientific name: Bactrocera dorsalis  (Hendel, 1912)  
Order/Family: Diptera /Tephritidae  
Other names include: Bactrocera  invadens , Bactrocera  papayae, Bactrocera  philippinensis , 
Bactrocera (Bactrocera) variabilis , Bactrocera ferruginea , Strumeta  dorsalis , Chaetodacus dorsalis , 
Chaetodacus ferrugineus , Chaetodacus ferrugineus dorsalis , Chaetodacus ferrugineus okinawanus , 
Dacus dorsalis , Dacus ferrugineus , Dacus ferrugineus dorsalis , Dacus ferrugineus okinawanus , 
Dacus (Bactrocera) dorsalis , Dacus (Bactrocera) semifemoralis , Dacus (Bactrocera) vilanensis  (CPC 
2020)  
 
Taxonomic notes:  CPC (2020) notes that Bactrocera dorsalis  is a member of the Oriental frui t fly 
Bactrocera dorsalis  species complex. B. dorsalis  was originally treated as a single species, until it was 
split into several species, with the description of B. carambolae , B. papayae  and B. philippinensis  by 
Drew and Hancock (1994) . Based on a total -evidence approach, B. papayae , B. invadens  and B. 
philippinensis  are now considered synonyms of B. dorsalis , but thes e names can still be found in 
numerous papers and internet website resources (Doorenweerd et al. 2018). Bactroce ra carambolae  
was left as a distinct species by Schutze et al. (2014). Bactrocera dorsalis  is known to hybridise with 
B. carambolae , and genetic  evidence suggests that there is historic hybridisation with B. kandiensis  
(Schutze et al. 2015 ). Records of B. pedestris  (Bezzi) from outside of the Philippines are mostly 
based on misidentifications of B. dorsalis  (CPC 2020) . 
 
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Bactrocera dorsalis meets the criteria to be a quarantine pest for New Zealand .  
• Bactrocera dorsalis has a strong association with citrus fruit  with low uncertainty . 
• Basic measure s are likely to reduce the likelihood of introduction of B. dorsalis by a low to 
moderate degree . Consequently , the likelihood of entry is considered to be moderate with low 
uncertainty.  
• Bactrocera dorsalis has a moderate  to high ability (with low  to moder ate uncertainty) to move 
from imported fruit and into a suitable environment to allow establishment, that is, onto a host 
plant.  
• The suitability of the New Zealand environment for B. dorsalis to establish is considered 
moderate  to high (with moderate uncertainty).  
• The level of impact caused by B. dorsalis is likely to be high, with low uncertainty . 
• Bactrocera dorsalis may be considered for additional measure s. 
 
Summary of risk assessment against criteria  
Criteria  Rating Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Moderate  Low 
The ability to move from the imported commodity  onto a suitable host  Moderate –high moderate  
Suitability of the N ew Zealand  environment  Moderate –high Low–moderate   
127 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Impacts on the New Zealand economy, environment, health and society  High Low 
 
8.3.1 Hazard  identification: quarantine status  
 
Given the arguments and evidence below,  Bactrocera dorsalis meets the criteria to 
be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause harm57). 
 
Bactrocera dorsalis is not known to be present in New Zealand:   
• Bactrocera dorsalis  is not recorded in NZInverts (2020) or NZOR  (2020) . 
• Bactrocera dorsalis is not recorded in PPIN (2020).  
• Bactrocera dorsalis is listed as ‘Regulated’ in ONZPR  (2020) . 
 
Bactrocera dorsalis has the potential to establish and spread in New Zealand:  
• Bactrocera dorsalis is distributed mainly in tropical areas (CPC 2020), but it also occurs in 
areas that have similar climate conditions to New Zealand.  
• Bactrocera dorsalis is highly polyphagous, with over 300 species of commercial/edible and 
wild hosts  (CPC 2020).   
• Hosts commercially grown in New Zealand and commonly found in home gardens include, 
but are not limited to: apple ( Malus domestica ), cherries , apricot ( Prunus armeniaca ), 
avocado ( Persea american a), capsicum ( Capsicum annuum ), citrus ( Citrus  spp.), cucumber 
(Cucumis sativus ), grapevine ( Vitis vinifera ), guava ( Psidium guajava ), loquat ( Eriobotrya 
japonica ), peach ( Prunus persica ), pear ( Pyrus  spp.), persimmon ( Diospyros kaki ) and plum 
(Prunus dome stica) (CPC 2020; EPPO 2020a).  
 
Bactrocera dorsalis has the potential to cause impacts on the economy and environment of New 
Zealand:  
• Bactrocera dorsalis has the potential to damage plant species that are of eco nomic 
importance to New Zealand, such as citrus, apple, avocado, pear and grapevine.  
• Bactrocera dorsalis has the potential to harm the New Zealand environment: B. dorsalis has 
been reported on plant species in genera that are present in New Zealand (NZPCN 2020).  
8.3.2 Hazard identification: commodity association  
 
Bactrocera dorsalis is associated with citrus fruit  
 
Bactrocera dorsalis is reported from citrus fruit : 
• Bactrocera dorsalis has been reported to infest citrus fruits (Cui et al. 2020).  
 
8.3.3 Risk assessment  
 
Likelihood of entry:  
 
Bactrocera dorsalis has a strong association with citrus fruit  with low uncertainty . 
Bactrocera dorsalis  has been reported to develop in various citrus species and cultivars.  
• Larvae of B. dorsalis  have been reported from various citrus cultivars, and a dults of B. 
dorsalis have been reared from citrus fruits of different citrus cultivars  (Leblanc et al. 2012 ; 
                                                      
57 Refer to ISPM 5  for the definition of a quarantine pest  under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 128 Allwood et al. 1999) . Citrus fruit host associations found in the literature are summarised  in 
Table 9.3.1.  
 
Table 9.3.1  Known citrus host association of Bactrocera dorsalis . 
Citrus host scientific 
name  Citrus host common name 
from the reference  Reference  Notes  
Citrus aurantifolia   Allwood et al. (1999)  Reared from field -
collected fruit  
Citrus aurantiifolia  Lime CPC (2020), Leblanc et al. 
(2013)  Field infestatioin  
Citrus aurantium  Sour orange  CPC (2020)   
Citrus reticulata  Clementine  USDA (2016)*   
Citrus reticulata  Italian tangerine, Willow-leaf 
mandarin  USDA (2016)*   
Citrus reticulata   USDA (2016)*   
Citrus maxima   Allwood et al. (1999)  Reared from field -
collected fruit  
Citrus hystrix  Mauritius bitter orange  CPC (2020)   
Citrus limon  Bush lemon  Hancock et al. (2000)  Breeding in fruit  
Citrus reticulata  Kabuchi, Keraji USDA (2016)*   
Citrus latifolia  Tahiti lime  Leblanc et al. (2013)  Reared from field -
collected fruit  
Citrus limon  Sweet lime  USDA (2016)*   
Citrus limon  Indian sweet lime  USDA (2016)*   
Citrus limon  Lemon  White and Elson -Harris (1992)  Larvae develop in the fruit 
Citrus medica var. Mata 
Kerbau   Ibrahim and Rahman (1982)   Experimental host (eggs 
were manually laid on fruit 
slice)  
Citrus maxima  Pomelo  Leblanc et al. (2013)  Reared from field -
collected fruit  
Citrus paradisi  Japanese summer grapefruit,  
Natsudaidai  USDA (2016)*   
Citrus reticulata  King orange  USDA (2016)*   
Citrus reticulata   USDA (2016)*   
Citrus paradisi   Hancock et al. (2000) (CPC 
2020 ; EPPO 2020a)  Breeding in fruit  
Citrus reticulata  Mandarin  CPC (2020), Allwood et al. 
(1999)  Reared from field -
collected fruit  
Citrus sinensis  Navel orange  Leblanc et al. (2013)  Reared from field -
collected fruit  
Fortunella  swinglei   CPC (2020)   
Citrus  spp. Tangerine, Orange, 
Grapefruit, Lemon  Loomans et al. (2019 )  
Poncirus  trifoliata  Trifoliate orange  Leblanc et al. (2013)  Reared from field -
collected fruit  
Citrus reticulata  Sweet orange  Han et al. (2011)  Field infestation  
Citrus reticulata x Citrus 
paradisi  Tangelo  EPPO (2020a)    
129 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  * For hosts listed in USDA (2016), USDA mentioned that , “The berries, fruit, nuts and vegetables of the listed plant species are now considered host articles 
for B. dorsalis. Unless proven otherwise, all cultivars, varieties, and hybrids of the plant species listed herein are consid ered suitable hosts of B. dorsalis .” 
However, there were no original references cited.  
 
Bactrocera  dorsalis can be associated with citrus fruit commodities.  
• Bactrocera dorsalis  has been intercepted over 90 times at the New Zealand border. Among 
these records, B. dorsalis  has been intercepted alive from fresh produce of limes (unknown 
life stage) and C. reticulata  (larval stage) (LIMS 2019).  
• Bactrocera dorsalis  has been intercepted on Citrus paradis i and C. maxima  in Europe (EPPO 
2020b).  
• In Hunan, China, the adult popula tion peak of B. dorsalis  coincided with the ripeness period of 
sweet oranges in October. Subsequently , larvae were found in sweet oranges between late 
September and early November (Han et al. 2011), suggesting that the fly is associated with 
mature fruits.   
• Adult females of B. dorsalis  lay eggs under the skin of the ripened or ripening fruits (Ye and 
Liu 2007).  
 
Bactrocera dorsalis  is present in a number of the citrus -exporting countries covered by  this IRA: 
• Bactrocera dorsalis  is present in China, Viet  Nam, the USA (California58, Hawaii), and 
Australia (Torres Strait Islands)59. 
 
Given the arguments and evidence below,  basic measure s are likely to reduce the 
likelihood of entry of B. dorsalis by a low  to moderate degree . Consequently , the 
likelihood of entr y is considered to be moderate , with low uncertainty : 
Some of the infested fruits may be detected and removed.  
• Oviposition of B. dorsalis  may cause necrosis around the puncture mark, followed by 
decomposition of the fruit (CPC 2020).  
• If bagging and culling are used in the export countries, these practices are likely to reduce the 
likelihood  to some extent.  Xia et al. (2019) found that fruit bagging and packing  house culling 
(including preliminary culling, washing, waxing, drying, inten sive culling, sorting and final 
culling and box -packing) could contribute to risk mitigation of fruit flies in citrus in China. The 
study found few oviposition marks and an absence of living tephritid fruit flies in bagged 
pomelo fruits (n=3,000)  (where n= sample size) , while 129 fruit fly -infested fruits (containing 
634 live larvae and 4 pupae of B. dorsalis ) were found in the unbagged fruits ( n=3,040 ). They 
also found that in fruit ( C. unsh iu) that received culling treatment (n=10,000) , fruit flies were 
absent, and 10 fruit s with oviposition marks (with no living fruit flies) were found, while in fruit 
that did not receive the culling treatment (n=10,000) , one infested fruit with 7 larvae of B. 
minax  and 25 fruit s with fruit fly oviposition marks were found.  
• Bactrocera dorsalis  can cause rot and fruit drop (Jiang et al. 2011). Rotting fruit and fruit  that 
drops on the ground is not likely to be picked up and exported.  
 
However, e ggs and larvae of B. dorsalis  are un likely to be visible in the course of general handling 
during and after harvest.  
• Eggs of  B. dorsalis are laid under the skin of the ripened or ripening fruits and the larvae feed 
inside the fruit (Ye and Liu 2007). Because general handling after harvesting  (e.g. washing 
and brushing) only treats the surface of fruit,  it is unlikely to remove the larvae of B. dorsalis  
inside citrus fruit.  
• Fruit will need to be cut open to reveal the larvae of B. dorsalis  inside, but eggs are harder to  
detect.  
 
It is likely that some infested fruits will not be detected.  
• A low level of infestation (fewer oviposition punctures  in fruit ) may not be obvious enough to 
be detected during general handling.  
                                                      
58 California is recorded as “Present, Transient under eradication” in CPC (20 20) and EPPO (2020a). CPC (2020) comments 
that as B. dorsalis  is repeatedly trapped in California in small numbers, whether or not the fly is actually established in 
continental America is a hotly debated topic.  
59 Reported as B. papaya or B. philippinensis . The fly is present in the Torres Strait Islands, but it has been eradicated from 
mainland Australia (Hancock et al. 2000).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 130 • The volume of the commodities can also affect efficiency of d etection. Low levels of 
infestation may not be easily detected, especially if the volume of commodities is large.  
• Bactrocera dorsalis  has been identified over 90 times at the New Zealand border. Among 
these records, B. dorsalis  has been intercepted alive from fresh produce of limes (unknown 
life stage) and C. reticulata  (larval stage) (LIMS 2019), suggesting that some infested fruit 
cannot be detected during general handling after harvest.  
 
Larvae of B. dorsalis  are likely to survive transit of some citrus commodities.  
• Larvae of Bactrocera dorsalis  have been intercepted alive in citrus fresh produce at the New 
Zealand border (LIMS 2019), suggesting that it can survive transit by air or sea in  some citrus 
commodit ies.  
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Bactrocera dorsalis has a moderate  to 
high ability (with low to moderate uncertainty) to move from imported fruit and into a 
suitable environment to allow establishment, that is, onto a host plant  (exposure) . 
Bactrocera dorsalis  can survive and develop on the waste of citrus  fruit (whole fruit or fruit pieces but 
probably not skin).  
• Adult B. dorsalis  have been reared from field -collected fruit of Citrus aurantiifolia , C. latifolia , 
C. maxima , C. reticulata , C. sinensis , C. trifoliata  and C. grandis  (Leblanc et al. 2012; Allwood 
et al. 1999).  
• If citrus fruit is disposed of as whole fruit or fruit pieces, it is likely that B. dorsalis  can survive 
in this waste. There is no evidence showing that B. dorsalis  can complete development by 
feeding on citrus fruit skin.  
 
Most of the waste in New Zealand would be disposed of using low -risk methods , so B. dorsalis  would 
either be killed or unable to escape from t he citrus  host.  
• The majority of  kitchen  waste in New Zealand is bagged and disposed of in landfills and run 
through  kitchen disposal units, and in these situations, B. dorsalis  is unlikely to reach a new 
host ( see the waste analysis in section 2.4.1 ). 
 
However,  some of the waste would be disposed of using high -risk methods, including composting in 
gardens and us e as animal feed.  
• Bactrocera dorsalis  is highly polyphagous. Many hosts (such as apple, apricot, avocado, 
capsicum, citrus, cucumber , grapevine,  guava, loquat , passionfruit, peach, pear, persimmon 
and plum)  are widely distributed in New Zealand and are commercially grown and/or 
commonly found in home gardens.  
• Adults of B. dorsalis  lay eggs below the skin of fruits, and eggs usually hatch within a day, but 
hatching can be delayed for up to 20 days in cool conditions. Larvae feed inside the fruit for 
9–35 days depending on the season. The fly pupates in the soil under the host plant 
(Christenson and Foote 1960).  
• An overwintering experiment in Hubei shows that while larvae and adults of B. dorsalis  could 
not survive during the winter (around freezing temperature), a small proportion of pupae 
survived. Successful overwintering of pupae depended on the date and the depth at which the 
pupae were placed i nto the soil (Han et al. 2011). This suggests that pupae of B. dorsalis  are 
cold-resistant and may  be able to overwinter in the soil after leaving the fruit host.  
• If hosts are not far from the composting site or animal feeding site ( see the waste analysis in 
section 2.4.1 ), adult B. dorsalis  is likely to locate a new host.  
 
Adult B. dorsalis  can fly for a moderate to long distance to food sources.  
• According to a laboratory test with a flight -mill system, the maximum flight distance of B. 
dorsalis  is 46  km (Liang et al. 2001).  
• Mean dispersal distances from below 1  km to 3.6  km have been reported for B. dorsalis . 
However, the maximum dispersal distance reported in these studies was limited to the 
distance of the trap placed furthest from the r elease point (Weldon et al. 2014).  
• Makumbe et al. (2020) investigated the tethered flight performance of B. dorsalis , showing 
that the longest total distance f lown in 1 hour was about 15  km.  
131 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
The longevity of adult B. dorsalis  is likely to increase the likelihood for locating a suitable host.  
• Adults of B. dorsalis  normally live for 1 to 3 months, depending on diet and temperature. The 
lifespan can be up to 12 months in cool mountain locations (Christenson and Foote 1960). 
The l ongevity of adults is likely to increase the chance for locating a mate and a suitable host.  
 
The level of uncertainty associated with the conclusion is low to moderate . First ly, waste data may not 
be very accurate and up to date , and it is not known how f requently suitable hosts will be present near 
composting sites in gardens or animal feeding locations (see section 2.4.1,  waste analysis ). Secondly, 
it is uncertain what proportion of composting sites are expos ed or enclosed (e.g. in a compost bin).   
 
Given the arguments and evidence below,  the suitability of the New Zealand  
environment  for B. dorsalis to establish is considered moderate  to high (moderate 
uncertainty) .  
The current known distribution of B. dorsalis is mostly tropical and subtropical are as, but the current 
distribution also covers areas with similar climate conditions to New Zealand.  
• Bactrocera dorsalis  is native to Asia, and its current distribution is predominantly in the tropics 
and subtropics ( Table 9.3.2).  
• The current distribution includes countries and areas with a climate match index (CMI) 
(Phillips  et al.  2018) of 0.7–0.8. These areas include Himachal Pradesh in India (CMI: 0.7 –
0.8), Anhui, Chongqing, Guizhou, Hubei, Hunan, Jiangsu, Shanghai, Yunnan, Zhej iang in 
China (CMI: 0.7) and Sichuan in China (CMI: 0.8). This suggests that B. dorsalis , or some 
populations of the species, can adapt to a colder, temperate climate.    
 
Table 9.3.2  Known geographic distribution of Bactrocera dorsalis . Information compil ed 11 September 
2020 from CPC (2020) and EPPO (2020a). Country/area with “*” is only recorded in CPC (2020); country/area 
with “**” is only recorded in EPPO (2020a). Country/area in bold  is included in the Citrus IHS project.  
Continent/Region  Country/area  
Africa  Angola , Benin , Botswana , Burkina Faso , Burundi , Cameroon , Cape Verde , Central African 
Republic , Chad , Comoros , Congo , Congo, Democratic republic of the , Cote d'Ivoire , Equatorial 
Guinea , Eritrea , Eswatini**, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea -Bissau, Kenya, 
Liberia, Madagascar, Mali, Mauritania, Mayotte, Mozambique, Namibia, Niger, Nigeria, R éunion, 
Rwanda, Senegal, Sierra Leone, Sudan, Swaziland*, Tanzania , Togo , Uganda , Zambia , 
Zimbabwe  
Asia Bangladesh , Bhutan , Brunei Darussalam , Camb odia, China  (Anhui, Chongqing, Fujian, 
Guangdong, Guangxi, Guizhou, Hainan, Hubei, Hunan, Jiangsu, Jiangxi, Shanghai, 
Sichuan, Tibet, Yunnan, Zhejiang, Hong Kong) , Christmas Island*, East Timor*, India , 
Indonesia , Lao, Malaysia , Myanmar , Nepal , Oman , Pakistan , Philippines , Singapore , Sri Lanka , 
Taiwan , Thailand , United Arab Emirates , Viet Nam 
North America  The USA (California60, Hawaii)  
Oceania  Australia61 (Torres Strait islands) , French Polynesia , Nauru , Christmas Island**, Northern 
Mariana Islands, Palau, Papua, New Guinea, Timor -Leste**  
 
Bactrocera dorsalis  has a very broad host range, therefore, host availability is unlikely to be a limiting  
factor for it to establish in New Zealand.  
• Bactrocera dorsalis  is categorised  by Vargas et al. (2015)  as a Category A spe cies 
(widespread invasive polyphagous generalists or highly destructive specialists that have 
                                                      
60 California is recorded as “Present, Transient under eradication” in CPC (2020) and EPPO (2020a). CPC (2020) comment s 
that as B. dorsalis  is repeatedly trapped in California in small number, whether or not the fly is actually established in 
continental America is a hotly debated topic.  
61 Reported as B. papaya or B. philippinensis . The fly is present in Torres Strait is lands, but it has been eradicated from 
mainland Australia (Hancock et al. 2000).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 132 become established outside their native ranges)  and is highly polyphagous . It has  over 300 
species of commercial/edible and wild hosts  (CPC 20 20).  
• Many hosts are commercially grown and commonly found in home gardens and parks, such 
as apple, apricot, avocado, capsicum, citrus, cucumber , grapevine, guava, loquat , peach, 
pear, persimmon and plum (CPC 2020; EPPO 2020a). Therefore, hosts are likely  to be 
available in all seasons and present in most areas in New Zealand.  
 
Bactrocera dorsalis  has a rapid dispersal ability.   
• Bactrocera dorsalis  has strong flight capability. A laboratory test with a flight -mill system 
shows that the maximum flight dista nce of B. dorsalis  is 46  km (Liang et al. 2001). According 
to Weldon et al. (2014), compared to other Bactrocera  species, mean dispersal distances 
recorded for B. dorsalis  in mark -release -recapture (MRR) studies are higher, ranging from 
below 1  km to 3.6  km, while mean dispersal distances for other Bactrocera  species recorded 
are well under 1  km.  
• Eggs and larvae of B. dorsalis  are inside the fruits, therefore, they are unlikely to be visible. 
Therefore, transporting of infested fruits is a major means by which the fly can spread to 
areas that were not infested previously.  
 
Bactrocera dorsalis  has a  high reproductive rate.   
• A female of B. dorsalis  can lay 3 –30 eggs in each oviposition (Fletcher 1989 , in Ye and Liu 
2007) and more than 1 ,000 eggs during its lifespan (Zhou et al. 1996, in Ye and Liu 2007). 
Under laboratory  conditions, a female can lay more than 1,000 eggs during its lifetime ( Shelly 
2000 ). 
• Female B. dorsalis  can release sex pheromones to attract males (Shen et al. 2019) , which 
increases the pr obability of females finding mates.  
• Female B. dorsalis re-mate , which implies that even if sperm reserves w ere depleted , egg 
laying would resume if the female found another male (Shelly 2000).  
 
Bactrocera dorsalis  has multiple overlapping generations in both warmer and colder climates . 
• The number of generations per year and occurrence of B. dorsalis  differ through its 
geographic distribution, but in general, B. dorsalis  has 3 –5 overlapping generations per year 
in most tropical areas in its distribution an d may reach 10 generations per year under optimal 
conditions (Ye and Liu 2007).  
• In Xishuangbana, Yunan, China (CMI: 0.6), B. dorsalis  is present all year round (Ye and Liu 
2007), while in Baoshanba, Yunan (CMI: 0.7 –0.8), B. dorsalis  occurs during April –November , 
with the population peak in August (Chen and Ye 2007). In Hubei, China (CMI: 0.7), where 
the typical climate is hot and wet in summer and freezing cold in winter, five generations per 
year were observed (Han et al. 2011).  
 
Bactrocera dorsalis  is a h ighly invasive species, both in its native and introduced range.  
• Bactrocera dorsalis  is highly invasive. The fly is native to Asia, but is now found in at least 65 
countries. It is a serious pest of a wide range of fruit crops throughout its native and 
introduced range (CPC 2020).  
• High genetic va riability  may facilitate the adaptation of B. dorsalis  to a new habitat during 
invasion. High genetic diversity within the B. dorsalis  population was observed in its native 
range, and multiple introductions and hybridisation among related populations in the 
introduced range may further enhance genetic diversity (Wan et al. 2012; Aketarawong et al. 
2007).  
 
The current national surveillanc e programme is likely to reduce the likelihood  of B. dorsalis  
establishing a permanent population in New Zealand.  
• Bactrocera dorsalis  is one of the targeted fruit fly species in the National Fruit Fly Surveillance 
Programme in New Zealand (MacLellan et al.  2019). The m ale of B. dorsalis  is attracted to 
methyl eugenol lure (Plant Health Australia 2001) . 
 
A modelling study indicates that many areas of New Zealand are likely to be suitable for the 
establishment and short -term population occurrence of B. dorsal is. 
• A CLIMEX™ model of B. dorsalis  indicates that under the reference climate (1961 –1990), it 
could establish throughout much of the low -lying areas of the North Island, and most parts of  
133 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  New Zealand could support short -term populations during the summer m onths (Kriticos et al. 
2007).  
 
Bactrocera dorsalis  is a highly invasive pest in both its native and introduced range, and the species 
has the biological and ecological features to be invasive in new habitats (e.g. high productivity rate, 
high genetic varia bility and strong flight ability). Its current distribution includes areas with similar 
climate to New Zealand. However, its current distribution is predominantly in the tropics and 
subtropics , which are warmer than the overall climate of New Zealand. Due to the uncertainty around 
the suitability of all of New Zealand’s climate for the fly, the level of uncertainty associated with the 
conclusion is moderate.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below,  the level of impact caused by B. dorsalis 
is likely to be high, with low uncertainty.  
Damage and symptoms caused by B. dorsalis  can reduce fruit quality.  
• Eggs of B. dorsalis  were laid under the skin of the ripened or ripening fruits , and the larvae 
feed on the fruit pulp, which causes severe damage to the fruits. Necrosis may form around 
the oviposition puncture mark, followed by decomposition of the fruit (CPC 2020).  
• Fruit infested with B. dorsalis  become malformed , and larval  feeding damage allows for 
infection by secondary pathogens, causing fruit to rot and ultimately fall from the plant (Tara 
et al. 2006).  
 
Bactrocera dorsalis has been reported to cause severe damage to and production loss of a wide 
range of fruit crops in tropical and subtropical areas, and areas with a similar climate to New Zealand . 
• Bactrocera  dorsalis  is a devastating pest  of a wide variety of fruits and vegetables throughout 
its range , and damage lev els can be up to 100% of unprotected fruit  (CPC  2020 ). 
• In Yunnan (CMI: 0.7), China , infestation rates by B. dorsalis  of over 30% have been reported 
on mango (Zhou et al. 1996).  
• In Sichuan (CMI: 0.8), infestations of B. dorsalis  occur on pear, apple, mango,  peach and 
guava. Infestation level s of fruit are usually 20% but can be as high as 50% (Zhang and Zhao 
1994).  
• In Hubei (CMI: 0.7), B. dorsalis  change s feeding patterns depending on host availability. In a 
survey in the area, larvae were first found in pears, follow ed by jujube fruit and persimmons. 
The most serious damage occurred in the fourth generation in citrus orchards (Han et al. 
2011).  
 
Bactroce ra dorsalis  is likely to cause impact on many plants of economic importance in New Zealand, 
and is especially likely to impact the  citrus , avocado and apple industries.  
• Hosts commercially grown in New Zealand include, but are not limited to: apple, apricot , 
avocado, capsicum, citrus, cucumber , grapevine, peach, pear, persimmon and plum (CPC 
2020; EPPO 2020a).  
• Pears, apples and peaches  have been reported to be severe ly damaged and infested by B. 
dorsalis  in areas with a similar climate to New Zealand (Han e t al. 2011; Zhang and Zhao 
1994; Zhou et al. 1996). Follet et al. (2019) found that B. dorsalis could produce 269 puparia 
per kg in Scifresh apples.  
• Pear s, apples and peaches  are important horticultural crops for New Zealand  (FOB export 
values: pears NZ$10.6 million, apples $829  million ; domestic and export value peaches $9.4  
million ) (Plant & Food Research  2019).  
• Kriticos et al. (2007) suggest that an incursion of B. dorsalis  could have a major impact on the 
citrus and avocado industries in particular . Their model predicted that almost all areas where 
mandarins and avocados are cultivated are areas projected to be suitable for the 
establishment of B. dorsalis . In addition, Citrus par adisi, C. reticulata , C. sinensis  and C. × 
tangelo  are reported as major hosts in EPPO (2020a), and avocado is one  of the most 
commonly attacked species (Weems et al. 2019).  
• Sales values (export and domestic) for citrus and avocado in 2019 in New Zealand are 
NZ$70.5  million and $160.8  million respectively ( Plant & Food Research  2019).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 134  
The impact on exports, including market access, is likely to be severe.  
• Detection of a fruit fly in the surveillance programme would need to be reported internationally 
and would be expected to result in reduced market access for New Zealand host  materials. In 
New Zealand, 80% of horticultural export value came from plants that are potential fruit  fly 
host (MacLellan et al. 2019).  
• The incursion of B. dorsalis  (reported as B. papaya e) in north Queensland was estimated to 
cause losses of nearly A U$100  million , mostly due to loss of market access (Drew 1997,  in 
Clark et al. 2005).  
• If B. dorsalis  established in New Zealand, additional post -harvest disinfestation costs would 
be necessary.  In Australia in 1996 , apples and citrus fruit under went  a cold treatment for fruit 
fly at a cost of approximately AU$200/tonne , avocados  were treated with hot forced air , 
costing approximately AU$125/tonne, and stone fruit , cucurbits and tomatoes were treated 
with a dimethoate dip , which cost approximately AU$100/tonne (MAF 1996).  
• Bactrocera dorsalis  is of quarantine significance to EPPO (European Plant Protection 
Organization), APPPC (Asia and Pacific Plant Protection Commission), COSAV (Comité de 
Sanidad Vegetal del Cono Sur), CPPC (Caribbean Plant Protectio n Commission), IAPSC 
(Inter -African Phytosanitary Council) and OIRSA (Organismo Internacional Regional de 
Sanidad Agropecuaria) countries  (CPC 2020).  
 
If B. dorsalis  is detected in New Zealand, the cost incurred by a response would be high.  
• The typical co st of responses is millions of dollars. For example, the Queensland fruit fly 
response in 2019 has cost approximately NZ$18 million (MPI 2020).  
• In Japan, eradication from the Ryukyu Islands has cost more than 200 million euros (Kiritani 
1998 , in CPC 2020 ). The cost for the eradication programme in northern Queensland (1995 –
1999) was AU$33 million  (Cantrell et al. 2002 , in CPC 2020).  
 
Bactrocera dorsalis is likely to have low  to moderate impact on the environment in New Zealand, with 
moderate uncertainty.  
• Bactrocera dorsalis  hosts include plant genera with native New Zealand plant species. Some 
of the native species in these genera have “ at risk ” or “ threatened ” conservation status, 
including : Piper excelsum  subsp. peltatum , P. excelsum  subsp. psittacorum , P. melchior , 
Planchonella costata , Solanum aviculare  var. aviculare , S. aviculare  var. latifolium , Streblus 
banksia , St. smithii , Syzygium maire . However, the magnitude of the impact of B. dorsalis  on 
the environment is uncertain.  
• Bactrocera dorsalis  has been reported to attack Syzygium  overseas (Ranganath et a l. 1994). 
Native Syzygium maire  could become an alternative host if B. dorsalis  established near native 
lowland forest where the tree species predominantly occurs (MAF 2009).  
 
Bactrocera dorsalis  may have impacts on the urban environment (soci ocultural consequence s). 
• Bactrocera dorsalis  is damaging to a number of plants grown in domestic gardens and parks, 
such as Vitis spp., Prunus  spp., Citrus  spp. and Malus  spp. Therefore, it is a potential 
nuisance pest in urban environment s. 
 
 
Risk assessment summary : 
 
Given the arguments and evidence below,  Bactrocera dorsalis  may be considered 
for additional measure s. 
• Bactrocera dorsalis has a strong association with fruit of a wide range of citrus 
species/cultivars . 
• Some infested fruit will not be detected, especially when the volume of commodities is large . 
• As the larvae feed internally in the fruit, general handling cannot remove the larvae, and citrus 
fruit need s to be cut open to reveal the larv ae of B. dorsalis . 
• Bactrocera dorsalis  has moderate  to high ability (with low  to moderate uncertainty) to move 
from imported fruit and into a suitable environment to allow establishment . 
• The suitability of the New Zealand environment for B. dorsalis  to establish is considered 
moderate  to high (moderate uncertainty) .  
135 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Bactrocera dorsalis  has a very broad host range , and  therefore, host availability is unlikely to 
be a limit ing factor for it to establish in New Zealand.   
• Bactrocera dorsalis  is a highly invasive species, both in its native and introduced range.  
• Bactrocera dorsalis  has been reported to be one of the most devastating pests in the tropics 
and subtropics, and severe damage of crops of economic importance has been reported from 
colder areas wi th a similar climate to New Zealand.  
• Bactrocera dorsalis   is present in citrus -exporting countries in this IHS : China, Viet  Nam and 
the USA (Hawaii and California; the presence/absence status of the fly in California is 
debatable) and Australia ( Torres Strait Islands ). 
 
 
8.3.4 References  
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932 fruit fly species in the tribe Dacini (Diptera, Tephritidae). ZooKeys, 730: 19 –56. 
Drew R  A I; Hancock , D L (1994 ) The Bactrocera dorsalis  complex of fruit flies (Diptera: Tephritidae: 
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Leblanc, L; Vueti, E T; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: 
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Leblanc, L; Vueti, E T; Drew, R A I; Allwood, A J (2012) Host plant records for fruit flies (Diptera: 
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Accessed 24 August  2020.  
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ONZPR  (2020) Official New Zealand Pest Register . MPI pu blic database. 
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algorithm for pest risk analysis: An evaluation with non -native ants in New Zealand.  Biological 
Invasions , 20: 777–791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , New Zealand.  https://www.freshfacts.co.nz/files/freshfa cts-
2019.pdf  Accessed 15 September  2020.   
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Bourtzis , K; Boykin , L M; Cáceres , C; Cameron , S L; Chapman , T A; Chinvinijkul , S; Chomi č, A; de 
Meyer , M; Drosopoulou , E; Englezou , A; Ekesi , S; Gariou -Papalexiou , A; Geib , S M; Hailstones , D; 
Hasanuzzaman , M; Haymer , D; Hee, A K W; Hendrichs , J; Jessup , A; Ji, Q; Khamis , F M; Krosch , M 
N; Leblanc , L; Mahmood , K; Malacrida , A R; Mavragani -Tsipidou , P; Mwatawala , M; Nishida , R; Ono, 
H; Reyes , J; Rubinoff , D; San Jose , M; Shelly , T E; Srikachar , S; Tan, K H; Thanaphum , S; Haq, I; 
Vijaysegaran , S; Wee , S L; Yesmin , F; Zacharopoulou , A; Clarke , A R (2014 ) Synonymization of key 
pest species within the Bactrocera dorsalis  species complex (Diptera: Tephritidae): taxonomic 
changes based on 20 years of integrative morphological, molecular, cytogenetic, behavioral, and 
chemoecological data. Systematic Entomology , 40(2):  456–471. 
Schutze , M K; Mahmood , K; Pavasovic , A; Bo, W; Newman , J; Clarke , A R; Krosch , M N; Cameron , S 
L (2015) One and the same: Integrative taxonomic evidence that Bactrocera invadens  (Diptera: 
Tephritidae) is the same species as the Oriental fruit fly Bactrocera dorsalis . Systematic Entomology , 
40: 472 –486. 
Shelly, T E (2000) Fecundity of female Oriental fruit flies (Diptera: Tephritidae): Effects of methyl 
eugenol -fed and multiple mates . Annals of the Entomological Society of America , 93(3): 559 –564. 
Shen, J M; Hu, L M; Zhou, X H; Dai, J Q; Chen, B H; Li, S F (2019) Allyl -2,6-dimethoxyphenol, a 
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range. Entomologia Experimentalis et Applicata , 167: 811 –819. 
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USDA (2016)  Oriental fruit fly, Bactrocera  dorsalis , Host List . 
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139 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.4 Bactrocera minax  (Chinese citrus fly ) 
 
Bactrocera minax  is a fruit fly species that oviposits through the skin of fruit  and causes internal 
feeding damage to fruit. It s only known hosts are citrus and the related genera of Rutaceae . 
Bactrocera  minax  is only known from Asia.  
 
Scientific name: Bactrocera minax (Enderlein , 1920 ) 
Order/Family: Diptera /Tephritidae  
Other names include: Bactrocera  (Tetradacus ) minax, Bactrocera citri, Callantra minax, Dacus citri, 
Dacus minax, Mellesis citri, Polistomimete s minax , Tetradacus citri  (EPPO 2020; CPC 2019; Kapoor 
2005)   
 
Taxonomic notes: CPC (2019) reported that Bactrocera citri had been erroneously listed as a 
synonym of B. tsuneonis  prior to the work of White and Wang (1992 ), and that confusion has caused 
some cataloguers to wrongly list B. minax  and B. tsuneonis  as synonyms . Bactrocera minax  and B. 
tsuneonis  can be distinguishe d through molecular diagnostic methods (Zheng et al. 2019).  
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Bactrocera minax meets the criteria to be a quarantine pest for New Zealand .  
• Bactrocera minax has a strong association with citrus fruit , with low uncertainty . 
• Basic measure s are likely to reduce the likelihood of introduction of B. minax by a moderate 
degree . Consequently , the likelihood of entry is considered to be low  to moderate , with low 
uncertainty.  
• Bactrocera minax has moderate ability (with low  to moderate uncertainty) to move from 
imported fruit and into a suitable environment to allow establishment, that is, onto a host 
plant.  
• The suitability of the New Zealand environment to for B. minax to establish is considered  high, 
with low uncertainty , but establishment is likely to be limited by distribution of its hosts.  
• The level of impact caused by B. minax is likely to be high , with low uncertainty.  
• Bactrocera minax may be considered for  requiring additional measure s. 
 
Summary of risk assessment against criteria  
Criteria  Rating Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Low 
The ability to move from the imported commodity onto a suitable host  Moderate  Low–moderate  
Suitability of the New Zealand  environment  High Low 
Impacts on the New Zealand economy, environment, health and society  High Low 
 
8.4.1 Hazard  identification: quarantine status  
 
Given  the arguments and evidence below,  Bactrocera minax meets the criteria to be 
a quarantine pest for New Zealand .  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 140 Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establis h and cause harm).  
 
Bactrocera minax is not known to be present in New Zealand:   
• Bactrocera minax  is not recorded in NZInverts (2020),  NZOR  (2020) or PPIN (2020);  
• Bactrocera minax  is an unwanted organism ( ONZPR  2020 ); 
• Bactrocera minax  is listed as ‘Regulated’ in ONZPR  (2020) . 
 
Bactrocera minax has the potential to establish and spread in New Zealand:  
• Bactrocera minax is present in Bhutan, China, Nepal (CPC 2019) and India (Xia et al. 2018). 
Some of the areas in China  that are reported to have the pest have  a similar climate to New 
Zealand.  
• Bactrocera minax is a specialist of citrus and related genera of Rutaceae, which means that 
plant species in these genera are the only known hosts of B. minax  (CPC 2019).   
• Citrus is commercially grown  in New Zealand and  commonly grown in home gardens.  
 
Bactrocera minax has the potential to cause impacts on the economy and environment of New 
Zealand:  
• Bactrocera minax has the potential to harm citrus , which is  of eco nomic importance to New 
Zealand . 
• Bactrocera minax has the potential to have soci ocultural impacts : citrus is commonly planted 
in home gardens . 
 
8.4.2 Hazard identification: commodity association  
 
Bactrocera minax is associated with citrus fruit . 
Bactrocera minax is reported from citrus fruit : 
• Bactrocera minax oviposits through the skin of citrus fruit , and larvae feed inside the fruit 
(CPC 2019).  
 
8.4.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Bactrocera minax has a strong  
association with citrus fruit , with low uncertainty . 
Larvae of B. minax  have been reported in citrus fruit.  
• Adult females of B. minax lay eggs through the skin of young fruit of citrus with diameters of 2 
to 4 cm. Nav el orange, other early -ripening cultivars and pomelo are preferred hosts of the 
insect in China, although pomelo have thick skins and are typically 15 –25 cm in size  (Xia et 
al. 2018) . CPC (2019) mentioned that B. minax  has a telescopic and pointed ovipositor, and it 
is a large powerful insect presumably adapted to oviposition thro ugh the thick skin of oranges.  
• After hatching from eggs, larvae feed inside the fruit until the third instar (Xia et al. 2018).  
 
Larvae of B. minax  are associated with citrus fruit commodities.  
• Heavy infestation of B. minax  causes fruit to drop prematurel y (Xia et al. 2018).  
• However, larvae can remain in citrus fruit during and after harvest. Low infestation in fruit may 
not cause premature drop, and th is fruit could be harvested. There is a period of 18 –52 days 
before larvae leave the fruit (Dorji et al. 2006). 
• Bactrocera minax  has frequently been found  on citrus fruit during import inspections in 
Europe (Steffen et al. 2015).  However, there is no interception record of B. minax  in New 
Zealand (LIMS 2019). This is probably because New Zealand do es not currently import host  
fruit from countries where the fly is present.   
141 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Citrus species/cultivars that are associated with Bactrocera minax  are shown in Table 9.4.1. 
 
Table 9.4.1   Known citrus host association of Bactrocera minax  
Citrus host scientific 
name  Citrus host 
common name 
from the 
reference  Reference  Notes  
All cultivated citrus 
species and cultivars  
in China   Xia et al. (2018)   
Citrus aurantium  Sour orange  / 
Bitter orange  CPC (2019), Xia et al. (2018)  Field fruit infestations  
Citrus aurantiifolia   EPPO (2020)   
Citrus tachibana   Xia et al. (2018)  Field fruit infestations  
Citrus maxima   Allwood et al. (1999)  Reared from field -collected fruit  
Citrus ichang austera 
hybrid   EPPO (2020), Xia et al. (2018)  ‘Cultivated host’ in Xia et al. 
(2018)  
Citrus  limon  Lemon  Allwood et al. (1999)  Reared from field -collected fruit  
Citrus maxima  Pummelo/ Pomelo  CPC (2019), Xia et al. (2018)  Field fruit infestations  
Citrus medica  Citron CPC (2019), Xia et al. (2018)  Field fruit infestations  
Citrus macroptera   Joint FAO/IAEA  (2009)  Interception on fruit  
Citrus reticulata  Ponkan  Xia et al. (2018)  Field fruit infestations  
Citrus reticulata  Mandarin  Xia et al. (2018), Dorji et al. (2006)  Field fruit infestations  
Citrus sinensis  Navel orange  / 
Sweet orange  CPC (2019),  Xia et al. (2018)  Field fruit infestations  
Citrus sinensis × Citrus 
maxima   Xia et al. (2018)  ‘Cultivated host’ in Xia et al. 
(2018)  
Citrus reticulata   EPPO (2020) , Xia et al. (2018)  Field fruit infestations  
Citrus reticulata  Satsuma mandarin  EPPO (2020) , Xia et al. (2018)  Field fruit infestations  
Citrus  reticulata   EPPO (2020)   
Citrus paradisi  Grapefruit  CPC (2019), EPPO (2020), Xia et al. 
(2018)  ‘Cultivated host’ in Xia et al. 
(2018)  
Citrus sarcodactylis   Zheng et al. (2019)   
 
Bactrocera minax  is present in a citrus -exporting country in the citrus fresh produce IHS . 
• Bactrocera minax  is present in China (Xia et al. 2018).  
 
Given the arguments and evidence below, basic measures are likely to reduce the 
likelihood of entry of B. minax  by a moderat e degree . Consequently , the likelihood of 
entry is considered  low to moderate , with low uncertainty . 
Infested fruits are usually easily detected and are likely to be removed.  
• Infested fruits are easily recognised by dark colour and the small nodule caused by 
oviposition. The colour around the oviposition scars is quite distinct from that of healthy fruit 
skin (Zhang 1989). Fruit with multiple oviposition punctures and damage  as described as 
above is likely to be removed during general handling.  
• Xia et al. ( 2019) found that fruit bagging and packing  house culling (including preliminary 
culling, washing, waxing, drying, intensive culling, sorting and final culling and box -packing) 
could contribute to risk mitigation of fruit flies in citrus in China. The study  found few 
oviposition marks and an absence of living tephritid fruit flies in bagged pomelo fruits 
(n=3,000) , while 129 fruit fly -infested fruits (containing 634 live larvae and 4 pupae of B. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 142 dorsalis ) were found in the unbagged fruits ( n=3,040 ). They als o found that in fruit ( C. unsh iu) 
that received culling treatment (n=10,000) , fruit flies were absent , and 10 fruits with 
oviposition marks (with no living fruit flies) were found, while in fruit that did not receive the 
culling treatment (n=10,000) , one i nfested fruit with seven larvae of B. minax  and 25 fruits with 
fruit fly oviposition marks were found.  
• Heavy infestation of B. minax  causes fruit to drop prematurely (Xia et al. 2018). Dropped fruit 
is unlikely to be exported.  
 
However, there is chance that a small quantity of infested fruit will not be detected.  
• Low infestation (fewer oviposition punctures  in fruit ) may not be obvious enough to be 
detected during general handling. The fly can be transported in the larval stage with fruit or as 
puparia in packing cases (Zhang 1989).  
• The volume of the commodities can also affect efficiency of detection. Low levels of 
infestation may not be easily detected, especially if the volume of commodities is large.  
• Bactrocera minax  has bee n frequently intercepted at the border in Europe (Steffen et al. 
2015), suggesting that some infested fruit is not detected during general handling after 
harvesting.  
 
General handling after harvesting is not likely to remove larvae of B. minax  inside citru s fruit.  
• As general handling after harvesting (e.g. washing and brushing) only treats the surface of 
fruit, it is unlikely to remove the larvae of B. minax  inside citrus fruit.   
• Fruit will need to be cut open to reveal the larvae of B. minax  inside.  
 
Larvae of B. minax  are likely to survive transit of some citrus commodities.  
• Transit of citrus fruits usually includes cold storage. Bactrocera minax is among the most 
cold-tolerant Bactrocera  species. In a laboratory experiment, at 0 °C, all third-instar larv ae of 
B. minax  survived until the 12th day of the experiment. Larval mortality reached 55% on day 
22 and 93% on day 23 (Fan et al. 1994).  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Bactrocera minax has moderate  ability 
(with low  to moderate uncertainty) to move from imported fruit and into a suitable 
environment to allow establishment, that is, onto a host plant (exposure) . 
Bactrocera minax can survive and develop on the waste of citrus  fruit (whole fruit or fru it pieces but 
probably not skin).  
• Bactrocera minax feeds exclusively on the fruit of citrus  and related genera of Rutaceae.  
Adult females lay eggs on  the fruit. The egg stage lasts for approximately one month, and the 
larvae feed inside the fruit until maturity (Xia et al. 2018).  
• If citrus fruit is disposed  of as whole fruit or fruit pieces, it is likely that B. minax  can survive in 
this waste. There is n o evidence to show that B. minax  can complete development by feeding 
on citrus fruit skin.  
 
Most of the waste in New Zealand would be disposed of using low -risk methods , so B. minax  would 
either be killed or unable to escape from the citrus  host.  
• The majo rity of kitchen  waste in New Zealand is bagged and disposed of in landfills and run 
through  kitchen disposal units, and in these situations, B. minax  is unlikely to reach a new 
host ( see the waste analysis  in section 2.4.1 ). 
 
However,  some of the waste would be disposed of using high -risk methods, including composting in 
gardens and us e as animal feed.  
• Adults of B. minax emerging from the soil are likely to be able to find food in the environment 
if citrus fruit waste is disposed of u sing high -risk methods. The mature larvae emerge from the 
fruits and drop into soil for overwintering and pupate (Xia et al. 2018). Sexually immature 
adults feed on honeydew from insects, nectar and sooty mould on non -host plants (Dong et 
al. 2014). Sexual ly mature adults lick sooty moulds, bird faeces and an unknown substance  
143 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  on citrus leaves and fruits. These fruit sources are common in farms, parks and home 
gardens.   
• It is reported that all cultivated Citrus  species and cultivars are hosts of B. minax (Xia et al. 
2018).  It is also reported from Fortunella  sp. and Poncirus trifoliata  (CPC 2019).  
• Hosts for oviposition and larval development are available in most areas of New Zealand. 
Citrus  is commercially produced in both the North Island and the South I sland, with most 
commercial production taking place in the North Island ( See section 2.4.2 ). Citrus  is also a 
common plant species grown in home gardens.  
• If Citrus  hosts are located near the composting site or animal feeding site ( see the waste 
analysis in section 2.4.1 ), adult B. minax is likely to locate the Citrus  host.  
 
Adult B. minax  can fly to food sources and locate Citrus  hosts, although it is not known whether it is a 
strong flier.  
• A field experiment (He et al. 2019) showed that e merging adults released from a citrus 
orchard could fly to the forest near the orchard. The mean straight -line distance from the 
release point to the third landing point was between 5 and 16  m. The total distance B. minax  
flew was longer than the mean stra ight-line distance, as it made two landings before flying to 
the third landing point.  
• No study investigating the flight capability of B. minax  has been found . However, studies on 
other tephritids reveal that the mean dispersal distance of tephritid flies is usually well below 
1 km, except that mean dispersal distances from below 1  km to 3.6  km have been reported 
for B. dorsalis . However, the maximum dispersal distance reported in many studies was 
limited to the distance of the trap placed furthest from the release point (Weldon et al. 2014).  
 
The level of uncertainty associated with the conclusion is low–moderate . First, waste data may not be 
very accurate and up to date , and it is not known how frequently suitable hosts would be  present near 
composting sites in gardens or animal feeding locations (see section 2.4.1,  waste analysis ). Second, 
it is uncertain what proportion of co mposting sites are expos ed or co vered  (e.g. in a compost bin).  
Third, although B. minax  can fly to seek food sources and citrus hosts, its flight capability is uncertain. 
There is a lot of information for other tephritid flies, but the maximum dispersal di stance reported from 
many studies was limited to the distance of the trap placed furthest from the release point . 
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for B. minax  to establish is considered high, with low  uncertainty , but 
the area of establishment is likely to be limited by the distribution of its hosts .  
Bactrocera minax  appears to be a temperate species.  
• Bactrocera minax is currently restricted to  Bhutan, China, Nepal (CPC 2019) and northwest 
India  bordering with China (Xia et al. 2018). In China, the known distribution is in areas 
between 24 –33 N latitude, usually 230 –1,500 m in altitude. It is present in Guangxi, Guizhou, 
Hubei, Hunan, Jiangxi, Shaanxi, Sichuan, Chongqing and Yunnan . Henan and Jia ngsu 
provinces have reported B. minax  previously, but the pest was either eradicated or 
disappeared  by itself (Xia et al. 2018).  
• Guizhou, Hubei, Hunan, Shaanxi, Sichuang, Chongqing, Yunnan and part of Northwest India 
have similar climate conditions to New Zealand, with Climate  Match Index  (CMI) between 
0.7–0.8 (Phillips et al. 2018).  
• Yunan -Guizhou Plateau is believed to be the region of origin for B. minax  (Xia et al. 2018). In 
spite of its low -latitude location, it has a CMI between 0.7 and 0.8.  
 
Bactrocer a minax is likely to survive cold temperature in New Zealand.  
• Bactrocera minax is among the most cold -tolerant Bactrocera  species. In a laboratory 
experiment, at 0 °C, all third-instar larvae of B. minax  survived until the 12th day of the 
experiment. Larval  mortality reached 55% on day 22 and 93% on day 23 (Fan et al. 1994).  
 
Bactrocera minax  has a moderate reproduction rate.  
• Bactrocera minax is univoltine ( has one generation per year ), unlike all other Bactrocera 
species (Dorji et al. 2006) . A female adult  lays 50 to 200 eggs (Xia et al.  2018 ) during its 
lifetime, and the average number of eggs produced is 48.33 per female (Zhang 1989). The 
average number of larvae in the infested fruit is 9.5 (Zhang 1989).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 144  
Host availability is unlikely to be a limiting fa ctor for B. minax  to establish in New Zealand, but 
establishment is likely to be limited by the distribution of its hosts.  
• Eggs of B. minax  are laid on citrus fruit, and the larvae develop in citrus fruit. Citrus is 
commercially produced in both the North  Island and the South Island, with most commercial 
production taking place in the North Island (see section 2.4.2 ). Citrus is also commonly grown 
in home gardens.  
• Adults of B. minax can feed on a wide range of food sources. Sexually immature adults feed 
on honeydew from insects (preferred food), nectar and sooty mould on non -host plants. 
Sexually mature adults lick sooty moulds, bird faeces and an unknown substance on citrus 
leaves and fruits (Dong et al. 2014; Zhang 1989).  
• Current known hosts of B. minax  are restricted to Citrus, Poncirus  and Fortunella . Therefore, 
if the fly establishes in New Zealand, the area of establishment is likely to be limited by the 
distribution of its hosts (commercial citrus -growing area s, see section  2.4.2 ).  
 
Bactrocera mina x has become a major pest of citrus outside its native range.  
• In Dhankuta, Ramechhap and Sindhuli (CMI: 0.5 –0.6), Nepal, B. minax  has been reported to 
be the major pest affecting citrus. At least 60% of fruit drops caused by B. minax  have been 
reported fro m Sindhuli and Ramechhap. Up to 100% production loss has been reported from 
the eastern region of Nepal, and growers had to replace sweet orange and lemon (preferred 
hosts of B. minax ) with mandarin (Acharya and Adhikari 2019).  
• In Bhutan, B. minax  is one o f the major citrus pests and can cause over 50% fruit drop of 
mandarin (Dorji et al. 2006).  
• Bactrocera m inax has also been reported as a devastating pest of citrus in India (Wang et al. 
2014), but details about damage and production loss in India were not found.  
 
It is not known that there is any effective attractant for trapping B. minax , and it may not respon d to 
lures in current fruit fly surveillance in New Zealand.  
• Without an effective attracta nt for B. minax , the possibility of missing an incursion is higher 
compared to other species that respond to lures. Surveillance for fruit flies in New Zealand 
uses trimedlure, cuelure and methyl eugenol  as lures ( MacLellan  et al. 2019). However, 
cuelure or methyl eugenol are not attractive to B. minax  (Xia et al. 2018), and no evidence 
was found that trimedlure is attractive to B.minax .  
• Hou et al. (2018) conducted a field trial to determine the efficacy of eight attractant traps62 for 
B. minax  and showed that the effectiveness of these attractant traps is low. 
• Food based lures are extensively used in citrus groves , and colo ured sticky spheres are being 
used in recent years in limited groves in China, but they are primarily for mass -trapping efforts  
(Xia et al. 2018).  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by B. minax  is 
likely to be high, with low uncertainty.  
Damage and symptoms caused by B. minax  can reduce fruit quality.  
• Oviposition of B. minax  leaves scars (or puncture) on the skin of citrus fruit with small 
nodules. The colour around the oviposition scar is yello wish and distinct from that of healthy 
                                                      
62 “(1) sugar mixture: a homemade sugar solution with vinegar and wine mixture (10 g sugar, 5 g ethylic acid, and 3 mL alcohol 
in 100 mL water); (2) torula yeast: 3 pellets per  300 mL water (Chemtica Internacional S.A., Santa Rosa, Costa Rica); (3) Great 
bait: Great® fruit fly bait, a protein -based bait, 1:3 (vol:vol) solution at the recommended application rate (Hubei Great® Biotech 
Co. Ltd, Wuhan, China); (4) sticky sphere: a green -colored sticky sphere, 7 cm diam, green polystyrene sphere, with 1 mm 
thickness transparent sticky glue on the surface (Nongjie Technology Development Co. Ltd, Changsha, Hunan, China); (5) 
methyl eugenol: a solid sustained -release preparation (Chemti ca Internacional S.A., Costa Rica); (6) cuelure: a solid sustained -
release preparation (Chemtica Internacional S.A., Costa Rica); (7) 2 -component: a 2 -component fruit fly bait with a solid 
sustained -release preparation of ammonium acetate + putrescine (Sce ntry Biologicals, Inc., Billings, Montana, USA); and (8) 3 -
component: a 3 -component fruit fly bait with a solid sustained -release preparation of ammonium acetate + putrescine + tri -
methylamine (Scentry Biologicals, Inc., Billings, Montana, USA).” Hou et al . (2018)   
145 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  fruit skin. Oviposition puncture and internal feeding by the larvae can lead to distortion and 
rotting of fruit (Zhang 1989).  
• Heavy infestation can cause premature fruit drop (Xia et al. 2018).  
 
Bactrocera minax  has been reported to cause severe damage and production loss of citrus in areas 
with a similar climate to New Zealand . 
• Bactrocera minax  is the most destructive citrus pest in south -central China. It can cause up to 
100% fruit damage in severe infestation (Xia et al. 2018; Zhang 1989).  
• Xia et al. (2018) summari ses field fruit infestations by B. minax  in different citrus orchards 
from the main citrus -producing provinces in China.  
o In Guizhou (CMI: 0.7 –0.8), B. minax  occurred in 68.8% (4 ,180 ha) of the surveyed 
area. Infestation varied from less than 1 % to 100% between 1994 and 1996.  
o In Hubei (CMI: 0.7), most surveys from 1980 to 2012 indicated 20% or higher (up to 
90%) of fruit infestations due to B. mi nax. 
o In Hunan (CMI: 0.7), surveys between 2010 to 2012 reveale d over 50% to 100% fruit 
infestation in some orchards.  
o In Sichuan (CMI: 0.8), surveys between 1982 to 1992 and between 1997 and 2011 
indicated average infestation caused by B. minax  was between 20 % and 30%.  
• The pest has been also reported to cause severe damage in warmer areas. Van Schoubroeck 
(1999) reports that B. minax caused 35 % to 75% fruit drop in citrus in mid - and high -altitude 
orchards (<1,100 masl) in Bhutan. A study in Sindhuli, Nepal found that B. minax caused 
56.7% fruit loss in sweet orange o rchards (Adhikari et al. 2020).  
• Citrus  is economically important in New Zealand ( for the value of citrus in New Zealand , see 
section 2.5.2 ). As high infestation rates (up to 100%) have been recorded in areas with a 
similar climate to New Zealand, the likely impact  of B. minax  on the New Zealand citrus 
industry is likely to be high, but the impact to the overall economy of New Zealand is likely to 
be moderate.  
 
If B. minax  is detected in New Zealand, the cost incurred by a response would be high.  
• The typical cost of responses is millions of dollars. For example, the Queensland fruit fly 
response in 2019 has cost approximately NZ$18 million (MPI 2020).  
 
Establishment of B. minax  is likely to increase phytosanitary measures required for export to countr ies 
where the pest is absent,  and therefore, the impact on exports, including market access, is likely to be 
severe.  
• Bactrocera minax  is only present in Bhutan, China, Nepal (CPC 2019) and India  (Xia et al. 
2018).  
• Detection of a fruit fly in the surveilla nce programme would need to be reported internationally 
and would be expected to result in reduced market access for New Zealand host materials. In 
New Zealand, 80% of horticultural export value came from plants that are potential fruit  fly 
hosts (MacLella n et al. 2019).  
• The incursion of another fruit fly species, B. dorsalis  (reported as B. papayae ), in north 
Queensland was estimated to cause losses of nearly A U$100  million , mostly due to loss of 
market access (Drew 1997, in Clark et al. 2005).  
• If a fruit fly species  established in New Zealand, additional post -harvest disinfestation costs 
would be necessary. In Australia in 1996,  apples and citrus fruit under went  a cold treatment 
for fruit fly at a cost of approximately AU$200/tonne , avocados were treated with hot forced 
air, costing approximately AU$125/tonne, and stone fruit , cucurbits and tomatoes weretreated 
with a dimethoate dip , which cost approximately AU$100/tonne (MAF 1996).  
 
Bactrocera minax  is likely to cause soci ocultural impacts on citrus in home gardens.  
• Citrus is commonly grown in home gardens.  
 
Since B. minax  is a citrus specialist , and there are no native species of Citrus  (or Poncirus  or 
Fortunella ), it seems likely that environmental impacts would be low.  
 
There is no evidence found on the impact of B. minax  on human health.  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 146  
Risk assessment summary : 
 
Given the arguments and evidence below,  Bactrocera minax may be considered for 
additional measure s. 
• Bactrocera minax  has a strong association with citrus frui t (all citrus cultivars in China);  
• Low rates of infested fruit may not be detected during general handling, especially when the 
volume of commodities is large;  
• As the larvae feed internally in the fruits, general handling cannot remove the larvae, and 
citrus fruits need to be cut open to reveal the larvae of B. minax ;  
• Bactrocera minax has moderate ability (with low  to moderate uncertainty) to move from 
imported fruit and into a suitable environment to allow establishment ; 
• New Zealand climate is likely to be suitable for the establishment of B. minax , but the area of 
establishment is likely to be limited by the distribution of its hosts.  
• Hosts of the pest, citrus,  are commercially grown in New Zealand and are common plants in 
home garden s; 
• Bactrocera minax has been recorded to cause severe (up to 100%) production loss of citrus 
in areas with a similar climate to New Zealand, and therefore, it is likely to cause hig h impact 
on the citrus industry in New Zealand and moderate impact to the overall economy of New 
Zealand;  
• Bactrocera minax  is present in one of the citrus -exporting countries in the citrus fresh produce 
IHS (China).  
 
8.4.4 References  
Acharya, U K; Adhikari, D ( 2019) Chinese citrus fly ( Bactrocera minax ) management in mid hills of 
Nepal. The Journal of Agriculture and Environment , 20: 47 –56. 
Adhikari, D; Thapa, R B; Joshi, S L; Liang, X H; Du, J J (2000) Area -wide control program of Chinese 
citrus fly Bactrocera minax (Enderlein) in Sindhuli, Nepal. American Journal of Agricultural and 
Biological Sciences , 15(1): 1 –7. 
Allwood, A J; Chinajariyawong, A; Drew, R A I; Hamacek, E L; Hancock, D L; Hengsawad, C; Jipanin, 
J C; Jirasurat, M; Kong Krong, C; Kritsaneepaiboon , S; Leong, C T S; Vijaysegaran, S (1999) Host 
plant records for fruit flies (Diptera: Tephitidae) in South East Asia. Raffles Bulletin of Zoology , 
Supplement No. 7:  1–92. 
CPC (2019) Crop Protection Compendium  - Bactrocera minax (Chinese citrus fly). 
https://www.cabi.org/cpc/datasheet/8726 . Accessed 24 August 2020.  
Dong, Y C; Wan, L; Pereira, R; Desneux, N; Niu, C Y (2014) Feeding and mating behaviour of 
Chinese citrus fly Bactrocera minax  (Diptera, Te phritidae) in the field. Journal of Pest Science , 87(4): 
647–657. 
Dorji, D; Clarke, A R; Drew, R A I; Fletcher, B S; Loday, P; Mahat, K; Raghu, S; Romig, M C (2006) 
Seasonal phenology of Bactrocera minax  (Diptera: Tephritidae) in western Bhutan . Bulletin o f 
Entomological Research , 96: 531 –538. 
EPPO (2020) EPPO Global Database - Bactrocera minax  (DACUCT) . 
https://gd.eppo.int/taxon/DACUCT/hosts  Accessed on 16 September 2020.  
Fan, J A; Zhao, X Q; Zhu, J (1994) A Study of the Cold -Resistance and Diapause in Tetradacus citri  
Chen. [ in Chinese] 柑桔大实蝇（ Tetradacus citri  Chen）耐寒及滞育性研究 . Journal of Southwest 
Agricultural University , 16: 532 –534.  
Gao, M  X; Wang, C ; Li, S R; Tang, Z  X (1999) The study of irradiation on  pest in orange and chestnut.  
[in Chinese] Plant Quarantine , 13: 197–199.  
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trajectory of newly emerged adult Chinese citrus flies with insect harmonic radar. Journal of Asia -
Pacific Entomology , 22: 853 –859. 
Hou, H; Ouyang, G; Xiao, F; Lu, Y; Zhang, Z; Tian, J; Meng, X; Xia, Y  (2018 ) Field evaluation of eight 
attractant traps for Bactrocera minax  (Diptera: Tephritidae) in a navel orange orchard in China. Florida 
Entomologist , 101(2): 260 –264. 
Joint FAO/IAEA (2009)  Insect Pest Control Newsletter, No 73  (INIS -XA--11K4444). Division of 
Nuclear Techniques in Food and Agriculture ; Vienna , Austria. Inte rnational Atomic Energy Agency 
(IAEA): IAEA.  
Kapoor, V C (2005) Taxonomy and biology of economically important fruit flies of India.  Israel Journal 
of Entomology , 35-36: 459–475. 
LIMS (2019) Laboratory Information Management System (LIMS) . Plant Health and  Environment. 
Accessed 2020.  
MacLellan, R; Pather, V; King, K (2019) National Fruit Fly Surveillance Programme . Surveillance , 
46(3): 83 –86. http://www.sciquest.org.nz/node/157809 . MAF (199 6) Economic  Risk Assessment: 
Oriental Fruit Fly ( Bactrocera dorsalis ). Lynfield Plant Protection Centre. Ministry of Agriculture and 
Forestry ; NZ. 
MPI (2020) Successful end to fruit fly operation in Auckland . https://www.mpi.govt.nz/news -and-
resources/media -releases/successful -end-to-fruit-fly-operation -in-auckland/  Accessed 9 September 
2020. 
NZInverts (2020) New Zealand Land Invertebrates. https://nzinverts.landcareresearch.co.nz/  
Accessed 24 August 2020.  
NZOR (2020) New Zealand Organisms Register. http://www.nzor.org.nz/ . Accessed 24 August 2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/   
Phillips , C B ; Kean , J M ; Vink , C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional ’ 
algorithm for pest risk analysis: An evaluation with non -native ants in New Zealand.  Biological 
Invasions , 20(3): 777–791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
PPIN (2020) Plant Pest Information Network. MPI internal database.  
Steffen, K; Grousset, F; Schrader, G; Petter, F; Suffert, M (2015) Identification of pests and  
pathogens recorded in Europe with relation to fruit imports. OEPP/EPPO Bulletin , 45(2): 223 –239. 
Van Schoubroeck, F (1999) Learning to Fight a Fly: Developing Citrus IPM in Bhutan . PhD thesis; 
Wageningen University and Research Centre, Netherlands.  
Wang, J; Zhou, H -Y; Zhao, Z -M; Liu, Y -H (2014). Effects of juvenile hormone analogue and 
ecdysteroid on adult eclosion of the fruit fly Bactrocera minax  (Diptera: Tephritidae). Journal of 
Economic Entomology , 107 (4): 1519 –1525.  
Weldon, C W; Schutze, M K; Karsten , M (2014) Trapping to Monitor Tephritid Movement: Results, 
Best Practice, and Assessment of Alternatives. In Shelly, T  E; Epsky, N; Jang, E B; Reyes -Flores, J; 
Vargas, R I (eds) Trapping and the Detection, Control, and Regulation of Tephritid Fruit Flies : Lures, 
Area -Wide Programs, and Trade Implications . Springer  Netherlands; Dordrecht, Netherlands; pp 175–
219. 
White, I M; Wang, X J (1992) Taxonomic notes on some dacine (Diptera: Tephritidae) fruit flies 
associated with citrus, olives and cucurbits. Bulle tin of Entomological Research , 82(2): 275 –279. 
Xia, Y; Huang, J; Jiang, F; He, J, Pan, X; Lin, X, Hu, H; Fan, G; Zhu, S; Hou, B; Ouyang, G (2019) 
The effectiveness of fruit bagging and culling for risk mitigation of fruit flies affecting citrus in China: A  
preliminary report . Florida Entomologist , 102(1):  79–84. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 148 Xia, Y; Ma, X L; Hou, B H; Ouyang, G C (2018) A review of Bactrocera minax  (Diptera: Tephritidae) in  
China for the purpose of safeguarding. Advances in Entomology , 6: 35 –61. 
Zhang, Y A (1989) Citrus fruit flies of Sichuan Province (China). OEPP/EPPO Bulletin , 19: 649 –654. 
Zhao, X  Q; Fan, J  A; Xie, C  L; Qin, Z ; Li, G ; Zhu, J ; Zeng, D  B; Kong, FC  (1995) Gamma irradiation as  
a quarantine treatment against Tetradacus citri in  pome lo and orange fruits. [ in Chinese]  Journal of 
Southwest Agricultural University , 17: 126–129.  
Zheng, L; Zhang, Y; Yang, W; Zeng, Y; Jiang, F; Qin, Y; Zhang, J; Jiang, Z; Hu, W; Guo, D; Wan, J; 
Zhao, Z; Liu, L; Li, Z (2019) New species -specific primers for molecular diagnosis of Bactrocera minax  
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149 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.5 Bactrocera trilineola  (Vanuatu fruit fly ) 
 
Bactrocera trilineola  is a fruit fly  species that has been reported to cause serious damage on fruit 
crops in Vanuatu. Main commercial host of B. trilineola  is mango, although it has been reported in 
Rutaceae (Plant Health Australia 2011). Its current distribution is restricted to three Paci fic Islands 
countries (Vanuatu, the Solomon Islands and New Caledonia).  
 
Scientific name: Bactrocera trilineola  Drew, 1989  
Order/Family: Diptera /Tephritidae  
Other names include: Dacus triseriatus , Dacus (Strumeta ) triseriatus, Bactrocera distotriseriata   
 
Taxonomic notes:  Bactrocera trilineola belongs to the frauenfeldi complex (Plant Health Australia 
2011). A specimen of B. trilineola  from New Caledonia has been misidentified as B. frauenfeldi  
(Hancock 2008).  
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Bactrocera trilineola meets the criteria to be a quarantine pest for New Zealand .  
• Bactrocera trilineola has a strong association with citrus fruit  with low uncertainty . 
• Basic measures  are likely to reduce the likelihood of introduction of B. trilineola by a moderate 
degree  (with moderate  to high uncertainty) . Consequently , the likelihood of entry is 
considered to be low  to moderate.  
• Bactrocera trilineola has low to moderate  ability (wi th moderate  to high uncertainty) to move 
from imported fruit and into a suitable environment to allow establishment, that is, onto a host 
plant.  
• The suitability of the New Zealand environment  for B. trilineola to establish is considered  low 
to moderate (with moderate uncertainty), and its establishment is likely to be restricted to the 
warmer parts  of the North Island, although short -term (seasonal) population s may occur  in 
other areas during summer months.  
• The level of impact caused by B. trilineola is likely to be high, with low uncertainty.  
• Bactrocera trilineola may be considered for  requiring additional measure s. 
 
Summary of risk assessment against criteria  
Criteria  Rate  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Moderate –high 
The ability to move from the imported commodity onto a suitable host  Low–moderate  Moderate –high 
Suitability of the N ew Zealand  environment  Low–moderate  Moderate  
Impacts on the New Zealand economy, environment, health and society  High Low 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 150 8.5.1 Hazard  identification: quarantine status  
 
Given the arguments and evidence below,  Bactrocera trilineola meets the criteria to 
be a quarantine  pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause harm63). 
 
Bactrocera trilineola is not known to be present in New Zealand .  
• Bactrocera trilineola is not recorded in NZInverts (2020),  NZOR  (2020) or PPIN (2020) . 
• Bactrocera trilineola is an unwanted organism ( ONZPR  2020 ). 
• Bactrocera trilineola is listed as ‘ regulated’ in ONZPR  (2020) . 
 
Bactrocera trilineola has the potential to e stablish and spread in New Zealand . 
• Bactrocera trilineola is only reported as present in Vanuatu (Leblanc et al. 2013a), Solomon 
Islands ( Vagalo  et al. 1997) and New Caledonia (Loyalty Islands) (Hancock 2008). The fly 
may be able to establish in warmer are as in New Zealand.  
• Bactrocera trilineola is polyphagous. It has been recorded from 32 fruit species from 18 plant 
families in Vanuatu (Allwood et al. 1996).   
• Some hosts of B. trilineola  are commercially grown or commonly found in home gardens, 
such as citrus, tomato, guava and avocado (Allwood 2000).   
 
Bactrocera trilineola  has the potential to cause impacts on the economy and environment of New 
Zealand . 
• Bactrocera trilineola  has the potential to harm to citrus and other hosts that are  of eco nomic 
importance to New Zealand . 
• Bactrocera trilineola  has the potential to have environmental impacts: B. trilineola  has been 
reported on plant species in genera  (such as Syzygium ) that have native species  in New 
Zealand  (NZPCN 2020).  
• Bactrocera trilineola  has the potential to have soci ocultural impacts : some hosts are 
commonly planted in home gardens, such as citrus and tomato . 
 
8.5.2 Hazard identification: commodity association  
 
Bactrocera trilineola  is associated with citrus fruit . 
Bactrocera trilineola  is reported from citrus fruit : 
• Citrus is a natural host of B. trilineola . Bactrocera trilineola  has been reared from field -
collected citrus fruits (Leblanc et al. 2013a).  
 
8.5.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Bactrocera trilineola  has a strong  
association with citrus fruit  with low uncertainty . 
Larvae of B. trilineola  can be associated with citrus fruit commodities.  
• Although  no interception records of B. trilineola  were found, like other Bactrocera  spp., larvae 
of B. trilineola  feed inside the fruit. Therefore, the larvae and eggs are unlikely to be visible.  
 
                                                      
63 Refer to ISPM 5  for the definition of a quarantine pest under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.   
151 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Larvae of B. trilineola  have been reported from fruits of various ci trus species.  
• Larvae  of B. trilineola  has been reared from field -collected fruit of various citrus species in 
Vanuatu (Leblanc et al. 2013).  
• Citrus species/cultivars that are associated with B. trilineola  are shown in Table 9.5.1. 
 
Table 9.5.1  Known citrus fruit host association of Bactrocera trilineola . 
Citrus host scientific 
name from the reference  Citrus host common 
name from the reference  Reference  Notes  
Fortunella  japonica  Round kumquat  Leblanc et al. (2013 a) Reared from field -collected fruit  
Citrus limon  Lemon  Leblanc et al. (2013 a) Reared from field -collected fruit  
Citrus maxima  Pomelo  Leblanc et al. (2013 a) Reared from field -collected fruit  
Citrus reticulata  Tangerine  Leblanc et al. (2013 a) Reared from field -collected fruit 
Citrus sinensis  Sweet orange  Leblanc et al. (2013 a) Reared from field -collected fruit  
 
Bactrocera trilineola  is reported as present in three citrus -exporting countries in this IHS:  
• Bactrocera trilineola  is reported as present in Vanuatu (Leblanc et al. 2013a ), New Caledonia 
(Hancock 2008) and Solomon Islands ( Vagalo  et al. 1997).  
 
Given the arguments and evidence below,  basic measures  are likely to reduce the 
likelihood of entry of B. trilineola  by a moderate degree (with moderate to high 
uncertainty) . Consequently , the likelihood of entry is considered  low to moderate.  
Some of the infested fruit may be easy to detect and will be removed.  
• Although there is little information on damage  to citrus fruit caused by  B. trilineola , oviposition 
puncture/scars of Bactrocera  spp. (e.g. B. dorsalis ) maybe visible during general handling, 
especially for fruit with multiple oviposition punctures. This damage may cause necrosis 
around the puncture o r even lead to decomposition of the fruit (CPC 2020).  
• If bagging and culling are used in the export countries, these practices are likely to reduce the 
risk to some extent. Xia et al. (2019) found that fruit bagging and packing  house culling 
(including pre liminary culling, washing, waxing, drying, intensive culling, sorting and final 
culling and box -packing) could contribute to risk mitigation of fruit flies in citrus from China. 
The study found few oviposition marks and an absence of living tephritid fruit  flies in bagged 
pomelo fruits ( n=3,000), while 129 fruit fly -infested fruits (containing 634 live larvae and 4 
pupae of B. dorsalis ) were found in the unbagged fruits ( n=3,040). They also found that in fruit 
(C. unsh iu) that received culling treatment ( n=10,000), fruit flies were absent , and 10 fruits 
with oviposition marks (with no living fruit flies) were found, while in fruit ( n=10,000) that did 
not receive the culling treatment, 1 infested fruit with 7 larvae of B. minax  and 25 fruits with 
fruit fly oviposition marks were found.  
 
However, there is a chance that a small number of infested fruits will not be detected.  
• Low infestation (fewer oviposition punctures  in fruit ) may not be obvious enough to be 
detected during ge neral handling.  
• The volume of the commodities can also affect efficiency of detection. Low levels of 
infestation may not be easily detected, especially if the volume of commodities is large.  
• Although other Bactrocera  fruit flies (e.g. B. dorsalis  and B. minax ) have been reported to 
cause fruit to drop prematurely in heavy infestation , and dropped fruit is unlikely to be 
exported, there is no evidence that B. trilineola  can cause fruit to drop prematurely.   
 
General handling after harvesting is not likely  to remove eggs and larvae of B. trilineola  inside citrus 
fruit. 
• As general handling after harvesting (e.g. washing and brushing) only treats the surface of 
fruit, it is unlikely to remove the larvae of B. trilineola  inside citrus fruit.   
• Fruit will need to be cut open to reveal the larvae of B. trilineola  inside.  
 
Bactrocera  trilineola  may be able to survive air or sea transit in citrus fruit commodities, but the 
uncertainty associated  with this  is moderate to high.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 152 • No interception records of B. trilineola  on citrus fruits were found in EPPO (2020). It has been 
intercepted three times on fresh produce64 commodities from Vanuatu (larvae, pupae and 
adults) and once on fresh avocado from Solomon Islands (eggs) ( LIMS 2019).  It is uncertain 
whether the small number of interceptions  is due to existing measures on fruit fly hosts or 
whether B. trilineola  cannot easily survive transit on existing pathways of citrus fruit . 
• The transit process of fresh produce usually involves cold storage in various temperat ures 
depending on the commodity. No study investigating the cold tolerance capability of B. 
trilineola  was found , although it has been intercepted on fresh produce commodities (rather 
than citrus).  
• Therefore, the uncertainty o f whether B. trilineola  can s urvive transit of citrus fruits i s 
moderate to high.  
 
The level of uncertainty associated with the conclusion is moderate  to high. First, there is little 
information on the damage caused by  B. trilineola . Information on damage used in this assessment is 
based on information from other Bactrocera  spp. Second, the uncertainty about  whether B. trilineola  
can survive transit of citrus fruits is moderate  to high, because there are few  interception record s for 
the fly, the transit conditions of  the interceptions are unknown, and no study investigating the cold 
tolerance of B. trilineola  has been found .  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Bactrocera trilineola  has a low to 
moderate  ability  (with moderate  to high uncertainty ) to move from imported fruit and 
into a suitable environment to allow establishment, that is, onto a host plant 
(exposure/ transfer) . 
Bactrocera trilineola  may survive and develop on the waste of citrus  fruit (whole fruit or fruit pieces , 
but probably not skin).  
• Adult B. trilineola  has been reared from field -collected fruit of different citrus species/cultivars 
(Leblanc et al. 2012), suggesting that the fly can survive and complete development in citrus 
fruit. 
• Although the duration of larv al development of B. trilineola  in citrus fruit is not known, the life 
cycle is completed in approximately 21 –22 days at 25 °C using a papaya/torula yeast Nipagin 
artificial diet (Allwood et al. 1996). When the fly and the citrus host are disposed of, the 
development duration may be different from the duration when the fly was reared using the 
artificial diet. Previous importation records of citrus fresh produce from Vanuatu can be found 
from July to January (QuanCargo 2020). The development duration of the fly is likely to be 
longer in New Zealand during this period due to lower temperature s, but the fly is still likely to 
be able to survive and develop in the citrus host in warmer months.  
• If citrus fruit is disposed  of as whole fruit or fruit pieces, it is likely that B. trilineola  can survive 
in this waste. There is no evidence showing that B. trilineola  can complete development by 
feeding on citrus fruit skin.  
 
Most of the kitchen  waste in New Zealand would be disposed of using low -risk methods , so B. 
trilineola  would either be killed or unable to escape from the citrus  host.  
• The majority of kitchen  waste in New Zealand is bagged and disposed of in landfills or run 
through  kitchen disposal units, and in these situations, B. trilineola  is unlikely to re ach a new 
host ( see the waste analysis in section 2.4.1 ). 
 
However,  some of the waste would be disposed of using high -risk methods, including composting in 
gardens and us e as animal feed.  
• Mature larvae of fruit fly come out of the fruit host and drop to t he ground to pupate in the soil. 
The pupae may be able to survive during summer months, but it is uncertain whether they 
can survive and develop in colder seasons.  
• Adults of B. trilineola  emerging from the soil are likely to be able to find food in the 
environment if citrus fruit waste is disposed of using high -risk methods  and the temperature is 
                                                      
64 Interception record shows that the fly was intercepted on Mango/Pacific Lychee/Pandanas/Hog Plum Fresh Produce, but it is 
not clear which commodity the fly was intercepted on.   
153 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  suitable for the fly . Although not specifically reported from B. trilineola , adult fruit flies  are 
reported to feed on various foods, including glandular secretions of plants ; nectar ; and plant 
sap exuding from trunk, stem, leaf or fruit injuries (Christenson and Foote 1960). These food 
sources are likely to be available in home gardens, parks and farms.  
• Hosts for oviposition and larval development are available in warmer areas of New Zealand , 
and some are present in colder areas. Bactrocera trilineola  is polyphagous. Hosts include 
commercially grown crops and crops commonly found in home gardens ( e.g. citrus, avocado, 
guava and papaya). Citrus is commercially produced in both the North Island and the South 
Island, with most commercial production taking place in the North Island ( see section 2.4.2 ), 
and the main production area s of avocado are North land and Bay of Plenty ( Plant & Food 
Research  2019) . 
• If hosts are located near the composting site or animal feeding site (see the waste analysis in 
section 2.4.1 ), adult B. trilineola  is likely to locate the citrus host.  
 
Adult B. trilineola  can fly to food sources and locate citrus hosts, although it is not known whether it is 
a strong flier.  
• No study  investigating  the flight capability of B. trilineola  was found . However, studies on 
other tephritids reveal that the mean dispersal distance o f tephritid flies is usually well below 
1 km, except that mean dispersal distances from below 1  km to 3.6  km have been reported 
for B. dorsalis . However, the maximum dispersal distance reported in many studies was 
limited to the distance of the trap placed  furthest from the release point (Weldon et al. 2014).  
 
It is uncertain whether B. trilineola  can survive cold temperature s if it arrives in New Zealand in cold 
seasons.  
• The current known distribution of B. trilineola  is restricted to three Pacific Island  countries 
(Vanuatu,  Solomon Islands and New Caledonia) located in tropical/subtropical areas.  
• No study  investigating the cold tolerance capability or lower development threshold of 
B. trilineola  was found . Although there are many studies on these aspects on other 
Bactrocera  spp., the cold tolerance of these species varies.  
• Therefore, if B. trilineola  arrives in New Zealand at a time with temperatures that are colder 
than its current distribution, it is un certain whether it can survive and develop and then locate 
a new host outdoors.  
 
The level of uncertainty associated with the conclusion is moderate  to high. First, fruit waste data may 
not be very accurate and up to date , and it is not known how frequent ly suitable hosts would be  
present near composting sites in gardens or animal feeding locations  (see section 2.4.1,  waste 
analysis ). Second, it is uncertain what proportion of composting sites are expos ed or co vered  (e.g. in 
a compost bin).  Third, although  B. trilineola can fly to seek food sources and citrus hosts, its flight 
capability is uncertain. There is a lot of information for other tephritid flies, but the maximum dispersal 
distance reported from many studies was limited to the distance of the trap  placed furthest from the 
release point . Fourth, since  no study investigating the cold tolerance and development temperature 
threshold of B. trilineola  was found, and its current distribution is restricted to tropical and subtropical 
areas, it is uncertain  whether it c ould survive and find a new host if it arrived in New Zealand during 
colder seasons.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for B. trilineola  to establish is considered low to moderate (with 
moderate uncertainty) , and its establishment is likely to be restricted to the warmer 
parts of the North Island and sheltered environment s, although short -term 
populations may establish in other areas during summer months.  
The current  known distribution of B. trilineola  is restricted to three Pacific Island countries located in 
tropical/subtropical area s.  
• The c urrent known distribution of B. trilineola is restricted to Vanuatu (Leblanc et al. 2013), 
Solomon Islands ( Vagalo  et al. 1997) and New Caledonia (Han cock 2008).  
• Although the main island of New Caledonia has  a climate match index (CMI) of 0.6–0.7 
(Phillips  et al. 2018 ), B. trilineola  has only been detected on Loyalty Islands but not the main 
island. No CMI values are provided for Vanuatu, Solomon Islands and Loyalty Islands in the 
Phillips et al. (2018) climate tool. The lowest average monthly minimum temperature s of Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 154 Solomon Island, Vanuatu and Loyalty Islands are 22, 18 and 15 °C respectively, and the 
highest average high monthly t emperature s are 31, 29 and 29 °C respectively (Weather Atlas 
2020).  
 
Based on the currently known geographic distribution of B. trilineola , establishment of B. trilineola  in 
New Zealand is likely to be restricted to some areas of the North Island and in sheltered 
environment s.  
• Bactrocera trilineola  may be able to establish in the northern part of the North Island (e.g. the 
Kaitaia, Whangarei and Auckland region s). These areas have a lowest average monthly 
temperature of about 11 –12°C65, which are the warmest  areas in New Zealand (NIWA 2001). 
It may be able to achieve short -term population establishment in the other areas during the 
summer season.  
• Bactrocera trilineola  has been detected in Maré, New Caledonia  (Hancock 2008). A climate 
niche analysis ( Figure 9.5.1) shows that some months in La Roche , Maré , have temperatures 
similar to New Zealand summers (Halloy 2020).  The mean annual temperature, the lowest 
monthly minimum mean  temperature  and the absolute minimum temperature of La Roche are 
22.2, 13.6 and 2. 8°C respectively (Méteo_France 2020) . As B. trilineola  adapts to these 
conditions, it is likely to tolerate cool temperatures over some areas of the North Island.  
• Bactrocera trilineola  may establish in  sheltered environment s with hosts present.  
 
 
Figure 9.5.1  Climate niches (temperature and precipitation range) of New Zealand (grey ellipse), northern 
New Zealand (including Northland, Auckland, and Bay of plenty; red ellipse), La Roche (pink ellipse), and 
northern New Zealand in a +4 °C climate change scenario (red dashes). These ellipses include 95% of 
climatic sites within the specific area. Northern New Zealand includes 68% of citrus productive area in New 
Zealand (Halloy 2020).  
 
Hosts may not be a limiting factor for the establishment of B. trilineo la in New Zealand.  
• Bactrocera trilineola  is listed in category B in Vargas et al. (2015), which are polyphagous fruit 
pests that are more restricted in distribution but at elevated risk of spreading to new locations.  
• Bactrocera trilineola  has been reported  from 32 hosts belonging to 18 plant families in 
Vanuatu. Some of the hosts of economic importance in Vanuatu are present in New Zealand, 
such as avocado, guava, lemon, kumquat, orange, papaya and soursop (Allwood 2000). 
Watermelon, tomato and eggplant are  conditional hosts (found in both laboratory and field 
cage test s) of B. trilineola  (Heimoana et al. 1996). Bactrocera trilineola  has also been reared 
from capsicum in laboratory condition s (Heimoana et al. 1996).  
• Most commercial production of citrus takes  place in the warmer part of New Zealand 
(including Northland regions) (see section  2.4.2 ), and the main growing regions of avocado 
are Northland and the Bay of Plenty (New Zealand Avocados 2020). These areas are the 
most suitable areas for the establishme nt of B. trilineola  in New Zealand.  
                                                      
65 The data are monthly averages  for the period 1971 –2000 for locations with at least five years of complete data.  
 
155 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Citrus, avocado, capsicum, tomato and eggplant are commonly found in home gardens.  
 
Bactrocera trilineola  occurs year -round in Vanuatu.  
• Bactrocera trilineola  occurs year -round in Vanuatu, but  tends to have population peaks in 
January –February and April –May, which coincides with the guava, mango and tropical 
almond fruiting times (Allwood 2000). This implies that if B. trilineola  establishes in the 
warmer areas in New Zealand, it may be active  during the warmer months (Figure 9.5.1). 
 
Although B. trilineola  is a serious pest of a wide range of economic hosts in Vanuatu, it has not been 
reported as an invasive species in other countries.  
• No economic damage of Bactrocera trilineola  has been repor ted from Solomon Island s and 
New Caledonia, although it is a serious pest in Vanuatu.  
 
Bactrocera trilineola responds to cu elure, which is used in the national fruit fly surveillance 
programme.  
• Three fruit fly lures, cuelure, trimedlure and methyl eugenol , are used in the national fruit fly 
surveillance programme in New Zealand ( MacLellan  et al. 2019 ). If a fruit fly species is 
responsive to any of these lures, it is likely to reduce the likelihood of its establishment in New 
Zealand.  
• A male lure test was conducted in seven Pacific Island countries . This test  indicat ed that B. 
trilineola responds to cuelure, but does not respond to methy l eugenol (Allwood 1996). It is 
not known whether B. trilineola responds to trimedlure.  
 
The level of uncertainty associa ted with the conclusion is moderate . The current distribution of 
B. trilineola  is restricted to the three Pacific Island countries located in tropical/subtropical areas. 
However, it is also detected in Maré, New Caledonia, where lower temperatures are well  within the 
ranges of parts of the North Island. It is not known if its restricted distribution is due to geographic 
boundar ies (i.e. islands) or  if it is because  not all the populations of the pest can establish in colder 
climates. In addition, no study h as been  found on  the cold tolerance and development threshold 
(temperature) of B. trilineola , and therefore, it is uncertain whether it can survive or build up 
populations in colder areas.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below,  the level of impact caused by B. trilineola  
is likely to be high , with low uncertainty.  
Damage and symptoms caused by B. trilineola  can reduce fruit quality.  
• Larvae of B. trilineola  feed inside the fruit of plant hosts.  Although little information is found on 
the damage of B. trilineola  specifically, oviposition of other Bactrocera spp. leaves scars (or 
punctures) on the skin of fruit, which may cause necrosis or darken the colour of fruit skin 
around the oviposition punc ture. Oviposition puncture s and internal feeding by the larvae of 
other Bactrocera  spp. can lead to distortion and rotting of fruit (CPC 2020).  
• Heavy infestation caused by other Bactrocera  spp. can cause premature fruit drop (Xia et al. 
2018; CPC 2020).  
 
Bactrocera trilineola  is a serious pest in Vanuatu, but economic damage has not been reported from 
other countries where it is present.  
• Bactrocera trilineola  has been recorded on 32 plant hosts, of which 22 are regarded as 
commercial or edible fruits (Allw ood 2000). Severe damage has been reported from some 
commercially grown fruits . A 90% damage rate on guava has been recorded in Vanuatu when 
there were no control measures on the fruit fly, while the damage rate reduced to 15% with 
control measures (Allwoo d et al. 2001). It is also reported that B. trilineola  attacks 64% of ripe 
Malay apples ( Syzygium malaccense ), 30% of breadfruit and 11% of ripe mangoes. However, 
these fruit crops are not commercially produced in New Zealand.  Leblanc et al. (2012b) report  
that B. trilineola can also  infest Suriname cherry (sample infested: 20%), Pacific almond Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 156 (40%), Tahiti chestnut (40%), avocado (23%), soursop (around 10%), papaya (around 5%), 
Pacific lychee (88%) and starfruit (50%).  
• No damage records for Citrus  have been reported from New Caledonia (Mille et al. 2012) and 
Solomon Islands.  
 
Bactrocera trilineola  may cause impact on citrus, avocado and other hosts grown in New Zealand.  
• Leblanc et al. (2013)  report infestation data of B. trilineola  on citrus , avocado  and 
banana /plantain (genus Musa ): 
o 9.17 flies per kg of avocado ( Persea americana ); 
o 20.63 flies per kg of C. reticulata ; 
o 8 flies per kg of C. maxima ; 
o 7.59 flies per kg of C. sinensis ; 
o 1.25 flies per kg of Fortunella  japonica ; 
o 0.63 flies per kg of C. limon ;  
o 28.57 flies per kg of Musa  sp. 
• The main  commercial production area s of citrus and avocado are in the northern part of the 
North Island. These areas are likely to be the most suitable areas for the establishment of 
B. trilineola  in New Zealand.  
• However, as there is no report found on quantifying the impact on citrus and avocado in areas 
with similar climate conditions to New Zealand, the impact on these two industries is 
uncertain.  
• Leblanc et al. (2013) also report 28.57 flies per kg of Musa  sp.  
• Bactrocera trilineola  may also cause impact on tomato, capsicum, eggplant and watermelon 
(Heimoana et al. 1996), but as tomato, eggplant and watermelon are conditional hosts (found 
in both laboratory and field cage test) , and B. trilineola  has only been known on capsicum in 
laboratory condition s, the uncertainty associated with the level of impact is high.  
 
The impact on exports, including market access, is likely to be severe.  
• Detection of a fruit fly in the surveillance programme would need to be reported internationally 
and would be expected to result in reduced market access for New Zealand host materials. In 
New Zealand, 80% of horticultural export value came from plants that are potential fruit  fly 
hosts (MacLellan et al. 2019).  The incursion o f B. dorsalis  (reported as B. papaya ) in north 
Queensland, Australia , was estimated to cause losses of nearly AU$100  million, and most of 
this was due to lost export markets (Drew 1997, in Clark et al. 2005).  
• The c urrent known distribution of B. trilineola  is restricted to three Pacific Island countries . If 
B. trilineola  establishes in New Zealand, other trading partners are likely to take measures on 
the host commodities or even limit market access of host commodities from New Zealand. 
Post-harvest disinfe station costs would be necessary, in particular for avocado and citrus.  In 
Australia  in 1996 , apples and citrus fruit under went  a cold treatment for fruit fly at a cost of 
approximately AU$200/tonne , avocados  are treated with hot forced air , costing approx imately 
AU$125/tonne, and stone fruit, cucurbits and tomatoes were treated with a dimethoate dip , 
which cost approximately AU$100/tonne (MAF 1996).  
 
If B. trilineola  is detected in New Zealand, the cost incurred by a response would be high.  
• The typical c ost of responses is millions of dollars. For example, the Queensland fruit fly 
response in 2019 has cost approximately NZ$18 million (MPI 2020).  
• In Japan, eradication of a fruit fly species from the Ryukyu Islands has cost more than 200 
million euros (Kir itani 1998 , cited in CPC 2020 ). The cost for the eradication programme in 
northern Queensland of the papaya fruit fly ( Bactrocera papayae ) (1995 –1999) was AU$33 
million  (Cantrell et al. 2002 , in CPC 2020).  
 
Bactrocera trilineola  may cause low impact on the  environment in New Zealand.  
• Bactrocera trilineola  has been reported to be a serious pest of Syzygium malaccense  in 
Vanuatu (Allwood et al. 2000). New Zealand has native Syzygium , which is S. maire.  
• Bactrocera trilineola  may cause impact on the native S. maire. This native tree produces fruits 
and can be found in wet sites in warmer parts of New Zealand (e.g. in Northland) (NZPCN 
2020).  
• If Bactrocera trilineola  establishes in New Zealand, S. maire  may be an alternative host to 
those commercial fruit crops.   
157 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Bactrocera trilineola  is likely to cause soci ocultural impacts on citrus in home gardens.  
• Some hosts are commonly grown in home gardens, such as citrus, avocado, capsicum, 
tomato and eggplants . 
 
There is no evidence found on the impact of B. trilineola  on human health.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence below,  Bactrocera trilineola may be considered 
for additional measure s. 
• Bactrocera trilineola  has a strong association with fruits of some citrus species.  
• Some infested fruit will  not be detected, especially when the volume of commodities is large.  
• As the larvae feed internally in the fruis, general handling cannot remove the larvae, and 
citrus fruit need s to be cut open to reveal the larvae of B. trilineola . 
• Bactrocera trilineola  has a low to moderate ability  (moderate  to high uncertainty ) to move from 
imported fruit and into a suitable environment to allow establishment.  
• The suitability of the New Zealand environment for B. trilineola  to establish is considered  low 
to moderate  (with moderate uncertainty), and its establishment is likely to be restricted to the 
North Island, although short -term population s may establish in other areas during summer 
months.  
• Hosts may not be a limiting factor for the establishment of B. trilineol a in New Zealand, as 
some hosts are commercially grown and commonly found in New Zealand.  
• Bactrocera trilineola  has been reported to cause severe impact on some tropical fruit crops 
and to attack citrus and avocado. However, economic damage is only known f rom lowland 
Vanuatu , not from areas with a similar climate to New Zealand.  
• Although economic damage has not been reported in areas with similar climate to New 
Zealand, as a fruit fly species, if it is detected and/or establish es in New Zealand, the impact  
on export and market access of New Zealand’s horticultural products (particularly citrus and 
avocado) is likely to be severe.  
• Bactrocera trilineola  is currently listed  in the citrus fresh produce IHS  in the following citrus 
exporting countries: Vanuatu, New Caledonia and Solomon Island s. 
 
8.5.4 References  
Allwood, A (2000) Fruit flies in Vanuatu. Pest Advisory Leaflet / Secretariat of the Pacific Community. 
Plant Protection Service; 27 . 
Allwood , A J (1996) Responses of fruit flies (Family Tephritidae) to male lures in seven Pacific Island 
countries.  In Allwood, A J; Drew, R A I ( eds) Management of Fruit Flies in the Pacific : A Regional 
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  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 160 8.6 Bactrocera tryoni  (Queensland fruit fly, Qfly ) 
 
Bactrocera tryoni  (Qfly) females lay their eggs through the skin of fruit. Maggots hatch from the eggs 
and feed within the fruit, causing damage and rotting . Qfly  has a very wide host range, including many 
economically important horticultural crops in Australia. The fly is native to Queensland and is invasive 
in other parts of Australia and in New Caledonia, French Polynesia and the Pitcairn Islands. It has 
been de tected in New Zealand on a number of occasions, including breeding populations, but has 
been successfully eradicated on each occasion.  
 
Scientific name: Bactrocera tryoni  (Froggatt, 1897)  
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera  (Bactrocera ) tryoni , Chaetodacus sarcocephali , Chaetodacus 
tryoni , Dacus ferrugineus  tryoni , Dacus tryoni , Strumeta melas , Strumeta tryoni , Tephritis tryon i (CPC 
2020)  
 
Taxonomic notes : Bactrocera tryoni  is a member of the B. tryoni  complex of species, which currently 
includes four named species: B. tryoni, B.  aquilonis, B. melas and B. neohumeralis . The species 
status of B. aquilonis  and B. melas is unclear ; they may be junior synonyms of B. tryoni  (Clarke et al. 
2011).  
 
Bactrocera  aquilonis  is distributed within northwestern Australia from Darwin across to northern 
Western Australia, and is completely allopatric to B. tryoni  (Cameron et al. 2006 , Sultana et al. 2020 ). 
However, B. aquilonis  and B. tryoni  cannot be separated reliably  based on morphology or by using a 
population genetic approach with microsatellite data, leading Cameron et al. (2010) to conclude that 
“there is no genetic evidence supporting the separation of B. aquilonis  and B. tryoni  as distinct 
species”. Cameron et a l. (2010) state “ from a quarantine perspective, the genetic similarity between 
B. tryoni  and the northwestern species [ B. aquilonis ] would suggest that control and disinfestation 
protocols should be similar in both regions”. More recent unpublished PhD res earch showed that B. 
aquilonis  forms a defined clade within the species tryoni  and is  possibly a population of tryoni  rather 
than a s eparate s pecies (K . Armstrong, pers. comm.). Similarly, Popa -Báez et al. (2020) concluded 
that, based on whole  genome analyses, the population of fruit flies in  the Northern Territory is B. 
tryoni , but that genetic differentiation has occurred due to its geographic isolation from the parent 
population.  
 
If B. aquilonis  is synonymised under B. tryoni , host and distribution  records for B. aquilonis  should be 
attributed to B. tryoni . However the distribution of this putative species is very restricted. It has only 
been reported from the very north of Australia above 16 ° of latitude.  
 
Summary of conclusions  
 
Given the argument s and evidence presented : 
 
• Bactrocera tryoni meets the criteria to be a quarantine pest for New Zealand.  
• Bactrocera tryoni has a low to moderate association with citrus fruit , with low uncertainty . 
• Basic measures  are likely to reduce the likelihood of entry of B. tryoni on the commodity by a 
moderate degree , with low uncertainty . Consequently the likelihood of entry is considered to 
be low , with low uncertainty . 
• Bactrocera tryoni is considered to have  a low to mod erate ability (with moderate uncertainty) 
to move from imported citrus fruit and into a n environment that is suitable for establishment.  
• The suitability of the New Zealand environment for the establishment of B. tryoni is 
considered to be low to moderate , with low uncertainty .  
• The level of impact caused by B. tryoni is likely to be high , with low uncertainty . Although its 
spread and economic impact may be limited by climate, even a temporary incursion is likely to 
be associated with significant trade barri ers and eradication costs.  
• Bactrocera tryoni  may be considered for requiring additional measures.   
161 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Summary of risk assessment against criteria  
Criteria  Rate  Uncertainty  
Strength or frequency of association with the commodity  Low to moderate  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from the imported commodity onto a suitable host  Low to moderate  Moderate  
Suitability of the New Zealand  environment  Low to moderate  Low 
Impacts on the New Zealand economy, environment, health and society  High Low 
 
8.6.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Bactrocera tryoni meets the criteria to be 
a quarantine pest for New Zealand . 
Criteria for being a quarantine pest relevant to this assessment are: not present in the New Zealand, 
and of potential importance (able to establish and cause harm66). 
 
Bactrocera tryoni is not known to be present in New Zealand:  
• NZOR (2020) reports B. try oni as “eradicated/destroyed”, and PPIN (2020) reports it as 
absent . 
• New Zealand has country freedom status for B. tryoni (MPI 2020a) . 
• Bactrocera tryoni  is an unwanted and notifiable organism and a regulated pest ( ONZPR  
2020).  
 
Bactrocera tryoni has the po tential to establish and spread within the warmer parts of New Zealand:  
• Climate modelling studies have concluded that B. tryoni is likely to be able to establish 
permanent populations in the warmer parts of New Zealand. It has established temporary 
populat ions in New Zealand on a number of occasions before being successfully eradicated.  
• Bactrocera tryoni is a widely polyphagous fruit fly , and suitable host plants are readily 
available throughout New Zealand commercially, in home gardens and in natural areas .  
 
The establishment of Bactrocera tryoni in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. tryoni has the potential to cause direct economic damage to many 
horticultural crops that are important to New Zealand. It also has the potential to cause 
significant control costs and to impact negatively on national and international trade.  
• The establishment of B. tryoni has the potential to have soci ocultural impacts: many of its 
hosts are commonly planted in home gardens.  
• Environmental and human health impacts caused by its establishment are likely to be very 
low or negligible.  
 
8.6.2 Hazard identification: commodity association  
 
Bactrocera tryoni is associated with citrus fruit  
• Bactrocera tryoni oviposits through the fruit skin of many plant species, and its larvae feed 
inside the fruit (CPC 2020).  
• There are validated records of infestation of many citrus species by B. tryoni  that satisfy the 
definition of a host in accordance with international standards.  
                                                      
66 Refer to ISPM 5  for the definition of a quarantine pest under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 162 8.6.3 Risk assessment  
 
Likeli hood of entry:  
 
Given the arguments and evidence below,  Bactrocera tryoni has a low to moderate 
association with citrus commodities.  
Many citrus species are hosts of B. tryoni , but citrus is not a favoured host.  
• Adult females of B. tryoni lay eggs below th e skin of the host fruit. Eggs hatch within 2 –3 days 
and the larvae feed within the fruit for another 10 –31 days (time is dependent on the host and 
the environmental conditions, particularly temperature) before leaving the fruit to pupate (CPC 
2020).  
• There are validated records of infestation of many Citrus  species by B. tryoni  that satisfy the 
definition of a host in accordance with international standards, e.g. ISPM 37 ( FAO 2016 a)67, 
RSPM 4 (2005) (Table 9.6.1 ).  
 
Table 9.6.1  Citrus  species reported to be hosts of Bactrocera tryoni   
The scientific and common host names are the names cited in the reference given . 
Host name  Common name  Reference (Country of record)  
Citrus aurantiifolia  Lime ; West Indian lime  Hancock et al. (2000); NTG  (2013) (Australia)  
Citrus aurantiifolia  Lime  Leblanc  et al. (2013) (French Polynesia)  
Citrus aurantium  Seville orange  Hancock et al. (2000) (Australia)  
Citrus maxima  Pummelo  Hancock et al. (2000) (Australia)  
Citrus jambhiri  Bush lemon  Hancock et al. (2000) (Australia)  
Fortunella  japonica  Round kumquat  Leblanc et al. (2013) (New Caledonia)  
Citrus latifolia  Tahiti an lime Leblanc et al. (2013) (French Polynesia, New Caledonia)  
Citrus limon  Sweet lemon  Hancock et al. (2000) (Australia)  
Citrus limon  Lemon  Hancock et al. (2000) (Australia)  
Citrus limon  Lemon  Lloyd et al. (2013) (Australia)  
Note: Lloyd et al. (2013) found lemons were poor hosts, 
especially green Eureka lemons . Conditional non -host 
status is a possibility for lemons.  
Citrus limon  Meyer  lemon  Hancock et al. (2000) (Australia)  
Citrus maxima  Pomelo  Leblanc et al. (2013) (French Polynesia, New Caledonia)  
Citrus medica  Citron  Hancock et al. (2000) (Australia)  
Citrus medica  Citron, Tangor  NTG (2013)  (Australia)  
Citrus paradisi  Grapefruit  Leblanc  et al. (2013) (New Caledonia)  
Citrus paradisi  Grapefruit and Pink 
grapefruit  Hancock et al. (2000) (Australia)  
Citrus  paradisi  Grape fruit White & Elson -Harris (1992) (Australia)  
Citrus reticulata  Mandarin, Tangelo and 
Tangerine  Hancock et al. (2000) (Australia)  
Citrus reticulata  Tangerine  Leblanc et al. (2013) (French Polynesia, New Caledonia)  
Citrus reticulata  Imperial, Ellendale and 
Murcott mandarins  Lloyd et al. (2013) (Australia)  
Citrus limon  Rangpur lime  DPIPWE (2011), NTG (2013)  (Australia)  
                                                      
67A host is a plant species or cultivar that has been scientifically found to be infested by the target fruit fly species under  natural 
conditions and able to sustain its development to viable adults (ISPM 37, FAO 2016a).   
163 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Host name  Common name  Reference (Country of record)  
Citrus sinensis  Navel and Valencia 
oranges  Lloyd et al. (2013) (Australia)  
Citrus sinensis  Orange  Hancock et al. (2000) (Australia)  
Citrus sinensis  Orange  Leblanc et al. (2012) (French Polynesia, New Caledonia)  
C. reticulata × C. paradisi  Tangelo  NTG (2013) (Australia)  
 
• However, Citrus species are generally considered to be relatively poor hosts of B. tryoni .  
o Field surveys of citrus hosts from unmanaged habitats have shown that the numbers 
of fruit flies produced per gram of fruit are much lower ( usually an order of magnitude) 
than those of the more susceptible noncitrus hosts such as guava ( Psidium guajava ), 
cherry guava ( P. littorale ), mulberry ( Morus nigra ), loquat ( Eriobotrya japonica ), and 
pear (Pyrus communis ) (Lloyd et al. 2013).  
o Hancock et al. (2000) do not report any species of Citrus  as favoured hosts, though 
they report B. tryoni  as a host of around 10 citrus taxa; and CPC (2020) do not list 
any Citrus  species as “main” hosts (all Citrus  species are cate gorised as “other”).  
o Muthuthantri (2013) reported that citrus fruit in general are poor hosts for B. tryoni , 
and that adult fly emergence from citrus was very low,  while adult fly production from 
nectarine was very high.  
o According to Lloyd et al. (2013), t he major citrus crops commercially cultivated in 
Australia have a relatively low susceptibility to B. tryoni , with Eureka lemons being a 
particularly poor host for this species  (Table 9.6.2) .  
 
Table 9.6.2  Host susceptibility of Citrus  species and other h osts of Bactrocera tryoni   
The host susceptibility ind ex is defined by Lloyd et al. (2013) as the n umber of adult flies produced 
per gram of fruit (infested at a calculated rate of one egg per gram of fruit ). 
 
Host common name  (from reference)  Host scientific name  (from reference)  Host  susceptibility index  
Citrus species  
Seville oranges  Citrus aurantium  0.237  
Murcott mandarins  Citrus reticulata  0.083  
Imperial mandarins  Citrus reticulata  0.052  
Navel oranges  Citrus sinensis  0.026  
Ellendale mandarins  Citrus reticulata  0.020  
Valencia oranges  Citrus sinensis  0.008  
Eureka (yellow) lemon  Citrus limon  0.002  
Eureka (green) lemon  Citrus limon  0.000  
Non-citrus species  
Guava  Psidium guajava  0.318  
Cherry guava  Psidium littorale  0.226  
Mulberry  Morus nigra  0.209  
Loquat  Eriobotrya japonica  0.148  
Pear  Pyrus communis  0.111  
 
Bactrocera tryoni  is present in countries that are included in the scope of this IRA: 
• Bactrocera tryoni is present in eastern Australia and in New Caledonia ( Table 9.6.3) . 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 164 Table 9.6.3  Geographic distribution of Bactrocera tryoni   
Areas in bold are potential exporting countries.  Sources: EPPO (2020), Clarke et al. (2011)  
Region  Country  Biostatus  
Oceania  Australia  Native in Queensland, otherwise invasive. 
Bactrocera tryoni  is considered to be a 
quarantine pest in Western Australia and 
Tasmania. In eastern Australia, only the 
Riverland Pest Free Area in South Australia is 
currently recognised as a pest free area for B. 
tryoni ). 
Oceania  French Polynesia (Austral Is lands , Soci ety Is lands ) Invasive  
Oceania  New Caledonia  Invasive  
Oceania  Pitcairn Islands  Invasive  
 
 
Given the arguments and evidence below,  basic measures  are likely to reduce the 
likelihood of entry of B. tryoni  by a moderate degree . 
In Australia, in -field controls can reduce B. tryoni  populations to a low level:  
• In-field and area -wide controls can greatly reduce B. tryoni  population levels in preferred host 
crops. Some untreated crops (e.g. peach in southeast Queensland) may have up to 100% 
infestati on (Bull 2004), while production losses in treated crops in endemic areas range from 
0.5–3% (Sultana et al. 2017).  
• Lloyd et al. (2000, in DPIPWE 2011) estimated infestation levels in commercial citrus 
orchards in the central Burnett area that used bait spr ay consistently were in the order of 
0.029 –0.047% at the 95% confidence level.  
• Subramaniam (2011) found that in -field control (field cover sprays and packhouse mitigation 
measures including washing, sorting and grading to remove defective and damaged frui t) and 
inspection in the packhouse was able to provide a high level of security in capsicum and 
tomato crops in Queensland.  
 
Bactrocera tryoni infestations may be visually detectable in the field and/or packhouses, leading to the 
removal of infested produc e, but some individuals are likely to be undetected:  
• Larval feeding within fruit induces premature fruit drop and fungal decay (Clarke et al. 2011, 
PHA 2016). Infested fruit may therefore be detected and is not likely to be exported.  
• However , low levels of  infestation, or feeding by early instars , may not be detected during  
harvest, after harvest or in on-arrival inspection, particularly if the volume of commodities is 
large. Oviposition sites are not always noticeable. In mature citrus, tephritid sting mar ks may 
be small brown depressed spot s, or the fruit may have an indistinct, bruised appearance . On 
green citrus fruit , the skin colours prematurely around the sting mark (PHA 2016). Therefore, 
infested fruit may not show any physical signs of oviposition o r internal feeding, particularly 
those containing eggs or early instar larvae (DPIPWE 2011). Late instar larvae may also enter 
the country if there are few in the fruit and if the damage caused is not conspicuous.  
• Internally feeding insects are difficult t o detect by non -destructive inspection. Even using fruit 
dissection, Gould (1995) found that detection rates for Carribean fruit fly ( Anastrepha 
suspensa ) could be as low as 17.9%. In this study, inspectors detected between 17.9% and 
83.5% of fruit infeste d with Carribean fruit fly . Variables influencing the detection rate were the 
fruit type, its ripeness and the inspector.  
• Border detections in Citrus  species : “Bactrocera tryoni complex”  (see taxonomic note) has 
been identified at the New Zealand border in various Citrus species (LIMS and Quancargo 
databases):  
o Nine dead larvae (molecular identification of “ Bactrocera tryoni  complex ”) were 
detected in a shipment of oranges from Australia in  2017 (consignment 
C2017/446874).   
165 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  o Four live larvae (molecular identification of “ Bactrocera tryoni  complex ”) were 
detected in lemons in 2016 (C16_00185, no further pathway information available).  
o “Bactrocera tryoni ” has also been identified alive in lemon s seized from passengers in 
1991, and also alive in Citrus reticulata  (mandarin) and Citrus limon  (lemon) in 2016 
(accession numbers C16_01154 and C16_00185 respectively; no further pathway 
information available).  
• Bactrocera tryoni  and “Bactrocera tryoni  complex” have been detected at the New Zealand 
border  in other fruit species (for example, alive in irradiated mangoes and litchis  from 
Australia , and alive i n apples and chillis  seized from passengers ). 
• EPPO has not reported any detections of B. tryoni in citrus fruit at the EU border (Steffen et 
al. 2015 ; EPPO 2020) .  
 
Bactrocera tryoni larvae may survive transit in some citrus commodities.  
• Transport of fruit is likely to be by sea and may take a number of  weeks. The optimum 
carrying temperature is variable depending on the fruit type (between 8 and 14°C for 
grapefruit, lemons and limes, and between 2 and 7°C for oranges; BMT 2020) . Carrying 
temperatures are therefore generally cool , though not very low – grapefruit and mandarin 
exhibit chilling injury at 7 and 8°C, respectively and unconditioned lemons below 14.5°C  
(McGregor 1987). Bactrocera tryoni is considered to be a tropical species (Clarke et al. 2011) 
with a n assumed  low tolerance  to cold . It is not known whether typical carrying temperatures  
affect its viability in citrus.  
 
The overall likelihood of entry for B. tryoni  on commercially produced citrus is considered to be low, 
with low uncertainty. Many commercially traded species of citrus are reporte d to be hosts of B. tryoni , 
though none are reported to be favoured hosts. There is evidence that in -field controls can be very 
effective in reducing, but not removing, B. tryoni  infestations. Infested fruit is difficult to detect by 
inspection, particular ly at low levels.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of Bactrocera tryoni to move 
from imported citrus fruit into a suitable environment to allow establishment is 
considered to be low to moderate, with moder ate uncertainty.  
Bactrocera tryoni is able to survive and develop on discarded fruit.  
• Bactrocera tryoni  is often reared on picked fruit in disinfestation experiments. In the field, fruit 
infested with fruit fly larvae often drop to the ground prematurely (Allwood and Leblanc 1997), 
where development continues until they leave the fruit to pupate. Pupation usually takes place 
in the soil (Weems and Fasulo 2002).  
• Infested fruit is likely to be discarded. Infested fruit must re main in a suitable condition long 
enough for larvae to develop to maturity (this time is temperature dependent) , and emerging 
larvae then need to find a suitable pupation site.  Citrus fruit is relatively robust and not highly 
perishable , compared to commod ities such as peaches or strawberries. Citrus  is likely to 
remain in good condition long enough for larvae to emerge and pupate.  
• However, Citrus  species are not favoured hosts for B. tryoni . Developmental times are 
generally longer than in favoured hosts, and the number of flies emerging from citrus 
commodities is likely to be lower than for favoured hosts (Lloyd et al. 2013 ; Muthuthantri 
2013 ; Table 2 ). 
 
Most organic waste in New Zealand is likely to be disposed of using lowrisk  methods, meaning that fly 
larvae would die before completing development.  
• The majority of waste in New Zealand is bagged and disposed of in landfills and into kitchen 
disposal units. In these situations, B. tryoni  is unlikely to continue development to s uccessful 
emergence of adults ( see section 2.4.1 ). 
 
However,  some waste is likely to be disposed of using high -risk methods, including composting in 
gardens, discarding into the environment (e.g. roadsides, parks) and use as animal feed , thus 
allowing larv ae to successfully emerge from fruit, pupate and become a dults .  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 166 • Adult B. tryoni emerging from the soil are likely to be able to find food in the environment.  Like 
most tephritids, both male and female B. tryoni  need protein in order to  become sexually 
mature (Meats et al.  2004 ; Clarke et al.  2011). Adult flies are presumed to obtain the majority 
of their protein through feeding on leaf surface bacteria. Research suggests that no single 
bacterial species is involved in a primary symbioti c relationship with B. tryoni  (Clarke et al.  
2011) , and it is assumed that these bacteria are widely available. Other food sources for adult 
tephritids include widely available substances such as bird droppings, nectar and plant sap 
(Christenson and Foote 1960).  
Adult B. tryoni  are mobile and can fly to food sources and locate hosts.  
• Adults are highly mobile and capable of independent dispersal. Most M RR (mark, release, 
recapture) studies have concluded that the mean dispersal distance of tephritid flies i s usually 
below 1 km. However, the maximum dispersal distance reported in many studies was limited 
to the distance of the trap placed furthest from the release point (Weldon et al. 2014). Long -
distance dispersal is reported and has been linked to isolated favourable habitats separated 
by resource -poor country that forced dispersing flies to make longer flights (Dominiak 2012).  
Fletcher (1973,1974) found that movement of B. tryoni  into and away from an orchard was 
seasonal and associated with the availabilit y of fruiting host trees, and Weldon (2005) found 
that flies dispersed further in spring than in autumn, noting that dispersal may be linked to 
habitat suitability, e.g. fewer fruiting hosts or other resources. It is therefore likely that flies will 
be abl e to disperse far enough to find the resources they require in New Zealand.  
 
There is moderate uncertainty associated with th e conclusion that the likelihood of exposure is 
moderate. Information about waste disposal may be inaccurate (section 2.4.1 ). The effect of 
seasonality on this likelihood is uncertain.   
 
Given the arguments and evidence below,  the suitability of New Zealand’s 
environment for the establishment of Bactrocera tryoni is considered to be low to 
moderate, with low uncertainty.  
Bactrocera t ryoni is described as a tropical species (Clarke et al. 2011) . The results of various climate 
models  suggest that it is likely to establish permanently in at least some parts of New Zealand , 
predominantly the northern half of the North Island : 
• Baker and Co wley (1988) predicted establishment of permanent populations in the northern 
North Island and the top of the South Island in Marlborough and Nelson. Summer populations 
were predicted around the coast of the southern North Island and down the east coast of the 
South Island.  
• Sutherst and Maywald (1989) predicted colonisation of the northern and eastern parts of the 
North Island.  
• Predictions by Kriticos (2007) using parameters from Yonow and Sutherst (1998) were more 
conservative. Bactrocera  tryoni  was projec ted to be capable of establishing persistent 
populations in New Zealand only as far south as the northern Waikato. This study also 
investigated a variety of climate -warming scenarios. Under these, B. tryoni  was projected to 
be capable of spreading further south in the North Island , and under a warm scenario for the 
2080s could even persist in the northern tip of the South Island.  
• Kean and Stringer (2019) modelled seasonal dynamics of B. tryoni  and concluded that it was 
unlikley to establish south of Napier  (eastern North Island ). 
 
Bactrocera tryoni has a high reproducti ve rate and is capable of finding mates.  
• Multiple larvae are contained within a single fruit . Forty B. tryoni  larvae have been found in 
one peach, and 67 adults have been reared from one apple  (Weems and Fasulo 2002 ), 
although fewer adults are likely to emerge from m ost citrus species ( Lloyd et al. 2013, 
Muthuthantri 2013; Table 2 ).  
• To found a population, a minimum of one male and one female must successfully emerge 
from imported fruit and sur vive long enough to locate each other and  mate. Enough adults to 
establish a population may therefore emerge from a single or a few discarded fruit. Males use 
pheromones and acoustic signals to attract sexually receptive females at dusk (Dominiak et 
al. 20 11). Mating takes place only if ambient temperatures are above 15 °C–16°C (Dominiak 
et al. 2011 , Meats and Fay 2000, in Meats 2006  respectively ). This temperature requirement 
is likely to be a constraint on successful mating taking place in parts of New Zea land,  
167 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  particularly since some citrus is imported from Australia during the colder months. Most 
orange fruit, for example, is imported from Australia from June through October. However, 
there is some trade in oranges virtually year round . In particular , importation of Australian 
oranges is not uncommon in the warmer months of November and December, although very 
few consignments are imported in January through to April (Quancargo database). 
Additionally, limes tend to be imported in the summer months. Im mature adult flies (the 
overwintering stage in Australia) are long -lived. The longest known period of adult survival is 
198 days (DPIPWE 2011) . Flies may ther efore survive until temperatures are suitable for 
mating. In addition, cold -acclimated flies show a much higher mating frequency at lower 
temperatures (Meats and Fay 1976).  
• Bactrocera tryoni is a more prolific egg producer than many other tephritids . Egg production is 
variable, with upper limits ranging from 80 to 100 –120 (maximum 160) eggs per female per 
day. The o viposition rate is likely to be influenced by host plant and environmental factors, 
particularly temperature (Clarke et al.  2011), so may  be lower in New Zealand.  
 
Host availability is unlikely to be a barrier to establishment and spread of B. tryoni . 
• Bactrocera tryoni  has a very broad host range of both commercial and wild fruit and 
vegetables, making it one of the most polyphagous of all  the tephritids. The fly has been 
recorded from 117 hosts, including commercial crops such as citrus, nuts, stone and pome 
fruit and tomato (Clarke et al. 2011). Many suitable hosts are present in New Zealand in 
natural and managed habitats.  
• Fruit is like ly to be available at many times of the year, but in any case , immature adults are 
long-lived and if fruit is not present for oviposition, adults may survive until fruiting occurs. If 
incursions take place when fruit is scarce or unavailable, establishment  would require the 
survival of at least one individual of both sexes , or a mated female,  until suitable fruiting hosts 
are available for oviposition.  
• Once established, B. tryoni  is capable of dispersing naturally and is also likely to be spread by 
the dist ribution of infested host fruit.  
 
Bactrocera tryoni  is likely to be detected and eradicated in the event of an incursion.  
• Surveillance for fruit flies in New Zealand uses trimedlure, cuelure and methyl eugenol as 
lures (MacLellan et al. 2019). Males are re sponsive to cuelure (IAEA 2003) , and early 
detection and therefore eradication of incursions is very likely.  An analysis of 211 eradication 
or emergency response programs against 17 species of fruit flies in 31 countries indicated 
that the failure rate for these fruit fly eradication programs was low (about 7%; Mcinnes et al. 
2017).  
• Bactrocera tryoni  has been det ected in New Zealand by the surveillance grid seven times 
since the mid -1990s (Kean et al. 2020). It has been successfully eradicated on all occasions, 
including when breeding populations were detected.  
 
 
Impacts in New Zealand:  
 
Given the arguments and ev idence below, the level of impact caused by B. tryoni  is 
likely to be high.  
Damage caused by B. tryoni  reduces fruit quality and can render it unmarketable.  
• Oviposition can cause necrosis around the puncture mark. Internal feeding by the larvae 
induces dec ay and premature fruit drop (Clarke et al. 2011 ; CPC 2020).  
 
Bactrocera tryoni has been reported to cause severe damage and production loss in many 
horticultural commodities  that are economically important to New Zealand.  
• DPIPWE (2011) lists stone fruit, citrus, pome, grape and tomato as major fruit industries 
affected by B. tryoni  in Australia. Between 76 and 100% infestation may occur in untreated 
peach crops in southeast Queensland (Bull 2004).  
• Fruit and vegetables grow n commercially in New Zealand that are known hosts of B. tryoni  
include citrus, avocados, walnuts, pears, stonefruit, capsicum, cucurbits, tree tomatoes, 
grapes and tomatoes (Underwood 2007).  
 
The economic impact of B. tryoni  in Australia is high.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 168 • The annual cost of pre -harvest bait and cover spraying over the period 2006 –2009 was 
estimated to be around  AU$48 million, while post -harvest treatments necessary to transport 
produce interstate exceeded AU$22 million p.a. Even with these treatments, produ ction 
losses in fruit fly endemic regions range from 0.5 –3% (Sultana et al. 2017). If fruit flies are not 
controlled, potential losses could reach AU$100 million per year, most being attributable to B. 
tryoni  (Lloyd et al. 2010). Production losses in New Z ealand are likely to be lower than in 
Australia , as the climate is less favourable for the development of high B. tryoni population 
levels. However, since there are no pest tephritids currently present in New Zealand and 
therefore no existing management pr ogrammes, there would be high costs associated with 
implementing such systems.   
 
The establishment or even an incursion of B. tryoni  is highly likely to cause trade impacts;  
• In addition to production losses, many trading partners are likely to impose expo rt restrictions 
and/or extra phytosanitary measures if B. tryoni  is present, even temporarily, in New Zealand. 
These may not be restricted to known host fruit and may be imposed for long periods. In 
response to the May 1996 incursion of C. capitata,  tradin g partners imposed restrictions on 
produce from the Auckland area which lasted 8  to 12 months or longer (Underwood 2007). 
Bactrocera tryoni  has a limited geographical distribution, meaning that the majority of our 
trading partners are likely to impose such  sanctions.  
 
If B. tryoni  is detected in New Zealand, the cost incurred by a response would be high.  
• The typical cost of responses is millions of dollars. For example, the Queensland fruit fly 
response in 2019 cost approximately NZ$18 million (MPI 2020b) .  
• Bactrocera tryoni  is considered a serious enough pest that many coutries undertake 
eradication programmes following detections. Successful responses include those undertaken 
in Easter Island, Perth and Rarotonga (Kean et al. 2020).  
 
Bactrocera tryoni is likely to cause soci o-cultural impacts on  home gardens.  
• Many favoured hosts , as well as citrus , are commonly grown in home gardens. Some 
untreated crops (e.g. peach in southeast Queensland) may have up to 100% infestation (Bull 
2004). Sultana et al. (2017 ) estimated that in Australia , 80% of the value of backyard fruit 
production is lost in the absence of eradication programmes.  
 
 Environmental impacts caused by the establishment of Bactrocera tryoni are likely to be low.  
• Bactrocera tryoni attacks some pla nt species in genera that have New Zealand native 
representatives , e.g. Passiflora , Solanum  and Syzygium (CPC 2020) . The two varieties of 
Solanum aviculare  present in New Zealand (neither endemic) and Syzygium maire  all have 
some form of threatened status (NZPCN 2020), and where their distributions overlap with B. 
tryoni , they may be at risk.  Other species of Solanum  and Passiflora  are reported as “main” 
hosts (CPC 2020) . However : 
o The fly has an unprecedently wide host ra nge, and Beever et al . (2007) have 
suggested that highly damaging polyphagous species appear to be exceptional and 
that the impact of relatively specialised organisms is likely to be greater . While 
Beever et al. (2007) did suggest that B. tryoni  was a pote ntial ( low) risk to Solanum 
aviculare , this conclusion was based on factors affecting the likelihood of this species 
becoming established, not just its anticipated impact .  
o The fruit of  the native Solanum  and Passiflora  species are small and much less fleshy 
than the preferred hosts of B. tryoni . 
o Other susceptible native plant s are likely to have populations in areas that are not 
suitable for the establishment of B. tryoni .  
o If the fly attacks only the flesh of ripe fruit, it is unlikely to impair seed development, 
number or viability.  
 
Bactrocera tryoni is unlikely to cause unwanted impacts on human health.   
• No evidence of such impacts has been found . 
 
 
Risk assessment summary : 
  
169 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Given the arguments and evidence below,  Bactrocera tryoni may be considered for 
additional measures . 
• Many Citrus  species are hosts, though none appear to be favoured hosts;  
• low levels of fruit infestation may not be detected during general handling, especially when 
the volume of commoditi es is large;  
• larvae feed internally in the fruit and cannot be removed by general handling; the fruit need to 
be cut open to reveal them;  
• Bactrocera tryoni  is capable of moving from imported fruit into a suitable environment to allow 
establishment;  
• warmer  parts of New Zealand are likely to be suitable for the establishment of B. tryoni ; 
• hosts are widely available;  and 
• the establishment or even an incursion of B. tryoni is likely to cause high economic impacts in 
New Zealand.  
 
8.6.4 References  
Allwood, A J; Leblanc, L (1997) Losses caused by fruit flies (Diptera: Tephritidae) in seven Pacific 
Island countries. In Allwood, A J; Drew, R A I (eds) Management of Fruit Flies in the Pacific : A 
Regional Symposium, Nadi, Fiji , 28–31 October 1996 . ACIAR Proceedings 76. ACIAR; Canberra, 
ACT, Australia; pp 208–211. 
Baker, R T; Cowley, J M (1988) A New Zealand view of quarantine security with special refer ence to 
fruit flies. 1st International Symposium on Fruit Flies in Tropics, Kuala Lumpur, Malaysia, Marc h 1988.  
Beever, R E; Harman, H; Waipara, N; Paynter, Q; Barker, G; Burns, B (2007) Native Flora Biosecurity 
Impact Assessment. Landcare Research Contract Report: LC0607/196. Manaaki Whenua ; New 
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BMT (2020) Cargo Handbook . https://www.cargohandbook.com/Welcome_to_CargoHandbook  
Accessed 11 October 2020 . 
Bull, R M (2004) Control of tephritid fruit flies in Australian stone fruit crops using low -dose fipronil bait 
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Africa; p p 301 –304. 
Cameron, E C (2006) Fruit Fly Pests of Northwestern  Australia . PhD thesis, University of Sydney.  
Cameron, E C; Sved, J A; Gilchrist, A S (2010) Pest fruit fly (Diptera: Tephritidae) in northwestern 
Australia: one species or two? Bulletin of Entomological Research , 100(2):  197–206. 
Christenson, L D; Foote, R H (1960) Biology of fruit flies . Annual Review of Entomology , 5: 171–192. 
Clarke, A R; Powell, K S; Weldon, C W; Taylor, P W (2011) The ecology of Bactrocera tryoni  (Diptera: 
Tephritidae): what do we know to assist pest management? Annals of Applied Biol ogy, 158(1): 26–54.  
CPC (2020) Crop Protection Compendium – Bactrocera tryoni  (Queensland fruit fly). 
https://www.cabi.org/cpc/datasheet/17693  Accessed September 2020.  
Dominiak, B C (2012) Review of dispersal, survival, and establishment of Bactrocera tryoni  (Diptera: 
Tephritidae) for quarantine purposes. Annals of the Entomological Society of America , 105(3): 434 –
446. 
Dominiak, B C; Daniels, D; Mapson, R (2011) Review o f the outbreak threshold for Queensland fruit 
fly (Bactrocera tryoni Froggatt). Plant Protection Quarterly , 26 (4): 141–147. 
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Parks, Water and Environment ; Devonport, Tasmania.  
EPPO (2020) EPPO reports on notifications of non -compliance: EPPO Reporting Service – Pests and 
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Phytosanitary  Measures No. 37. Published by FAO on behalf of the Secretariat of the International 
Plant Protection Convention (IPPC) ; Rome, Italy.  
Fletcher, B  S (1973) The ecology of a natural population of the Queensland fruit fly, Dacus tryoni . IV. 
The immigration and emigration of adults. Australian Journal of Zoology , 21: 541 –565. 
Fletcher, B.S. (1974) The ecology of a natural population of the Queensland fruit fly, Dacus tryoni . V. 
The dispersal of adults. Australian Journal of Z oology , 22: 189 –202.  
Gould, W P (1995) Probability of detecting Caribbean fruit ﬂy (Diptera: Tephritidae) infestations by 
fruit dissection. Florida Entomologist , 78: 502 –507. 
Hancock, D L; Hamacek, E L; Lloyd, A C; Elson -Harris, M M (2000) The distributio n and host plants of 
fruit flies (Diptera: Tephritidae) in Australia. Department of Primary Industries ; Brisbane , Queensland, 
Australia . 
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FAO/IAEA Divisio n of Nuclear Techniques in Food and Agriculture, International Atomic Energy 
Agency ; Vienna , Austria.  
Kean, J M ; Stringer, L D  (2019) Optimising the seasonal deployment of surveillance traps for 
detection of incipient pest invasions. Crop Protection  123: 36–44. 
Kean, J M; Suckling, D M; Sullivan, N J; Tobin, P C; Stringer, L D et al. (2020) Global eradication and 
response database. http://b3.net.nz/gerda  Accessed 19 September 2020.  
Kriticos , D J (2007) Risks of establishment of fruit flies in New Zealand under climate change. Ensis 
Client Report No. 12244 ; Kingston, Australia.  
Leblanc, L; Vueti, E T; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: 
Dacini) in the  Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of the Hawaiian 
Entomological Society , 45: 83 –117.  
Leblanc, L; Vueti, E T; Drew, R A I; Allwood, A J (2012) Host plant records for fruit flies (Diptera: 
Tephritidae: Dacini) in the  Pacific Islands. Proceedings of the Hawaiian Entomological Society , 44: 
11–53. 
LIMS (20 20) Laboratory Information Management System (LIMS) Plant Health and Environment. 
Accessed 2020.  
Lloyd, A C; Hamacek, E ; Smith, D; Kopittke, R A; Gu, H (2013) Host su sceptibility of citrus cultivars to 
Queensland fruit fly (Diptera: Tephritidae). Journal of Economic Entomology , 106(2): 883 –890. 
DOI:10.1603/ec12324.  
Lloyd , A C; Hamacek , E L; Kopittke , R A; Peek , T; Wyatt , P M; Neale , C J; Eelkema , M; Gu, H (2010)  
Area -wide management of fruit flies (Diptera:  Tephritidae) in the Central Burnett district of  
Queensland,  Australia. Crop Protection , 29: 462–469. 
MacLellan, R; Pather, V; King, K (2019) National Fruit Fly Surveillance Programme. Surveillance , 
46(3): 83 –86. http://www.sciquest.org.nz/node/157809 . Accesed 21 September 2019 . 
McGregor, B (1987) Tropical Products Transport Handbook . USDA; Washington DC. (Agriculture 
Handbook No. 668 ) https://naldc.nal.usda.gov/download/CAT89930509/PDF  Accessed 27 November 
2020.  
Mcinnis, D O; Hendrichs, J; Shelly, T; Barr, N; Hoffman, K; Rodriguez, R; Lance, D R; Bloem, K; 
Suckling, D M; Enkerlin, W; Gomes, P; Tan, K H (2017) Can polyphagous invasive tephritid pest 
populations escape detection for years under favorable climatic and host conditions? American 
Entomologist , 63 (2): 89 –99. 
Meats, A (2006) Attributes pertinent to overwintering potential do not explain why Bactrocera 
neohumeralis  (Hardy) (Diptera: Tephritidae) does not spread further south within the geographical 
range of B. tryoni  (Froggatt). Australian Journal of Entomology , 45(1): 20 –25. 
Meats, A; Fay, H A C (1976) The effect of acclimation on mating frequency and mating 
competitiveness in the Queensland fruit fly ( Dacus tryoni ) in optimal and cool mating regimes. 
Physiological Entomology , 1: 207 –212.  
171 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Meats, A; Holmes, H M; Kelly, G L (2004) Laboratory adaptation of Bactrocera tryoni  (Diptera: 
Tephritidae) decreases mating age and increases protein consumption and number of eggs produced 
per milligram of protein. Bulletin of Entomological Research , 94: 517 –524. 
MPI (2020a) Country Freedom Status database. https://www.mpi.govt.nz/news -and-
resources/resources/registers -and-lists/country -freedom -status/ . Accessed 18 September 2020.  
MPI (2020b) Success ful end to fruit fly operation in Auckland.  https://www.mpi.govt.nz/news -and-
resources/media -releases/successful -end-to-fruit-fly-operation -in-auckland/  Accessed 9 September 
2020.  
Muthuthantri, W S N (2013) Citrus Host Utilisation by the Queensland fruit fly , Bactrocera tryoni  
(Frogatt) (Diptera: Tephritidae): From Individuals to Populations . PhD thesis, School of Earth, 
Environmental  and Biological Sciences, Queensland University of Technology ; Brisbane, Australia.  
NTG (2013) Northern Territory Plant Health Manual . Version 3.0. Northern Territory Government, 
Australia.  
NZOR (2020) New Zealand Organisms Register. http://www.nzor.org.nz/  Accessed 18 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database . 
https://pierpestregister.mpi.govt.nz/  
PHA (2016) The Australian Handbook for the Identification of Fruit Flies . Version  2.1. Plant Health 
Australia ; Canberra, ACT , Australia . 
Popa -Báez, Á -D; Catullo, R; Lee, S F; Yeap, H L; Mourant, R G; Frommer, M; Sved, J A; Cameron, E 
C; Edwards, O R; Taylor, P W; Oakesch ott, J G (2020) Genome -wide patterns of differentiation over 
space and time in the Queensland fruit fly. Scientific Reports , 10: 10788.  
PPIN (2020) Plant Pest Information Network. MPI internal database. Accessed 18 September 2020.  
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(APPPC) Regional Standard for Phytosanitary Measures (RSPM) 4: Guidelines for the confirmation of 
non-host status of  fruit and vegetables to tephritid fruit flies.  
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pathogens recorded in Europe with relation to fruit imports. OEPP/EPPO Bulletin , 45(2): 223 –239. 
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system approach for tomato and capsicum production in Bowen. Final report, HAL Project VG06028. 
Horticulture Australia Ltd.  
Sultana, S; Baumgartner, J B; Dominiak, B C; Roy er, J E; Beaumont, L J (2017) Potential impacts of 
climate change on habitat suitability for the Queensland fruit fly. Scientific Reports , 7(1):13025. DOI: 
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Sutherst, R W; Maywald, G F (1989) An analysis of CLIMEX predictions of  establishment of Dacus 
spp. in New Zealand. CSIRO Long Pocket Laboratories. Consultative report prepared for the 
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Underwood, R (2007) Fruit fly: likely impact of an incursion of fruit fly in the Bay  of Plenty, Hawkes 
Bay or Nelson. Fruition Horticulture (BOP) Ltd. Commissioned by Horticulture New Zealand.  
Weems, H V; Fasulo, T R (2002 and updates) Queensland Fruit Fly, Bactrocera tryoni  (Froggatt) 
(Insecta: Diptera: Tephritidae). University of Flori da IFAS Extension EENY -259. 
http://entnemdept.ufl.edu/creatures/fruit/tropical/queensland_fruit_fly.htm . Accessed 18 September 
2020.  
Weldon, C W (2005) Dispersal and Mating Behaviour of Queensland Fruit Fly , Bactrocera tryoni  
(Froggatt) (Diptera: Tephritidae): Implications For Population Establishment and Control . PhD thesis, 
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173 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.7 Bactrocera tsuneonis  (Japanese orange fly ) 
 
Bactrocera tsuneonis  is a fruit fly that specialises on citrus and other closely related plants and can be 
a serious pest of citrus if uncontrolled.  
 
Scientific name: Bactrocera tsuneonis  (Miyake , 1919 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera  (Tetrad acus ) tsuneonis  (Miyake), Dacus cheni  Chao, Dacus 
tsuneonis  Miyake, Tetradacus tsuneonis  (Miyake), Japanese orange fly, citrus fruit fly, Japanese 
orange fruit fly  
 
Taxonomic notes:  Bactrocera tsuneonis  belongs to the subgenus Tetradacus . Some workers in the 
past have mistakenly listed B. citri  as a synonym of B. tsuneonis . However, B. citri is a synonym of  B. 
minax , which is very similar in appearance  to B. tsuneonis  (White and Elson -Harris 1994) . 
 
Summary of conclusions  
 
Given the argum ents and evidence presented : 
 
• Bactr ocera tsuneonis  meets the criteria to be a quarantine pest for New Zealand . 
• Bactr ocera tsuneonis  has a strong association with citrus fruit . 
• Basic measures  are likely to reduce the likelihood of entry of B. tsuneonis  by a moderate 
degree; consequently, the likelihood of entry is considered to be low  to moderate (with 
moderate uncertainty) . 
• Bactrocera tsuneonis  has a moderate ability (with low  to moderate uncertainty) to move from 
imported fruit and into a suitable environment to allow establishment, that is, onto a host 
plant.  
• The suitability of the New Zealand environment for B. tsuneonis  to establish is considered 
high, but the area of establishment is likely to be limited by the distribution of its hosts . 
• The lev el of impact caused by B. tsuneonis  is likely to be moderate . 
• Bactrocera tsuneonis  may be considered for additional measures . 
 
Summary of risk assessment against criteria:  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Moderate  
The ability to move from the imported commodity  onto a suitable host  Moderate  Low–moderate  
Suitability of the N ew Zealand  environment  High Low 
Impacts on the New Zealand economy, environment, health and society  Moderate  Low 
 
8.7.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Bactrocera tsuneonis  meets the criteria to 
be a quarantine pest for New Zealand . 
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause harm68). 
 
Bactrocera tsuneonis is not known to be present in New Zealand:  
• Bactrocera tsuneonis  is not  recorded in NZInverts (2020), NZOR (2020) or PPIN (2020);  
                                                      
68 Refer to ISPM 5  for the definition of a quarantine pest under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 174 • The quarantine status of B. tsuneonis  in New Zealand is ‘regulated’ , and it is an unwanted 
organism ( ONZPR  2020).  
 
Bactrocera tsuneonis has the potential to establish and spread in New Zealand:  
• Bactrocera  tsuneonis  is recorded from Japan and China (EPPO 2020), both of which have 
areas with climatic similarity to New Zealand, and therefore may be able to establish in areas 
of New Zealand , particularly warmer areas in the north . 
• Bactrocera  tsuneonis  is a specialist on Citrus  spp. and closely related species in the 
Rutaceae  family  (CABI 2020).  
• Citrus  is grown in New Zealand both commercially and domestically (see Chapter 2).  
 
Bactrocera tsuneonis has the potential to cause impacts on the New Zealand economy through 
impacts on the citrus industry:  
• Bactrocera  tsuneonis  is a serious pest on Citrus  spp. (White and Elson -Harris 1994) which 
are grown  commercially  in New Zealand (see section  2.5.2). 
 
8.7.2 Hazard identification: commodity association  
 
Bactrocera t suneonis  is associated with citrus fruit  
 
Bactrocera tsuneonis is reported from citrus fruit:  
• Larvae of B. tsuneonis  develop in the fruit of Citrus  species including C. aurantium , C. 
reticulata , C. sinensis  and C. tangerina  (White and Elson -Harris 1994) . 
 
8.7.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Bactrocera tsuneonis  has a strong 
association with citrus fruit:  
 
The eggs and larvae of B. tsuneonis  can be associated with citrus fruit commodities.  
• Bactrocera tsuneonis  females lay their eggs below the rind of the fruit. Usually , a single 
oviposition puncture is made in a fruit , and two to six eggs are deposited in a puncture. 
Usually , only one larva develops in the fruit , where it feeds on the contents of from two to te n 
carpels (segments). Larvae, which are mature about the time fruit drops from the tree, leave 
the fruit to pupate in the soil (Weems and Fasulo 2015).  Therefore, larvae may still be present 
in the commodity at harvest.  
• Larvae of B. tsuneonis  have been rec orded developing in the fruit of several Citrus  species 
including C. aurantium  L. (sour orange ), C. reticulata  Blanco  (tangerine ), and C. sinensis  (L.) 
Osbeck  (sweet orange ) (White and Elson -Harris 1994).  
 
Bactrocera tsuneonis  is found in multiple citrus species . 
• Bactrocera  tsuneonis  has been recorded from species of Citrus  and Fortunella  in the family 
Rutaceae (White and Elson -Harris 1994; Allwood et al. 1999) , and  it is considered a citrus 
specialist ( CABI 2020) (Table 9.7.1).  
• Adults have been reared from fruit of Citrus aurantium (sour orange), C. reticulata (tangerine), 
C. sinensis  (sweet orange), C. tangerine  (C. reticulata ), Fortunella crassifolia  (meiwa 
kumquat), F. japonica  (oval kumquat)  and F. margarita  (round kumquat ) (White & Elson -
Harris 1994; Allwood et al. 1999) . 
• Zhang (1989) records Citrus unshiu  as a host.   
175 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • USDA (1995) lists grapefruit  [C. paradisi ], orange and mandarin orange as hosts of B. 
tsuneonis  in a pest risk assessment for unshu orange fruits ( Citrus reticulata  Blanco var. 
unshu  Swingle) from Japan.  
• Other citrus names have been listed as hosts: Citrus kikokuni , C. deliciosa  (Zheng et al. 
2019); C. sunki  (Gong et al. 2008); ponkan, komikan, tachibana (Biosecurity Australia 2009).  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 176 Table 9.7.1  Citrus  species reported as hosts for Bactrocera tsuneonis.  
Citrus host scientific name  Citrus host common name  Reference  
Citrus aurantium  Sour orange  White and Elson -Harris 1994 , Gong et al. 2008  
Citrus paradisi  grapefruit  USDA 1995  
Citrus reticulata  _ Zheng et  al. 2019  
Citrus tachibana  _ Zheng et al. 2019, Gong et al. 2008  
Citrus reticulata  Mandarin  White and Elson -Harris 1994 , Gong et al. 2008  
Citrus sinensis  Sweet orange  White and Elson -Harris 1994 , Gong et al. 2008  
Citrus reticulata var. austera   Gong et  al. 2008  
Citrus reticulata  Tangerine  White and Elson -Harris 1994 , Zhang 1989 , Gong et al. 
2008  
Citrus reticulata  Unshu mandarin, Satsuma  Zhang 1989 , Gong et al. 2008  
 
Bactrocera tsuneonis  is present in two citrus -exporting countries considered in this import risk 
assessment , China and Japan . 
• Bactrocera tsuneonis  is known to occur only in Asia, specifically in China (Zhang 1989; 
Hancock and Drew 2018; Hou et al. 2018) and Japan (Hancock and Drew 2018; EPPO 
2020).  
• Although some papers report B. tsuneonis  as present in Viet  Nam (which is also one of the 
countries under consideration) , recent surveys have failed to find it (Leblanc et al. 2018) , and 
it is considered absent from that country (EPPO 2020).  
 
Given the arguments and evidence below, basic measures are likely to reduce 
likelihood of entry by a moderate degree; consequently, the likelihood of entry is 
considered low  to moderate (with moderate uncertainty):  
Infested fruits are usually easily detect ed and are likely to be removed.  
• Attacked fruit usually shows signs of oviposition punctures , and sugary exudates from the 
puncture may solidify on the fruit surface. In oranges, the oviposition puncture initially 
discolours to whitish , after which a brown ish gummy exudate is secreted by the fruit. The area 
around the puncture becomes yellowish (on otherwise green fruit) and spreads. It then turns  
reddish , often becoming a longitudinal mark along the infested carpel, although it may appear 
circular or irreg ular in shape (Miyake 1919, in CABI 2020) . 
• According to Zhang (1989), who describes both B. tsuneonis  and B. minax , infested fruits are 
easily recognised by their dark colour , the small nodule of the oviposition scar and the colour 
around the oviposition s car, which  is yellowish and distinct from healthy skin. Symptoms of 
infestation can include punctures in skin, winding tunnels beneath the fruit skin, distortion of 
fruit and rotting fruit. It is assumed this description applies to both species.  
• Therefore,  fruit showing obvious signs of infestation by B. tsuneonis  is likely to be detected 
and removed from a line or consignment during packhouse activities and inspections.  
 
However, infested fruit may be not be detected in some circumstances.  
• Eggs and larvae are inside the fruit and are observed indirectly by signs on the fruit surface. 
Usually , only a single oviposition puncture is made in a fruit, and usually , a single larva 
develops within the fruit , damaging as few as two carpels or segments (Weems and Fasulo 
2015).  
• Therefore, low levels of infestation may go undetected , especially at high volumes of the fruit 
commodity.  
 
General handling and processing after harvesting is not likely to remove eggs and larvae of B. 
tsuneonis  from citrus fruit.  
• Eggs and larvae are found inside the fruit and so would not be removed by routine activities in 
the packhouse , such as washing and brushing , which only treat the fruit surface.  
 
Larvae of B. tsuneonis  are likely to survive transit of some citrus commodities.   
177 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Storag e and transport of citrus consignments from exporting countries to New Zealand is 
likely to occur at cool temperatures, with the length of time for shipment varying depending on 
exporting country.  
• Bactrocera  tsuneonis  and B. minax  are widely regarded as th e two most cold -tolerant species 
in the genus Bactrocera  (Xia et al. 2019).  
• In a study on the effect of different temperatures on pupariation and pupal development in B. 
tsuneonis , Yasuda et al. (1994) found that a small number of adults (2) emerged from p upae 
(10) exposed to 5 °C for the first 45 days. These authors concluded that some development 
proceeds at 5 °C. 
• No interception records of B. tsuneonis  in citrus fruits were found.  
• There is some uncertainty around the ability of B. tsuneonis  to survive sto rage and transport 
conditions , as little information was found on temperature requirements. No information was 
found to indicate that storage and transport conditions would have a detrimental effect on the 
survival of larvae.  
 
The level of uncertainty asso ciated with the conclusion is moderate , based on the lack of interception 
data for B. tsuneonis  and the amount of information available on the impacts of low temperatures to 
inform the likelihood of B. tsuneonis  larvae surviving standard storage and transp ort at low 
temperatures.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Bactrocera tsuneonis  has a moderate 
ability (with low to moderate uncertainty) to move from imported fruit and into a 
suitable environment to allow establishment, that is, onto a host plant (transfer) . 
Bactrocera tsuneonis  can survive and develop on discarded citrus fruits and fruit pieces.  
• Bactrocera tsuneonis  is univoltine (Zhang 1989). Eggs and larvae are found on only Citrus  
and the related genus Fortunella  in the Rutaceae. Eggs are laid under the skin of the fruit and 
a single larva develops feeding inside the carpels (segments). Mature larvae leave the fruit to 
pupate when the fruit drops to ground, although sometimes larvae leave the fruit while  it is still 
in the tree. Pupation, which takes place over winter, usually occurs in the soil but may take 
place in other situations such as packaging (Zhang 1989). Bactrocera tsuneonis  may have a 
pupal diapause (Yasuda et al. 1994).  
• Therefore, i f infested  citrus fruit is discarded as whole fruits or fruit pieces, B. tsuneonis  may 
complete larval development in the waste and find a suitable location to pupate.  
 
Most of the fruit waste in New Zealand is likely to be disposed of using low -risk methods , so any B. 
tsuneonis  present would either be killed or unable to escape from the citrus host.  
• In New Zealand, the majority of kitchen  waste is either bagged and sent to landfill or run 
through kitchen disposal units (see section 2.4.1 , waste analysis). Bactrocera  tsuneonis  is 
unlikely to survive in these circumstances.  
 
However, some of the waste would be disposed of using high -risk methods, including composting in 
gardens, use as animal feed or discard ing directly into the environment . 
• A small percentage of infested fruit is likely to be discarded in a home compost bin or open 
compost heap, or directly into the environment (see section 2.4.1 , waste analysis).  
• Bactrocera tsuneonis  larvae move from citrus fruit to pupate in the soil (in th e top two inches 
or 5 cm (Weems and Fasulo 2015) but may also pupate in other sheltered situations such as 
in packaging (Zhang 1989). Therefore, some larvae or pupae associated with discarded citrus 
may find suitable conditions to develop to adulthood.  
• Adults emerging from the soil are likely to be able to find food in the environment. Sexually 
immature adults need supplementary nutrients, such as honeydew excreted from aphids, 
coccids and psyllids, before oviposition to enable health, longevity and egg pro duction (Zhang 
1989; Weems and Fasulo 2015).  
• Hosts for oviposition and larval development are available in many areas of New Zealand, 
Citrus  is commercially produced in many parts of the North Island and in parts of the South 
Island, with most production t aking place in warmer northern regions (see section  2.4.2). Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 178 Citrus  is also commonly grown in domestic gardens, although species favoured by B. 
tsuneonis  are not likely to be grown in southern regions of New Zealand.  
• If citrus hosts are located near the sit e for the citrus fruit waste, B. tsuneonis  adults are likely 
to find them.  
 
Adult B. tsuneonis  can fly to food sources and locate hosts.  
• Bactrocera tsuneonis  is described as a large, powerful insect ( CABI 2020). Adults are larger 
than those of most other s pecies of Bactrocera : the adult female is approximately 11 mm 
long, excluding the ovipositor, with a wing expanse of about 10 mm; the male is slightly 
smaller (Weems and Fasul o 2015). Therefore, it is assumed that, like other Bactrocera , the 
adult can read ily fly to food sources and locate citrus hosts.  
• No information was found on flight capability or distances covered by B. tsuneonis . However, 
studies on other tephritids show that the mean dispersal distance of tephritid flies is usually 
well below 1  km, a lthough mean dispersal distances from below 1  km to 3.6  km have been 
reported for B. dorsalis . However, the maximum dispersal distance reported in many studies 
was limited to the distance of the trap placed furthest from the release point (Weldon et al. 
2014). 
 
The level of uncertainty associated with this conclusion is low to moderate. Firstly, waste data may 
not be very accurate or up to date, and it is not known how frequently suitable hosts are available 
near composting sites in gardens or animal feedin g locations (see section 2.4.1 , waste analysis). 
Secondly, it is uncertain what proportion of composting sites are exposed or uncovered (e.g., in a 
compost bin). Thirdly, although B. tsuneonis  can fly to seek food sources and citrus hosts, its flight 
capab ility is uncertain.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for B. tsuneonis  to establish is considered high, but the area of 
establishment is likely to be limited by the distribution of its hosts  
Bactrocera tsuneonis  is known to occur in subtropical and temperate areas.  
• The known distribution for B. tsuneonis  is China and southern parts of Japan (Kyushu, 
Ryuk yu Islands) (EPPO 2020).  
• Bactrocera tsuneonis  occurs in temperate areas of China, such as t he mountainous terrains 
of Guizhou, Guangxi, and Yunnan (Hou et al. 2018). In Guangdong, B. tsuneonis  has recently 
been detected in Huaiji County on the northwest border, adjacent to Guangxi Province where 
B. tsuneonis  is known to occur (Hou et al. 2018). The temperature in Huaiji County is lower 
than that of the coastal plain of Guangdong, which may contribute to the presence of B. 
tsuneonis  there (Hou et al. 2018).  
• In China, B. tsuneonis  has been reported from the following provinces:  
o Guangxi (Hancock and  Drew 2018; Hou et al. 2018 ; Zhang 1989)  
o Guizhou (Hancock and Drew 2018; Hou et al. 2018)  
o Hunan (Hancock and Drew 2018; Hou et al . 2018)  
o Jiangsu (Hancock and Drew 2018; Zhang 1989)  
o Sichuan (Hancock and Drew 2018; Hou et al. 2018 ; Zhang 1989)  
o Yunnan (Hou et  al. 2018)  
o Guangdong (Hou et al. 2018)  
• Some of these areas have similar climate conditions to New Zealand, with a climate  match 
index  (CMI) of 0.7 or greater (Phillips et al. 2018):  
o Guizhou (0.7 –0.8 CMI), Hunan (0.7 CMI), Jiangsu (0.7 CMI), Sichuan (0.7–0.9 CMI), 
Yunnan (0.7 –0.8 CMI).  
• Therefore, based on the known geographic distribution and CMI values, Bactrocera tsuneonis  
is likely to find the climate suitable for it to establish in at least some regions of New Zealand 
where citrus is grown.  
 
Bactr ocera tsuneonis  has a low reproductive rate.  
• Bactrocera tsuneonis  is univoltine (one generation per year). The ratio of males to females is 
approximately one to one (Weems and Fasulo 2015). A female may lay 30 –40 eggs in its 
lifetime (Biosecurity Australia  2009), but only 2 –6 eggs are laid in a single fruit via a single 
oviposition puncture. Frequent copulation apparently is necessary, as this occurs after each 
batch of eggs has been deposited (Weems and Fasulo 2015).   
179 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Usually a single larva develops in a fr uit, and therefore , mate -finding would be enhanced by 
more than one infested fruit being deposited in an area, either at the same spot or nearby.  
• The production of sex pheromones would increase the ability of males and females to locate 
each other when present in low numbers and thereby improve mating success. Ono et al. 
(2020) have found that male B. tsuneonis  biosynthesis e a range of chemicals in the rectal 
gland that may represent sex pheromones and act to bring the sexes together, but their exact 
function remains unknown.  
 
Host availability is unlikely to be a limiting factor for establishment, but  the area of  establishment is 
likely to be limite d by the distribution of the hosts.  
• Bactrocera tsuneonis  has been recorded only from species of Citrus  and Fortunella  in the 
family Rutaceae. Citrus  is commercially produced in both the North and South Island, with 
most commercial production taking place i n the North Island (see section 2.4.2). Citrus  is also 
commonly grown in domestic gardens, although species favoured by B. tsuneonis  are not 
likely to be grown in southern regions of New Zealand.  
• Therefore, if B. tsuneonis  establishes in New Zealand, the a rea of establishment is likely to be 
limited by the distribution of its  known  hosts.  
 
Bactrocera tsuneonis  may not respond to lures used in current fruit fly surveillance in New Zealand.  
• Males are not known to be attracted to any synthetic lures (White and  Elson -Harris 1994 ; 
Hancock and Drew 2018 ; Plant Health Australia 2018 ; Zheng 2019 ; CABI 2020).  
• Both sexes may be monitored using protein bait traps (either protein hydrolysate or protein 
autolysate) (C ABI 2020).  
• As a result, B. tsuneonis  might not be disc overed until after it h as established in 
New Zealand.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by B. 
tsuneonis  is likely to be moderate, but the impact to the New Zealand citrus industry 
is likely to be high . 
Damage and symptoms caused by B. tsuneonis  can reduce fruit quality.  
• Fruit quality and quantity are reduced as a result of larval feeding which takes place e ntirely 
inside the fruit (Weems and Fasulo 2015). The skin of the fruit may discolour around the 
oviposition scar and look unhealthy in comparison with the rest of the fruit.  
 
Bactrocera tsuneonis  is considered a serious pest of citrus with impacts on comm ercial production, 
including in areas with similar climate to New Zealand.  
• In Japan , B. tsuneonis  has been considered an important pest of citrus , with outbreaks where 
up to 60% of fruit have been infested occurring in some commercial citrus areas since 19 47 
(Weems and Fasulo 2015).  
• Miyake (1919 , in CABI 2020) noted that up to 50% of the harvest could be destroyed but that 
10–20% was more typical.  
• In China, Zhang (1989), Hou et al. (2018) and Xia et al. (2019) describe B. tsuneonis  as a 
serious pest of cit rus. Zhang et al. (2019) states that B. tsuneonis  and B. minax  are 
considered major pests of citrus crops, causing large -scale economic losses, doing great 
harm to the export of citrus, suppressing international trade  and leading to trade barriers.  
• Bactroc era tsuneonis  mainly attacks C. sunki , C. reticulata , C. unshiu , C. tangerina, C. 
aurantium , C. sinensis  and C. kinokuni  in Ningming, Guangxi. The infestation rate is usually 
30%, but as high as 86.92% has been observed (Gong et al. 2008). In Pingxiang, Guangxi, 
the infestation rate reached 75% in 2005  (Gong et al. 2008).  
• Bactrocera tsuneonis  was reported to infest 50% of oranges in Kiangtsin, in the Szechwan 
[Sichuan] Province of southwestern China, during 1940 (Weems and Fasulo 2015).  
• Some of the areas in China where B. tsuneonis  is a serious pest of citrus have similar 
climates to New Zealand. For example, the climate match  index  of Sichuan  is 0.7–0.9. 
• Citrus  is of economic importance to New Zealand (see section  2.5.2 ). As infestation rates of 
around 50 % have been recorded in areas with a similar climate to New Zealand, the impact of Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 180 B. tsuneonis  on the New Zealand citrus industry is likely to be high, but the impact to the 
overall New Zealand economy is likely to be moderate.  
 
If B. tsuneonis  is detecte d in New Zealand, the cost incurred by a response would be expensive . 
• The typical cost of a response is millions of dollars. For example, the Queensland fruit fly 
response in 2019 cost approximately NZ$18 million (MPI 2020).  
 
Establishment of B. tsuneonis  is likely to increase phytosanitary measures required for export of citrus 
fresh produce to countries where B. tsuneonis  is not present.  
• Bactrocera tsuneonis  is recorded as present only in China and Japan . 
 
It is likely that B. tsuneonis  will cause a low l evel of sociocultural impacts in New Zealand . 
• Citrus  is grown domestically , particularly in warmer northern regions of the country.  
• Bactrocera tsuneonis  will affect fruit quality, although not the plants themselves.  
 
It is likely that B. tsuneonis  will ha ve a very low level of impact on the environment . 
• The host range of B. tsuneonis  is confined to species of Citrus  and the closely related 
Fortunella  in the family Rutaceae . 
• There are no Citrus  or Fortunella  species native to New Zealand. There are two genera within 
Rutaceae endemic to New Zealand: Leionema  and Melicope . Neither the Leionema  nor 
Melicope  species are considered threatened (NZPCN 2020).  
 
It is likely that B. tsuneonis  will have negligible impacts on human health . 
• No evidence was found that B. tsuneonis  has an impact on human health.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence below, Bactrocera tsuneonis  meets the criteria to 
be considered for additiona l measures . 
 
• Bactrocera tsuneonis  has a strong association with fruits of some citrus species.  
• Some infested fruits will not be detected, especially when the volume of commodities is large.  
• As the larvae feed internally in the fruits, general handling (e.g. washing and brushing) cannot 
remove the larvae . 
• Bactrocera tsuneonis  has a moderate ability (with low  to moderate uncertainty) to move from 
imported fruit and into a suitable environment to allow establishment, that is, onto a host 
plant.  
• The suitabi lity of the New Zealand environment for B. tsuneonis  to establish is considered 
high, but the area of establishment is likely to be limited by the distribution of its hosts.  
• The citrus hosts of B. tsuneonis  are grown commercially in New Zealand and are com mon 
garden plants, especially in warmer northern regions of New Zealand.  
• The level of impact caused by B. tsuneonis  is likely to be moderate to the overall economy of 
New Zealand, but high for the citrus industry.  
• Bactrocera tsuneonis  is present in citrus -exporting countries considered in this import risk 
assessment: China, Japan.  
 
8.7.4 References  
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Zhang, Y (1989) Citrus fruit flies of Sichuan Province (China). Bulletin OEPP/EPPO Bulletin , 19: 649 –
654. 
Zheng, L; Zhang, Y; Yang, W; Zeng, Y; Jiang, F; Qin, Y; Zhang, J; Jiang, Z; Hu, W; Guo, D; Wan, J; 
Zhao, Z; Liu, L; Li, Z (2019) New species -specific primers for molecular diagnosis of Bactrocera minax  
and Bactrocera tsuneonis  (Diptera: Tephritidae) in China based on DNA barcodes. Insects , 10: 447 . 
14 pages . 
 
   
183 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.8 Bact rocera  xanthodes  (Pacific fruit fly ) 
 
Bactrocera  xanthodes is a polyphagous , multivoltine  (more than one generation per year)  
tropical/subtropical fruit fly. It has been recorded from 34 host species from 20 families , including 
citrus , and has been reported to cause serious damage to fruit crop s.  
 
Scientific name: Bactrocera xanthodes  (Broun, 1904)  
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera (Notodacus) xanthodes,  Chaetodacus xanthodes , Dacus 
xanthodes , Notodacus xanthodes , Tephritis xanthodes  
 
Taxonomic notes:  Bactrocera  xanthodes belongs to a species complex of closely related sibling 
species, based on morphological comparisons, host records, geographic distributions and DNA 
samples . Other species in the complex are B. paraxanthodes Drew and Hancock , present in New 
Caledo nia, B. neoxanthodes Drew and Romig in Vanuatu (Drew and Romig 199 7; Allwood et al. 
1997a; Li et al. 2019) and a n as yet undescribed species in Samoa (White and Elson -Harris 1994 ; 
Tunupopo Laiti et al. 2002; CPC 2020). Only B. xanthodes has been classified  as a pest species.  
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Bactrocera xanthodes meets the criteria to be a quarantine pest for New Zealand.  
• Bactrocera xanthodes has a strong association with citrus fruit.  
• Basic measure s are likely to reduce the likelihood of introduction of Bactrocera xanthodes by 
a moderate degree (with moderate to high uncertainty) . Consequently the likelihood of entry is 
low to moderate (with moderate  to high  uncertainty).  
• Bactrocera xanthodes has a low to moderate ability (with moderate to high uncertainty) to 
move from imported fruit and into a suitable environment,  to allow for establishment.  
• The suitability of the New Zealand environment for Bactrocera xanthodes to establish is 
considered low to m oderate (with low to moderate uncertainty),  and its establishment is likely 
to be restricted to the northern part of the North Island and sheltered environments , although 
short -term populations may appear in other areas during summer months.  
• The level of impact caused by Bactrocera xanthodes is likely to be high ( with low to moderate 
uncertainty).  
• Bactrocera xanthodes may be considered for additional measures.  
 
Summary of risk assessment against criteria  
Criteria  Rating Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–Moderate  Moderate –high 
The ability to move from the imported commodity  onto a suitable host  Low–Moderate  Moderate –high 
Suitability of the N ew Zealand  environment  Low–moderate  Low–moderate  
Impacts on the New Zealand economy, environment, health and society  High Low–moderate  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 184 8.8.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Bactrocera xanthodes meets the criteria 
to be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are : the pest is not present in New 
Zealand, and is of potential importance (able to establish and cause harm ). 
 
B. xanthodes is not known to be present in New Zealand:  
• B. xanthodes  is not recorded in NZInverts (2020) and NZOR (2020).  
• B. xanthodes is recorded in PPIN (2020) ; however , it was entered for use in border, post -
border and post -entry quarantine identification and has been classified as not present in New 
Zealand.  
• B. xanthodes is listed as an unwanted organism in New Zealand ( ONZPR  2020).  
• B. xanthodes is listed as ‘ regulate d’ in New Zealand (ONZPR  2020).  
 
B. xanthodes has the p otential to establish and spread in New Zealand:  
• B. xanthodes is only reported from areas with climates warmer than that of NZ ; however , its 
restricted distribution may be a result of geographic barriers to dispersal (i.e. being present on 
remote island s) rather than strict climate requirements.   
• Furthermore, while coastal climates of these islands are indeed warmer than New Zealand, 
montane areas do have cooler climates (Halloy 2020). As no information was found regarding 
specific distribution (i.e . if distribution is restricted to mountainous and/or coastal areas), there 
is a probability  that B. xanthodes may have evolved some tolerance to cooler climates. 
Therefore, the climate of the species’ current distribution may not be a good indicator of its 
potent ial distribution , and the  fruit fly may  be able to establish in some  areas of New Zealand.   
 
B. xanthodes is polyphagous and has been  recorded from 34 hosts species in 20 plant families , 
including several species grown commercially and in home gardens in New Zealand .  
B. xanthodes has the potential to cause impacts on the economy and environment of New Zealand:  
• B. xanthodes has the potential to damage plant species that are of economic importance to 
New Zealand, such as citrus, tomato and avocado.  
• B. xanth odes has the potential to harm the New Zealand environment , as it has been reported 
on plant species in genera that are present in New Zealand (NZPCN 2020).  
• B. xanthodes has the potential to have soci ocultural impacts , as some hosts , such as citrus, 
tomato  and guava , are commonly planted in home gardens.  
 
8.8.2 Hazard identification: commodity association  
 
Bactrocera xanthodes is associated with citrus fruit.  
B. xanthodes has been  reported from citrus fruit:  
• Adult B. xanthodes have been reared from field -collected fruit of different citrus 
species/cultivars (Leblanc et al. 2013) , suggesting that the fruit fly can survive and complete 
development on citrus  (Leblanc et al. 2012; Leblanc et al. 2013) .  
 
8.8.3 Risk assessment  
 
Likelihood of entry:  
 
Given the argumen ts and evidence below,  Bactrocera xanthodes has a strong 
association with citrus fruit.  
B. xanthodes  has been reported to develop in various citrus species and cultivars.   
185 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Larvae and adults of B. xanthodes  have been reared from various citrus fruits and cul tivars 
(Leblanc et al. 2013). Citrus fruit host association s found in the literature are summarised in 
Table 9.8.1.  
• In Samoa, laboratory host status tests revealed that B. xanthodes adults can be reared  from 
damaged grapefruit exposed to gravid females (Leblanc et al. 2013).  
 
Table 9.8.1  Known citrus fruit host association of Bactrocera xanthodes . An asterisk indicates B. 
xanthodes  was only bred on damaged fruits exposed to gravid females.   
Citrus host scientific 
name from the reference  Citrus host common name 
from the reference  Reference  
Citrus latifolia   Tahitian Lime*  Leblanc et al. (2013)  
Fortunella japonica  Round kumquat  Leblanc et al. (2012; 2013)  
Citrus limon  Lemon * Leblanc et al. (2013)  
Citrus maxima  Pomelo  Leblanc et al. (2012; 2013)  
Citrus paradisi  Grapefruit * Leblanc et al. (2013)  
Citrus reticulata  Mandarin /Tangerine  Leblanc et al. (2012; 2013); CPC (2020)  
Citrus sinensis  Navel  orange  Leblanc et al. (2012; 2013)  
 
B. xanthodes is present in three citrus -exporting countries in this IHS:  
• B. xanthodes is present in the Cook Islands, Fiji and Samoa (Leblanc et al. 2013; CPC 2020; 
EPPO 2020a).  
 
Given the arguments and evidence below,  basic measures  are likely to reduce the 
likelihood of entry of Bactrocera xanthodes by a moderate degree (with moderate to 
high uncertainty) . Consequently , the likelihood of entry is low to moderate.  
 
Some of the infested fruits may be easy to detect and removed. Given the duration of each life stage 
of B. xanthodes, the likelihood of entry of eggs and larvae is moderate.  
• Reproduction in B. xanthodes is biparental and females oviposit just under the skin of the 
fruit, usually at the start of ripening. The process of egg -laying introduces  bacteria into the 
fruit, which becomes  spoiled. The rotting flesh provides the developing larvae with a food 
source (Tunupopo Laiti et al. 2002).  
• The fruit falls to the ground , and the larvae exit to pupate within the soil. Adults emerg e from 
pupation and will immediately seek mates. The whole lifecycle from egg to egg at 26 ± 1°C 
(under laboratory rearing conditions) is a minimum of 35 days (Clare 1997).  
• There do not appear to be records of how many eggs are laid at any one time by B.xanthodes 
in citrus. However, approximately 750 B. xanthodes larvae were found in a single breadfruit 
(Artocarpus altilis ) from Niue (Baker and Cowley 1991) , indicating several females had 
oviposited in the one fruit. Since the average  egg to pupation period is 10 days, there is a 
higher likelihood of larvae entering in fruit arriving by air than by sea.  
• As pupation occurs in the soil , it is considered unlikely pupae would enter with Citrus fruit.  
• Adults have a lifespan of approximate ly 1–5 months (possibly longer in some cases), with 
females capable of laying about 1 ,000–1,300 eggs during their lifetime (Cowley et al. 1993).  
• Xia et al. (2019) found that fruit bagging and packing house culling could mitigate risk from 
fruit flies to c itrus commodities in China. The study found decreased oviposition marks and an 
absence of viable individuals in bagged pomelo fruit ( n=3,000), while 129 fruit fly -infested 
fruits were found in unbagged fruit ( n=3,040). They also found that in fruit ( C. uns hiu) that 
received culling treatments ( n=10,000), fruit flies were absent , and only 10 fruits with 
oviposition marks were found, while in fruit ( n=10,000) that did not receive the culling 
treatment, 1 infested fruit with 7 larvae of B. minax  and 25 fruits with fruit fly oviposition marks 
were found.  
• If bagging and culling are used in the export countries, these practi ces are likely to reduce the 
risk to some extent.   Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 186 • Like other Bactrocera  fruit flies (e.g. B. dorsalis  and B. minax ), heavy infestation of B. 
xanthodes  may cause fruit to rot and drop prematurely, and dropped fruit is unlikely to be 
exported.  
 
However, there is a chance that a small quantity  of infested fruit will not be detected.  
• Fruits with low infestation (fewer oviposition punctures) may not be obvious enough to be 
detected during general handling.  
• The volume of the commodities can also affect efficiency of detection. Low levels of 
infestation may more difficult to detect .  
 
General handling after harvesting is not likely to remove eggs and larvae of B. xanthodes inside citrus 
fruit.  
• Because  general handling after harvesting (e.g. washing and brushing) only treats the surface 
of fruit, it is unlikely to remove the larvae of B. xanthodes inside citrus fruit.  
• Fruit will need to be cut open to reveal the larvae of B. xanthodes inside.  
 
B. xanthodes has the potential to survive transit of fruit commodities.  
• B. xanthodes has not be en specifically identified on any commodities in Eu rope (EPPO 
2020b).  
• B. xanthodes  has been identified 155 times at the New Zealand border between 1929 and 
2019. In total , 1,097 specimens were intercepted (LIMS 2019).  
o 75.5% of specimens were either dead or non -viable, 18.5% were either alive or 
viable , and the status of 6% of specimens w as unknown.  
o Approximately 99% of specimens were eggs (65.5%) or larvae (34.5%). The 
remaining specimens were recorded as adults , or their life stage was unknown.  
o 60% of interceptions were on passenger pathways, 25% did n ot record any details 
on the pathway , and 15% were on air/sea cargo.  
o The specimens were intercepted on :  
▪ Pomelo (Citrus maxima ) and starfruit ( Averrhoa carambola ), 2% (fresh 
produce, live larvae  from Fiji) . The specimens were intercepted from two 
fresh pr oduce consignments from Fiji (one including both pomelo and 
starfruit and the other importing only pomelo).  
▪ Breadfruit ( Artocarpus altilis ), 87% (fresh produce, cooked and peeled)  
▪ Mango ( Mangifera indica ), 3% (fresh produce)  
▪ Watermelon ( Citrullus lanatus ), 3% (fresh produce)  
▪ Avocado ( Persea americana ), 2% (fresh produce)  
▪ Fresh produce guava ( Psidium guajava ), pawpaw ( Asimina triloba ) and 
plantain plant material ( Musa sp.), total 3% (fresh produce)  
o 52% of specimens were from Samoa, 34% from Tonga, 9% from Fiji and 3% from 
Niue, Tokelau and Tuvalu , and 2% of specimens did not record  the country of origin  
or the country of origin was unknown.  
▪ Of the specimens from Samoa (a country included in the scope of this IRA ) 
10% were alive/viable , 31% were larvae , and 69% were eggs. Commodities 
the specimens were intercepted on included but were not limited to 
breadfruit, avocado and mango.  
▪ Of the specimens from Fiji (a country included in the scope of this IRA ), 40% 
were alive/viable , 42% were larvae , and 57% were eg gs. Commodities the 
specimens were intercepted on included but were not limited to breadfruit, 
avocados and pomelo.  
• Transit of fresh produce usually involve s cool storage. No study investigating the cold -
tolerance capability of B. xanthodes  has been found . However, of the interceptions recorded 
in LIMS (2019), all the specimens (eggs and larvae) on the air/sea cargo pathway (15%) 
were documented as dead, non -viable or unknown.  
• Furthermore, it can be assumed if B. xanthodes distribution is restricted to co astal areas of 
tropical Pacific countries, then the fruit fly species is likely to be relatively susceptible to cold 
storage temperatures. However, Anthony (2008) states B. xanthodes has been recorded to 
breed in Tonga when minimum temperatures fell to 9 °C in 1986.  
 
The level of uncertainty associated with this conclusion is moderate to high.   
187 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  1. Species -specific information about the detectability of B. xanthodes on citrus fruit  is not 
available .  
2. It is uncertain whether B. xanthodes can survive transit, as only 15% of interceptions were 
made on air/sea cargo pathways , and no study has been found investigating the cold 
tolerance of B. xanthodes.  
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Bactrocera xanthodes has a low to 
moderate  (with moderate to high uncertainty) to move from imported fruit and into a 
suitable environment to allow for establishment on a host plant . 
 
B. xanthodes may survive and develop on citrus fruit waste.  
• The d uration of pupation for B. xanthodes is eight days at 30 °C and 39 days at 14 °C. The 
mean egg  to adult development time is 23 days. Adult females begin oviposition at day 35 
(at the adult age of 12 days) (Anthony 2008). Suboptimal humidity can prolong 
developmental rates of the immature stages and inhi bit adult maturation (Fletcher 1987).  
• The developmental time from egg to adult was found to be inversely proportional to 
temperature in B. dordalis  (Diptera: Tephritidae) (Rashmi et al. 2020). Thus, t he 
development time of B. xanthodes is likely to be lon ger in New Zealand due to lower 
temperatures . Nevertheless, the fruit fly is expected to be able to survive and develop in 
Citrus spp. hosts in warmer months.  
• In its native distribution, B. xanthodes is abundant between January and June, as this is 
when i ts primary host species (Artocarpus altilis, Ochrosia oppositifolia and Barringtonia 
edulis ) is also available ( Tora Vueti et al.  1997a). Previous importation records of citrus 
fresh produce from Vanuatu can be found from July to January (QuanCargo 2020).  
• B. xanthodes  have been observed ovipositing in fallen fruits (Allwood 199 7a). They can 
also be reared successfully in artificial larval substrates of pawpaw and sugarcane 
bagasse, rehydrated carrot, and wheat (Tora Vueti et al. 199 7a), illustrating the 
adaptability of the species to develop in various host environments.   
• If citrus fruits are disposed of as whole fruits or fruit pieces, it is likely that B. xanthodes 
can survive in the resulting waste. There is no evidence to suggest B. xanthodes can 
complete development on citrus fruit skin.  
 
Most of the citrus waste in New Zealand would be disposed of using low -risk methods. Thus, B. 
xanthodes would either be killed  or unable to escape from the citrus host.  
• Most of the  kitchen waste in New Zealand is bagged and disposed of in landfills or run 
through  kitchen disposal units. In these situations, B. xanthodes is unlikely to reach a new 
host ( see the w aste analysis in section 2.4.1 ).  
 
However,  some of the waste would be disposed of using high -risk methods, including composting in 
gardens and use as animal feed.  
• Mature fruit fly larvae emerge from host fruit and drop to the ground to pupate in soil. In 
New Zealand, t he pupae may be able to survive during summer months, but it is uncertain 
whether they will survive and develop in colder seasons.  
• Adults of B. xanthodes  emerging from the soil are likely to be able to find food in the 
environment if citrus fruit waste is disposed of using high -risk methods and  the temperature is 
suitable for the species.  
• Although not specifically reported from B. xanthodes , adult fruit flies have been known to feed 
on various foods, including glandular secretions of plants, nectar and pl ant sap exuding from 
trunk, stem, leaf or fruit injuries (Christenson and Foote 1960). These food sources are likely 
to be available in household gardens, parks and farms.  
• Hosts for oviposition and larval development are available in warmer areas of New Z ealand , 
and some are present in colder areas. B. xanthodes is polyphagous , and hosts include 
species commonly grown commercially and in home gardens (e.g. citrus, avocado, guava and 
papaya). Citrus and avocados are  commercially produced in multiple regions  of New Zealand, 
with most commercial production taking place in the Gisborne (1 ,136 ha citrus  planted) and Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 188 Northland region s (313 ha  citrus,  1,647 ha  avocados  planted ) (see section 2.4.2 ) (Plant & 
Food Research  2019) .  
• If citrus or other potential hosts are located near the composting site or animal feeding site 
(see the waste analys is, section 2.4.1 ), adult B. xanthodes  are likely to locate the citrus host.  
 
B. xanthodes  can spread via adult flight and human -assisted mo vement of infested fruit (CPC 2020).  
• Studies on other tephritids estimate that  the mean dispersal distance of tephritid flies is 
usually under 1  km. The exception is the average dispersal distances of between 1  km and 
3.6 km for B. dorsalis . However, the maximum dispersal distance reported in many studies 
was limited to the distance of the trap placed furthest from the release point (Weldon et al. 
2014).  
• While it is known  that B. xanthodes are active fliers (Cowley et al. 1993) , no informat ion was 
found on the specific dispersal patterns and flight capabilities.  
• As mentioned previously, 60% of B. xanthodes interceptions at New Zealand borders were on 
the passenger pathway (LIMS 2019).  
 
It is uncertain if B. xanthodes would be able to estab lish if it arrive d in New Zealand during colder 
months.  
• The current known distribution of B. xanthodes  is restricted to Pacific Island countries in 
tropical/subtropical areas , which may reflect the species’ climate requirement . However, on 
some of these i slands , there is a possibility of cooler montane climates (Halloy 2020).  
• No research has been done to date on  the cold tolerance capability of B. xanthodes. 
However, there are many studies on these aspects for other Bactrocera  spp., which indicates 
variab le cold tolerance for the genus.   
• Thus, if B. xanthodes were to arrive in New Zealand at a time when temperatures are colder 
than regions where it is currently distributed, it is uncertain whether it will be able to survive 
and locate a suitable host to develop.  
 
The level of uncertainty associated with this c onclusion is moderate to high.  
1. Waste data may not be accurate or current. Also, it is unknown how frequently suitable hosts 
are present near composting sites in gardens or animal feeding locations are ( see section 
2.4.1,  waste analysis ). Furthermore, w hen the fruit fly and citrus fresh produce hosts are 
disposed of, development time may vary from specimens reared on artificial diets.  
2. It is uncertain what proportion of composting sites are exposed or covered (e.g. in a compost 
bin).  
3. Although B. xanthodes is an active flier , its exact flight capability is uncertain.  
4. No specific  studies were  found investigating the cold tolerance o f B. xanthodes . Its current 
distribution is restricted to tropical and subtropical areas , some of which have  montane forests 
and reach average temperatures well within New Zealand ranges. Hence, there  is uncertainty 
associated with  whether B. xanthodes  could survive and find a suitable host if it arrive d in 
New Zealand during colder months  and whether it would  be able to establish a  sustainable 
population due to the climate.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for Bactrocera xanthodes to establish is considered low to moderate 
(low to moderate uncertainty). Establishment is likely to be restri cted to northern 
parts of the North Island and sheltered environments , although short -term 
populations may establish in other areas during summer months.  
 
• The current distribution of B. xanthodes is restricted to the tropical/subtropical Pacific Islands, 
found between 13  and 21°S (Table 9.8.2). It is classified as a major pest fruit fly species in 
the South Pacific region because of its ability to inflict heavy crop losses and the trade 
restrictions applied against crops grown in some coun tries due to its presence.  
• In Broun’s  original species description, B. xanthodes  was listed as being found in fruit 
imported into New Zealand from Rarotonga Island (Cook Islands), Suva and Tonga. 
According to Drew (1982), these records were based on occurr ence of larve  in fruit and not 
on adults bred from the larvae.  Drew  reported that  B. xanthodes had never subsequently 
been recorded from Rarotonga  (Cook Islands)  and so this  record of B. xanthodes  in  
189 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Rarotonga  (Cook Islands)  was likely incorrect. No other literature on B. xanthodes  in 
Rarotonga ( Cook Islands ) has been  found.  
• The main islands of Fiji have a low climate similarity with New Zealand  (climat e match index 
(CMI) of 0.4 , which is a poor match with New Zealand). While  other countries where B. 
xanthodes has been found do not have a mapped CMI score (Phillips et al. 2018) , there is 
considerable temperature overlap with equatorial mid -altitude regions of Pacific tropical island 
countries and the New Zealand climate (Halloy 2020).  
• New Zealand’s Citrus is mainly grown in the Gisborne and Northland region s (Plant & Food 
Research  2019).  
• Comparing climate indicators of countries where B. xanthodes has established with the 
Gisborne and Northland region s shows that the average rainfall and sunshine hours are 
similar to  Niue and Vanuatu (Table 9.8.3). However, the average monthly temperature in Niue 
and the average annual rainfall in Vanuatu is higher than in Gisborne or Northland.  
• The Gisborne and Northland regions also  produce significant quantities of avocados, squash 
and tomatoes, all of which are hosts of B. xanthodes (Leblanc et al 2013; Plant & Food 
Research  2019).  
• Hence, establishment of B. xanthodes is likely to be restricted to northern regions of New 
Zealand an d sheltered environments . Short -term populations of the fruit fly species may be 
able to establish in other areas during warmer months.  
• B. xanthodes is also likely to establish in greenhouses where suitable hosts are present.  
 
Table 9.8.2  Known geographi c distribution of bactrocera xanthodes. Information compiled 21 September  
2020 . Countr ies/area s in bold  are included in the citrus IHS project . 
COUNTRY  Status  Reference  
American Samoa  Present, no details  CPC 2020; EPPO 2020a  
Cook Islands  Present, no details  CPC 2020; EPPO 2020a  
Fiji Present, no details  CPC 2020; EPPO 2020a  
Nauru  Absent, eradicated  Drew, Allwood and Tau 1997; CPC 2020; EPPO 2020a  
Niue Present.  Heimoana et al. 1997; CPC 2020; EPPO 2020a  
Tonga  Present, no details  CPC 2020; EPPO 2020a  
Tuvalu  Present, restricted distribution  CPC 2020; EPPO 2020a  
Vanuatu  Absent, no details  Allwood et al. 199 7a; Drew and Romig 199 7; Li et al. 
2019  
Wallis and Futuna  Present, no details  CPC 2020  
Samoa  Present, no details  Leblanc et al. 2013  
 
 
Table 9.8.3  Comparison of average Northland and Gisborne  climate indicators.  
REGION  Mean monthly 
temperature ( °C) Mean annual 
rainfall (mm)  Average annual 
sunshine hours  References  
Niue  25.4 1,960 2,211 Statistics Niue 2020  
Tonga  24 1,777 3,441 Weather  and Climate 
2020; Weather Atlas 
2020  
French Polynesia 
(Austral Islands)  23 2,005 1,925 NOAA 2018  
Cook Islands  26 2,169 2,125 Weather and Climate 
2020;  
American Samoa  24.5 1,803 2,400 NOAA 2018  
Northland  20 1,759 2,162 Plant & Food Research  
2019, Chappell 2013  
Gisborne  15–20 1,029 2,294 Plant & Food Research  
2019; Chappell 2016  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 190 B. xanthodes has a broad host range, and therefore , host availability is unlikely to be a limiting factor 
for the species to establish in New Zealand.  
• B. xanthodes is polyphagous in the countries it is established  in (Table 9.8.2).  
• B. xanthodes has been recorded on hosts from 20 families, in 24 genera and 34 species. Of 
these, there are over 22 which are commercial/edible host species (Leblanc et al. 2013) .  
• Several hosts of B. xanthodes, besides Citrus spp., are economically important to 
New Zealand (Table 9.8.4).  
• Adult flight and the transport of infested fruit are the major means of movement and dispersal 
to areas previously not infested by the fruit fly (CPC 2020).  
• Eggs and larvae of B. xanthodes are typically found inside fruit (Table 9.8.4). Thus, they are 
unlikely to be visible. Therefore,  the transport  of infested fruit is a significant means by which 
the species can spread to areas where it was not previously found.  
• Little is known about the life cycle of B. xanthodes and its reproductive rate (CPC 2020).  
 
B. xanthodes responds to methyl eugenol and so is likely to be detected in the National Fruit Fly 
Surveillance Programme . 
• Three fruit fly lures, cuelure, trimedlure and methyl eugenol are used in the National Fruit Fly 
Surveillance Programme in New Zealan d (MacLellan , Pather and King  2019 ). If a fruit fly 
species is responsive to one or more of these lures, early detection of an incursion is more 
likely , which will reduce the likelihood of its establishment in New Zealand.  
• A male lure test was conducted in  the Cook Islands, Vanuatu, Fiji, Tonga and Samoa, 
indicating that B. xanthodes responds to methyl eugenol (Allwood 199 7b).  
• Reponse to methyl eugenol was confirmed recently in a study by Royer et al. (2019), but the 
authors note that B. xanthodes ’s attraction to methyl -isoeugenol is three times greater.  
 
The level of uncertaint y associated with the above conclusions is moderate to high.  
1. B. xanthodes is currently distributed in various Pacific Island nations with tropical climates, 
which are predominantly warmer than New Zealand . However, if the species has evolved to 
adapt to cooler montane climates found in tropical Pacific islands , then establishment in  the 
New Zealand climate is possible.  
2. It is not known if the fruit fly’s distribution is  restricted by a geographic boundary (i.e. islands) 
or if it is unable to  establish in colder climates.  
3. Additionally, no research has been done to date on the cold tolerance of B. xanthodes.  
4. However, the Northland and Gisborne regions have similar climat e indicators to some Pacific 
Island countries where the fruit fly has established.  
 
Table 9.8.4  Host range of Bactrocera xanthodes. Species names in bold  are considered significant to New 
Zealand’s economy by Plant & Food Research  (2019 ).  
Family  Species  Common Name  Country  Reference  
Anacardiaceae  Mangifera india  Mango  Cook Islands, Nauru ( prior to 
eradication), Tonga  Leblanc et al. 2012  
Annonaceae  Annona cherimola   Cherimoya  Cook Islands  Leblanc et al. 2012  
Annona muricata  Soursop  Samoa, Tonga  Leblanc et al. 2012  
Apocynaceae  Cerbera manghas  Sea Mango  Tonga  Tora Vueti et al. 
1997a; Leblanc et 
al. 2012  
Ochrosia oppositifolia   Fiji, Tonga  Leblanc et al. 2012  
Bromeliaceae  Ananas comosus69 Pineapple   Leblanc et al. 2013  
Calophyllaceae  Calophyllum inophyllum  Tamanu  Cook Islands  Leblanc et al. 2012  
Caricaceae  Carica papaya  Papaya  Cook Islands, Fiji, Samoa, 
Tonga  Heimoana et al. 
1997; Leblanc et al. 
2012  
                                                      
69 Reports of B. xanthodes in Tonga and in Fiji are dubious. B. xanthodes in Fiji were demonstrated not t o breed on damaged pineapple 
exposed to gravid females in the laboratory. No fruit flies ever emerged from the 143 ripe pineapples sampled in the Pacific Islands during 
the RFFP surveys.   
191 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Family  Species  Common Name  Country  Reference  
Combretaceae  Terminalia catappa   Tropical almond  Samoa, Tonga  Leblanc et al. 2012  
Terminalia samoensis   Samoa, Tonga  Leblanc et al. 2012  
Convolvulaaceae  Stictocardia tiliifolia  Spottedheart  Tonga  Leblanc et al. 2012  
Cucurbitaceae  Citrullus lanatus  Watermelon70 Tonga  Heimoana et al. 
1997; Leblanc et al. 
2012; Leblanc et al. 
2013  
Cucumis sativus  Cucumber71 Tonga  Leblanc et al. 2013  
Cucurbita pepo  Squash72 Fiji Leblanc et al. 2013  
Luffa cylindrica  Luffa73 Fiji Leblanc et al. 2013  
Mormordica charantia  Bittergourd92 Fiji Leblanc et al. 2013  
Ebenaceae  Diospyros vera   Tonga  Leblanc  et al. 2012  
Euphorbiaceae  Excoecaria agallocha  Milky mangrove  Tonga  Leblanc et al. 2012  
Lauraceae  Persea americana  Avocado  Cook Islands, Samoa, Tonga  Leblanc et al. 2012  
Lecythidaceae  Barringtonia edulis    Fiji Tora Vueti et al. 
1997a; Leblanc et 
al. 2012  
Barringtonia racemosa  Fiji Leblanc et al. 2012  
Barringtonia seaturae   Fiji Leblanc et al. 2012  
Leguminosae  Inocarpus fagifer  Tahitian chestnut  Cook Islands, Fiji, Wallis and 
Futuna  Leblanc et al. 2012  
Malvaceae  Hibiscus tiliaceus  Sea hibiscus   Leblanc et al. 2013  
Theobroma cacao  Cacao tree  Fiji Leblanc et al. 2012  
Moraceae  Artocarpus altilis  Breadfruit  American Samoa, Cook 
Islands, Fiji, Nauru (prior to 
eradication) Samoa, Tonga, 
Wallis and Futuna  Tora Vueti et al. 
1997a; Leblanc et 
al. 2012  
Artocarpus heterophyllus  Jackfruit  Cook Islands, Fiji, Samoa  Leblanc et al. 2012  
Musaceae  Musa × paradisiaca  Banana  Samoa  Leblanc et al. 2013  
Myrtaceae  Psidium guajava  Common guava74  Leblanc et al. 2013  
Oxalidaceae  Averrhoa carambola  Starfruit75 Samoa  Leblanc et al. 2013  
Passifloraceae  Passiflora edulis  Passion fruit  Tonga  Leblanc et al. 2012  
Passiflora ligularis  Sweet granadilla  Tonga  Leblanc et al. 2012  
Passiflora quadrangularis  Granadilla  Fiji, Tonga, Samoa  Leblanc et al. 2012  
                                                      
70 Watermelon was observed to be infested by B. xanthodes in the field  in Tonga. In laboratory host status tests in Tonga, B. 
xanthodes was bred from damaged but not from intact watermelons when exposed to gravid females.  
 Watermelon was observed to be infested by B. xanthodes, in the field, in Tonga. In laboratory host status tests, B. xanthodes was bred 
from damaged but not from intact watermelons, when exposed to gravid females in Tonga . 
71 B. xanthodes was not bred from intact cucumber in Fiji. However, B. xanthodes was bred from damaged (but not from intact) 
cucumber in Tonga.  
72 Bred from damaged fruit exposed to gravid females.  
73 Heimoana et al. (1997) reported that in Fiji, B. xanthodes was not bred from intact “spongy gourd” (likely L. cylindrica ) 
exposed to grav id females, but B. xanthodes was bred from damaged fruits.  
74 The record of B. xanthodes on guava in Drew (1989) was not confirmed by subsequent surveys and is viewed as 
questionable.  
75 B. xanthodes was bred from damaged (but not from intact) fruit exposed to gravid females.  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 192 Family  Species  Common Name  Country  Reference  
Rutaceae  Fortunella japonica  Kumquat  Fiji Leblanc et al. 2012  
Citrus latifolia  Tahitian lime80 Samoa  Leblanc et al. 2013  
Citrus limon  Lemon80 Fiji Leblanc et al. 2013  
Citrus maxima  Pomelo  Fiji, Tonga  Leblanc et al. 2012  
Citrus paradisi  Grapefruit80 Samoa  Leblanc et al. 2013  
Citrus reticulata  Mandarin76 Fiji, Tonga  Leblanc et al. 2013  
Citrus sinensis  Orange  Tonga  Leblanc et al. 2012  
Santalaceae  Santalum yasi  Fijian sandalwood  Tonga  Leblanc et al. 2012  
Sapindaceae  Pometia pinnata  Pacific lychee77  Leblanc et al. 2013  
Sapotaceae  Burckella richii   Tonga  Leblanc et al. 2012  
Chrysophyllum cainito  Star apple  Tonga  Leblanc et al. 2012  
Pouteria caimito  Abiu Samoa  Leblanc et al. 2012  
Solanaceae  Capsicum annuum  Capsicum  Fiji, Samoa, Tonga  Leblanc et al. 2013  
Solanum lycopersicum  Tomato  Fiji, Tonga  Leblanc et al. 2012  
Solanum mauritianum  Bugweed  Cook Islands  Leblanc et al. 2012  
Solanum melongena  Eggplant  Tonga, Samoa, Vanuatu, Fiji  Leblanc et al. 2013  
 
 
Impacts  in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by B. 
xanthodes is likely to be high (low to moderate uncertainty).  
Damage and symptoms caused by B. xanthodes  can reduce fruit quality.  
• Larvae of B. xanthodes feed inside fruit (fruit flesh, pod or seed) (Table 9.8.4). Although little 
information is available  on the damage by B. xanthodes specifically, oviposition by Bactrocera 
spp. is known to leave scars (or punctures) on skin of fruits, which is likely to cau se necrosis 
or darken the colour of fruit skin around the oviposition puncture . Larval feeding damage may 
also allow for infection by secondary pathogens, causing fruit rot  (CPC 2020).  
• Heavy infestation by other Bactrocera  spp. can cause premature fruit d rop (Xia et al. 2018; 
CPC 2020).  
 
Bactrocera  xanthodes attacks several commercial ly grown  fruit species  in several South Pacific 
islands . However, m ost collected individuals have either been trapped or reared in laboratory 
experiments (Leblanc et al. 2012;  Leblanc et al. 2013; CPC 2020).  
• Allwood and Leblanc (199 7) report that B. xanthodes can cause between 19 –37% fruit loss in 
a local variety of papaya, and 4 –31% fruit loss in the Sunset variety of papaya.  
• Although reports on quantifying the impact on com mercially important crops in New Zealand 
were not found, the areas likely to be the most suitable for B. xanthodes establishment in New 
Zealand is northern regions. These regions have the highest hectares of planted Citrus spp. 
and avocadoes, both of which  are economically important crops for New Zealand and 
confirmed hosts of B. xanthodes .  
• Bactrocera  xanthodes  has been  bred from pineapple,  citrus,  papaya,  granadilla , guava  and 
tomatoes.  Hence,  the species  has the potential  to become  a very serious  pest if introduced  
into areas  where  extensive  horticulture  is carried  out and the climate  is suitable  (Drew  1982).   
• Leblanc  et al. (2013)  showed  that breadfruit,  along  with papaya,  soursop  and avocado  are the 
host species  with the highest  flies per kg of fruit sampled  and percentage  of samples  infested  
by B. xanthodes.   
                                                      
76 Larvae develop in the fruit (fruit flesh, pod or seed).  
77 The confirmed records of host on Pacific lychee by White and Elson -Harris (1992) have not been confirmed by subsequent host fruit 
surveys and are therefore treated as u nlikely.   
193 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Avocados, along with several other hosts of B. xanthodes , are important horticultural crops 
(Table 9.8.4) (FOB export values: avocados NZ$104.3  million, squash $59.7  M, capsicums 
$20.6  M, citrus $12.0  M) (Plant & Food Research  2019). Sales values for avocado in 2019 in 
New Zealand were  NZ$56.5  million  (domestic) and $104.3  M (exports)  (Plant & Food 
Research  2019).  
• Other hosts commercially grown in New Zealand include, but are not limited to , passionfruit, 
eggplants, tomatoes, guava and cucumber (Leblanc et al. 2012; Leblanc et al. 2013; CPC 
2020).  
• However, as there is no report found on quantifying the impact on citrus and avocado in areas 
with similar climate conditions to New Zealand, the impact on these two industries is 
uncertain.  
• Bactrocera  xanthodes is likely to cause impact on hosts (e.g. tomato, capsicum, avocado, 
cherimoya ) grown in greenhouses in New  Zealand.  Field infestations of capsicum crops have 
been observed in Tonga; however, these records are considered to be dubious as they have 
not been confirmed by recent host fruit surveys (Leblanc et al. 2013). Field infestations of 
tomatoes have been obs erved in Fiji.  
 
The impact on exports, including market access, is likely to be severe.  
• Citrus spp. grown in New Zealand is almost entirely sold on the domestic market with very 
limited export. However, a high -quality niche export market does exist , which includes Japan, 
the USA and China. A search of the Imported Country Phytosanitary Requirements (ICPR) 
(2020) revealed that B. xanthodes is a quarantine pest in Japan and China but is not 
regulated in the USA.  
• New Zealand Avocado (2020) state s avocados a re exported between August and March to a 
predominantly Australian market. However, the exports to Asia are growing rapidly, where 
avocado exports amount to NZ$22 million ( Plant & Food Research  2019). Of the Asian 
countries where New Zealand avocados are e xported, Thailand, China and Japan have listed 
B. xanthodes as a quarantine pest (ICPR 2020).   
• Detection of a fruit fly in the surveillance programme would need to be reported internationally 
and would be expected to result in reduced market access for some of  New Zealand ’s 
horticultural products . In New Zealand, 80% of horticultural export value came from plants 
that are potential fruit -fly host (MacLellan , Pather and King 2019). The incursion of B. dorsalis  
(reported as B. papaya ) in north Queensland was  estimated to cause loss es of nearly 
AU$100  million , most of this due to lost export markets (Clark et al. 2005).  
• If B. xanthodes  established in New Zealand, additional postharvest disinfestation costs would 
be necessary. In Australia in 1996, apples and c itrus fruit underwent  a cold treatment for fruit 
fly at a cost of approximately AU$200/tonne , avocados were treated with hot forced air , 
costing approximately AU$125/tonne, and stone fruit, cucurbits and tomatoes were treated 
with a dimethoate dip , which co st approximately AU$100/tonne (MAF 1996 ).  
 
If B. xanthodes  is detected in New Zealand, the cost incurred by a response would be high.  
• The typical cost of responses is millions of dollars. For example, the Queensland fruit fly 
response in 2019 cost approx imately NZ$18 million (MPI 2020).  
• In Japan, eradication of a fruit fly species from the Ryukyu Islands cost more than 200 million 
euros (Kiritani 1998). The cost for the eradication programme in northern Queensland (1995 –
1999) was AU$33 million (Cantrell et al. 2002).  
 
Bactrocera  xanthodes is likely to have low impact on the environment in New Zealand .  
• Bactrocera  xanthodes hosts include, but are not limited to, species from the Myrtaceae , 
Passifloraceae  and Lauraceae , which include New Zealand native species (NZPCN 2020). 
However, no New Zealand native species have been confirmed as hosts .  
 
Bactrocera  xanthodes  may have impacts on the urban environment (soci ocultural impacts ). 
• Bactrocera  xanthodes  is damaging to sever al plants grown in domestic gardens and parks, 
such as Citrus  spp., Passiflora spp., Hibiscus spp., Cucumis spp. and Psidium spp. Therefore, 
it is a potential nuisance pest in urban environments.  
 
There is no evidence found that B. xanthodes has an impact  on human health.  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 194  
Risk assessment summary : 
 
Given the arguments and evidence below,  Bactrocera xanthodes may be considered 
for additional measures . 
 
• Bactrocera  xanthodes has a strong association with fruits of some citrus species/cultivars . 
• Some infested fruit will not be detected, especially when the volume of commodities is large . 
• Because  the larvae feed internally in the fruit, general handling cannot remove the larvae, and 
citrus fruit need to be cut open to reveal the larvae of B. xanthodes . 
• Bactrocer a xanthodes has a low to moderate ability (with moderate to high uncertainty) to 
move from imported fruit and into a suitable environment to allow establishment.  
• The suitability of the New Zealand environment for B. xanthodes  to establish is considered 
low to moderate ( low to moderate uncertainty), and its establishment is likely to be restricted 
to the northern part of the North Island and sheltered environments, although a short -term 
population may establish in other areas d uring summer  months.  
• Bactrocera  xanthodes  has a broad host range , which includes commonly grown domestic and 
commercial species,  and therefore, host availability is unlikely to be a limiting factor for it to 
establish in New Zealand . 
• Bactrocera  xanthodes has been reported to cause impact on tropical fruit crops and attack 
citrus and avocado. However, damage is only known from some Pacific Island nations and 
not from areas with a similar climate to New Zealand.  
• Nevertheless, as a fruit fly species, if it is  detected and/or establishes in New Zealand, the 
impact on the export and market access of New Zealand’s horticultural products (particularly 
of citrus and avocado) is likely to be severe.  
 
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preliminary report. Florida Entomologist , 102(1):  79–84. 
Xia, Y; Ma , X L; Hou , B H; Ouyang , G C (2018) A review of Bactrocera minax  (Diptera: Tephritidae) in 
China for the purpose of safeguarding. Advances in Entomology , 6: 35 –61. 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 198 8.9 Bactrocera zonata  (peach fruit fly ) 
 
Description:  Bactrocera zonata  is a polyphagous fruit fly species  that oviposits through the skin of 
fruits and cause s internal feeding damage to fruits. The main hosts are guava, mango and peach , but 
B. zonata has been recorded from over 50 wild and cultivated plant species, including citrus. Within its 
current range , it is considered a major economic pest.  
 
Scientific name: Bactrocera zonata (Saunders , 1842 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Dasyneura zonatus, Dacus zonatus, Dasyneura zonata, Rivellia persicae, 
Strumeta zonata, B. maculigera  
 
Taxonomic notes: Bactrocera  maculigera  Doleschall  was previously listed as a synonym of B. zonata . 
White and Evenhuis (1999) have shown that it is unrelated (EPPO 2005).  
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Bactrocera  zonata meets the criteria to be a quarantine pest for New Zealand.  
• Bactrocera  zonata has a strong association with citrus fruit . 
• Basic measures  are likely to reduce the likelihood of introduction of B. zonata by a moderate 
degree  (with moderate uncertainty) . Consequently, the likelihood of entry is considered to be 
low to moderate (with moderate uncertainty).  
• Bactrocera  zonata has a moderate  to high ability (with moderate uncertainty) to move from 
imported fruit and into a suitable environment to allow establishm ent, that is, onto a host 
plant.  
• The ability of B. zonata  to transfer from imported fruit into a suitable environment to allow 
establishment (exposure) is considered to be moderate to high (with moderate uncertainty) . 
• The suitability of the New Zealand env ironment for B. zonata  to establish in the short  term is 
considered to be moderate to high (with moderate uncertainty), and in the long  term low (with 
high uncertainty)  
• The level of impact caused by B. zonata is likely to be high.  Although its spread and economic 
impact may be limited by climate, even a temporary incursion is likely to be associated with 
trade barriers and eradication costs.  
• Bactrocera  zonata may be considered for additional measures.  
 
Summary of risk assessment against criteria  
Criteria  Rate  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Moderate  
The ability to move from the imported commodity  onto a suitable host  Moderate –high Moderate  
Suitability of the N ew Zealand  environment (short -term establishment)  Moderate –high Moderate  
Suitability of the N ew Zealand  environment (long -term establishment)  Low High 
Impacts on the New Zealand economy, environment, health and  society  High Low 
   
199 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.9.1 Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Bactrocera  zonata meets the criteria to be 
a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: the pest is not present in New 
Zealand, and is of potential importance (able to establish and cause harm).  
 
Bactrocera  zonata is not known to be present in New Zealand:  
• Bactrocera  zonata  is not recorded in PPIN (2020), NZOR (2011)  or NZInverts (2016) . 
• Bactrocera  zonata  is an unwanted organism ( ONZPR  2020) . 
• Bactrocera  zonata  is listed as ‘ regulated’ in ONZPR  (2020).  
 
Bactrocera  zonata has the potential to establish and spread in New Zealand:  
• Four records of  B. zonata are from areas with a similar climate to New Zealand (Phillips et al. 
2018; GBIF.org 2020) , and modelling suggests that a large proportion of New Zealand has a 
climate suitable for the establishment of the species (Ni et al. 2012; EFSA et al. 2019) .  
• Bactrocera  zonata  is polyphagous with over 50 host species in 19 different families (EPPO 
2010), the majority of which are grown in New Zealand  commercially or in home gardens .  
 
Bactrocera  zonata has the potential to cause economic, environmental and sociocultural impacts in 
New Zealand:  
• Bactrocer a zonata has the potential to harm a number of horticultural crops of economic 
importance to New Zealand, including apples, avocados, lemons, apricots, oranges, peaches 
and mandarins.  It also has the potential to cause significant control costs and to impa ct 
negatively on national and international trade . 
• Bactrocera  zonata has the potential to harm several native species that belong to the same 
genus as known hosts.  Two of these species are threatened or at risk ( Solanum aviculare var. 
aviculare – threatened (nationally vulnerable) ; S. a. var. latifolium – at risk (naturally 
uncommon) ; and Syzygium maire  – threatened (nationally critical) ) (NZPCN 2020).  
• Bactrocera  zonata has the potential to harm plants traditionally used by Māori ( Elaeocarpus  
denta tus, E. hookerianus, S. aviculare , S. laciniatum  and S. maire ). 
• Bactrocera  zonata has the potential to have sociocultural impacts , because its hosts include 
plants commonly grown in domestic gardens.  
• Currently , there is no evidence that B. zonata  could have a  negative  impact on human health .  
 
8.9.2 Hazard identification: commodity association  
 
Bactrocera  zonata is associated with citrus fruit . 
Bactrocera  zonata has been reported from citrus fruit:  
• Bactrocera  zonata oviposits through the skin of citrus fruit , and larvae feed inside the fruit 
(Christenson and Foote 1960; Saafan et al. 2005).  
 
8.9.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Bactrocera  zonata has a strong 
association with citrus fruit.  
Larvae of B. zonata  have been reported in citrus fruits.  
• Bactrocera  zonata larvae have been found infesting field -collected navel oranges ( C. 
sinensis ), Baladi oranges ( C. sinensis ), Valencia oranges  (C. sinensis ), mandarins ( C. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 200 reticulat a), grapefruit ( C. paradisi ), sour o ranges ( C. aurantium ), lemons ( C. limon ) (Saafan et 
al. 2005) and kinnow ( C. reticulat a) (Singh and Sharma 2013).  
• Based on literature searches and communication with plant protection officials and research 
scientists, EPPO consider s Mexican  lime ( C. aurantiifolia ), sour orange ( C. aurantium ), 
lemon/ baramasi ( C. limon ), citron ( C. medica ), king orange/tangor ( C. reticulata × C. 
sinensis ), grapefruit ( C. paradisi ), mandarin/tangerine ( C. reticulata ) and sweet orange ( C. 
sinensis ) to be hosts of B. zona ta (EPPO 2010).  
• Citrus  is considered a minor host by EPPO (2020a) ; however , B. zonata  is considered a 
serious citrus pest in India, Pakistan and Egypt  (Delrio and Cocco 2012; Ashfaq et al. 2020; 
CABI 2020).  
• Substantial rates of infestation have been reported in Egypt in navel oranges (15.4%), Baladi 
oranges (10.2%), mandarins (8.8%), grapefruit (10.1%) and sour oranges (5.8%) (Saafan et 
al. 2005).  
• Under the environmental conditions of countries within the current range of B. zonata (tropics 
and subtro pics), eggs and larvae are likely to be within host fruit for a relatively short time 
(eggs 1 –3 days, larvae 4 –10 days) (Duyck et al. 2004). It is common, however, for larvae to 
overwinter within fruit (Syed 1968; Fletcher 1987) .  
 
Bactrocera  zonata  is pre sent in citrus -exporting countries included in th is IRA : 
• Bactrocera  zonata  is present in Egypt and Viet  Nam. 
 
Given the arguments and evidence below, basic measures are likely to reduce the 
likelihood of entry of Bactrocera  zonata  by a moderate degree  (with moderate 
uncertainty) . Consequently, the likelihood of entry is considered to be low  to 
moderate (with moderate uncertainty):  
Bactrocera zonata infestations may be visually detectable in the field and/or packhouses, leading to 
the removal of infeste d produce . 
• Signs of oviposition on citrus can be seen with the naked eye (Ashfaq et al. 2020). Larval 
feeding damage allows for infection by secondary pathogens, causing fruit rot (Delrio and 
Cocco 2012). Fruit with multiple oviposition punctures and feedi ng damage is likely to be 
removed during general handling.  
• Fruit bagging and packhouse culling have been reported to be effective in reducing levels of 
infestation in some citrus commodities in China  (Xia et al. 2019) . Fruit bagging is not widely 
practiced  due to its labour intensity.  
 
However, there is a chance that a small quantity  of infested fruit will not be detected.  
• Fruit with low infestation (fewer oviposition punctures) may not be obvious enough to be 
detected during general handling, as puncture holes are difficult to see (European Food 
Safety Authority 2007).  
• The volume of the commodities can also affect efficiency of detection. Low levels of 
infestation may not be easily detected, especially if the volume of commodities is large.  
 
General hand ling after harvesting is not likely to remove larvae of B. zonata  inside citrus fruit.  
• General handling after harvesting (e.g. washing and brushing) only treats the surface of fruit. 
These procedures are therefore highly unlikely to remove the larvae of B. zonata  inside citrus 
fruit. 
• Fruit will need to be cut open to reveal the larvae of B. zonata  inside. Internally feeding 
insects are likely to be particularly problematic to detect by non -destructive inspection. Even 
using fruit dissection, Gould (1995)  found that detection rates for Caribbean fruit fly 
(Anastrepha suspensa ) could be as low as 17.9%. In this study, inspectors detected between 
17.9% and 83.5% of fruit infested with Caribbean fruit fly; variables influencing detection rate 
were the fruit ty pe, its ripeness and the inspector  (Gould 1995) . 
 
Larvae of B. zonata  may survive transit in citrus commodities.  
• The majority of interceptions of B. zonata on non -citrus hosts (guava, Psidium  guajava ) in 
New Zealand have been of live eggs or larvae (LIMS 2019).  
• Transit of citrus fruit usually includes cold storage. Holding citrus fruit at a maximum of 1.7 °C 
for a minimum of 18 days should result in no B. zonata survivors at the 95% level of  
201 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  confidence (Hallman et al. 2013). However, it is not known whether  usual storage 
temperatures and transit times from countries in this IRA where B. zonata  is present will be 
sufficient to prevent survival of B. zonata  larvae.  
 
The level of uncertainty associated with both the degree to which basic measures  reduce the 
likelihood of entry (moderate) and the consequent likelihood of entry (low to moderate)  is moderate. 
Firstly, species specific information about the detectability of low levels of infestation of citrus fruits 
with B. zonata is not available. Secondly, there i s uncertainty around whether standard transit times 
and storage temperatures of citrus commodities will be enough to prevent survival of B. zonata  larvae.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of Bactrocera  zonata to transfer 
from imported fruit into a suitable environment to allow establishment (exposure) is 
considered to be moderate  to high (with moderate  uncertainty).  
Bactrocera  zonata can survive and develop on waste of citrus fruit (whole fruit or fruit pie ces but 
probably not skin).  
• Bactrocera  zonata females pierce the skin of host fruit and lay a batch of 2 –9 eggs into the 
flesh. Upon hatching, larvae feed on the pulp of the fruit  and drop to the ground upon maturity 
to pupate in the soil  (Delrio and Cocco  2012).  
• Larvae of B. zonata  have been successfully reared to the pupal stage within field -collected 
fruit incubated in the laboratory. The resulting pupae reached adulthood (Saafan et al. 2005).  
• Infested fruit is likely to be discarded. Infested fruit mus t remain in a suitable condition long 
enough for larvae to develop to maturity (this time is temperature -dependent) , and emerging 
larvae then need to find a suitable pupation site.  Citrus fruit is relatively robust and not highly 
perishable (compared to co mmodities such as peaches or strawberries). It is likely to remain 
in good condition long enough for larvae to emerge and pupate . 
• If citrus fruit is disposed of as whole fruit or fruit pieces, it is likely that B. zonata  can survive 
and reach adulthood in this waste. There is no evidence showing that B. zonata  can complete 
development by feeding on citrus fruit skin.  
 
Most of the fruit waste in New Zealand is likely to be disposed of using low -risk methods , so any B. 
zonata present would either be killed or  be unable to escape from the citrus host.  
• The majority of kitchen waste in New Zealand is bagged and disposed of in landfills or run 
through  kitchen disposal units, and in these situations, B. zonata  is unlikely to reach a new 
host ( see the waste analysi s in section 2.4.1 ). 
 
However, some of the waste would be disposed of using high -risk methods, including composting in 
gardens and being used as animal feed.   
• Adults of B. zonata emerging from the soil are likely to be able to find food in the environment 
if citrus fruit wastes are disposed of using high risk methods. The mature larvae emerge from 
the fruits and drop into soil to pupate. Emerged adults feed on honeydew, plant exudates, bird 
faeces and bacteria on host plants (Delrio and Cocco 2012). These f ood sources are common 
in farms, parks and home gardens.  
• Because B. zonata is polyphagous, hosts for oviposition and larval development are available 
in most areas of New Zealand, either in commercial plantations or in home gardens.  
• If citrus hosts are l ocated near composting sites or animal feeding sites, adult B. zonata  are 
likely to locate them ( see the waste analysis in  section 2.4.1 ). 
 
Adult s of B. zonata are strong flier s and can fly moderate to long distances to food sources.  
• Mark –recapture trappi ng experiments have shown that male B. zonata readily disperse 8 –
32 km and can travel up to 40  km. This experiment was limited to the distance of the trap 
placed furthest from the release point, therefore, the actual maximum dispersal distance may 
be large r. Additionally, only male dispersal was measured , and it is not certain how female 
dispersal differs (Qureshi et al. 1975).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 202 • In Iran, low genetic structuring among B. zonata  sampled from sites up to 420 km apart  
(Koohkanzadeh et al. 2019)  indicates a high level of gene flow and confirms the dispersal 
ability of this species.  
 
The level of uncertainty associated with the ability of B. zonata to move from imported fruit to a 
suitable host (moderate to high)  is moderate. Firstly, waste data m ay not be very accurate or up to 
date, and it is not known how frequently suitable hosts are present near composting sites or animal 
feeding locations (see section 2.4.1,  waste analysis). Secondly, it is uncertain what proportion of 
composting sites are ex posed or covered (e.g. in a compost bin). Thirdly, although B. zonata  can fly 
to seek food sources and hosts, and males can disperse up to 40  km, female dispersal distances are 
not known.  Fourthly, the effect of seasonality on this likelihood is uncertain.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for Bactrocera  zonata to establish in the short  term is considered 
moderate to high (with moderate uncert ainty) and in the long  term low (with high 
uncertainty) .  
The native range of B. zonata is tropical , but it has successfully established in a colder and more arid 
region.  
• The native range of B. zonata is in tropical Asia , and much of its range expansion has been 
into other tropical areas in Asia, and also Mauriti us and R éunion. The species has, however, 
successfully established in the colder and more arid, coastal areas of Egypt, indicating a 
degree of adaptability in the species (Delrio and Cocco 2012).  
 
The current distribution of B. zonata is mainly in areas of  low climate match with New Zealand , but 
modelling predicts that the species could establish in New Zealand, particularly in the north.  
• Reliable records of B. zonata occurrence78 are almost exclusively found in areas with a 
dissimilar climate to New Zealand  (climate  match index (CMI) <0.7). Five records (where 
species identity has been verified by experts), however, are from the foothills of the 
Himalayas in India and Pakistan, in areas with a similar climate to New Zealand (CMI = 0.7 –
0.8) (Phillips et al. 2 018; GBIF.org 2020). It is not certain whether those records represent a 
one-off occurrence, or a transient or persistent population. It is also not known how much of 
this distribution is a result of host availability rather than climate.  
• CLIMEX modelling predicts that, under current climate conditions, B. zonata should be able to 
establish in northern New Zealand and that the area suitable for establishment is likely to 
expand with climate change (Ni et al. 2012).  
• Using climate comparisons between Egypt an d southern Europe, and CLIMEX modelling in 
Cobos -Suárez et al. (2010), the European Food Safety Authority considered central and 
southern Spain, central and southern Portugal, Madeira, the Azores, Italy, Malta, Greece and 
Cyprus to be areas suitable for lo ng-term establishment of B. zonata (EFSA et al. 2019). All of 
these regions are of a very high climate similarity with New Zealand (CMI 0.7 –0.9). EFSA 
notes that, because of the difficulty in estimating overwintering survival, the northern limit of 
the pot ential range cannot be reliably delimited.  
 
Bactrocera  zonata is likely to establish a transient summer population across much of the North Island 
and the north of the South Island, and establishment of a persistent population in these areas may 
also be p ossible.  
• Depending on the experiment, the lower developmental thresholds for B. zonata  egg, larval 
and pupal stages are estimated to be 10 –12.7°C, 10–12.6°C and 11.8 –13.6°C, respectively 
(Mohamed 2000; Duyck  et al. 2004; Choudhary et al. 2020). Many areas across New Zealand 
(as far south as Christchurch) have higher mean daily minimum temperatures than this from 
December to March, and some areas further north exceed these temperatures from October 
to May (NIW A data 1981 –2010). However, minimum temperatures in all these areas are well 
below the lower developmental thresholds outside these months. This indicates that a 
persistent B. zonata population may not survive winter temperatures even in the north, unless 
individuals can successfully overwinter in New Zealand conditions. Detailed information about 
                                                      
78 Records are from GBIF and only those based on material samples or preserved specimens were included in the analysis. All 
samples/specimens are lodged at the Royal Museum for Central Africa, Natural History Museum, London or held in the 
Barcode o f Life Data System; therefore, species identity is likely to be reliable.   
203 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  overwintering in B. zonata  is not available ; however, the species is capable of surviving 
winters with temperatures at or close to freezing in North Sinai in Egyp t (European Food 
Safety Authority 2007). This indicates that the establishment of a persistent population across 
the North Island and  the north of the South Island may be possible.  
• The range of mean minimum daily temperatures across much of the North Island and the 
north of the South Island are suitable for the establishment of a transient summer population.  
 
Bactrocera  zonata has a high reproductive rate , which is likely to decrease, but still be relatively high, 
under conditions across most of New Ze aland in summer.  
• Under laboratory conditions, B. zonata  can complete 8 consecutive generations in a year 
(Shehata et al. 2008) , and a female can lay up to 93 eggs per day and as many as 564 in a 
lifetime (Qureshi et al. 1974; Duyck et al. 2004).  
• Under labo ratory conditions, optimal temperatures for egg hatch, and larval and pupal survival 
are 25 –30°C. However, there is still substantial egg hatch (10 –51%) at 15 °C and egg hatch 
(54–89%), larval survival (63 –88%) and pupal survival (87 –96%) at 20 °C (Qureshi e t al. 1993; 
Mohamed 2000; Duyck et al. 2004; Choudhary et al. 2020). Females are unable to produce 
eggs at 15 °C (Qureshi et al. 1993; Duyck et al. 2004; Choudhary et al. 2020) . However, at 
20°C, the average number of eggs produced per female in a lifetime is 91 (Choudhary et al. 
2020).  
• Mean daily maximum temperatures between 25 and 30 °C are extremely rare in New Zealand , 
but mean daily maximum temperatures ranging between 20 and 25 °C are common across 
much of the country during the spring and summer months (NIWA data 1981 –2010). This 
indicates that many areas of New Zealand may be suitable for B. zonata to complete 
development during the summer months.  
 
The biology of adult B. zonata means that they are likely to find mates if they are present.  
• Adult f emale and male B. zonata  emit volatile chemicals at dusk that are detected by each 
sex and likely play a role in mate location and sexual selection (Levi -Zada et al. 2020) . This 
behaviour may increase the likelihood of encounters between the sexes to mate.  
 
Host and food availability is unlikely to be a limiting factor for B. zonata  to establish in New Zealand.  
• Bactrocera  zonata  is polyphagous with over 50 host species in 19 different families (EPPO 
2010), the majority of which are grown in New Zealand . Hosts fo r oviposition and larval 
development are available in most areas of New Zealand, either in commercial plantations or 
in home gardens.  
• Emerged adults feed on honeydew, plant exudates, bird faeces and bacteria on host plants 
(Delrio and Cocco 2012). These fo od sources are common in farms, parks and home 
gardens.  
 
Bactrocera  zonata  has become a major pest outside of its native range.  
• In the years following its establishment in Egypt in the late 1990s, B. zonata caused an 
estimated US$188 million of direct dama ge annually to citrus (Delrio and Cocco 2012).  
 
Bactrocera  zonata  responds to methyl eugenol and so is likely to be detected in the National Fruit Fly 
Surveillance Programme . 
• Three fruit fly lures, cuelure, trimedlure and methyl eugenol , are used in the National Fruit Fly 
Surveillance Programme  in New Zealand (MacLellan et al. 2019) . If a fruit fly species is 
responsive to one or more of these lures, early detection of an incursion is more likely, which 
reduces the likelihood of the species’ establishment in New Zealand.  
• Methyl eugenol is a potent attractant of B. zonata  males (Qureshi et al. 1981) and has been 
used as an attractant in experimental (Qureshi et al. 1981) and real -world control programs 
using male annihilation techniques (Sookar et al. 2006) for the species.  
 
The level of uncertainty associated with the likelihood of establishment of B. zonata in the short term  
(moderate to high)  is moderate, and the level of uncertainty associated with the likelihood of 
establishment of B. zonata in the long term (low)  is high. Firstly, the constant temperatures used in 
these studies do not reflect real -world daily temperature fluctuations , and it is not known how this 
would affect survivorship and fecundity in the wild.  Secondly, the lower temperature thresho lds for 
egg, larval and pupal survival are extrapolated from survivorship curves of B. zonata reared under Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 204 laboratory conditions, i.e. on an artificial diet and under constant temperature. Actual developmental 
thresholds in the wild may be substantially di fferent to these estimates.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by Bactrocera  
zonata  is likely to be high.  
Damage and symptoms caused by B. zonata  can reduce fruit quality.  
• Oviposition puncture sites and larval feeding damage allows for infection by secondary 
pathogens, causing fruit rot (Delrio and Cocco 2012).  
 
Bactrocera  zonata has been reported to cause severe damage and production losses to a number of 
fruit crops . 
• Bactrocera  zonata is cons idered a serious fruit pest in India, Pakistan and Egypt (CABI 2020).  
• In India , B. zonata  has been reported to cause  losses of 25 –100% in peach ( Prunus persica ), 
apricot ( Prunus  armeniaca ), guava ( Psidum  guajava ) and figs ( Ficus  carica ) (CABI 2020).  
• In Pakistan, B. zonata  has been reported as damaging 25 –50% of guava fruit (CABI 2020) 
and causing yield losses of 18.9%, 9.7% and 4.0% in C. reticulata, C. sinensis and C. paradisi  
respectively (Ashfaq et al. 2020).  
• Substantial rates of infestation have been  reported in Egypt in navel oranges (15.4%), Baladi 
oranges (10.2%), mandarins (8.8%), grapefruit (10.1%) and sour oranges (5.8%) (Saafan et 
al. 2005). In the years following its establishment in Egypt in the late 1990s, B. zonata caused 
an estimated US$188 million of direct damage annually to citrus (Delrio and Cocco 2012).  
 
Bactrocera  zonata is likely to negatively impact many plants of economic importance to New Zealand.  
• Bactrocera  zonata hosts include several important horticultural export crops: apple (Malus  
domestica , FOB export value: NZ$828.8  million); avocado ( Persea  americana , FOB export 
value: $104.3  M); lemon ( C. limon , fob export value: $9.8  M); apricot ( Prunus  armeniaca , FOB 
export value: $2  M); sweet orange ( C. sinensis , FOB export value: $1.7  M); peach ( Prunus  
persica , FOB export value: $0.4  M) and mandarin ( C. reticulata , FOB export value: $0.4  M) 
(Plant & Food Research 2019).  
• Many of these crops are grown in the warmer areas of New Zealand , which coincides with the 
areas where B. zonata  is most likely to establish.  
• Using structured expert elicitation, EFSA estimated the percentage of yield losses due to 
B. zonata damage if the pest were to establish in the EU on a range of fruit commodities 
(EFSA et al. 2019). They estimated yield loss to be:  
o 18% on exotic fruit (in particular avocado, mango, guava and papaya) ;  
o 8.6% on citrus ; and   
o 9% on peach (including both peaches and nectarines) .  
The area of the EU considered in these estimates is of a high climate match with New 
Zealand (CMI 0.7 –0.9), s o these estimates may be generalisable to the local horticulture 
industry.  
• Even if B. zonata  were to only establish for a single summer, the impact on a single growing 
season is likely to be high.  
• Since there are no pest tephritids  currently present in New Zealand , and therefore no existing 
management programmes, costs of control in the event of B. zonata establishment  are likely 
to be high.  
 
If B. zonata  is detected in New Zealand, the cost incurred by a response would be expensive .  
• The typical cost of responses is millions of dollars. For example, the Queensland fruit fly 
response in 2019 cost approximately NZ$18 million (MPI 2020).  
 
Establishment of B. zonata  is likely to increase phytosanitary measures required for export to 
countries where the pest is absent.  
• B. zonata is not present in any of the top 10 export destinations for New Zealand’s 
horticultural produce (Plant & Food Research 2019) . 
  
205 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Bactrocera  zonata is likely to cause low  to moderate sociocultural impacts on plants  in home gardens , 
with moderate uncertainty.  
• Several host species of B. zonata  are commonly grown in home gardens (e.g. citrus, apple, 
apricot, peach, pear and tomato). If control measures become necessary in residential areas , 
this is likely to have a neg ative sociocultural impact.  
 
Bactrocera  zonata is likely to have very low impacts on the environment in New Zealand (with high 
uncertainty ) and also very low impacts on Māori cultural values  (with high uncertainty ). 
• Bactrocera  zonata hosts include species in genera that also contain the following native 
species: Elaeocarpus  dentatus , E. hookerianus , Solanum americanum , S. aviculare , S. 
laciniatum , S. opacum  and Syzygium maire . 
• Solanum aviculare var. aviculare is threatened (nationally vulnerable), S. a. var. latifolium is at 
risk (naturally uncommon) , and Syzygium maire  is threatened (nationally critical) (NZPCN 
2020).  
• Several native species in the same genera as B. zonata hosts have traditional Māori uses 
(Landcare Research 2020):  
o E. dentatus (hīnau) was an important cultivated crop for Māori, being used as a food 
source, as a mordant for fixing dyes, as medicine and for construction.  
o E. hookerianus (pōkākā) was traditionally used as a mordant for fixing dyes and as 
medicine.  
o S. avicula re and S. laciniatum (poroporo) was traditionally used as a food source, as 
medicine, as a tattoo dye and for making musical instruments.  
o S. maire (maire tawake) was traditionally used as a food source, as medicine and as 
a dye.  
• The fruit of the native plant species are small and much less fleshy than those of the preferred 
hosts of B. zonata , so the native species may not make attractive hosts.  
• If the fly attacks only the flesh of ripe fruit, it is unlikely to impair seed develop ment, number or 
viability  of native plant species . 
• If the native plant species make suitable hosts for B. zonata,  if the association has negative 
impacts on the hosts’ biology and if the fly establishes in area near where these species are 
found, then B. zonata establishment could have a negative environmental impact  and a 
negative impact on Māori cultural values . 
 
There is no evidence found that B. zonata has an impact on human health.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence below,  Bactrocera  zonata may be considered  for 
additional measures . 
• Bactrocera  zonata has a strong association with citrus fruit . 
• Fruit with a low level of infestation may not be detected during general handling, especially 
when the volume of commodities is large . 
• Because larvae feed internally inside fruit, general handling (e.g. washing and brushing) 
cannot remove the larvae, and citrus fruit need to be cut open to reveal the larvae of B. 
zonata . 
• Bactrocera  zonata has a moderate  to high ability (with low  to mode rate uncertainty) to move 
from imported fruit and into a suitable environment to allow establishment . 
• The suitability of the New Zealand environment for B. zonata to establish in the short term  is 
considered to be moderate  to high (with moderate uncertainty) and in the long  term low (with 
high uncertainty) . 
• The establishment of B. zonata in New Zealand is likely to cause high economic impacts.  
 
8.9.4 References  
Abobatta, W F (2019) Citrus varieties in Egypt: An impression. International Research Journa l of 
Applied Sciences 1(1): 63 –66. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 206 Ashfaq, M; Khan, M; Gogi, M D; Rehman, A (2020) Loss assessment and management of Bactrocera 
zonata (Diptera: Tephritidae) in citrus orchards. Pakistan Journal of Agricultural Sciences , 57(2): 451 –
456. 
CABI (2020) Bactroc era zonata (peach fruit fly) [original text by A. Bakri]. In Invasive Species 
Compendium . CAB International ; Wallingford, UK. www.cabi.org/isc  Accessed 16 September 2020.  
Choudhary, J S; Mali, S S; Naaz, N; Mukherjee, D; Mo anaro, L; Das, B; Singh, A K; Rao, M S; Bhatt, 
B P (2020) Predicting the population growth potential of Bactrocera zonata (Saunders) (Diptera: 
Tephritidae) using temperature development growth models and their validation in fluctuating 
temperature conditio n. Phytoparasitica , 48(1): 1 –13. 
Christenson, L D; Foote, R H (1960) Biology of fruit flies. Annual Review of Entomology , 5(1): 171 –
192. 
Cobos -Suárez J  M; Catalán -Ruescas, D ; Guitián -Castrillón J  M (2010) The potential geographic 
distribution of Bactrocera zonata (Saunders) in Eur ope and the Mediterranean Basin. [Abstract only] 
In Sabater Muñoz, B; Navarro Llopis, V; Urbaneja, A (eds) 8th International Symposium on Fruit Flies 
of Economic Importance, Valencia (Spain ), 26 September  – 1 October 2010 . Universitat Polit ècnica 
de Valencia ; Valencia, Spain; p 205.  
Delrio, G; Cocco, A (2012) The peach fruit fly, Bactrocera zonata : A major threat for Mediterranean 
fruit crops? Acta Horticulturae , 940: 557 –566. 
Duyck, P -F; Sterlin, J F; Quilici, S (2004) S urvival and development of different life stages of 
Bactrocera zonata (Diptera: Tephritidae) reared at five constant temperatures compared to other fruit 
fly species. Bulletin of Entomological Research , 94: 89 –93. 
EFSA; Baker, R; Gilioli, G; Behring, C; Ca ndiani, D; Gogin, A; Kaluski, T; Kinkar, M; Mosbach -Schulz, 
O; Neri, F, Maria; Preti, S; Rosace, M, Chiara; Siligato, R; Stancanelli, G; Tramontini, S (2019) 
Bactrocera zonata – Pest Report to support ranking of EU candidate priority pests . European Food 
Safety Authority.  
EPPO (2005) Data sheets on quarantine pests – Bactrocera zonata . EPPO Bulletin , 35: 371 –373. 
EPPO (2010) PM 9/11 (1): Bactrocera zonata : procedure for official control. EPPO Bulletin , 40(3): 
390–395. 
EPPO (2020a) EPPO global database. https://gd.eppo.int  Accessed 29  October 2020.  
EPPO (2020b) EPPO Interceptions on imported commodities v10.0 database.  
European Food Safety Authority (2007) Opinion of the scientific panel on plant health (PLH) on the 
pest risk analysis made by Spain on Bactrocera zonata . EFSA Journal , 5(5): 1 –25. 
Fletcher, B S (1987) The biology of dacine fruit flies. Annual Review of Ent omology , 32(1): 115 –144. 
GBIF.org (2020) GBIF Occurrence Download https://doi.org/10.15468/dl.f5juf8  Accessed 16 
September 2020.  
Gould, W P (1995) Probability of detecting Caribbean fruit fly (Diptera: Tephritidae) infestations by 
fruit dissection. The Florida Entomologist , 78(3): 502 –507. 
Hallman, G J; Myers, S W; Taret, G; Fontenot, E A; Vreysen, M J B (2013) Phytosanitary cold 
treatment for oranges infested with Bactrocera zonata (Diptera: Tephritidae ). Journal of Economic 
Entomology , 106(6): 2336 –2340.  
Koohkanzadeh, M; Pramual, P; Fekrat, L (2019) Genetic Analysis of populations of the peach fruit fly, 
Bactrocera zonata (Diptera: Tephritidae), in Iran. Neotropical Entomology , 48(4): 594 –603. 
Landcare Research (2020) Ngā Tipu Whakaoranga database. 
http://maoriplantuse.landcareresearch.co.nz  Accessed 24 September 2020.   
207 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Levi-Zada, A; Levy, A; Rempoulakis, P; Fefer, D; Steiner, S; Gazit, Y; Nestel , D; Yuval, B; Byers, J A 
(2020) Diel rhythm of volatile emissions of males and females of the peach fruit fly Bactrocera zonata . 
Journal of Insect Physiology , 120: 103970.  
LIMS (2019) MPI internal database. Laboratory Information Management System (LIMS) Plant Health 
and Environment Laboratory.  
MacLellan, R; Pather, V; King, K (2019) National Fruit Fly Surveillance Programme annual report. 
Surveillance , 46(3): 83 –86. 
Manaaki Whenua - Landcare Research (2016) New Zealand Arthropod Collection (NZAC) specimen  
data. https://nzinverts.landcareresearch.co.nz/default.aspx  Accessed 15 September 2020.  
Mohamed, A M (2000) Effect of constant temperatures on the development of the peach fruitfly, 
Bactrocera zonata (Saunders) (Diptera: Tephritidae) [Abstract only]. Assiut Journal of Agricultural 
Sciences 31(2): 329 –339. 
MPI (2020) Successful end to fruit fly operation in Auckland. https://www.mpi.govt.nz/news -and-
resources/media -releases/successful -end-to-fruit-fly-operation -in-auckland/  Accessed 22 September 
2020.  
Ni, W L; Li, Z H; Chen, H J; Wan, F H; Qu, W W; Zhang, Z; Kriticos , D J (2012) Including climate 
change in pest risk assessment: the peach fruit fly, Bactrocera zonata (Diptera: Tephritidae). Bulletin 
of Entomological Research , 102(2): 173 –183. 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
NZPCN (2020) New Zealand Plant Conservation Network. https://www.nzpcn.org.nz/  Accessed 24 
June 2020.  
ONZPR  (2020) Official New Zealan d Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/   
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest ris k analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (201 9) Fresh Facts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , New Zealand.   
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 Septembe r 2020.  
Qureshi, Z A; Ashraf, M; Bughio, A R; Hussain, S (1974) Rearing, reproductive behaviour and gamma 
sterilization of fruit fly, Dacus zonatus (Diptera: Tephritidae). Entomologia Experimentalis et Applicata , 
17(4): 504 –510. 
Qureshi, Z A; Ashraf, M; Bu ghio, A R; Siddiqui, Q H (1975) Population fluctuation and dispersal 
studies of the fruit fly, Dacus zonatus Saunders.  Proceedings of the Symposium on the Sterility 
Principle For Insect Control jointly organized by the IAEA and the FAO of the United Nation s, 
Innsbruck, 22 –26 July 1974 . pp 201 –206. 
Qureshi, Z A; Bughio, A R; Siddiqui, Q H (1981) Population suppression of fruit fly, Dacus zonatus 
(Saund .) (Dipt., Tephritidae) by male annihilation technique and its impact on fruit infestation. 
Zeitschrift für Angewandte Entomologie , 91(1–5): 521 –524. 
Qureshi, Z; Hussain, T; Carey, J R; Dowell, R V (1993) Effects of temperature on development of 
Bactrocera zonata (Saunders) (Diptera: Tephritidae). Pan-Pacific Entomologist , 69(1): 71 –76. 
Saafan, M H; Foda, S M; Abdel -Hafez, T A (2005) Ecological studies on Mediterranean fruit fly, 
Ceratitis capitata (Wied.) and peach fruit fly, Bactrocera zonata (Saund.) in citrus orchards . Egyptian 
Journal of Agricultural Research , 83(3): 1157 –1170.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 208 Sheha ta, N; Younes, M W F; Mahmoud, Y (2008) Biological studies on the peach fruit fly, Bactrocera 
Zonata (Saunders) in Egypt. Journal of Applied Sciences Research , 4(9): 1103 –1106.  
Singh, S; Sharma, D R (2013) Biology and morphometry of Bactrocera dorsalis and Bactrocera 
zonata on different fruit crops. Indian Journal of Agricultural Sciences , 83(12): 1423 –1425.  
Sookar, P; Gungah, B; Alleck, M (2006) An area wide control of fruit flies in Mauritius. In Proceedings 
of the 7th international symposium on fruit flies of economic importance, Salvador, Brasil 10 –15 
September . 
Syed, R A (1968) Studies on the Ecology of Some Important Species of Fruit Flies and Their Natural 
Enemies in West Pakistan . Commonwealth Institute of Biological Control Station Report . 
https://books.google.co.nz/books?id=qvZWyQEACAAJ . 
White, I M; Evenhuis, N L (1999) New species and records of Indo -Australasian Dacini (Diptera: 
Tephritidae). Raffles Bulletin of Zoology , 47(2): 48 7–540. 
Xia, Y; Huang, J -h; Jiang, F; He, J -y; Pan, X -b; Lin, X -j; Hu, H -q; Fan, G -c; Zhu, S -f; Hou, B -h; 
Ouyang, G -c (2019) The effectiveness of fruit bagging and culling for risk mitigation of fruit flies 
affecting citrus in China: a preliminary report. The Florida Entomologist , 102(1): 79 –84. 
 
   
209 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
8.10 Ceratitis capitata  (Mediterranean fruit fly, medfly ) 
 
Ceratitis capitata  (medfly)  females lay their eggs through the skin of fruit. Maggots hatch from the 
eggs and feed within the fruit , causing damage and rotting . Medfly  is extremely polyphagous and is a 
highly invasive pest of fruit crops, with a wide geographical distribution. It is endemic to sub -Saharan 
Africa but has been spread accidentally to many other regions.  
 
Scientific name: Ceratitis capitata (Wiedemann , 1824)  
Order/  Family: Diptera/  Tephritidae  
Other names include: Ceratitis citriperda, Ceratitis hispanica, Pardalaspis asparagi, Tephritis 
capitata (CPC 2020)  
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Ceratitis capitata meets the criteria to be a quarantine pest for New Zealand.  
• Ceratitis capitata has a strong association with most citrus fruit , with low uncertainty . 
• Basic measures  are likely to reduce the likelihood of entry of C. capitata on the c ommodity by 
a low to moderate degree  with moderate uncertainty . Consequently , the likelihood of entry is 
considered to be low to moderate , with low uncertainty . 
• Ceratitis capitata is considered to have a moderate ability to move from imported citrus fruit 
and into a n environment t hat is suitable for e stablishment , with moderate uncertainty . 
• The suitability of the New Zealand environment for C. capitata to establish is considered to be 
moderate , with low uncertainty .  
• The level of impact caused by C. capitat a is likely to be high , with low uncertainty . Although its 
spread and economic impact may be somewhat limited by climate, even a temporary 
incursion is likely to be associated with trade barriers and eradication costs.  
• Ceratitis capitata may be considered for additional measures.  
 
Summary of risk assessment against criteria  
Criteria  Rating Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Low 
The ability to move from the imported commodity  onto a suitable host  Moderate  Moderate  
Suitability of the N ew Zealand  environment  Moderate  Low 
Impacts on the New Zealand economy, environment, health and society  High Low 
 
8.10.1  Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Ceratitis capitata meets the criteria to be 
a quarantine pest for New Zealand.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 210 Criteria for being a quarantine pest relevant to this assessment are: the pest is not present in New 
Zealand, and is of potential importance (able to establish and cause harm79). 
 
Ceratitis capitata is not known to be present in New Zealand:  
• There are no records for C. capitata in NZOR (2020) , and PPIN (2020) reports it as absent . 
• New Zealand has country freedom status for C. capitata (MPI 2020a) . 
• Ceratitis capitata  is an unwanted and notifiable organism and a regulated pest ( ONZPR  
2020).  
 
Ceratitis capitata has the potential to establish and spread within the wa rmer parts of New Ze aland:  
• Ceratitis capitata is established in parts of the world with climates similar to that of parts of 
New Zealand. It has previously established temporary populations in New Zealand before 
being successfully eradicated.  
• Ceratitis capitata is a widely po lyphagous fruit fly , and suitable host plants are readily 
available throughout New Zealand commercially, in home gardens and in natural areas.  
 
The establishment of C. capitata in New Zealand has the potential to cause unwanted impacts:  
• The establishment of C. capitata has the potential to cause direct economic damage to many 
horticultural crops that are important to New Zealand. It also has the potential to cause 
significant control costs and to impact negatively on national and internat ional trade.  
• The establishment of C. capitata has the potential to have soci ocultural impacts: many of its 
hosts are commonly planted in home gardens.  
• Environmental and human health impacts are likely to be very low or negligible.  
 
8.10.2  Hazard identification: c ommodity association  
 
Ceratitis capitata is associated with citrus fruit.  
• Ceratitis capitata oviposits through the fruit skin of many plant species, and its larvae feed 
inside the fruit (CPC 2020).  
• There are validated records of infestation of many Citrus species by C. capitata that satisfy 
the definition of a host in accordance with international standards.  
 
8.10.3  Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Ceratitis capitata has a strong association 
with citrus commodities.  
Many citrus species are hosts of C. capitata , and some are favoured hosts.  
• Adult females lay eggs below the skin of the host fruit . Although they show a preference for 
discontinuities in the fruit surface such as cracks, bird pecks and insect damage (Batema n 
1972) , the fly is capable of ovipositing  into sound  citrus  fruit (Papachristos  and P apadopoulos  
2009 , DPIPWE 2011) . Eggs  usually hatch in 2 –4 days (up to 18 days in cool weather) and the 
larvae feed for another 6 –11 days (at 13 –28°C) before leaving the fruit to pupate  (CPC 2020).  
• C. capitata  is highly polyphagous  and there are validated records of infestation of many citrus 
species by C. capitata  which satisfy the definition of a host in accordance with international 
standards , e.g. ISPM 3780, RSPM 4 (Ta ble 9.10.1 ).  
 
                                                      
79 Refer to ISPM 5  for the definition of a quarantine pest under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.  
80 A host is a plant species or cultivar that has been scientifically found to be infested by the target fruit fly species under natural 
conditions and able to sustain its development to viable adults (ISPM 37, FAO 2016a).   
211 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Table 9.10.1  Citrus  species reported to be hosts of Ceratitis  capitata  
(The common hosts names are the names cited in the reference given ). 
Host name  Common name  
Citrus aurantiifolia  Lime, West Indian lime (DPIPWE 2011); Lime (Thomas et al. 2019, CPC 2020); Sour lime 
(Mexican lime) (USDA 2017)  
Citrus aurantium  Seville orange (DPIPWE); Sour orange (USDA 2017, CPC 2020); Sour orange, Seville 
orange, Bitter-sweet orange (Thomas et al. 2019)  
Citrus reticulata  Mediterranean mandarin (USDA 2017)  
Citrus limon  Rough lemon (USDA 2017)  
Citrus latifolia  Tahitian lime (DPIPWE 2011); Persian lime (USDA 2017)  
Citrus limon  Sweet lemon (USDA 2017 ; CPC 2020)  
Citrus aurantiifolia  Palestine sweet lemon (USDA 2017)  
Citrus limon  Lemon, Meyer lemon (DPIPWE 2011); lemon (USDA 2017 ; Thomas et al. 2019 ; CPC 2020)  
Note : Thomas et al. (2019) state that C. limon  are heavily infested except 'Eureka', 'Lisbon', 
and 'Villa Franca' cultivars (smooth -skinned sour lemon).  
Citrus limon  Canton lemon (USDA 2017); Mandarin lime (CPC 2020)  
Citrus maxima  Pummelo (DPIPWE 2011, as Citrus grandis ); Pummelo (USDA 2017 ; CPC 2020); Pummelo, 
Pomelmous shaddock, Pernambuco (Thomas et al. 2019)  
Citrus medica  Citron, Tangor (DPIPWE 2011); Citron  (USDA 2017, Thomas et al. 2019, CPC 2020)  
Citrus limon  Meyer lemon (DPIPWE 2011, USDA 2017)  
Citrus aurantium  Myrtle -leaf orange (USDA 2017)  
Citrus reticulata  Tangor (CPC 2020); King orange (USDA 2017); King orange (Thomas et al. 2019, as Citrus   
× nobilis ) 
Citrus paradisi  Grapefruit (DPIPWE 2011; USDA 2017 ; CPC 2020 as Citrus × paradisi ); Grapefruit, Pomelo 
(Thomas et al. 2019 as Citrus × paradisi ) 
Citrus reticulata var. 
austera  Cleopatra mandarin (USDA 2017)  
Citrus reticulata  Mandarin , Tangelo, Tangerine (DPIPWE 2011); Mandarin (USDA 2017 ; CPC 2020); 
Mandarin, Tangerine (Thomas et al. 2019)  
Citrus reticulata var. 
austera  Rangpur lime (DPIPWE 2011 ; NTG 2013 ) 
Citrus reticulata × 
Citrus paradisi  Tangelo (CPC 2020)  
Citrus sinensis  Sweet orange (DPIPWE 2011); Navel orange (CPC 2020); Orange (USDA 2017); 'Valencia' 
and 'Parson Brown' and 'Lue Gim Gong' , Malta orange, Lambs summer orange (Thomas et 
al. 2019)  
Citrus reticulata  Satsuma mandarin (USDA 2017)  
Citrus reticulata × 
Citrus paradisi  Tangelo (DPIPWE 2011; USDA 2017)  
 
 
Ceratitis capitata  is present  in countries that are included in the Citrus IHS project  (Tables 9.10.2 and 
9.10.3).  
• Ceratitis capitata  is present in Australia, Brazil, Egypt, Spain and Peru. The United States and 
Mexico are subject to recurrent incursions .. 
 
Table 9.10.2  General overview of geographic distribution of Ceratitis capitata  
Information is compiled at 22 September 2020 from E PPO (2020b) and CPC (2020). Countries marked* are only 
reported by CPC (2020). Potential exporting countries are bolded . 
Continent /Region  Country/area  
Africa  Algeria ; Angola ; Benin ; Botswana ; Burkina Faso ; Burundi ; Cameroon ; Cape Verde ; Comoros ; 
Congo ; Democratic Republic of the Congo ; Cote d ’Ivoire ; Egypt ; Eritrea ; Eswatini* ; Ethiopia ; 
Gabon ; Ghana ; Guinea ; Kenya ; Liberia ; Libya ; Madagascar ; Malawi ; Mali; Mauritius ; Morocco ; 
Mozambique ; Namibia ; Niger ; Nigeria ; Réunion ; Saint Helena ; São Tom é and Principe ; Senegal ; 
Seychelles ; Sierra Leone ; South Africa ; Sudan ; Swaziland ; Tanzania ; Togo ; Tunisia ; Uganda ; 
Zambia ; Zimbabwe  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 212 Continent /Region  Country/area  
Asia India (eradicated); Iran; Iraq; Israel; Jordan; Lebanon; Saudi Arabia; Syria; Turkey*; Yemen  
The Americas  Argentina ; Belize (under eradication) ; Bolivia ; Brazil ; Chile (under eradication) ; Bermuda 
(eradicated); Colombia ; Costa Rica ; Dominican Republic (eradicated); Ecuador ; El Salvador ; 
Guatemala ; Honduras ; Jamaica (eradicated); Mexico  (see Table 9.10.3 ); Nicaragua ; Panama; 
Paraguay ; Peru ; United States : California , Florida, Texas ( under eradication  or eradicated); 
United States: Hawaii ; United States: Puerto Rico  (under eradication) ; Uruguay ; Venezuela  
Europe  Albania ; Belgium (eradicated); Bosnia and Herzegovina ; Bulgaria ; Croatia ; Cyprus ; France 
(including Corsica) ; Germany (under eradication) ; Greece (including Crete) ; Hungary (eradicated); 
Italy (including Sardinia and Sicily ); Malta ; Montenegro ; Poland (transient); Portugal (including the 
Azores and Madeira) ; Romania ; Russia (including Southern Russia) ; Serbia ; Slovenia ; Spain  
(including Balearic and Canary Islands) ; Switzerland ; Turkey ; Ukraine (under eradication) ; United 
Kingdom (transient)  
Oceania  Australia  (see Table 9.10. 3); New Zealand (eradicated)  
 
 
Table 9.10.3  Distribution of Ceratitis capitata in potential exporting countries  
Source: EPPO (2020b), unless otherwise stated.  
Country  Distribution in country  
Australia  Localised distribution. Present in Western Australia. Occasional incursions in South Australia and 
Northen Territory but always subject to eradication measures.  All other Australian states and 
territories are currently considered free from C. capitata  (Sultana et al. 2020) . 
Brazil  Widespread. Present in: Acre (CPC 2020), Alagoas, Amap á, Bahia, Cear á, Distrito Federal, Esp írito 
Santo, Goi ás, Maranh ão, Mato Grosso, Mato Grosso do Sul, Minas Gerais, Par á, Para íba, Paran á, 
Pernambuco, Piau í, Rio de Janeiro, Ri o Grande do Norte, Rio Grande do Sul, Rond ônia, Roraima 
(CPC 2020), Santa Catarina, S ão Paulo, Tocantins  
China  Absent, reported once in error from Hubei  
Cook Islands  Not reported  
Egypt  Widespread, present in all Governorates  
Fiji Not reported  
Japan  Not reported  
Korea  Absent  
Mexico  Most of Mexico is designated “Pest Absent” , i.e. there are no records of the presence of the pest 
confirmed by surveys in 28 states of the 32 states . The southern border states of Chiapas, Tabasco 
and Campeche  are subject to incursions  (Enkerlin et al. 2015 ). In 2019 an outbreak was detected in 
Manzanillo, Colima , which was e radicated in April 2020.  
New Caledonia  Not reported  
Peru  Present, with no details  
Samoa  Not reported  
Spain  Present, widespread, including the  Balearic and Canary Islands  
Solomon Islands  Not reported  
USA  • Present and widespread in Hawai ʻi. 
• Recurrent incursions in California that are always subject to eradication measures . Some  
workers have suggest ed that despite numerous eradication attempts , C. capitata  and 
other fruit fly species are  now established and widespread in California a t population 
levels  that are too low to be detected by surveillance (e.g. Papadopoulos et al. 2013), 
however this opinion is not generally accepted (e.g. McInnes et a l. 2017 ). 
• Historical eradications from Florida and Texas.   
213 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Country  Distribution in country  
Vanuatu  Not reported  
Viet Nam  Not reported  
 
 
Given the arguments and evidence below, basic measures are likely to reduce the 
likelihood of entry of C. capitata  by a low to moderate degree  (with moderate 
uncertainty) . Consequently the likelihood of entry is considered to be low to 
moderate : 
In-field controls may reduce C. capitata  populations, but the extent is likely to be widely variable:  
• Citrus  spp. are favoured hosts for C. capitata . Losses for citrus crops vary by location and 
host species and cultivar, with thicker -skinned species being described as poor hosts. 
Reports of damage range from 7% to around 66% of fruit, and infestation rates appear to be 
determined by the level of in -field control.  
o Woods et al. (2005) reported 40% infestation of unmanaged grapefruit grown in 
parks, gardens and backyards in Australia.  
o In a commercial spray -free orchard study in the Azores (Portugal) , infestation levels 
in oranges were recorded to be around 6 6% of fruit, with fruit yielding around seven 
pupae per fruit (Medeiros et al. 2007).  
o Studies in commercial grapefruit orchards in Gaza and Egypt reported infestation 
levels of around 26% and 28% respectively (Saleh and El -Hamalawii 2004 ; 
Lysandrou 2009).  
o Studies in commercial orange orchards in Gaza and Egypt reported infestation levels 
of around 24% and 7% respectively (Saleh and El -Hamalawii 2004 ; Lysandrou 2009).  
 
Ceratitis  capitata infestations may be visually detectable in the field and/or packhouses , leading to the 
removal of infested produce, but some individuals are likely to be undetected:  
• Larval feeding within fruit induces decay , and females show a preference for ovipositing in 
cracked or otherwise damaged fruit . Infested fruit may therefore be detected and is not likely 
to be exported.  
• However , females are able to ovipo sit into sound citrus fruit and oviposition sites are not 
always visible  (Papachristos  and P apadopoulos  2009 , DPIPWE 2011). I nfested fruit may 
show no outward signs , particularly at low levels of infestation . Feeding by early instars may 
not be detected during or after harvest or in on-arrival inspection, particularly if the volume of 
commodities is large.  
• Internally feeding insects , and partic ularly those whose eggs are laid within fruit, are likely to 
be particularly problematic to detect by non -destructive inspection  (Kendra et al. 2011). Even 
using fruit dissection, Gould (1995) found that detection rates for Carib bean fruit fly 
(Anastrepha suspensa ) could be as low as 17.9%. In this study, inspectors detected between 
17.9% and 83.5% of fruit infested with Cari bbean fruit fly; variables influencing detection rate 
were the fruit type, its ripeness and the inspector .  
• Ceratitis  capitata  has bee n identified at the New Zealand  and European Union borders in 
various Citrus species81 (LIMS and Quancargo databases ; EPPO 2020a ): 
o Dead C. capitata larvae were identified at the New Zealand border in oranges from 
Spain in 2000 (Accession 19622), and in 2015 , live larvae were detected in lemons 
carried by an air passenger (LIMS accession C15_00635).  
o In contrast to the few New Zealand border detections on citrus, C. capitata  is 
frequently detected on citrus at E U borders (EPPO 2020 a). Citrus commodities 
include (reported names): Citrus aurantium, C. limon, C. paradisi, C. reticulata  (most 
common),  and C. sinensis  (EPPO 2020 a). 
o Detections of C. capitata  have been made at EU  border s on citrus commodities 
originating from the following countries:  Argentina, Brazi l, Croatia, Egypt, France, 
Greece, Israel, Italy, Lebanon, Morocco, South Africa, Spain, Turkey and Uruguay 
(EPPO 2020 a). 
 
                                                      
81 Ceratitis capitata  has been detected at the New Zealand border on other hosts.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 214 Ceratitis capitata larvae are likely to survive transit in some citrus commodities.  
• Transport of fruit is likely to be by sea and may  take a number of weeks. The optimum 
carrying temperature is variable depending on the fruit type (between 8 and 14°C for 
grapefruit, lemons and limes, and between 2 and 7°C for oranges; BMT 2020) . Carrying 
temperatures are therefore generally cool , though  not very low – grapefruit and mandarin 
exhibit chilling injury at 7 and 8°C, respectively , and unconditioned lemons below 14.5°C  
(McGregor 1987). Ceratitis capitata  is considered to be a relatively temperate fruit fly species. 
Both eggs and larvae may sur vive cool temperatures during transport  to New Zealand.  
 
The level of uncertainty associated with the conclusion is moderate. Although infestation rates appear 
to be determined by the level of in -field control, the effectiveness of this control appears to  be widely 
variable and not extremely high. The detectability of infested fruit is likely to be variable depending on 
a variety of factors. The impact of cool temperature transit82 on survival of C. capitata  eggs and larvae 
is uncertain.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of Ceratitis capitata to move  
from imported fruit into a suitable environment to allow establishment (exposure) is 
considered to be moderate.  
Ceratitis capitata is able to survive and deve lop on discarded citrus fruit.  
• Ceratitis capitata  is often reared on picked fruit in disinfestation experiments. In the field, fruit 
infested with fruit fly larvae often drop to the ground prematurely (Allwood and Leblanc 1997), 
where development continues  until they leave the fruit to pupate. Pupation usually takes place 
in the soil (CPC 2020).  
• Infested fruit is likely to be discarded. Infested fruit must remain in a suitable condition long 
enough for larvae to develop to maturity (this time is temperatur e-dependent) , and emerging 
larvae then need to find a suitable pupation site.  Citrus fruit is relatively robust and not highly 
perishable (compared to commodities such as peaches or strawberries). It is likely to remain 
in good condition long enough for la rvae to emerge and pupate . 
• Many Citrus  species are favoured hosts for C. capitata . 
 
Most organic waste in New Zealand is likely to be disposed of using low -risk methods, meaning that 
fly larvae would die before completing development.  
• The majority of waste in New Zealand is bagged and disposed of in landfills and into kitchen 
disposal units. In these situations, C. capitata  is unlikely to continue development to 
successful emergence of adults (see section 2.4.1 ). 
 
However,  some waste is likely to be disposed of using high -risk methods, including composting in 
gardens, discarding into the environment (e.g roadsides, parks) and use as animal feed , allowing 
larvae to successfully emerge from fruit, pupate and become a dults .  
• Adult C. capitata emerging from the soil are likely to be able to find food in the environment.  
Male and female  tephritids need protein in order to become sexually mature , and they also 
need  sugars for other behavioural activities ( Meats et al. 2004, Farria  et al. 2008 ; Clarke et al. 
2011 ; Kouloussis  2017). Adult flies are presumed to obtain the majority of their protein 
through feeding on leaf surface bacteria (Clarke et al. 2011) , and it is assumed that these 
bacteria are widely available. Other sources of  food for adult tephritids include widely 
available substances such as bird droppings, nectar and plant sap (Christenson and Foote 
1960).  
 
Adult C. capitata  are mobile and can fly to food sources and locate hosts.  
• Adults are highly mobile and capable of i ndependent dispersal.  Meats and Smallridge (2007) 
showed that adult C. capitata  are able to disperse over long distances (up to 9.5 km), but  90% 
                                                      
82 Cool storage differs from cold treatment, which usually  involves a lower temperature for a shorter time period. Cold 
treatments are monitored by temperature probes to ensure the temperature does  not increase beyond a certain set limit, e.g. 
0.5°C .  
215 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  of them remain within 400 –700 m of the point of emergence. Long -distance dispersal may 
occur in response to scarce resources.  
 
There is moderate uncertainty associated with th e conclusion that the likelihood of exposure is 
moderate . Information about waste disposal may be inaccurate (section 2.4.1 ). 
 
Given the arguments and evidence below,  the suitability of New  Zealand’s 
environment for the establishment of C. capitata is moderate.  
Ceratitis capitata is likely to establish permanently in at least some parts of New Zealand:  
• Ceratitis capitata  is found in some areas with similar climates to parts of New Zealand, f or 
example , Switzerland  (Table 9.10. 2), and it was briefly established in Tasmania.  
• Worner (1988) used climate modelling to predict sites suitable for establishment of C. capitata  
and concluded that the regions of Gisborne, Bay of Plenty and Northland were  all climatically 
suitable for establishment. Other more marginal areas include the west coast of the North 
Island from Manawatu through to Taranaki and Marlborough in the South Island.  
• Szyniszewska and Tatem (2014) used MaxEnt modelling to show that parts  of the South 
Island , including the important fruit -growing region of Central Otago, could be considered 
environmentally suitable for the establishment of C. capitata . 
• Kean and Stringer (2019) used daily air temperatures to predict that C. capitata  might 
currently establish in the upper half of the North Island, though favourable microclimates may 
allow populations to establish even as far south as Alexandra.  
• Breeding populations of C. capitata  have been reported (and subsequently eradicated) in 
New Zealand on two occasions, providing some evidence of its potential to establish : 
o Cockayne (1907) reported C. capitata  breeding populations in Napier and Blenheim  
in the summer of 1906/07.   
o Ceratitis  capitata  was detected in Auckland in 1996 . Two males we re found in a 
monitoring trap in Mt Roskill (Auckland) . A further 41 adults were caught within the 
first 13 days of the response , and larval infestation of fruit (feijoa, grapefruit and 
tangelo) was detected in properties adjacent to the initial find (Hold er et al. 2007 ; 
Kean et al. 2020).  
 
Ceratitis capitata has a high reproduction rate , and mates are located using pheromones . 
• Multiple larvae are contained within a single fruit . For example , Zeki et al. (2008) re ported an 
average of 30 larvae per peach fruit (a preferred host; fewer adults are likely to  emerge from 
some citrus species).  
• A minimum of one male and one female is needed to successfully emerge from imported fruit 
and to survive long enough to locate ea ch other and to mate. Enough adults may therefore 
emerge from a single or a few discarded fruit to  establish a population. Males use 
pheromones  to attract sexually receptive females (Baker et al. 1985).   
• Females lay 1 –14 eggs per fruit and can lay 300 –1,000 eggs throughout life (Fletcher 1989).  
Oviposition rate is likely to be influenced by host plant and environmental factors, particularly 
temperatu re, so may be lower in New Zealand . 
 
Host availability is unlikely to be a barrier to the establishment and  spread of C. capitata . 
• Ceratitis capitata  is highly polyphagous on a wide range of hosts. Liquido et al. (2019) report 
over 400 plants species with validated records of infestation under natural field conditions. 
Potential host plants are available throug hout New Zealand in climatically suitable areas in 
commercial groves, home gardens, parks and reserves.  
• Suitable oviposition hosts are likely to be available at many times of the year.  
• Once established, C. capitata  is capable of dispersing naturally and i s also likely to be spread 
by the distribution of infested host fruit.  
 
Ceratitis capitata  is likely to be detected and eradicated in the event of an incursion.  
• Surveillance for fruit flies in New Zealand uses trimedlure, cuelure and methyl eugenol as 
lures (MacLellan et al. 2019). Male C. capitata  are responsive to trimedlure (IAEA 2003) and 
early detection , and therefore , eradication of incursions is very likely.  An analysis of 211 
eradication or emergency response programs against 17 species of fruit fli es in 31 countries Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 216 indicated that the failure rate for these fruit fly eradication programs was low ( about 7% ; 
Mcinnes et al. 2017).  
• Ceratitis capitata  has been detected in New Zealand twice : in 1907 and in 1996 (Kean et al. 
2020). On both occasions , larva l infestations were detected (in 1996 subseqent to the 
detection of adult males in the surveillance grid) , and on both occassions , the fly was 
successfully eradicated.  
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by C. capitata  
is likely to be high.  
Damage caused by C. capitata  reduces fruit quality and can render it unmarketable.  
• Attacked fruit usually shows signs of oviposition punctures. Larvae feed on the pulp of host 
fruit, sometimes tunneling through it and eventually reducing the whole fruit to a juicy, inedible 
mass (Thomas et al. 2019). Larval feeding also induces decay and  premature fruit drop (CPC 
2020 ; Allwood and Leblanc 1997 ). 
 
Ceratitis capitata has been reported to cause severe damage and production loss in many 
horticultural commodities  that are economically important to New Zealand:  
• Ceratitis capitata  is a major pes t of citrus, though it is often a more serious  pest in some 
deciduous fruits, such as peach, pear and apple. In some Mediterranean countries, only the 
earlier varieties of citrus are grown because the flies develop so rapidly that late -season fruits 
are to o heavily infested to be marketable. Some infested areas in the Mediterranean have 
had almost 100% infestation in stone fruit (Thomas et al. 2019).  
• Damage to crops through fruit loss is considerable in invaded areas. In Argentina, 143 ,000 
tonnes of produce  are lost annually to fruit fly damage caused by the two main pest species, 
C. capitata and Anastrepha fratercula , at an estimated value of US$37 million (Guillén  and 
Sánchez 2007). Fruit losses ranging from 15% for plums to 91% for peaches have been 
attributed to damage by C. capitata  (Fischer -Colbrie and Busch -Petersen 1989). It has been 
estimated that the cost of controlling established medfly in California alon e could range from 
US$493 million to $875 million, and the imposition of trade embargos from Asian countries 
would result in additional revenue losses of $564 million and cost more than 14,000 jobs 
(Szyniszewska  and Tatem  2014) . 
• Zeki et al. (2008) report i nfestation levels in commercial apple orchards of 1% of fruits on 
trees and 4% of fallen fruit, and a study in commercial orchards in Gaza reported infestation 
levels (based on emergence of adult flies from fruit) in oranges of around 24%.  
• Over 90% of fre sh fruit and vegetable exports by value are of produce that could host 
C. capitata  (Underwood 2007) , including apple and grapes (CPC 2020) , which  are among the 
top three export earners for horticultural produce ( PFR 2019 ). The establishment of 
C. capitata  would necessitate management programmes to be instated. Since there are no 
pest tephritids currently present in New Zealand and therefore no existing management 
programmes, the associated costs are likely to be high.  
 
The establishment or even an incursion  of C. capitata  is likely to cause trade impacts . 
• In addition to production losses, trading partners are likely to impose export restrictions and/or 
extra phytosanitary measures if C. capitata  is present, even temporarily, in New Zealand. 
These may not be restricted to known host fruit and may last for long periods. In response to 
the May 1996 incursion of C. capitata,  trading partners imposed restrictions on produce from 
the Auckland area , which lasted 8 –12 months or longer (Underwood 2007). Although widel y 
distributed in Europe, C. capitata  is a quarantine pest for some of New Zealand’s most 
important trading partners in Asia and eastern Australia.  
 
If C. capitata  is detected in New Zealand, the cost incurred by a response would be high.  
• The typical cost of responses is millions of dollars. For example, the Queensland fruit fly 
response in 2019 cost approximately NZ$18 million (MPI 2020b).  
 
Ceratitis capitata is likely to cause soc iocultural impacts on  home gardens.   
217 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Many favoured hosts are commonly grown in home gardens. Some favoured hosts  may have 
up to 90% infestation rates  (e.g. peach in Jordan)  (Fischer -Colbrie and Busch -Petersen 
1989).  
 
The likelihood of environmental impacts caused by the establishment of C. capitata is considered to 
be very low.  
• Ceratitis capitata attacks some plant  species in genera that have New Zealand native 
representatives , e.g. Passiflora , Solanum  and Syzygium (CPC 2020) . The two varieties of 
Solanum aviculare  present in New Zealand (neither endemic) and Syzygium maire  all ha ve 
some form of threatened status (NZPCN 2020), and where their distributions overlap with C. 
ceratitis , they may be at risk. However : 
o neither genus contains species that have been reported as main hosts (CPC 2020);  
o the fly has an unprecedently wide host r ange and Beever et al . (2007) have 
suggested that highly damaging polyphagous species appear to be exceptional and 
that the impact of relatively specialised organisms is likely to be greater ; and  
o the fruit of native Solanum  and Passiflora  species are small and much less fleshy 
than preferred hosts of C. capitata.  
• Other susceptible native plant s are likely to have populations in areas that are not suitable for 
the establishment of C. capitata.   
• If the fly attacks only the flesh of ripe frui t, it is unlikely to impair seed development, number or 
viability.  
 
Ceratitis capitata is unlikely to cause unwanted impacts on human health.   
• Ceratitis  capitata  has been demonstrated to vector  Escheria coli  and coliform bacteria from 
damaged to intact apples (as has the vinegar fly Drosophila melanogaster , which is 
widespread in New Zealand). However , no direct evidence of human disease caused by 
medfly has been found.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence below,  Ceratitis capitata may be considered for 
additional measures . 
• Many citrus species are hosts , and some are favoured hosts . 
• Low levels of fruit infestation may not be detected during general handling, especially when 
the volume of commodities is large . 
• Larvae feed internally in  fruit, and general handling cannot remove them; the fruit need to be 
cut open to reveal them .  
• Ceratitis capitata  is capable of moving from imported fruit into a suitable environment to allow 
establishment . 
• Warmer parts of New Zealand are likely to be sui table for the establishment of C. capitata . 
• Hosts are widely available . 
• The establishment or even an incursion of C. capitata  is likely to cause high economic 
impacts in New Zealand.  
 
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221 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.11 Zeugodacus cucurbitae  (melon fly ) 
 
Description:  Zeugodacus cucurbitae  is a polyphagous fruit fly species that oviposits through the skin 
of fruits, causing internal feeding damage. The main hosts are all in the family Cucurbitaceae , but 
Z. cucurbitae has been recorded from field infestations in over 136 host taxa from 62 genera and 30 
families.  About 60% of the host species are from families other than Cucurbitaceae, including several 
citrus species  (McQuate et al. 2017) . 
 
Scientific name: Zeugodacus (Zeugodacus) cucurbitae (Coquillett, 1899) (Virgilio et al. 2015)  
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera (Zeugodacus) cucurbitae, Dacus cucurbitae, Dacus yuiliensis, 
Dacus aureus, Chaetodacus cucurbita e 
 
Taxonomic notes: Zeugodacus cucurbitae  was originally described as Dacus cucurbitae . The species 
was later placed in the subgenus Zeugodacus , firstly  in the genus Dacus then subsequently in the 
genus Bactrocera . Recently , the systematic position of Zeugodacus  was revised , and a new 
classification of Zeugodacus (Zeugodacus) cucurbitae  was proposed (Virgilio et al. 2015) . This 
classification is not yet universally accepted, so many publications and databases still refer to 
Bactrocera cucurbitae . 
 
Summa ry of conclusions  
 
Given the arguments and evidence presented : 
 
• Zeugodacus cucurbitae meets the criteria to be a quarantine pest for New Zealand.  
• Zeugodacus cucurbitae has a moderate association with citrus fruit . 
• Basic measures  are likely to reduce the likelihood of introduction of Z. cucurbitae by a 
moderate degree (with moderate uncertainty) . Consequently, the likelihood of entry is 
considered to be  low to moderate (with moderate uncertainty).  
• The ability of Z. cucurbitae  to transfer from imported fruit into a suitable environment to allow 
establishment (exposure) is considered to be moderate to high (with moderate uncertainty).  
• The suitability of the New Zealand environment fo r Z. cucurbitae  to establish is considered to 
be moderate to high (with moderate uncertainty) . 
• The level of impact caused by Z. cucurbitae is likely to be high. Even a temporary incursion is 
likely to be associated with trade barriers and eradication costs.  
• Zeugodacus cucurbitae may be considered for add itional measures.  
 
Summary of risk assessment against criteria  
 
Criteria  Rating Uncertainty  
Strength or frequency of association with the commodity  Moderate  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Moderate  
The ability to move from the imported commodity  onto a suitable host  Moderate –high Moderate  
Suitability of the N ew Zealand  environment  Moderate –high Moderate  
Impacts on the New Zealand economy, environment, health and society  High Low 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 222 8.11.1  Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Zeugodacus cucurbitae meets the criteria 
to be a quarantine pest for New Zealand . 
Criteria for being a quarantine pest relevant to this assessment are: the pest is not presen t in New 
Zealand, and is of potential importance (able to establish and cause harm83). 
 
Zeugodacus cucurbitae is not known to be present in New Zealand:  
• Zeugodacus cucurbitae  is not reported to be present in New Zealand (PPIN 2020)  and is not 
recorded in NZOR (2011) . 
• New Zealand has country freedom status for Z. cucurbitae (listed as B. cucurbitae ) (MPI 
2020a) . 
• Zeugodacus cucurbitae  is listed as a notifiable organism and a regulated pest (as Bactrocera 
cucurbitae ) (ONZPR  2020) . 
• Zeugodacus cucurbitae is listed as ‘ regulated’ in ONZPR  (2020) . 
 
Zeugodacus cucurbitae has the potential to establish and spread in New Zealand:  
• Zeugodacus cucurbitae is present in areas with a high climate similarity to New Zealand 
(Phillips et al. 2018; GBIF.org 2020) , and species distribution models  predict that 
Z. cucurbitae could establish in Europe in areas with a very similar climate to New Zealand 
(Godefroid et al. 2015; Phillips et al. 2018) .  
• Climate modelling shows that most of the North Island and the north of the South Is land are 
suitable for Z. cucurbitae to establish ( H. Narouei -Khandan pers. comm.)  
• Zeugodacus cucurbitae  is polyphagous with over  136 host taxa from 62 genera and 30 
families , the majority of which are grown either in commercial plantations or in home garde ns 
in New Zealand  (McQuate et al. 2017) .  
 
Zeugodacus cucurbitae has the potential to cause economic, environmental, and sociocultural 
impacts in New Zealand:  
• Zeugodacus cucurbitae has the potential to harm several horticultural crops of economic 
importanc e to New Zealand, including avocado, squash, beans, capsicum, sweet orange and 
mandarin . It also has the potential to cause significant control costs and to impact negatively 
on national and international trade.  
• Zeugodacus cucurbitae has the potential to harm several native species that belong to the 
same genus as known hosts. Varieties of one of these species are threatened or at risk 
(Solanum aviculare var. aviculare – threatened (nationally vulnerable); and S. a. var. latifolium 
– at risk (naturally uncommon) ). 
• Zeugodacus cucurbitae has the potential to harm plants traditionally used by Māori ( Solanum 
aviculare, S. laciniatum and Passiflora  tetrandra ). 
• Zeugodacus cucurbitae has the potential to have sociocultural impacts , because its  hosts 
include plants commonly grown in domestic gardens.  
• Currently , there is no evidence that Z. cucurbitae could have a  negative  impact on human 
health .  
 
8.11.2  Hazard identification: commodity association  
 
Zeugodacus cucurbitae is associated with citrus fruit . 
Zeugodacus cucurbitae has been reported from citrus fruit:  
• Zeugodacus cucurbitae oviposits through the skin of citrus fruit , and larvae feed inside the 
fruit (White and Elson -Harris 1994; Vayssières et al. 2007) . 
 
                                                      
83 Refer to ISPM 5  for the definition of a quarantine pest under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.   
223 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand    Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 224 8.11.3  Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Zeugodacus cucurbitae has a moderate 
likelihood of entry  with citrus fruit.  
Larvae of Z. cucurbitae  have been reported in citrus fruits.  
• Zeugodacus cucurbitae  larvae have been recorded from field infestation of various citrus 
cultivars ( Table 9.11.1 ): 
o Zeugodacus cucurbitae  larvae have been found infesting field -collected sweet 
oranges ( Citrus  sinensis ) and tangerines ( C. reticulata ) in West Africa. Larvae withi n 
field-collected fruit were allowed to develop into pupae and adults in the laboratory, 
and infestation rates were calculated as the mean number of pupae per kg of fruit. 
Infestation rates were much lower in the Citrus species (1 to 25 pupae/kg of fruit) than 
the preferred hosts ( Cucurbita ceae, 1 to over 100 pupae/kg of fruit) (Vayssières et al. 
2007) . 
o In Sudan, Z. cucurbitae have been found infesting field -collected sweet oranges 
(C. sinensis ) at a rate of 3.2 individuals per kg of fruit (Ali et al. 2014 , in McQuate et 
al. 2017) . 
o Zeugodacus cucurbitae have been found infesting 13 of 52 field -collected citron s 
(C. medica ) in India (Gupta and Verma 1978 , in McQuate et al. 2015) . 
o Other field -collected host records of Z. cucurbitae in citrus include: adults (n umber not 
given) reared from two makrut limes ( C. hystrix ) in Southeast Asia (Allwood et al. 
1999) ; an infestation (number not given) of a single pomelo ( C. grandis ) in Malaysia 
(Keng -Hong and Soo -Lam 1982) ; a single adult reared from field -collected tange rine 
(C. reticulata ) in Hawaii (McBride and Tanada 1949) ; an infestation of 10% of field -
collected orange fruits ( C. sinensis ) in Pakistan  (numbers of oranges and larvae not 
given) (Inayatullah et al. 1991 , in McQuate et al. 2015) ; and a single adult reared from 
sweet orange ( C. sinensis ) in Hawaii (Ehrhorn 1910 , in McQuate et al. 2015) . 
 
Table 9.11.1  Field infestation records of Zeugodacus  cucurbitae  in citrus , i.e. Citrus  species that are 
natural hosts  (Aluja and Mangan 2008)  
Species name  Common name  Collection 
location  Reference  
Citrus sinensis  Sweet orange  West Africa  
Pakistan  
Hawaii  
Sudan  Vayssières et al. 2007  
Inayatullah et al. 1991 , in McQuate et al. 2015  
Ehrhorn 1910 , in McQuate et al. 2015  
Ali et al. 2014 , in McQuate et al. 2017  
Citrus hystrix  Makrut lime  Southeast Asia  Allwood et al. 1999  
Citrus maxima  Pomelo  Malaysia  Keng -Hong and Soo -Lam 1982  
Citrus medica  Citron  India  Gupta and Verma 1978 , in McQuate et al. 2015  
Citrus reticulata  Tangerine  West Africa  
Hawaii  Vayssières et al. 2007  
McBride and Tanada 1949  
 
• In addition to the natural hosts  listed above, sour orange ( C. aurantium ) has been identified 
as a conditional (Aluja and Mangan 2008)  host in a laboratory experiment (Rajamannar 1962  
in McQuate et al. 2015) . 
• The following species have also been listed as hosts with no supporting data : Italian tangerine 
(C. deliciosa ), lemon ( C. limon ), myrtle-leaf orange ( C. myrtifolia ), tangor ( C. nobilis ) and 
grapefruit ( C. paradisi ) (McQuate et al. 2015; McQuate et al. 2017 ). Lemon has been shown 
to be a non -host (Aluja and Mangan 2008) , although this designation is currently only from a 
single study (Rajamannar 1962 , in McQuate et al. 2015) . 
  
225 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Zeugodacus cucurbitae  is present in citrus -exporting countries in this IHS:  
• Zeugodacus cucurbitae  is present in: the U SA (in Hawaii ); China (in Fujian, Guangdong, 
Guangxi, Guizhou, Hainan, Jiangsu, Xianggang (Hong Kong), Yunnan, and Zhejiang); 
Viet Nam; Australia; and  Solomon Islands (EPPO 2020a) . 
 
Given the arguments and evidence  below, basic measures are likely to reduce the 
likelihood of entry of Zeugodacus cucurbitae  by a moderate degree (with moderate 
uncertainty) . Consequently, the likelihood of entry is considered to be low to 
moderate (with moderate uncertainty):  
Zeugodacus  cucurbitae infestations may be visually detectable in the field and/or packhouses, leading 
to the removal of infested produce.  
• Puncture holes from oviposition are visible with the naked eye on citrus (Vayssières et al. 
2007) . The oviposition site often oo zes fluid , which becomes a brown resinous deposit , and 
the surrounding tissue can become necrotic and slightly concave. Extensive larval feeding 
causes fruit rot or distortion (Dhillon et al. 2005) . Fruit with multiple oviposition punctures and 
feeding damage is likely to be removed during general handling.  
• Fruit bagging and packhouse culling have been reported to be effective in reducing levels of 
infestation in some citrus commodities in China (Xia et al. 2019) . Fruit bagging is not widely 
practiced due to its labour intensity.  
 
However, there is a chance that a small quantity of infested fruit will not be detected.  
• Low levels of infestation (fewer oviposition punctures) may not be obvious enough to be 
detected during general handling. Low infestation levels may be more prevalent in less 
preferred hosts such as citrus.  
• The volume of the commodities can also affect efficiency of detection. Low levels of 
infestation may not be easily detected, espec ially if the volume of commodities is large.  
• Zeugodacus cucurbitae was intercepted over 70 times at the European border  between 2003 
and 2020 (EPPO 2020b) , and over 200 times at the US border between 1923 and 2017 
(McQuate et al. 2017)  on a variety of (ma inly cucurbit) host species.  
 
General handling after harvesting is not likely to remove larvae of Zeugodacus cucurbitae  inside citrus 
fruit. 
• General handling after harvesting (e.g. washing and brushing) only treats the surface of fruit. 
These procedures ar e therefore highly unlikely to remove the larvae of Z. cucurbitae  inside 
citrus fruit.  
• Fruit will need to be cut open to reveal the larvae of Z. cucurbitae  inside. Internally feeding 
insects are likely to be particularly problematic to detect by non -destru ctive inspection. Even 
using fruit dissection, Gould (1995)  found that detection rates for Caribbean fruit fly 
(Anastrepha suspensa ) could be as low as 17.9%. In this study, inspectors detected between 
17.9% and 83.5% of fruit infested with Caribbean fruit  fly; variables influencing detection rate 
were the fruit type, its ripeness and the inspector (Gould 1995) . 
 
Larvae of Z. cucurbitae  may survive transit in citrus commodities.  
• Between 1923 and 2017, live larvae, pupae or adults of Z. cucurbitae  were inter cepted at the 
US border over 100 times on a variety of (mainly cucurbit) host species. The only interception 
of Z. cucurbitae  on citrus  was of 22 live larvae from Citrus sp. being shipped domestically 
within Hawaii (McQuate et al. 2017) . 
• Viable eggs and li ve larvae of  Z. cucurbitae  have been intercepted at the New Zealand border 
in sea-shipped cucurbit from India (Keall 1981 , in MAF 2007) . There has also been an 
interception at the New Zealand border of two live Z. cucurbitae larvae on chillies ( Capsicum 
frutescens ) being carried by a passenger (LIMS 2019) . 
• Transit of citrus fruit usually includes cold storage. Eggs and larvae of Z. cucurbitae are very 
cold-tolerant. At 1.5 –2°C within navel oranges ( C. sinensis ), eggs can survive for up to 6 
days, first -instar larvae up to 10 days, second -instar larvae 14 days , and third -instar larvae  up 
to 10 days  (Follett et al. 2018) . It is not known whether usual storage temperatures and transit 
times from countries in this IHS where Z. cucurbitae  is present will be suf ficient to prevent 
survival of Z. cucurbitae eggs and larvae.  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 226 The level of uncertainty associated with both the degree by which basic measures  reduce the 
likelihood of entry (moderate) and the consequent likelihood of entry (low to moderate) is moderate. 
Firstly, species -specific information about the detectability of low levels of infestation of citrus fruit with 
Z. cucurbitae is not available.  Secondly, there is uncertainty around whether standard transit times 
and storage temperatures of citrus commodities will be enough to prevent survival of Z. cucurbitae 
eggs and larvae.  
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of Zeugodacus cucurbitae to 
transfer from imported fruit into a suitable environment to allow establishment 
(exposure) is considered to be moderate to high (with moderate uncertainty).  
Zeugodacus cucurbitae  can survive and develop on the waste  of citrus fruit (whole fruit or fruit pieces 
but probably not skin).  
• In the laboratory , Z. cucurbitae can successfully develop to the adult stage in oranges 
(C. sinensis ) and tangerines ( C. reticulata ) (McQuate et al. 2015)  
• Zeugodacus cucurbitae  females p ierce the skin of host fruit and lay 1 –40 eggs into the flesh. 
Upon hatching, larvae feed on the pulp of the fruit and drop to the ground upon maturity to 
pupate in the soil (Severin et al. 1914) .  
• Infested fruit is likely to be discarded and begin decayin g. Z. cucurbitae larvae can develop on 
both decaying and non -decaying hosts (Severin et al. 1914) . 
• If citrus fruits are disposed of as whole fruit or fruit pieces, it is likely that Z. cucurbitae  can 
survive and reach adulthood in th is waste. There is no evidence showing that Z. cucurbitae  
can complete development by feeding on citrus fruit skin.  
 
Most of the fruit waste in New Zealand is likely to be disposed of using low -risk methods , so any 
Z. cucurbitae  present would either be kill ed or be unable to escape from the citrus host.  
• Most of the waste in New Zealand is bagged and disposed of in landfills or run through  
kitchen disposal units, and in these situations, Z. cucurbitae  is unlikely to reach a new host 
(see the waste analysis i n section 2.4.1 ). 
 
However, some of the waste would be disposed of using high -risk methods, including composting in 
gardens and using as animal feed.   
• Adults of Z. cucurbitae emerging from the soil are likely to be able to find food in the 
environment if citrus fruit waste is disposed of using high -risk methods. Emerged adults have 
been observed feeding on juice from decaying fruits and rotting caterpillars (Severin et al. 
1914 ), and their diet is likely to be typical of other tephritid fruit fly adults, i.e. including plant 
exudates, honeydew, decaying insects and bird droppings (Christenson and Foote 1960) . 
These food sources are common in farms, parks and home gardens.  
• Becau se Z. cucurbitae is polyphagous, hosts for oviposition and larval development are 
available in most areas of New Zealand, either in commercial plantations or in home gardens.  
• If citrus hosts are located near composting sites or animal feeding sites, adult  Z. cucurbitae  
are likely to locate them (see  the waste analysis in  section 2.4.1 ). 
 
Adults of Z. cucurbitae are strong fliers and can fly moderate to long distances to food sources.  
• Mark –recapture trapping experiments during a sterile insect control prog ramme have shown 
that sterile adult Z. cucurbitae can disperse up to 50  km over water (Kawai et al. 1978) , and 
the maximum recorded distance is 256  km (also over water) (Waterhouse 1993) . It is 
assumed that when hosts are plentiful, Z. cucurbitae adults be come non -dispersive (Fletcher 
1989) . 
 
The level of uncertainty associated with the ability of Z. cucurbitae to move from imported fruit to a 
suitable host (moderate to high) is moderate. Firstly, waste data may not be very accurate or up to 
date, and it is  not known how frequently suitable hosts are present near composting sites or animal 
feeding locations (see the waste analysis in section 2.4.1 ). Secondly, it is uncertain what proportion of 
composting sites are exposed or covered (e.g. in a compost bin). Thirdly, the effect of seasonality on 
this likelihood is uncertain.  
  
227 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Given the arguments and evidence below, the suitability of the New Zealand 
environment for Zeugodacus cucurbitae  to establish is considered to be moderate to 
high (with moderate uncertainty) .  
Zeugodacus cucurbitae is present in areas with a high climate similarity to New Zealand.  
• Occurrence records within the native range (Pakistan, India and Bangladesh) (Virgilio et al. 
2010)  of Z. cucurbitae  are found in areas with a dissimilar  climate to New Zealand ( climate  
match index  (CMI) <0.7)  (Phillips et al. 2018; GBIF.org 2020) . However, the species has 
expanded its range into several areas with a similar climate to New Zealand ( southern China, 
Taiwan, Ethiopia, Uganda and Kenya, CMI 0. 7–0.8) (Phillips et al. 2018; GBIF .org 2020) . 
 
Modelling predicts that Z. cucurbitae could establish in Europe in areas with a very similar climate to 
New Zealand.  
• Projections of climatic suitability for Z. cucurbitae establishment in Europe show that the 
areas where the species is highly likely to establish have a very similar climate (CMI 0.7 –0.9) 
to New Zealand (Godefroid et al. 2015; Phillips et al. 2018) . 
 
Zeugodacus cucurbitae is likely to be capable of establish ing across most of the North Island and  the 
north of the South Island.  
• Depending on the experiment, the lower developmental thresholds for Z. cucurbitae  egg, 
larval and pupal stages are estimated to be 10 –15.9°C, 6.6 –13.4°C and 7.4 –12.6°C, 
respectively (Vargas et al. 1996; Vayssières et al. 200 8; Mkiga and Mwatawala 2015) . The 
lower of these estimates has a higher likelihood of being more accurate , because they are 
based on experiments where development and survival of all life stages was recorded and 
measured at 15 –16°C (Vargas et al. 1996; Vay ssières et al. 2008) .  
• Under laboratory conditions, optimal temperatures for egg, larval and pupal survival are 24 –
29°C. However, there is still substantial egg hatch (93% at 16 °C, 95% at 18 °C), larval survival 
(84% at 16 °C, 85% at 18 °C) and pupal survival  (95% at 16 °C, 96% at 18 °C) at 16 °C and 
18°C. Larval and pupal survival both decline at 32 °C (88.7% and 62.0% respectively) (Vargas 
et al. 1996) . 
• Climate modelling, using 7.5 °C as the lower temperature limit, 16 –24°C as the optimum 
temperature range and 36 °C as the upper temperature threshold, indicates that most of the 
North Island is highly suitable, and the north of the South Island is suitable, for the long -term 
establishment of Z. cucurbitae  (Figure 9.11.1 , H. Narouei -Khandan pers. comm.).  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 228 Figure 9.11.1  Map of the ecoclimatic index (Kriticos et al. 2015)  for Z. cucurbitae  showing the suitability 
of the New Zealand environment for establishment (lower temperature limit = 7.5 °C, optimum 
temperature range = 16 –24°C, upper temperature limit = 36 °C). Values of 20 or over are considered 
suitable for establishment.  
 
 
Zeugodacus cucurbitae has a high reproductive rate , which is likely to decrease, but still be high, 
under conditions across most of New Zealand in summer.  
• Under laboratory conditions, Z. cu curbitae females can lay up to 578 fertile eggs in their 
lifetime at 24 °C. This number decreases with decreasing temperature but remains high at 
both 18 °C (364 fertile eggs/lifetime) and 16 °C (142 fertile eggs/lifetime) (Vargas et al. 1997) .  
• Climate modelling using 322 degree days (the number of days of one degree above the 
developmental threshold required to complete development) per generation (Vayssières et al. 
2008)  shows that Z. cucurbitae can complete between 5 and 11 generations per yea r across 
most of the North Island and  the north of the South Island ( Figure 9.11.2 , H. Narouei -
Khandan pers. comm.).  
 
 
229 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Figure 9.11.2  Map of the number of generations Z. cucurbitae  could complete given 322 degree days  
 
Host and food availability are unlike ly to be limiting factors for Z. cucurbitae to establish in 
New Zealand.  
• Zeugodacus cucurbitae  is polyphagous with over 136 host taxa from 62 genera and 30 
families (McQuate et al. 2017) , the majority of which are grown in New Zealand . Hosts for 
oviposition and larval development are available in most areas of New Zealand, either in 
commercial plantations or in home gardens.  
• Emerged adults feed on juice from injured fruit and rotting caterpillars, and probably on 
honeydew, plant exudates, rotting insects and bird faeces (Severin et al. 1914; Christenson 
and Foote 1960) . These food sources are common in farms, parks and home gardens.  
 
Zeugodacus cucurbitae  has become a major pest outside of its native range.  
• Zeugoda cus cucurbitae is considered a major pest of commercially grown cucurbits in Hawaii 
and Africa (De Meyer and Ekesi 2016) . 
• Zeugodacus cucurbitae is considered one of the most destructive “Category A” fruit fly 
species – “Category A” includes widespread inva sive polyphagous generalists  (species that 
use a wide range of resources)  or highly destructive specialists  (species that occupy a 
narrower ecological niche)  that have become established outside  their native range (Vargas 
et al. 2015) . 
 
Zeugodacus cucurbit ae responds to cuelure and so is likely to be detected in the National Fruit Fly 
Surveillance Programme . 
• Three fruit fly lures, cuelure, trimedlure and methyl eugenol are used in the National Fruit Fly 
Surveillance Programme  in New Zealand (MacLellan et al . 2019) . Melolure (raspberry ketone 
formate) was found to be a stronger attractant than cuelure in Hawaii (Casana -Giner et al. 
2003). If a fruit fly species is responsive to one or more of these lures, early detection of an 
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 230 incursion is more likely, which reduces the likelihood of the species’ establishment in New 
Zealand.  
• Zeugodacus cucurbitae adults are attracted to cuelure (Dhillon et al. 2005; Vayssières et al. 
2007) , although a mixture of cuelure with methyl eugenol may be more effective (Ramsamy et 
al. 1987) . 
• Cuelure has been used successfully for the monitoring and control of Z. cucurbitae  (Dhillon et 
al. 2005; Sookar and Deguine 2016) . 
 
The level of uncertainty associated with the moderate to high likelihood of establishment of 
Z. cucurbitae  is moder ate. Firstly, the constant temperatures used in these studies do not reflect real -
world daily temperature fluctuations , and it is not known how this would affect survivorship and 
fecundity in the wild. Secondly, the lower temperature thresholds for egg, la rval and pupal survival are 
extrapolated from survivorship curves of Z. cucurbitae reared under laboratory conditions, i.e. on an 
artificial diet and under constant temperature. Actual developmental thresholds in the wild may be 
substantially different to these estimates.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by 
Zeugodacus cucurbitae  is likely to be high.  
Damage and symptoms caused by Zeugodacus cucurbitae  can reduce yield.  
• If Z. cucurbitae eggs are la id into fruits , then extensive larval feeding will cause fruit rot or 
distortion (Severin et al. 1914; Dhillon et al. 2005) . Although Z. cucurbitae cannot oviposit into 
harder fruits such as pumpkins, or through thicker skin such as found in oranges, it will 
oviposit via injuries (Severin et al. 1914; McQuate et al. 2015) .  
• Zeugodacus cucurbitae also oviposit s in stems, leaf petioles and flowers of cu curbits. Eggs 
laid into flowers can cause flower drop, preventing fruit production. If larvae develop in stems , 
they can penetrate the roots and destroy plants entirely (Severin et al. 1914; White and Elson -
Harris 1994) .  
 
Zeugodacus cucurbitae has been re ported to cause infestation, damage and production losses to 
several fruit and vegetable crops . 
• Prior to the initiation of suppression activities of Z. cucurbitae  on the southwestern islands of 
Japan in 1972, infestation rates of cucurbit hosts ranged up t o 100% on some islands 
(McQuate and Teruya 2015) . 
• In Nepal, yield losses due to Z. cucurbitae damage have been estimated as 28.7 –59.2% in 
pumpkin ( Cucurbita  sp.), 24.7 –40.0% in bitter gourd ( Momordica  charantia ), 27.3 –49.3% in 
bottle gourd ( Lagenaria  siceraria ), 19.4 –22.1% in cucumber ( Cucumis sativus ) and 0 –26.2% 
in sponge gourd ( Luffa sp.) (Pradhan 1977 , in Sapkota et al. 2010)  
• In squash ( Cucurbita  pepo ) grown in Nepal, Zeugodacus cucurbitae caused the loss of 9.7% 
of female flowers and damage or loss of 26% of fruits (Sapkota et al. 2010) . 
• Damage by Z. cucurbitae of 28.6% and 31.3% has been reported on watermelon ( Citrullus 
lanatus ) and bitter gourd ( Momordica  charantia ) in India (Singh et al . 2000) . 
• In West Africa and on Réunion Island, infestation rates (measured as the mean number of 
pupae formed from larvae within field -collected fruits per kilogram of fruit) exceeded 100 in 
many cucurbit hosts and ranged between 1 and 25 for non -cucurbit hosts (Vayssières et al. 
2007) . 
 
Zeugodacus cucurbitae  is likely to negatively impact many plants of economic importance to New 
Zealand.  
• Zeugodacus cucurbitae hosts include several important horticultural export crops:  avocado 
(Persea americana , FOB export value: NZ$104.3  million); squash ( Cucurbita  spp., FOB 
export value: $59.7  M); beans ( Phaseolus vulgaris , FOB export value: $ 41.1 M); capsicum 
(Capsicum  annuum , FOB export value: $20.6  M); sweet orange ( Citrus  sinensis , FOB export 
value: $1.7  M); and mandarin/tangerine ( Citrus  reticulata , FOB export value: $0.4  M) (Plant & 
Food Research 2019) . 
• Zeugodacus cucurbitae has been shown to be capable of infesting intact and damaged gold 
kiwifruit and damaged green kiwifruit under laboratory conditions, and gold kiwifruit in the field  
231 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  (in field experiments ) (Follett et al. 2019a) . Z. cucurbitae  has also been shown to be capa ble 
of infesting intact and damaged apples under laboratory conditions but not in field 
experiments (Follett et al. 2019b) . Although kiwifruit and apples make poor hosts when 
compared to papaya ( Carica papaya – a preferred host), these two fruits are New Z ealand’s 
highest value export crops (kiwifruit , FOB export value: NZ$2,302.2  million;  apples , FOB 
export value: $828.8  M). Additionally, even though kiwifruit are conditional hosts  (Aluja and 
Mangan 2008) , there is a risk that they could be infested in the  absence of preferred  hosts.  
• Many of these crops are grown in the warmer areas of New Zealand , which coincides with the 
areas most suitable for  Z. cucurbitae  establishment . 
• Even if Z. cucurbitae  were to only establish for a single summer, the impact on a single 
growing season is likely to be high.  
• Since there are no pest tephritids currently present in New Zealand and therefore no existing 
management programmes, costs of control in the event of Z. cucurbitae establishment are 
likely to be high.  
 
If Z. cucurbitae  is detected in New Zealand, the cost incurred by a response would be high.  
• The typical cost of responses is millions of dollars. For example, the Queensland fruit fly 
response in 2019 cos t approximately NZ$18 million (MPI 2020b) .  
 
Establishment of Z. cucurbitae  is likely to increase phytosanitary measures required for export to 
countries where the pest is absent.  
• Zeugodacus cucurbitae is not present in five of the top 10 export destinati ons for New 
Zealand’s horticultural produce (Plant & Food Research 2019)  and is a quarantine pest in the 
top three destinations (Australia – National Priority Plant Pest No. 4; USA – quarantine pest; 
China – A2 list) (Department of Agriculture Water and th e Environment 2019; EPPO 2020a) . 
 
Zeugodacus cucurbitae is likely to cause low to moderate sociocultural impacts on plants in home 
gardens with moderate uncertainty.  
• Several host species of Z. cucurbitae  are commonly grown in home gardens (e.g. pumpkins 
and squash, cucumbers, capsicums and chillies, and tomato). If control measures become 
necessary in residential areas , this is likely to have a negative sociocultural impact.  
 
Zeugodacus cucurbitae is likely to have very low impacts on the environment in New Zealand (with 
high uncertainty), and very low impacts on Māori cultural values (with high uncertainty).  
• Zeugodacus cucurbitae hosts include species in genera , which also contain the following 
native species: Passiflora  tetrandra , Solanum americanum , S. aviculare , S. laciniatum  and 
S. opacum . 
• Solanum aviculare var. aviculare is threatened (nationally vulnerable) and S. a. var. latifolium 
is at risk (naturally uncommon) (NZPCN 2020) . 
• Several native species in the same genera as Z. cucurbitae hosts have traditional Māori uses 
(Landcare Research 2020) : 
o S. aviculare and S. laciniatum (poroporo) was traditionally used as a food source, as 
medicine, as a tattoo dye and for making musical in struments.  
o Passiflora  tetrandra  (kōhia) was traditionally used as a medicine and as cable for 
making tools  and anchors and for construction.  
• The fruit of the native plant species are small and much less fleshy than those of preferred 
hosts of Z. cucurbitae , so the native species may not make attractive hosts. However, 
Z. cucurbitae has been reported infesting several wild Solanum species in the field at very low 
levels  (e.g. S. capsicoides  (0.33 –0.39 pupae per fruit;  S. nigrum  – 1.14 larvae and pupae/kg 
fruit; and S. pseudocapsicum  – 0.403 larvae and pupae/kg fruit ) (Liquido et al. 1994; Harris et 
al. 2003; Jacquard et al. 2013) . 
• If Z. cucurbitae lays eggs into flowers or stems of these native species (as it does in cucurbit 
species) , then it could impair  their seed development, number or viability.  It is not known 
whether Z. cucurbitae is capable of  producing population -level effects in wild species.  
 
There is no evidence that Z. cucurbitae could have a  negative  impact on human health.  
 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 232 Risk assessment summary : 
 
Given the arguments and evidence below,  Zeugodacus cucurbitae meets the criteria 
to be considered for additional measures . 
• Zeugodacus cucurbitae  has a moderate association with citrus fruit . 
• Fruit with a low level of infestation may not be detect ed during general handling, especially 
when the volume of commodities is large . 
• Because larvae feed internally inside fruit, general handling (e.g. washing and brushing) 
cannot remove the larvae, and citrus fruits need to be cut open to reveal the larvae o f 
Z. cucurbitae ;  
• Zeugodacus cucurbitae  has a moderate to high ability (with moderate uncertainty) to move 
from imported fruit and into a suitable environment to allow establishment;  
• The suitability of the New Zealand environment for Z. cucurbitae to establish is considered to 
be moderate to high (with moderate uncertainty) . 
• The establishment of Z. cucurbitae  in New Zealand is likely to cause high economic impacts.  
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  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 236 8.12 Other fruit flies  
 
This hazard identification  considers 23 species of fruit flies of economic significance. The earlier 
PRAs ( Chapter  9, sections 9.1 –9.11), carried out individually for 11 species from various geographic 
distributions , levels of host specificity and host range, showed several elements in common across all 
assessments. For this assessment, these elements have been addressed at a higher level for all fruit 
flies, and, where relevant, information particular t o each fruit fly species has been considered 
separately to determine whether the potential impacts of an incursion or establishment warrant 
consideration of additional measures on the pathway.  
 
The fruit fly species included here are:  
• Bactrocera aquilonis  
• Bactrocera melas  
• Bactrocera neohumeralis  
• Bactrocera jarvisi  
• Bactrocera kraussi  
• Bactrocera trivialis  
• Bactrocera frauenfeldi  
• Bactrocera melanotus  
• Bactrocera passiflorae  
• Bactrocera species near  passiflorae  
• Bactrocera kirki  
• Bactrocera curvipennis  
• Bactrocera psidii  
• Bactrocera distincta  
• Bactrocera correcta  
• Bactrocera latifrons  
• Bactrocera carambolae  
• Zeugodacus tau  
• Anastrepha obliqua  
• Anastrepha serpentina  
• Anastrepha sororcula  
• Anastrepha striata  
• Anastrepha suspensa  
 
This section contains:  
• Pest identity, hazard identification and host lists for each individual fruit fly species.  
• A general assessment of:  
o The strength of association of each of the above species with citrus fruit ; 
o The degree by which basic measures  are likely to reduce the likelihood of entry of the  
above species and the consequent likelihood of entry ; 
o The likelihood of establishment of the above species ; and 
o The level of impact of the above species if they were to enter or establish in New 
Zealand.  
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• The fruit fly species listed above  meet the criteria to be quarantine pests for New Zealand.  
• For the fruit flies in this assessment, the strength of association with citrus fruit ranges from 
weak to moderate –strong , depending on the species (with moderate to high uncertainty).   
237 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Basic measures  are likely to reduce the likelihood of entry of the fruit flies listed above  by a 
moderate degree (with moderate to high uncertainty) . Consequently , the likelihood of entry is 
considered to be low  to moderate (with moderate uncertainty).  
• The ability of the fruit fly species listed above to transfer from imported fruit into a suitable 
environment to allow establishment (exposure) is considered to be moderate to high (with 
moderate uncertainty).  
• The suitability of the New Zealand environment for the fruit flies listed above to establish is 
considered to be:  
o Moderate to high (with low uncertainty) for Bactrocera . melas , , B. correcta, B. 
latifrons, A. obliqua, A. serpentina, A. sororcula , A. striata , and A. suspensa ; 
o Low (with low uncertainty) for B. frauenfeldi ; and 
o Low (with moderate uncertainty) for the remaining species.  
• The level of impact caused by the fruit flies listed above  is likely to be high. Although their 
spread and  economic impact may be limited by climate, even a temporary incursion is likely to 
be associated with trade barriers and eradication costs.  
• The fruit fly species listed above  may be considered for additional measures.  
 
Summary of risk assessment against c riteria  
Criteria  Rate  Uncertainty  
Strength or frequency of association with the commodity  Weak to 
moderate –strong*  Moderate –high 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Moderate  
The ability to move from the imported commodity  onto a suitable host  Moderate –high Moderate  
Suitability of the N ew Zealand  environment ( Bactrocera   melas, , B. correcta, B. 
latifrons,  Anastrepha obliqua, A. serpentina, A. sororcula , A. striata  and A. 
suspensa ) Moderate –high Low 
Suitability of the N ew Zealand  environment ( Bactrocera frauenfeldi ) Low Low 
Suitability of the N ew Zealand  environment (all other fruit flies in this PRA)  Low Moderate  
Impacts on the New Zealand economy, environment, health and society  High Low 
* Rating is species specific, see likelihood of entry section below for details  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 238 8.12.1  Bactrocera aquilonis  (Northern Territory fruit fly)  
 
Scientific name: Bactrocera aquilonis (May, 1965)  
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera  (Bactrocera ) aquilonis , Dacus aquilonis , Strumeta aquilonis  
 
Taxonomic  notes : Bactrocera aquilonis  is a member of the B. tryoni  complex of species, which 
currently includes four named species: B. tryoni, B. aquilonis, B. mel as and B. neohumeralis . 
Bactrocera aquilonis may be a junior synonym of B. tryoni (Clarke et al. 2011) ; however, microsatellite 
and morphological data suggest that B. aquilonis is simply a western, allopatric population of B. tryoni 
(Cameron 2006; Cameron et al. 2010)  (see taxonomic notes in B. tryoni  PRA for full details).  
 
Hazard identification  
 
Bactrocera aquilonis meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are:  not present in the PRA area 
(New  Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera aquilonis is not known to be present in New Zealand:  
• The putative species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera aqu ilonis  is a regulated pest and a notifiable organism (ONZPR  2020) . 
Bactrocera aquilonis has low potential to establish and spread within New Zealand ; however, a 
transient summer population is possible, particularly in the north of New Zealand :  
• The distribution of B. aquilonis is restricted to the north of the Northern Territory and of 
Western Australia (Sultana et al. 2020) , which are areas of low climate similarity with New 
Zealand (climate match index , CMI, 0.4 –0.5, Phillips et al. 2018) . Bactrocera aquilonis is, 
therefore, unlikely to establish in New Zealand in the longer term ; however , transient summer 
population s in the north of New Zealand are possible. Even a temporary incursion is likely to 
be associated with trade barriers and eradicati on costs . 
• The putative species is polyphagous and suitable hosts include species grown throughout 
New Zealand both commercially and by home gardeners ( Table 9.12.1 ).  
The establishment of B. aquilonis in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. aquilonis has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including apples ( Malus 
domestica , FOB export value: $828.8 million), avocados ( Persea americana, FOB export 
value: $104.3 million) and capsicum ( Capsicum annuum , FOB export value: $20.6 million) 
(Plant & Food Research 2019) . 
• The establishment of B. aquilonis  also has the potential to cause sig nificant control costs and 
to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as host plants are commonly grown by 
home gardeners.  
• If B. aquilonis was detected in New Zealand, the cost incur red by a response is likely to be 
high (see the Impacts section below) . 
Distribution in countries considered in this IRA : Australia (Hancock et al. 2000) . 
Lure: Cuelure (Hancock et al. 2000) . 
 
Table 9.12.1  Bactrocera aquilonis  citrus hosts and other hosts grown in New Zealand. The type of record 
for the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus maxima  Pomelo  Listing only White and Elson -Harris (1994)  
Citrus limon  Lemon  Listing only  White and Elson -Harris (1994)   
239 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Citrus paradisi  Grapefruit  Listing only  White and Elson -Harris (1994)  
Citrus reticulata  Mandarin  Listing only  White and Elson -Harris (1994)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Persea americana  Avocado  Hancock et al. (2000) ; CABI (2020)  
Malus domestica  Apple  Hancock et al. (2000) ; CABI (2020)  
Prunus persica  Peach  Hancock et al. (2000) ; CABI (2020)  
Capsicum annuum  Capsicum  Hancock et al. (2000) ; CABI (2020)  
Solanum lycopersicum  Tomato  Hancock et al. (2000) ; CABI (2020)  
 
References  
CABI (2020) Bactrocera aquilonis . In Invasive Species Compendium . CAB International ; Wallingford, 
UK. www.cabi.org/isc  Accessed 14 October 2020.  
Cameron, E C (2006) Fruit fly pests of Northwestern Australia.  PhD thesis . University of Sydney ; 
Sydney, Australia.  http://hdl.handle.net/2123/1711   
Cameron, E C; Sv ed, J A; Gilchrist, A S (2010) Pest fruit fly (Diptera: Tephritidae) in northwestern 
Australia: one species or two? Bulletin of Entomological Research , 100(2): 197 –206. 
Clarke, A R; Powell, K S; Weldon, C W; Taylor, P W (2011) The ecology of Bactrocera try oni (Diptera: 
Tephritidae): what do we know to assist pest management? Annals of Applied Biology , 158(1): 26 –54. 
Hancock, D; Hamacek, E; Lloyd, A; Elson -Harris, M M (2000) The distribution and host plants of fruit 
flies (Diptera: Tephritidae) in Australia . Department of Primary Industries ; Queensland , Australia . 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database . 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available a t: https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary industries internal 
database. Accessed 15 September 2020.  
Sultana, S; Baumgartner, J B; Dominiak, B C; Royer, J E; Beaumont, L J (2020) Impacts of climate 
change on high priority fruit f ly species in Australia. PLOS One , 15(2): e0213820.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 240 8.12.2  Bactrocera melas  (no common name)  
 
Scientific name: Bactrocera melas (Perkins & May, 1949)  
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera  (Bactrocera ) melas , Strumeta melas  
 
Taxonomic  notes : Bactrocera melas  is a member of the B. tryoni  complex of species, which currently 
includes four named species: B. tryoni, B. aquilonis, B. melas and B. neohumeralis . Although most 
Australian entomologists consider Bactrocera melas to be a junior synonym of B. tryoni , it continues 
to hold the status o f a valid taxonomic species (Clarke et al. 2011) . 
 
Hazard identification  
 
Bactrocera melas meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera melas is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera melas  is a regulated pest (ONZPR  2020) .  
Bactrocer a melas has the potential to establish and spread within New Zealand:  
• The distribution of Bactrocera melas includes southeast Queensland (Hancock et al. 2000) , 
an area with a similar climate to  all of  New Zealand (CMI 0.7 –0.8, Phillips et al. 2018) .  
• The species is polyphagous , and suitable hosts include species grown throughout New 
Zealand both commercially and by home gardeners (Table 9.12.2 ).  
The establishment of B. melas in New Zealand has the potential to cause unwanted impacts:  
• The establishment of  B. melas has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , pear ( Pyrus communis , FOB export value: $10.6 million)  
and apples ( Malus domestica , FOB export value: $828.8 million) (Plant & Food Research 
2019) . 
• The establishment of B. melas  also has the potential to cause significant control costs and to 
impact negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as host plants are commonly grown by 
home gardeners.  
• If B. melas was detected in New Zealand, the cost incurred by a response is likely to be high 
(see Impacts section below) . 
Distribution in count ries considered in this IRA : Australia (Hancock et al. 2000) . 
Lure: Cuelure (Hancock et al. 2000) . 
   
241 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Table 9.12.2  Bactrocera melas  citrus hosts and other hosts grown in New Zealand. The type of record for 
the citrus hosts is given to indicate the strength of association with citrus hosts. All hosts below are listed in 
White and Elson -Harris (1994)  as being possible or likely hosts, but are only known from old records and not 
confirmed  by surveys.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus paradisi  Grapefruit  Listing only  White and Elson -Harris  (1994)  
Citrus sinensis  Orange  Listing only  White and Elson -Harris  (1994)  
Other hosts grown in New Zealand  
Host  name  Common name  Reference  
Eriobotrya japonica  Loquat  White and Elson -Harris  (1994)  
Malus domestica  Apple  White and Elson -Harris  (1994)  
Prunus persica  Peach  White and Elson -Harris  (1994)  
Prunus domestica  Plum  White and Elson -Harris  (1994)  
Pyrus communis  Pear  White and Elson -Harris  (1994)  
Fortunella japonica  Kumquat  White and Elson -Harris  (1994)  
 
References  
Clarke, A R; Powell, K S; Weldon, C W; Taylor, P W (2011) The ecology of Bactrocera tryoni (Diptera: 
Tephritidae): what do we know to assist pest management? Annals of Applied Biology , 158(1): 26 –54. 
Hancock, D; Hamacek, E; Lloyd, A; Elson -Harris, M M (2000) The distribution and host plants of fruit 
flies (Diptera: Tephritidae) in Australia . Department of Primary Industries ; Queensland , Australia . 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database.  
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticultur e. The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 242 8.12.3  Bactrocera neohumeralis  (lesser Queensland fruit fly)  
 
Scientific name: Bactrocera neohumeralis (Hardy, 1951)  
Order/Family: Diptera/Tephritidae  
Other names: Bactrocera  (Bactrocera ) neohumeralis , Chaetodacus humeralis , Dacus tryoni  var. 
neohumeralis , Dacus neohumeralis  
 
Taxonomic  notes : Bactrocera neohumeralis  is a member of the B. tryoni  complex of species, which 
currently includes four named species: B. tryoni, B. aquilonis, B. melas and B. neohumeralis . 
Although the taxonomic status of B. aquilonis and B. melas is unclear, B. neohumeralis  is accepted as 
a valid species ; however, its populations in Papua New Guinea attributed to B. neohumeralis  may 
constitute an unrecognised, additional species in the complex (Clarke et al. 2011) . 
 
Hazard identification  
 
Bactrocera neohumeralis meets the criteria to be a quarantine pest f or New Zealand  
. 
Criteria for being a quarantine pest relevant to this assessment are: the pest is not present in the PRA 
area (New Zealand), and  the pest  is of potential importance (able to establish and cause harm).  
 
Bactrocera neohumeralis is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera neohumeralis  is a regulated pest and a notifiable organism (ONZPR  2020) . 
• New Zealand has country freedom status for B. neohumeralis (MPI 2020) . 
Bactrocera neohumeralis has the potential to establish and spread in New Zealand:  
• The distribution of B. neohumeralis  extends along eastern Australia, from Queensland to 
central New South Wales (Sultana et al. 2020) and with occasional detections as far s outh as 
Sydney (Dominiak and Worsley 2016). Dominiak (2021) considers Sydney to be free of B. 
neohumeralis , though low numbers are trapped in many years. Kriticos (2007) assessed the 
risk of establishment of fruit flies in New Zealand under climate change using CLIMEX 
modelling, and concluded that that, even under the warmest climate change scenarios 
considered (in the 2080s ), B. neohumeralis would be barely able to persist even at the 
northernmost tip of Cape Reinga. According to Sultana et al. (2020), B. neohumeralis has a 
substantially narrower climate tolerance than B. tryoni . However Wan et al. (2020) used 
MAXENT to predict that most of the North Island and Central Otago were areas of high 
climate suitability for B. neohumeralis . It is likely that B. neohumeralis  would be able to 
establish in warmer northern regions of New Zealand but there is a moderate to high level of 
uncertainly associated with this  assessment  .  
• The species is polyphagous , and suitable hosts include species grown throughout New 
Zealand both commercially and by home gardeners ( Table 9.12. 3).  
The establishment of B. neohumeralis in New Zealand has the potential to cause unwanted impacts . 
Direct impacts may be limited by its likely restricted distribution, athough there is a moderate to high 
level of uncertainty about how limited its distribution is likely to be  since the outputs of climate models 
for this species are somewhat conflicting ) 
• The establishment of B. neohumeralis has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , apples ( Malus domestica , FOB export value: $828.8 
million) and capsi cum ( Capsicum annuum , FOB export value: $20.6 million) (Plant & Food 
Research 2019) . It also has the potential to cause significant control costs and to impact 
negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as host plants are commonly grown by 
home gardeners.  
• If B. neohumeralis was detected in New Zealand, the cost incurred by a response is likely to 
be high (see the Impacts section below) .  
243 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Distribution in countries considered in this IRA : Australia (Sultana et al. 2020) .  
Lure: Cuelure (Hancock et al. 2000)  
 
Table  9.12.3  Bactrocera neohumeralis  citrus hosts and other hosts grown in New Zealand. The type of 
record for the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantiifolia  Mexican lime  Listing only  Hancock et al. (2000)  
Citrus maxima  Pomelo  Listing only  Hancock et al. (2000)  
Citrus limon  Lemon , bush lemon, sweet 
lemon  Listing only  Hancock et al. (2000)  
Citrus  paradisi Grapefruit  Listing only  Hancock et al. (2000)  
Citrus reticulata  Mandarin  Listing only  Hancock et al. (2000)  
Citrus sinensis  Sweet orange  Listing only  Hancock et al. (2000)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Passiflora edulis  Passionfruit  Hancock et al. (2000)  
Malus domestica  Apple  Hancock et al. (2000)  
Prunus persica  Peach  Hancock et al. (2000)  
Prunus armeniaca  Apricot  Hancock et al. (2000)  
Prunus domestica  Plum  Hancock et al. (2000)  
Prunus persica var. nucipersica  Nectarine  Hancock et al. (2000)  
Capsicum annuum  Capsicum  Hancock et al. (2000)  
Solanum lycopersicum  Tomato  Hancock et al. (2000)  
 
References  
Clarke, A R; Powell, K S; Weldon, C W; Taylor, P W (2011) The ecology of Bactrocera tryoni (Diptera: 
Tephritidae): what do we know to assist pest management? Annals of Applied Biology , 158(1): 26 –54. 
Dominiak, B C; Worsley, P (2016) Lesser Queensland fruit  fly Bactrocera neohumeralis  (Hardy) 
(Diptera: Tephritidae: Dacinae) not detected in inland New South Wales or south of Sydney. General 
and Applied Entomology 44: 9 –15. 
Dominiak, B C (2021) Surveillance for exotic fruit fly of the subfamily Dacinae (Insecta, Diptera, 
Tephrididae) and a review of the Dacinae established in Sydney, Australia, between 2010 and 2019, 
New Zealand Entomologist , DOI:10.1080/00779962.2021.1896061 . 
Hancock, D; Hamacek, E; Lloyd, A; Elson -Harris, M M (2000) The distribution and host plants of fruit 
flies (Diptera: Tephritidae) in Australia . Department of Primary Industries ; Queensland , Australia . 
Kriticos, D J (2007) Risks of establishment of fruit flies in New Zealand under climate change. Ensis 
Client Report No. 12244, Kingston, Australia.  
MPI (2020) Country freedom status database. https://www.mpi.govt.nz/news -and-
resources/resources/registers -and-lists/country -freedom -status/  Accessed 2 October 2020.  
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’  
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts. New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary industries internal 
database. Access ed 15 September 2020.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 244 Sultana, S; Baumgartner, J B; Dominiak, B C; Royer, J E; Beaumont, L J (2020) Impacts of climate 
change on high priority fruit fly species in Australia. PLOS One , 15(2): e0213820.  
Wan, J; Qi, G -J; Jun, M A; Ren, Y; Wang, R; McKirdy, S (2020) Predicting the potential geographic 
distribution of Bactrocera bryoniae and Bactrocera neohumeralis  (Diptera: Tephritidae) in China using 
MaxEnt ecological niche modelling. Journal of Integrativ e Agriculture 19 (8): 2072 –2082.  
 
   
245 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.4  Bactrocera jarvisi  (Jarvis’ fruit fly)  
 
Scientific name: Bactrocera jarvisi (Tryon, 1927)  
Order/Family: Diptera/Tephritidae  
Other names: Chaetodacus jarvisi , Dacus jarvisi  
 
Hazard identification  
 
Bactrocera jarvisi meets  the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera jarvisi is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera jarvisi  is a regulated pest and a notifiable organism (ONZPR  2020) .  
• New Zealand has country freedom status for B. jarvisi  (MPI 2020) . 
Bactrocera jarvisi has the potential to establish and spread in New Zealand:  
• The distribution of B. jarvisi extends from northwest Western Australia, across the Northern 
Territory to northern Queensland  (Sultana et al. 2020) . Sultana et al. (2020) also report that in 
favourable years it may spread d own the east coast of Australia  into northern coastal New 
South Wales, an area with a similar climate to all of New Zealand (CMI 0. 8–0.9, Phillips et al. 
2018) . However Dominiak and Worsley (2017) consider most records from N SW to be 
incursions, and that the southern boundary of the endemic range of B. jarvisi  is somewhere 
north of the border between Queensland  and N SW. Kriticos (2007) assessed the risk of 
establishment of fruit flies in New Zealand under climate  change using CLIMEX modelling, 
and concluded that that, even under the warmest climate change scenarios considered (in the 
2080s), B. jarvisi  would be barely able to persist even at the northernmost tip of Cape Reinga. 
It is likely that B. jarvisi  would b e capable of establishing persistent populations only in the 
most n ortherly regions  of New Zealand.  
• The species is polyphagous , and suitable hosts include species grown throughout 
New Zealand both commercially and by home gardeners ( Table 9.12.4 ).  
The est ablishment of B. jarvisi in New Zealand has the potential to cause unwanted impacts , though 
direct impacts would be limited by its likely  restricted distribution :  
• The establishment of B. jarvisi has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , pear ( Pyrus communis , FOB export value: $10.6 million)  
and apples ( Malus domestica , FOB export value: $828.8 million) and avocados ( Persea 
americana, FOB export value: $104.3 million) (Plant & Food Research 2019) . It also has the 
potential to cause significant control costs and to impact negatively on national and 
international trade.  
• It also has the potential to cause sociocultural  impacts , as host plants are commonly grown by 
home gardeners.  
• If B. jarvisi was detected in New Zealand, the cost incurred by a response is likely to be high 
(see the Impacts section be low). 
 
Distribution in countries considered in this IRA : Australi a (New South Wales, Northern Territory , 
Queens land, W estern Australia ) (Hancock et al. 2000)  
 
Lure: Weakly attracted to cuelure  in northern W estern Australia  but not elsewhere (Drew 1989) . Males 
are attracted to zingerone (Fay 2012) . 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 246 Table  9.12.4   Bactrocera jarvisi  citrus hosts and other hosts grown in New Zealand. The type of record for 
the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantiifolia  Mexican lime  Listing only  Hancock et al. (2000)  
Citrus maxima  Pomelo  Listing only  Hancock et al. (2000)  
Citrus limon * Lemon  Listing only  Hancock et al. (2000)  
Citrus paradisi* Grapefruit  Listing only  Hancock et al. (2000)  
Citrus reticulata * Mandarin  Listing only  Hancock et al. (2000)  
Citrus sinensis*  Sweet orange  Listing only  Hancock et al. (2000)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Persea americana  Avocado  Hancock et al. (2000)  
Malus domestica^  Apple  Hancock et al. (2000)  
Prunus persica  Peach  Hancock et al. (2000)  
Prunus armeniaca  Apricot  Hancock et al. (2000)  
Diospyros kaki^  Persimmon  Hancock et al. (2000)  
Pyrus communis ^ Pear  Hancock et al. (2000)  
* Occasional host  
^ Moderate host  
 
References  
Dominiak, B C; Worsley, P (2017) Review of the southern boundary of Jarvis fruit fly Bactrocera jarvisi  
(Tryon) (Diptera: Tephritidae: Dacinae) and its likely southern distribution in Australia. General and 
Applied Entomology 45: 17.  
Drew, R A I (1989) The tropical fruit flies (Diptera: Tephritidae: Dacinae) of the Australasian and 
Oceanian regions . Memoirs  of the Queensland Museum, 26.  
Fay, H A C (2012) A highly effective and selective male lure for Bactrocera jarvisi (Tryon) (Diptera: 
Tephritidae). Australian Journal of Entomology , 51(3): 189 –197. 
Hancock, D; Hamacek, E; Lloyd, A; Elson -Harris, M M (2000) The distribution and host plants of fruit 
flies (Diptera: Tephritidae) in Australia . Department of Primary Industries ; Queensland , Australia . 
Kriticos, D J (2007) Risks of establishment of fruit flies in New Zealand under climate change. Ensis 
Client Report No. 12244, Kingston, Australia.  
MPI (2020) Country freedom status database. https://www.mpi.govt.nz/news -and-
resources/resources/registe rs-and-lists/country -freedom -status/  Accessed 2 October 2020.  
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public data base. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with no n-native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Hortic ulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary industries internal 
database. Accessed 15 September 2020.  
Sultana, S; Baumgartner, J B; Domi niak, B C; Royer, J E; Beaumont, L J (2020) Impacts of climate 
change on high priority fruit fly species in Australia. PLOS One , 15(2): e0213820.  
 
   
247 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.5  Bactrocera kraussi  (Krauss’s fruit fly)  
 
Scientific name: Bactrocera kraussi (Hardy, 1951)  
Order/Family: Diptera/Tephritidae  
Other names: Dacus kraussi  
 
Hazard identification  
 
Bactrocera kraussi meets the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera kraussi is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera kraussi  is a regulated pest (ONZPR  2020) . 
Bactroc era kraussi  has low potential to establish and spread within New Zealand ; however, a 
transient summer population is possible, particularly in the north of New Zealand :  
• The distribution of B. kraussi is restricted to the north of Australia (Torres Strait Islands and 
northeast Queensland as far south as Townsville, Sultana et al. 2020) , an area of low climate 
similarity with New Zealand (CMI 0.4 –0.6, Phillips et al. 2018) . Bactrocera kraussi  is, 
therefore, unlikely to establish in New Zealand in the longer t erm; however, the establishment 
of a transient summer population in the north of New Zealand is possible. Even a temporary 
incursion is likely to be associated with trade barriers and eradication costs . 
• The species is reported from multiple Citrus spp., which are grown in some regions of 
New Zealand both commercially and by home gardeners (Table 9.12.5 ).  
The establishment of B. kraussi in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. kraussi has the potential to cause ec onomic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million)  and capsicum (Capsicum annuum , FOB export value: 
$20.6 million) (Plant & Food Research 2019) . It also has the potential to cause significant 
control costs and to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as citrus trees are commonly grown 
by home gardeners.  
• If B. kraussi  was detec ted in New Zealand, the cost incurred by a response is likely to be high 
(see the Impacts section below) . 
Distribution in countries considered in this IRA : Australia (Torres Strait Islands and northeast 
Queensland as far south as Townsville) (Hancock et al. 2000)  
 
Lure: Cuelure  and isoeugenol (Hancock et al. 2000; Royer 2015)  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 248 Table 9.12.5  Bactrocera kraussi  citrus hosts and other hosts grown in New Zealand. The type of record for 
the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantiifolia  Mexican lime  Listing only  Hancock et al. (2000)  
Citrus aurantium  Sour orange  Listing only  Hancock et al. (2000)  
Citrus limon  Lemon  Listing only  Hancock et al. (2000)  
Citrus paradisi Grapefruit  Listing only  Hancock et al. (2000)  
Citrus reticulata  Mandarin  Listing only  Hancock et al. (2000)  
Citrus sinensis  Sweet orange  Listing only  Hancock et al. (2000)  
Citrus limon  Bush lemon  Listing only  Hancock et al. (2000)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Solanum lycopersicum  Tomato  Hancock et al. (2000)  only two records  
Capsicum annuum  Capsicum  Hancock et al. (2000)  only two records  
 
References  
Hancock, D; Hamacek, E; Lloyd, A; Elson -Harris, M M (2000) The distribution and host plants of fruit 
flies (Diptera: Tephritidae) in Australia . Department of Primary Industries ; Queensland , Australia . 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B;  Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Informa tion Network, Version 5.03.01. Ministry for Primary Industries Internal 
Database. Accessed 15 September 2020.  
Royer, J E (2015) Responses of fruit flies (Tephritidae: Dacinae) to novel male attractants in north 
Queensland, Australia, and improved lures for  some pest species. Austral Entomology , 54(4): 411 –
426. 
Sultana, S; Baumgartner, J B; Dominiak, B C; Royer, J E; Beaumont, L J (2020) Impacts of climate 
change on high priority fruit fly species in Australia. PLOS One , 15(2): e0213820.  
  
249 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.6  Bactrocera trivialis  (no common name)  
 
Scientific name: Bactrocera trivialis (Drew, 1971)  
Order/Family: Diptera/Tephritidae  
Other names:  Bactrocera  (Bactrocera ) trivialis , Dacus trivialis  
 
Hazard identification  
 
Bactrocera trivialis meets the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), a nd of potential importance (able to establish and cause harm).  
 
Bactrocera trivialis is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera trivialis  is a regulated pest and a notifiable organism (ONZPR  2020) . 
Bactrocera trivialis has low potential to establish and spread within New Zealand ; however, a transient 
summer population is possible, particularly in the north of New Zealand :  
• Bactrocera trivialis is native to Papua New Guinea and West Papu a, but it makes seasonal 
incursions into the Torres Strait Islands (Plant Health Australia 2018) . All of these areas have 
a dissimilar climate to New Zealand (CMI 0.3 –0.6, Phillips et al. 2018) . Bactrocera trivialis is, 
therefore, unlikely to establish in New Zealand in the longer term ; however, the establishment 
of a transient summer population in the north of New Zealand is possible. Even a temporary 
incursion is likely to be associated with trade barriers and eradication costs.  
• Hosts of the species inclu de plants grown in regions of New Zealand both commercially and 
by home gardeners (Table 9.12.6 ).  
The establishment of B. trivialis in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. trivialis has the potential to cause e conomic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million)  and peaches (Prunus persica , FOB export value: $ 0.4 
million) (Plant & Food Research 2019) . It also has the potential to cause significant control 
costs and to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as citrus trees are commonly grown 
by home gardeners.  
• If B. trivialis was det ected in New Zealand, the cost incurred by a response is likely to be high 
(see the Impacts section below) . 
Distribution in countries considered in this IRA : Australia  (seasonal incursions into Torres Strait 
Islands ) (Plant Health Australia 2018) .  
 
Lure: Cuelure (Leblanc et al. 2013)  
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 250 Table  9.12.6  Bactrocera trivialis  citrus hosts and other hosts grown in New Zealand. The type of record for 
the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the numbers in 
brackets indicate the numbers of fruit from which adults emerged out of the total number of samples collected for 
the host plant.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus paradisi Grapefruit  Listing only  Leblanc et al. (2013) ; White and Elson -Harris  (1994)  
Citrus sinensis  Sweet orange  Field record (1/11)  Leblanc et al. (2013)  
Other relevant hosts to New Zealand  
Host name  Common name  Reference  
Prunus persica  Peach  Leblanc et al. (2013)  
Capsicum annuum  Chilli  Leblanc et al. (2013)  
 
References  
Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of the Hawaiian 
Entomological Society , 45: 83 –177. 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd; Auckland , NZ.  
Plant Health Australia (2018) The Australian Handbook for the Identification of Fruit Flies. Version 3.1 . 
Plant Health Australia. Canberra, ACT , Australia . 
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primar y Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
  
251 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.7  Bactrocera frauenfeldi  (mango frui t fly)  
 
Scientific name:  Bactrocera frauenfeldi (Schiner, 1868)  
Order/Family: Diptera/Tephritidae  
Other names: Dacus frauenfeldi , Strumeta frauenfeldi  
 
Hazard identification  
 
Bactrocera frauenfeldi meets the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), and  of potential importance (able to establish and cause harm).  
 
Bactrocera frauenfeldi is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera frauenfeldi  is a regulated pest and a notifiable organism (ONZPR  2020) .  
Bactrocera frauenfeldi has low potential to establish and spread within New Zealand ; however, a 
transient summer  population is possible, particularly in the north of New Zealand :  
• The distribution of B. frauenfeldi is in northern Australia and the Pacific Islands  – areas with a 
dissimilar average climate to New Zealand (Phillips et al. 2018) . 
• Bactrocera frauenfeldi has not expanded its range southward in Australia , despite the 
absence of any controls and an abundance of available hosts, and it is unlikely to be able to 
establish in areas that do not fulfil the following conditions:  
o a minimum temperature for the cold est month greater than 13.2°C ;  
o an annual temperature range (the difference between the maximum temperature of 
the warmest month and the minimum temperature of the coldest month) less than 
19.3°C ; 
o a mean temperature of the driest quarter greater than 20.2° C;  
o precipitation of the wettest month greater than 268 mm ;  
o precipitation of the wettest quarter greater than 697 mm ;  
o temperature seasonality (the annual range in weekly mean temperature) less than 
30.9°C (Royer et al. 2016) . 
• Given that no part of New Ze aland fulfils the above climate requirements, B. frauenfeldi  is 
unlikely to establish in New Zealand in the longer term ; however, the formation  of a transient 
summer population in the north of New Zealand is possible.  Even a temporary incursion is 
likely t o be associated with trade barriers and eradication costs . 
• The species is reported from multiple Citrus spp. and Persea americana (avocado) , which are 
grown in some regions New Zealand both commercially and by home gardeners ( Table 
9.12.7 ). Therefore, suit able hosts would be present to support establishment.   
The establishment of B. frauenfeldi in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. frauenfeldi has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , avocado (Persea americana, FOB export value: $104.3 
million) and cap sicum  (Capsicum annuum , FOB export value: $20.6 million) (Plant & Food 
Research 2019) . It also has the potential to cause significant control costs and to impact 
negatively on national and international trade.  
• It also has the potential to cause sociocultur al impacts , as citrus trees are commonly grown 
by home gardeners.  
• If B. frauenfeldi was detected in New Zealand, the cost incurred by a response is likely to be 
high (see  the Impacts section below) . 
Distribution in countries considered in this IRA : Australia (Hancock et al. 2000)  and Solomon Islands 
(Leblanc et al. 2013)  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 252 Lure: Cuelure , Melolure (raspberry ketone formate)  (Hancock et al. 2000)  
 
Table 9.12.7   Bactrocera frauenfeldi  citrus hosts and other hosts grown in New Zealand. The type of 
record  for the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the 
numbers in brackets indicate the numbers of fruit from which adults emerged out of the total number of samples 
collected for the host plant.   
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantium  Sour orange  Field record (3/34)  Leblanc et al. (2012)  
Citrus maxima  Pomelo  Field record (5/58)  Leblanc et al. (2012)  
Citrus limon  Lemon  One field record  Hancock et al. (2000)   
Citrus paradisi  Grapefruit  Field record (2/16)  Hancock et al. (2000) ; Leblanc et al. (2012)   
Citrus reticulata  Mandarin  Field record (18/34)  Hancock et al. (2000) ; Leblanc et al. (2012)  
Citrus sinensis  Sweet orange  Field record (10/33)  Hancock et al. (2000) ; Leblanc et al. (2012)  
Citrus reticulata  Calamondin  Field record (5/20)  Leblanc et al. (2012)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Persea americana  Avocado  Hancock et al. (2000) ; Leblanc et al. (2012)  
Capsicum annuum  Capsicum  Hancock et al. (2000) ; Leblanc et al. (2012)  
 
References  
Hancock, D; Hamacek, E; Lloyd, A; Elson -Harris, M M (2000) The distribution and host plants of fruit 
flies (Diptera: Tephritidae) in Australia . Department of Primary Industries ; Queensland , Australia . 
Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of the Hawaiian 
Entomological Society , 45: 83 –177. 
Leblanc, L; Vueti, E; Drew, R; Allwood, A (2012) Host plant records for fruit flies (Diptera: Tephritidae: 
Dacini) in the Pacific Islands. Proceedings of the Hawaiian Entomological Society 44: 11 -53. 
NZOR (2011) The New Zealand Organis ms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at: https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Pla nt Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
Royer, J E; Wright, C L; Hancock, D L (2016) Bactrocera frauenfeldi (Diptera: Tephritidae), an 
invasive fruit fly in Australia that  may have reached the extent of its spread due to environmental 
variables. Austral Entomology , 55(1): 100 –111. 
 
   
253 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.8  Bactrocera melanotus  (no common name)  
 
Scientific name: Bactrocera melanotus (Coquillett , 1909)  
Order/Family: Diptera/Tephritidae  
Other names: Bactrocera  (Bactrocera ) melanotus , Bactrocera melanota , Chaetodacus melanotus , 
Dacus melanotus , Dacus rarotongae , Strumeta melanota  
 
Hazard identification  
 
Bactrocera melanotus meets the criteria to be a quarantine pest for New Zealand . 
 
Crite ria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera melanotus is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera melanotus  is a regulated pest and a notifiable organism (ONZPR  2020) . 
Bactrocera melanotus has the potential to establish and spread in New Zealand:  
• The distribution of B. melanotus is restricted to the Cook Islands (Leblanc et al. 2012) . The 
CMI of this island is not available (Phillips et al. 2018) , but the average climate is likely to be 
dissimilar to that of New Zealand. The suitability of the New Zealand environment for 
establishme nt of B. melanotus  cannot be definitively ruled out , because a distribution on a 
single remote island may not be reflective of the fundamental niche of this species but rather 
of geographic isolation.  
• The species is polyphagous , and suitable hosts include species grown throughout 
New Zealand both commercially and by home gardeners ( Table 12.9.8 ).  
The establishment of B. melanotus in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. melanotus has the potential to cause econom ic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million)  and avocados ( Persea americana, FOB export value: 
$104.3 million) (Plant & Food Research 2019) . It also has the potential to cause significant 
control costs and to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as host plants are commonly grown by 
home gardeners.  
• If B. melanotus was dete cted in New Zealand, the cost incurred by a response is likely to be 
high (see the Impacts section below) . 
 
Distribution in countries considered in th is IRA: the Cook Islands (Leblanc et al. 2012)  
 
Lure: Cuelure (Leblanc et al. 2012)  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 254 Table 9.12.8   Bactrocera melanotus  citrus hosts and other hosts grown in New Zealand. The type of record 
for the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the number 
in brackets indicates the numbers of fruit fro m which adults emerged (total number of samples not available).  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantium  Sour orange  Listing only*  Leblanc et al. (2013)  
Citrus maxima  Pomelo  Field record (4)  Leblanc et al. (2012)  
Citrus paradisi Grapefruit  Field record (4)  Leblanc et al. (2012)  
Citrus reticulata  Mandarin  Field record (1)  Leblanc et al. (2012)  
Citrus sinensis  Sweet orange  Field record (8)  Leblanc et al. (2012)  
Other relevant hosts to New Zealand  
Host name  Common name  Reference  
Persea americana  Avocado  Leblanc et al. (2012)  
Solanum lycopersicum  Tomato  Leblanc et al. (2012)  
Solanum melongena  Eggplant  Leblanc et al. (2012)  
* According to Leblanc et al. (2013) , “there is a plausible record of B. melanotus  on C. aurantium  in Bezzi  (1928) , but cited 
by White and Elson -Harris (1992)  as requiring confirmation” .  
 
References  
Bezzi, M (1928) Diptera Brachycera and Athericera of the Fiji Islands: based on material in the British 
Museum (Natural History) . Printed by Order of the Trustees of the British Museum; London , UK. 
Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedin gs of the Hawaiian 
Entomological Society , 45: 83 –177. 
Leblanc, L; Vueti, E; Drew, R; Allwood, A (2012) Host plant records for fruit flies (Diptera: Tephritidae: 
Dacini) in the Pacific Islands. Proceedings of the Hawaiian Entomological Society , 44: 11 –53. 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research L td; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1992) Fruit Flies of Economic Significance : Their Identification a nd 
Bionomics.  CAB International ; Wallingford, UK.  
 
   
255 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.9  Bactrocera kirki  (no common name)  
Scientific name: Bactrocera kirki (Froggatt, 1910)  
Order/Family: Diptera/Tephritidae  
Other names: Dacus kirki , Strumeta kirki  
 
Hazard identification  
 
Bactrocera kirki meets the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), and  of potential importance (able to establish and cause harm).  
 
Bactrocera kirki is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera kirki  is a regulated pest and a notifiable organism (ONZPR  2020) .  
Bactrocera kirki has the potential to establish and spread in New Zealand:  
• Bactrocera kirki is present in several Pacific Islands (Leblanc et al. 2012)  – all locations where 
a CMI is unavailable (Phillips et al. 2018)  but where the average climate is likely to be 
dissimil ar to that of New Zealand. The suitability of the New Zealand environment for 
establishment of B. kirki  cannot be definitively ruled out , because a distribution on remote 
islands may not be reflective of the fundamental niche of this species but rather of geographic 
isolation.  
• The species is polyphagous and suitable hosts include species grown throughout 
New Zealand both commercially and by home gardeners ( Table 9.12.9 ).  
The establishment of B. kirki in New Zealand has the potential to cause unwanted impac ts:  
• The establishment of B. kirki has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , avocados ( Persea americana, FOB export value: $104.3 
million) and capsicum ( Capsicum annuum , FOB export value: $20.6 million) (Plant & Food 
Research 2019) . It also has the potential to cause significant control costs and to impact 
negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as host plants are commonly grown by 
home gardeners.  
• If B. kirki was detected in New Zealand, the cost incurred by a response is likely to be high 
(see the Impacts section below) . 
Distribution in countries  considered in th is IRA: Fiji (Rotuma) and Samoa (Leblanc et al. 2012)  
 
Lure: Cuelure (Leblanc et al. 2013)  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 256 Table 9.12.9  Bactrocera kirki  citrus hosts and other hosts grown in New Zealand. The type of record for 
the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the numbers in 
brackets indicate the numbers of fruit from which adults emerged out of the total number of samples collected for 
the host plant.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantifolia  Mexican lime  Laboratory host * Leblanc et al. (2013)  
Citrus latifolia  Tahitian lime  Laboratory host * Leblanc et al. (2013)  
Citrus maxima  Pomelo  Field record (27/214)  Leblanc et al. (2013)  
Citrus paradisi  Grapefruit  Laboratory host * Leblanc et al. (2013)  
Citrus reticulata  Mandarin  Field record (3/70)  White and Elson -Harris  (1994) ; Leblanc et al. (2013)  
Citrus sinensis  Sweet orange  Field record (5/119)  White and Elson -Harris  (1994) ; Leblanc et al. (2013)  
Other hosts  grown in New Zealand  
Host name  Common name  Reference  
Persea americana  Avocado  Leblanc et al. (2013)  
Passiflora edulis  Passionfruit  Leblanc et al. (2013)  
Prunus persica  Peach  Leblanc et al. (2013)  
Capsicum annuum*  Capsicum  Leblanc et al. (2013)  
Solanum lycopersicum  Tomato  Leblanc et al. (2013)  
Solanum melongena  Eggplant  Leblanc et al. (2013)  
* Flies have been bred from damaged fruits exposed to gravid females . 
 
References  
Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of the Hawaiian 
Entomological Society , 45: 83 –177. 
Leblanc, L; Vueti, E; Drew, R; Allwood, A (2012) Host plant records for fruit flies (Diptera: Tephritidae: 
Dacini) in the Pacific Islands. Proceedings of the Hawaiian Entomological Society , 44: 11 –53. 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean , J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
 
   
257 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.10  Bactrocera passiflorae  (Fijian fruit fly)  
 
Scientific name: Bactrocera passiflorae (Froggatt, 1910)  
Order/Family: Diptera/Tephritidae  
Other names:  Bactrocera  (Bactrocera ) passiflorae , Dacus passiflorae , Strumeta passiflorae  
 
Hazard identification  
 
Bactroce ra passiflorae meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area (New 
Zealand), and  of potential importance (able to establish and cause harm).  
 
Bactrocera passiflorae is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera passiflorae  is a regulated pest and a notifiable organism (ONZPR  2020) . 
Bactrocera passiflorae has the potential to establish and spread in New Zealand:  
• Bactrocera passiflorae is found in Fiji (CMI 0.4) and two other Pacific Island  countries  (Niue, 
Wallis and Futuna ) (Leblanc et al. 2012)  where the CMI is unavailable (Phillips et al. 2018)  
but wher e the average climate is likely to be dissimilar to that of New Zealand. The suitability 
of the New Zealand environment for establishment of B. passiflorae  cannot be definitively 
ruled out , because the remote island distribution of this species may not be reflective of its 
fundamental niche but rather of geographic isolation.  
• The species is polyphagous , and suitable hosts include species grown throughout 
New Zealand both commercially and by home gardeners ( Table 9.12.10 ).  
The establishment of B. passiflor ae in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. passiflorae has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , avocadoes ( Persea americana, FOB export value: 
$104.3 million) and capsicum ( Capsicum annuum , fob export value: $20.6 million) (Plant & 
Food Research 2019) . It also has the potential to cause significant control costs and to  impact 
negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as host plants are commonly grown by 
home gardeners.  
• If B. passiflorae was detected in New Zealand, the cost incurred by a response is likely  to be 
high (see  the Impacts section below) . 
Distribution in countries considered in this IRA : Fiji (Leblanc et al. 2013)  
 
Lure: Cuelure (Leblanc et al. 2013)  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 258 Table  9.12.10   Bactrocera passiflorae  citrus hosts and other hosts grown in New Zealand. The type of 
record for the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the 
numbers in brackets indicate the numbers of fruit from which adults emerged out of the total number of samples 
collected for the host plant.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantium  Sour orange  Listing only  Leblanc et al. (2013)  
Citrus maxima  Pomelo  Field record (21/79)  Leblanc et al. (2013)  
Citrus limon  Lemon  Field record (9/219)  Leblanc et al. (2013)  
Citrus paradisi Grapefruit  Field record (13/96)  Leblanc et al. (2013)  
Citrus reticulata  Mandarin  Field record (13/137)  Leblanc et al. (2013)  
Citrus sinensis  Sweet orange  Field record (14/221)  Leblanc et al. (2013)  
Fortunella japonica  Kumquat  Field record (40/146)  Leblanc et al. (2013)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Persea americana  Avocado  Leblanc et al. (2013)  
Capsicum annuum  Capsicum  Leblanc et al. (2013)  
Solanum lycopersicum  Tomato  Leblanc et al. (2013)  
 
References  
Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of the Hawaiian 
Entomological Society , 45: 83 –177. 
Leblanc, L; Vueti, E; Drew, R; Allwood, A (2012) Host plant records for fruit flies (Diptera: Tephritidae: 
Dacini) in the Pacific Islands. Proceedings of the Hawaiian Entomological Society 44: 11 –53. 
NZOR (2011) The New Zealand Organis ms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at: https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Pla nt Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
 
 
 
   
259 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.11  Bactrocera  species near passiflorae  (no common name)  
 
Scientific name : Bactrocera species near passiflorae (sensu  Drew and Hancock , 1995)  
Order/Family: Diptera/Tephritidae  
Other names: none  
 
Taxonomic notes: Characterized by Drew and Hancock (1995)  as the pale form of B. passiflorae , 
though not described, designated or named as a new species (Leblanc et al. 2012)  
 
Hazard identification  
 
Bactrocera sp. nr.  passiflorae meets the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area (New 
Zealand), and of potential importance (a ble to establish and cause harm).  
 
Bactrocera sp. nr.  passiflorae is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera sp. nr.  passiflorae  does not have an assigned regulatory status . 
Bactrocera sp. nr  passiflorae has the potential to establish and spread in New Zealand:  
• Bactrocera sp. nr. passiflorae is found in Fiji (CMI 0.4) and several Pacific Islands (Leblanc et 
al. 2012)  where the CMI is unavailable (Phillips et al. 2018)  but where the average climate is 
likely to be dissimilar to that of New Zealand. The suitability of the New Zealand environment 
for establishment of B. sp. nr.  passiflorae  cannot be definitively ruled out , because the remote 
island distribution of this sp ecies may not be reflective of its fundamental niche but rather of 
geographic isolation.   
• The species is polyphagous , and suitable hosts include species grown throughout New 
Zealand both commercially and by home gardeners ( Table 9.12.11 ).  
The establishme nt of B. sp. nr  passiflorae in New Zealand has the potential to cause unwanted 
impacts:  
• The establishment of B. sp. nr  passiflorae has the potential to cause economic impacts by 
directly damaging horticultural crops that are significant to New Zealand, in cluding citrus 
(Citrus sp., FOB export value: NZ$12.0 million)  and avocado (Persea americana, FOB export 
value: $104.3 million) (Plant & Food Research 2019) . It also has the potential to cause 
significant control costs and to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as citrus trees are commonly grown 
by home gardeners.  
• If B. sp. nr  passiflorae  was detected in New Zealand, the cost incurred by a response is likely 
to be high (see  the Impacts section below) . 
Distribution in countries considered in this IRA : Fiji (Leblanc et al. 2013)   
 
Lure: Cuelure (Leblanc et al. 2013)  
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 260 Table  9.12.11  Bactrocera sp. nr. passiflorae  citrus hosts and other hosts grown in New Zealand. The type 
of record for the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the 
numbers in brackets indicate the numbers of fruit from which adults emerged out of the total number of samples 
collected for the host plant.  
Citrus spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantiifolia*  Mexican lime  Listing only  Leblanc et al. (2013)  
Citrus reticulata  Mandarin  Field record ^ Leblanc et al. (2013)  
Citrus sinensis  Sweet orange  Field record (3/14)  Leblanc et al. (2013)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Persea americana  Avocado  Leblanc et al. (2013)  
* Not confirmed  
^ Infestation rate not given  
 
References  
Drew, R A I; Hancock, D L (1995) New species, subgenus and records of Bactrocera Macquart from 
the South Pacific (Diptera: Tephritidae: Dacinae). Australian Journal of Entomology , 34(1): 7 –12. 
Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records fo r fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of the Hawaiian 
Entomological Society , 45: 83 –177. 
Leblanc, L; Vueti, E; Drew, R; Allwood, A (2012) Host plant records for fruit f lies (Diptera: Tephritidae: 
Dacini) in the Pacific Islands. Proceedings of the Hawaiian Entomological Society , 44: 11 –53. 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
 
   
261 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.12  Bactrocera curvipennis  (banana fruit fly)  
 
Scientific name: Bactrocera curvipennis (Froggatt, 1909)  
Order/Family: Diptera/Tephritid ae 
Other names: Bactrocera  (Bactrocera ) curvipennis , Chaetodacus curvipennis, Dacus curvipennis , 
Strumeta curvipennis  
 
Hazard identification  
 
Bactrocera curvipennis meets the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera curvipennis is not known to be present in New Zealand:  
• The species  is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera curvipennis  is a regulated pest and a notifiable organism (ONZPR  2020) . 
Bactrocera curvipennis has the potential to establish and spread in New Zealand:  
• The distribution of Bactrocera curvipennis  is restricted to New Caledonia  and Vanuatu 
(Aneityum Island)  (Leblanc et al. 2012) . The CMI s of these island s are not available (Phillips 
et al. 2018) , but the average climate is likely to be dissimilar to that of New Zealand. The 
suitability of the New Z ealand environment for establishment of B. curvipennis  cannot be 
definitively ruled out , because a distribution on a single remote island may not be reflective of 
the fundamental niche of this species but rather of geographic isolation.  
• The species is repo rted from multiple Citrus spp., which are grown in some regions  of 
New Zealand both commercially and by home gardeners ( Table 9.12.12 ).  
The establishment of B. curvipennis in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. curvipennis has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million)  and capsicum (Capsicum annuum , FOB export value: 
$20.6 million) (Plant & Food Research 2019) . It also has the potential to cause significant 
control costs and to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as citrus trees  are commonly grown 
by home gardeners.  
• If B. curvipennis  was detected in New Zealand, the cost incurred by a response is likely to be 
high (see the Impacts section below) . 
Distribution in countries considered in this IRA : New Caledonia (Amice and Sales 1996) . There has 
also been a record from Aneityum in Vanuatu  (three specimens collected in the 1930s) , but this was 
unconfirmed and is not considered reliable (Allwood et al. 1996) . 
 
Lure: Only weakly attracted to cuelure . However, Royer et al. (2019)  demo nstrated that lures using 
isoeugenol resulted in 15 times more catches of flies compared to cuelure  and four times more 
catches compared to  dihydroeugenol.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 262 Table 9.12.12  Bactrocera curvipennis  citrus hosts and other hosts grown in New Zealand. The type o f 
record for the citrus hosts is given to indicate the strength of association with citrus hosts.  For field records, the 
numbers in brackets indicate the numbers of fruit from which adults emerged out of the total number of samples 
collected for the host p lant. 
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus latifolia  Tahitian lime  Field record (1/33)  Leblanc et al. (2013)  
Citrus maxima  Pomelo  Field record (1/28)   Leblanc et al. (2013)  
Citrus paradisi  Grapefruit  Field record (1/18)   Leblanc et al. (2013)  
Citrus reticulata  Mandarin  Field record (2/18)   Leblanc et al. (2013)  
Citrus sinensis  Orange  Field record (1/35)  Leblanc et al. (2013)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Capsicum annuum  Capsicum  Amice and Sales (1996)  
 
References  
Allwood, A J; Tumukon, T; Tau, D; Kassim, A (1996) Fruit fly fauna in Vanuatu. In Allwood , A J;  Drew , 
R A I  (eds) Management of Fruit Flies in the Pacific: A Regional Symposium, Nadi, Fiji , 28–31 
October 1996 . ACIAR Proceedings 76. ACIAR; Canberra, ACT, Australia; pp 77 –80. 
Amice, R; Sales, F (1996) Fruit fly fauna in New Caledonia. In Allwood , A J;  Drew , R A I  (eds) 
Management of Fruit Flies in the Pacific:  A Regional Symposium, Nadi, Fiji , 28–31 October 1996 . 
ACIAR Proceedings 76. ACIAR; Canberra, ACT, Australia; pp 68 –76. 
Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of  the Hawaiian 
Entomological Society , 45: 83 –177. 
Leblanc, L; Vueti, E; Drew, R; Allwood, A (2012) Host plant records for fruit flies (Diptera: Tephritidae: 
Dacini) in the Pacific Islands. Proceedings of the Hawaiian Entomological Society , 44: 11 –53. 
NZOR ( 2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https:// pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
Royer, J E; Mille, C; Cazeres, S; Brinon, J; Mayer, D G (2019) Isoeugenol, a more attractive male lure  
for the cue -lure-responsive pest fruit fly Bactrocera curvipennis (Diptera: Tephritidae: Dacinae), and 
new records of species responding to zingerone in New Caledonia. Journal of Economic Entomology , 
112(3): 1502 –1507.  
 
   
263 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.13  Bactrocera psidii  (South Sea guava fruit fly)  
 
Scientific name: Bactrocera psidii (Froggatt, 1899)  
Order/Family: Diptera/Tephritidae  
Other names: Bactrocera  (Bactrocera ) psidii , Tephritis psidii , Dacus virgatus , Dacus ornatissimus , 
Strumeta psidii  
 
Hazard identification  
 
Bactrocera psidii meets the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area 
(New  Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera psidii is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera psidii  is a regulated pest and a notifiable organism (ONZPR  2020) . 
Bactrocera psidii has the potential to establish and sp read in New Zealand:  
• The distribution of Bactrocera psidii is restricted to New Caledonia (Leblanc et al. 2012) . The 
CMI of this island is not available (Phillips et al. 2018) , but the average climate is likely to be 
dissimilar to that of New Zealand. The  suitability of the New Zealand environment for 
establishment of B. psidii  cannot be definitively ruled out , because a distribution on a single 
remote island may not be reflective of the fundamental niche of this species but rather of 
geographic isolation.  
• The species is polyphagous , and suitable hosts include species grown throughout 
New Zealand both commercially and by home gardeners ( Table 9.12.13 ).  
The establishment of B. psidii in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. psidii has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million)  and grapes ( Vitis vinifera, wine FOB export value: $1 .8 
billion) (Plant & Food Research 2019) . It also has the potential to cause significant control 
costs and to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural  impacts , as host plants are  commonly grown by 
home gardeners.  
• If B. psidii  was detected in New Zealand, the cost incurred by a response is likely to be high 
(see the Impacts section below) . 
Distribution in countries considered in this IRA : New Caledonia (Leblanc et al. 2013)   
 
Lure: Cuelure  (Amice and Sales 1996)  
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 264 Table 9.12.13   Bactrocera psidii  citrus hosts and other hosts grown in New Zealand. The type of record for 
the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the numbers in 
brackets indicate the numbers of fruit from which adults emerged out of the total number of samples collected for 
the host plant.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus maxima  Pomelo  Field record (1/28)  Leblanc et al. (2013)  
Citrus  paradisi  Grapefruit  Listing only  Margosian et al. (2007)  
Citrus  limon  Lemon  Listing only  Margosian  et al. (2007)  
Citrus  sinensis  Orange  Listing only  Margosian et al. (2007)  
Citrus  reticulata  Mandarin  Listing only  Margosian et al. (2007)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Prunus persica var. nucipersica  Nectarine  Leblanc et al. (2013)  
Prunus domestica  Plum  Leblanc et al. (2013)  
Diospyros kaki  Persimmon  Leblanc et al. (2013)  
Vitis vinifera  Grape  Leblanc et al. (2013)  
 
References  
Amice, R; Sales, F (1996) Fruit fly fauna in New Caledonia. In Allwood , A J;  Drew , R A I (eds) 
Management of Fruit Flies in the Pacific:  A Regional Symposium, Nadi, Fiji , 28–31 October 1996 . 
ACIAR Proceedings 76. ACIAR; Canberra, ACT, Australia; pp 68 –76. 
Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of the Hawaiian 
Entomological Society , 45: 83 –177. 
Leblanc, L; Vuet i, E; Drew, R; Allwood, A (2012) Host plant records for fruit flies (Diptera: Tephritidae: 
Dacini) in the Pacific Islands. Proceedings of the Hawaiian Entomological Society , 44: 11 –53. 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database.  
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J ; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version  5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
 
   
265 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.14  Bactrocera distincta  (no common name)  
 
Scientific name: Bactrocera distincta (Malloch, 1931)  
Order/Family: Diptera/Tephritidae  
Other names: Bactrocera  (Bactrocera ) distincta , Dacus distinctus , Strumeta distincta, Dacus 
(Strumeta ) distinctus  
 
Hazard identification  
 
Bactrocera distincta meets the criteria to be a quarantine pest for New Zealand . 
 
Criteria for being a quarantine pest relevant to this assessment are: not  present in the PRA area 
(New  Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera distincta is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera distincta  is a regulated pest (ONZPR  2020) . 
Bactrocera distincta has the potential to establish and spread in New Zealand:  
• Bactrocera distincta is found in Fiji (CMI 0.4) and several Pacific Islands (White and Elson -
Harris 1994; Drew and Romig 1996; Leblanc et al.  2012)  where the CMI is unavailable 
(Phillips et al. 2018)  but where the average climate is likely to be dissimilar to that of New 
Zealand. The suitability of the New Zealand environment for establishment of B. distincta  
cannot be definitively ruled out , because the remote island distribution of this species may not 
be reflective of its fundamental niche but rather of geographic isolation.   
• The species is oligophagous and suitable hosts include pomelo , a species grown in 
New Zealand by home gardeners ( Table 9.12.14 ).  
The establishment of B. distincta in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. distincta  has the potential to cause economic impacts  by directly 
damaging citrus crops (Citrus sp., FOB export value: NZ$12.0 million)  (Plant & Food 
Research 2019) . 
• The establishment of B. distincta has the potential to cause sociocultural impacts as host 
plants are grown by home gardeners.  
• If B. distincta  was detected in New Zealand, the cost incurred by a response is like ly to be 
high (see  the Impacts section below).  
Distribution in countries considered in this IRA : Fiji and Samoa (Leblanc et al. 2012)   
 
Lure: Cuelure (Leblanc et al. 2012)  
 
Table 9.12.14   Bactrocera distincta  citrus hosts. The type of record for the citrus hosts is given to indicate the 
strength of association with citrus hosts. For field records, the numbers in brackets indicate the numbers of fruit 
from which adults emerged out of the total number of samples collected for the host plant.  
Citrus spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus maxima  Pomelo  Field record (1/79)  Leblanc et al. (2013)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
N/A N/A Leblanc et al. (2013)  
 
References  
Drew, R A I; Romig, M C (1996) Overview – Tephritidae in the Pacific and Southeast Asia. In Allwood , 
A J; Drew , R A I  (eds) Management of Fruit Flies in the Pacific:  A Regional Symposium, Nadi, Fiji , 28–
31 October 1996 . ACIAR Proceedings 76. ACI AR; Canberra, ACT, Australia; pp 46 –53. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 266 Leblanc, L; Vueti, E; Allwood, A J (2013) Host plant records for fruit flies (Diptera: Tephritidae: Dacini) 
in the Pacific Islands: 2. Infestation statistics on economic hosts. Proceedings of the Hawaiian 
Entomologic al Society , 45: 83 –177. 
Leblanc, L; Vueti, E; Drew, R; Allwood, A (2012) Host plant records for fruit flies (Diptera: Tephritidae: 
Dacini) in the Pacific Islands. Proceedings of the Hawaiian Entomological Society , 44: 11 –53. 
NZOR (2011) The New Zealand Org anisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 7 77–791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Researc h Ltd ; Auckland , NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identificatio n and 
Bionomics.  CAB International, Wallingford, UK.  
 
 
   
267 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.15  Bactrocera correcta  (guava fruit fly)  
 
Scientific name: Bactrocera correcta (Bezzi , 1916 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera (Bactrocera ) correcta,  Chaetodacus correctus, Dacus correctus  
 
Hazard identification  
 
Bactrocera correcta meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area (New 
Zealand), and  of pot ential importance (able to establish and cause harm).  
 
Bactrocera correcta is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera correcta  is a regulated pest (ONZPR  2020) . 
Bactrocera correcta has the potential to establish and spread within New Zealand:  
• The distribution of B. correcta includes areas with a similar climate to New Zealand – Yunnan 
(EPPO 2020)  and Hebei (GBIF.org 2020)  in China (CMI 0.7 for both, Phillips et al. 2018) , 
Himachal P radesh (EPPO 2020)  in India (CMI 0.8, Phillips et al. 2018) , Bhutan (0.4–0.7, 
Phillips et al. 2018; EPPO 2020) , Myanmar (0.2–0.7, Phillips et al. 2018; EPPO 2020) , Nepal 
(0.4–0.8, Phillips et al. 2018; EPPO 2020)  and Pakistan (0.4–0.8, Phillips et al. 2018 ; EPPO 
2020) . 
• The species is polyphagous and suitable hosts include species grown throughout New 
Zealand both commercially and by home gardeners ( Table 9.12.15 ).  
The establishment of B. correcta in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. correcta has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million)  and peaches ( Prunus persica , FOB export value:$0.4 
million) (Plant & Food Research 2019) . 
• The establishment of B. correcta  also has the potential to cause significant control costs and 
to impact negatively on national and international trade.  
• Bactrocera correcta  also has the potential to  cause sociocultural impacts , as host plants are 
commonly grown by home gardeners.  
• If B. correcta was detected in New Zealand, the cost incurred by a response is likely to be 
high (see  the Impacts section below).  
Distribution in countries considered in this IRA : China ,Thailand  and Viet Nam  (Drew and Raghu 2002; 
Kamiji et al. 2014; EPPO 2020) . 
 
Lure: Methyl eugenol (White and Elson -Harris 1994)  and beta-caryophyllene (a species -specific 
attractant that is more attractive than methyl eugenol) (Plant Health  Australia 2018) . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 268 Table 9.12.15  Bactrocera correcta  citrus hosts and other hosts grown in New Zealand. The type of record 
for the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the number 
in brackets i ndicates the numbers of fruit from which adults emerged (total number of samples not available) . 
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus maxima*  Pomelo  Field record (1)  Allwood et al. (1999) , Yan et al. (2016)  
Citrus sinensis*  Orange  Field record  Yan et al. (2016)  
Citrus reticulata  Mandarin  Field record (7)  Allwood et al. (1999)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Prunus persica  Peach  White and Elson -Harris (1994)  
Cucumis melo  Muskmelon  Allwood et al. (1999)  
* Records from Yan et al. (2016)  are for adults reared from field -collected fruits (numbers not available) . 
 
References  
Allwood, A J; Chinajariyawong, A; Kritsaneepaiboon, S; Drew, R A I; Hamacek, E L; Hancock, D L; 
Hengsawad, C; Jipanin, J C; Jirasurat, M; Krong, C K; Leong, C T S; Vijaysegaran, S (1999) Host 
plant records for fruit flies (Diptera: Tephritidae) in Southeas t Asia. Raffles Bulletin of Zoology , 
47(Supplement 7): 1 –92. 
Drew, R; Raghu, S (2002) The fruit fly fauna (Diptera: Tephritidae: Dacinae) of the rainforest habitat of 
the Western Ghats, India. Raffles Bulletin of Zoology 50(2): 327 -352. 
EPPO (2020) EPPO gl obal database. https://gd.eppo.int  Accessed 29  October 2020.  
GBIF.org (2020) GBIF Occurrence Download https://doi.org/10.15468/dl.2rjx67  Accessed 26 October 
2020.  
Kamiji , T; Arakawa, K; Kadoi, M (2014) Effect of temperature on the development of a Vietnamese 
population of Bactrocera correcta (Bezzi) (Diptera: Tephritidae). Japanese Journal of Environmental 
Entomology and Zoology 25(3): 101 -109. 
NZOR (2011) The New Zealand  Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi. govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
Plant Health Australia (2018) The Australian Handbook for the Identification of Fruit Flies. Version 3.1 . 
Plant Health Australia ; Canberra, ACT , Australia . 
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries interna l 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
Yan, Z; Liu, N; Tang, G; Wang, W; Li, L; Xiao, M; Tao, M; Chen, G (20 16) Daily activity and their host 
species survey of guava fruit fly. Southwest China Journal of Agricultural Sciences , 29(8): 1864 –1868.  
 
 
   
269 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.16  Bactrocera latifrons  (Malaysian fruit fly)  
 
Scientific name: Bactrocera latifrons (Hendel , 1915 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera (Bactrocera ) latifrons , Chaetodacus antennalis, Chaetodacus 
latifrons, Dacus latifrons  
 
Hazard identification  
 
Bactrocera latifrons meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria f or being a quarantine pest relevant to this assessment are: not present in the PRA area (New 
Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera latifrons is not known to be present in New Zealand:  
• The species is not recor ded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera latifrons  is a regulated pest and a notifiable organism (ONZPR  2020) . 
Bactrocera latifrons has the potential to establish and spread within New Zealand:  
• The distribution of B. latifrons includes areas with a similar climate to all of New Zealand  – 
Gansu , Fujian, Guangdong, Guanxhi and Yunnan  (EPPO 2020; GBIF.org 2020)  in China 
(CMI 0.6 –0.8, Phillips et al. 2018) , Nairobi municipality (GBIF.org 2020)  in Kenya (CMI 0.7, 
Phillips et al. 2018) , Arusha and Kilimanjaro regions (GBIF.org 2020)  in Tanzania (CMI 0.7 for 
both, Phillips et al. 2018) , Pakistan (Phillips et al. 2018; EPPO 2020)  and Himachal Pradesh 
(GBIF.org 2020)  in India (CMI 0.8, Phillips et al. 2018) . 
• The species is polyphagous , and suitable hosts include species grown throughout New 
Zealand both commercially and by home gardeners ( Table 9.12.16 ).  
The establishment of B. latifrons in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. latifrons has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million)  and capsicum (Capsicum annuum , FOB export value: 
$20.6 million) (Plant & Food  Research 2019) . 
• The establishment of B. latifrons  also has the potential to cause significant control costs and 
to impact negatively on national and international trade.  
• Bactrocera latifrons  also has the potential to cause sociocultural impacts , as host p lants are 
commonly grown by home gardeners.  
• If B. latifrons was detected in New Zealand, the cost incurred by a response is likely to be 
high (see  the Impacts section below).  
Distribution in countries considered in this IRA : China, Japan, Viet  Nam, USA (H awaii)  (EPPO 2020) . 
 
Lure: Not attracted to cuelure or methyl eugenol (White and Elson -Harris 1994) . Alpha -ionol and cade 
oil is the best attractant for this species , though it is not as attractive as cuelure or methyl eugenol  is 
to other species . It is, however, more attractive than a protein bait  (McQuate et al. 2018) . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 270 Table 9.12.16   Bactrocera latifrons  citrus hosts and other hosts grown in New Zealand. The type of record 
for the citrus hosts is given to indicate the strength of association with citrus  hosts. For field records, the number 
in brackets indicates the numbers of fruit from which adults emerged (total number of samples not available) . 
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantiifolia  Lime  Field record (1) Allwood et al. (1999)  
Citrus reticulata  Mandarin  Laboratory host  McQuate et al. (2015)  
Citrus limon*  Lemon  Listing only  McQuate and Liquido (2013)  
Citrus sinensis*  Sweet orange  Listing only  McQuate and Liquido (2013)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Capsicum annuum  Capsicum  Allwood et al. (1999) , Liquido et al. (1994)  
Solanum lycopersicum  Tomato  Allwood et al. (1999) , Liquido et al. (1994)  
Cucumis sativus  Cucumber  Allwood et al. (1999) , Liquido et al. (1994)  
* Records for C. limon and C. sinensis described as “doubtful” in McQuate and Liquido (2013) . 
 
References  
Allwood, A J; Chinajariyawong, A; Kritsaneepaiboon, S; Drew, R A I; Hamacek, E L; Hancock, D L; 
Hengsawad, C; Jipanin, J C; Jirasurat, M; Krong, C K; Leong, C T S; Vijaysegaran, S (1999) Host 
plant records for fruit flies (Diptera: Tephritidae) in Southeas t Asia. Raffles Bulletin of Zoology , 
47(Supplement 7): 1 –92. 
EPPO (2020) EPPO global database. https://gd.eppo.int  Accessed 29  October 2020.  
GBIF.org (2020) GBIF Occurrence Download. https://doi.org/10.15468/dl.vub9ex  Accessed 28 
October 2020.  
Liquido, N J; Harris, E J; Dekker, L A (1994) Ecology of Bactrocera latifrons  (Diptera: Tephritidae) 
populations: Host plants, natural enemies, distribution, and abundance. Annals o f the Entomological 
Society of America , 87(1): 71 –84. 
McQuate, G T; Follett, P A; Liquido, N J; Sylva, C D (2015) Assessment of navel oranges, clementine 
tangerines, and rutaceous fruits as hosts of Bactrocera cucurbitae and Bactrocera latifrons (Diptera: 
Tephritidae). International Journal of Insect Science , 7: 1–9. 
McQuate, G T; Royer, J E; Sylva, C D (2018) Field trapping Bactrocera latifrons (Diptera: Tephritidae) 
with select eugenol analogs that have been found to attract other ‘non-responsive ’ fruit f ly species. 
Insects , 9(2): 50.  
McQuate, G; Liquido, N (2013) Annotated world bibliography of host fruits of Bactrocera latifrons 
(Hendel) (Diptera: Tephritidae). Insecta Mundi , 289: 1 –61. 
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available a t: https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.   
271 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  PPIN (2020) Plan t Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
 
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 272 8.12.17  Bactrocera carambolae  (carambola fruit fly)  
 
Scientific name: Bactrocera carambolae (Drew and Hancock , 1994 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera (Bactrocera ) carambolae , Bactrocera species A.  
 
Taxonomic notes: Bactrocera  carambolae  belongs to the B. dorsalis  species complex (Drew and 
Hancock 1994)  
 
Hazard identification  
 
Bactrocera carambolae meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relev ant to this assessment are: not present in the PRA area (New 
Zealand), and of potential importance (able to establish and cause harm).  
 
Bactrocera carambolae is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Bactrocera carambolae  is a regulated pest and a notifiable organism (ONZPR  2020) . 
Bactrocera carambolae has low potential to establish and spread within New Zealand ; however, a 
transient summer population is possible, particularly in the north of New Zealand:  
• The distribution of B. carambolae is in southeast Asia, South America and Timor -Leste in 
areas of low climate similarity with New Zealand ( see Table 9.12.24).  
• Bactrocera carambolae is, therefore, unlikely to establish in New Zealand in the lo nger term ; 
however, transient summer populations in the north of New Zealand are possible. Even a 
temporary incursion is likely to be associated with trade barriers and eradication costs.  
• The species is polyphagous , and suitable hosts include species grown  throughout New 
Zealand both commercially and by home gardeners ( Table 9.12.17 ).  
The establishment of B. carambolae in New Zealand has the potential to cause unwanted impacts:  
• The establishment of B. carambolae has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , avocados ( Persea americana, FOB export value: $104.3 
million) and ca psicum ( Capsicum annuum , FOB export value: $20.6 million) (Plant & Food 
Research 2019) . 
• The establishment of B. carambolae  also has the potential to cause significant control costs 
and to impact negatively on national and international trade.  
• Bactrocera carambolae  also has the potential to cause sociocultural impacts , as host plants 
are commonly grown by home gardeners.  
• If B. carambolae was detected in New Zealand, the cost incurred by a response is likely to be 
high (see the Impacts section below) . 
Distribution in countries considered in this IRA : Viet  Nam and Brazil (EPPO 2020) . 
 
Lure: Methyl eugenol (Plant Health Australia 2018) .  
273 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Table 9.12.17  Bactrocera carambolae  citrus hosts and other hosts grown in New Zealand. The type of 
record for the citrus hosts is given to indicate the strength of association with citrus hosts. For field records, the 
number in brackets indicates the numbers of fruit from which adults emerged either out of the total number of 
samples collected for the host plant, or ( for single numbers) only the number of fruit from which adults emerged 
(total number of samples not available).  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantiifolia  Lime  Field record (1)  Allwood et al. (1999)  
Citrus reticulata  Mandarin  Field record (15/140)  
Field record (1)  van Sauers -Muller  (2005)  
Allwood et al. (1999)  
Citrus limon  Lemon  Field record (2)  Allwood et al. (1999)  
Citrus sinensis  Sweet orange  Field record (8/640)  van Sauers -Muller  (2005)  
Citrus paradisi  Grapefruit  Field record (4/122.5)  van Sauers -Muller  (2005)  
Citrus reticulata  Calamansi  Listing only  Allwood et al. (1999)  
Citrus aurantium  Bitter orange  Listing only  Allwood et al. (1999)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Capsicum annuum  Capsicum  Allwood et al. (1999)  
Solanum lycopersicum  Tomato  Allwood et al. (1999)  
Persea americana  Avocado  Allwood et al. (1999)  
 
References  
Allwood, A J; Chinajariyawong, A; Kritsaneepaiboon, S; Drew, R A I; Hamacek, E L; Hancock, D L; 
Hengsawad, C; Jipanin, J C; Jirasurat, M; Krong, C K; Leong, C T S; Vijaysegaran, S (1999) Host 
plant records for fruit flies (Diptera: Tephritidae) in Southeas t Asia. Raffles Bulletin of Zoology , 
47(Supplement 7): 1 –92. 
Drew, R A I; Hancock, D L (1994) The Bactrocera dorsalis complex of fruit flies (Diptera: Tephritidae: 
Dacinae) in Asia. Bulletin of Entomological Research Supplement Series , 2: 1–68. 
EPPO (2020)  EPPO global database. https://gd.eppo.int  Accessed 29  October 2020.  
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official  New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Res earch Ltd ; Auckland , NZ.  
Plant Health Australia (2018) The Australian Handbook for the Identification of Fruit Flies. Version 3.1.  
Plant Health Australia ; Canberra, ACT , Australia . 
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
Van Sauers -Muller, A (2005) Host plants of the carambola fruit fly, Bactrocera carambolae Drew & 
Hancock (Diptera: Tephritidae), in Suriname, South America. Neotropical Entomology , 34: 203 –214. 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 274 8.12.18  Zeugodacus tau  (no common name)  
 
Scientific name: Zeugodacus tau (Walker, 1849)  
Order/Family: Diptera/Tephritidae  
Other names include: Bactrocera tau, Chaetodacus tau, Dacus caudatus var. nubilus, Dacus 
hageni, Dacus nubilus, Dacus tau, Dasyneura ta u, Zeugodacus nubilus  
 
Hazard identification  
 
Zeugodacus tau meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are:  not present in the PRA area (New 
Zealand), and of potential importance (able to establish and cause harm).  
 
Zeugodacus tau is not known to be present in New Zealand:  
• The species is not recorded in NZOR (2011)  or PPIN (2020) .  
• Zeugodacus tau  is a regulated pest (ONZPR  2020) . 
Zeugodacus tau has the potential to establish and spread within New Zealand:  
• The distribution of Z. tau includes areas with a similar climate to all of New Zealand – 
Chongqing, Fujian, Guangdong, Guangxi, Guizhou, Hubei,  Shaanxi, Sichuan, Yunnan and 
Zhejiang (CABI 2020)  in China (CMI 0.4 –0.8, Phillips et al. 2018) , Taiwan (CMI 0.4 –0.8, 
Phillips et al. 2018; CABI 2020)  and Bhutan (CMI 0.4 –0.7, Phillips et al. 2018; CABI 2020) . 
• The species is polyphagous , and suitable hosts include species grown throughout New 
Zealand both commercially and by home gardeners ( Table 9.12.18 ).  
The establishment of Z. tau in New Zealand has the potential to cause unwanted impacts:  
• The establishment of Z. tau has the potentia l to cause economic impacts by directly damaging 
horticultural crops that are significant to New Zealand, including citrus (Citrus sp., FOB export 
value: NZ$12.0 million) , pear ( Pyrus communis , FOB export value: $10.6 million)  and squash 
(Cucurbita sp., FOB export value: $59.7 million) (Plant & Food Research 2019) . 
• The establishment of Z. tau  also has the potential to cause significant control costs and to 
impact negatively on national and international trade.  
• Zeugodacus tau  also has the potential to caus e sociocultural impacts , as host plants are 
commonly grown by home gardeners.  
• If Z. tau was detected in New Zealand, the cost incurred by a response is likely to be high 
(see the Impacts section below).  
Distribution in countries considered in this IRA : China, Viet  Nam (CABI 2020)  
 
Lure: Cuelure (White and Elson -Harris 1994)  
 
   
275 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Table 9.12.18  Zeugodacus tau  citrus hosts and other hosts grown in New Zealand. The type of record for 
the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus reticulata * Mandarin  Laboratory host  Wu et al. (2011) ; Lin et al. (2005)  
Citrus maxima# Pomelo  Listing  White and Elson -Harris (1994)  
Citrus sinensis ^ Sweet orange  Laboratory host  Lin et al. (2005)  
Citrus paradisi ^ Grapefruit  Laboratory host  Lin et al. (2005)  
Citrus reticulata  × Citrus paradisi ^ Tangelo  Laboratory host  Lin et al. (2005)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Citrullus lanatus  Watermelon  Liquido et al.  (2016)  
Cucumis melo  Muskmelon  Liquido et al.  (2016)  
Cucumis sativus  Cucumber  Liquido et al.  (2016)  
Cucurbita maxima  Pumpkin  Liquido et al.  (2016)  
Cucurbita moschata  Butternut pumpkin  Liquido et al.  (2016)  
Cucurbita pepo  Squash  Liquido et al.  (2016)  
Pyrus communis  Pear  Liquido et al.  (2016)  
Solanum lycopersicum  Tomato  Liquido et al.  (2016)  
* Choice experiments, C. reticulata least preferred host compared to four non -citrus hosts . 
# Unconfirmed record from 1968 for Dacus hageni , which was “probably B. tau rather than B. caudata i”. 
^ Methodology not described in paper but likely to be no -choice tests . 
 
References   
CABI (2020) Bactrocera tau . In Invasive Species Compendium . CAB International ; Wallingford, UK. 
https://www.cabi.org/isc/  Accessed 30 October 2020.  
Lin, M Y; Chen, S K; Liu, Y C (2005) The host plants of Bactrocer a tau in Taiwan. [in Chinese ] 
Research Bulletin of Tainan District Agricultural Research and Extension Station , (45): 39 –52 
Liquido, N; Norrbom, A L; Mcquate, G T; Ching, A J; Marnell, S A; Birnbaum, A L; Inskeep, J R; 
Hanlin, M A; Nakamichi, K A A (2016) Host plant records of  Bactrocera (Zeugodacus)  tau complex 
(Diptera: Tephritidae).  Compendium of Fruit Fly Host Information (CoFFHI). United States Department 
of Agriculture . https://coffhi.cphst.org/  
NZOR (2011) Th e New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpest register.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Aucklan d, NZ.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 276 Wu, B; Shen, K; An, K; Huang, J; Zhang, R (2011) Effect of larval density and host species on 
preimaginal development of Bactrocera tau (Diptera: Tephritidae). Journal of Economic Entomology , 
104(6): 1840 –1850.  
   
277 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.19  Anastrepha obliqua  (West Indian fruit fly)  
 
Scientific name: Anastrepha obliqua  (Macquart, 1835)  
Order/Family: Diptera/Tephritidae  
Other names include: Tephritis obliqua , Acrotoxa obliqua , Anastrepha fraterculus  var. 
mombinpraeoptans , Anastrepha fraterculu s var. ligata , Anastrepha trinidadensis , Trypeta obliqua , 
Antillean fruit fly  
 
Hazard identification  
 
Anastrepha obliqua  meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are:  not present in the PRA area (New 
Zealand), and  of potential importance (able to establish and cause harm).  
 
Anastrepha obliqua  is not known to be present in New Zealand:  
• Anastrepha obliqua  is not recorded in NZOR (2011)  or PPIN (2020) .  
• Anastrepha obliqua  is a regulated pest and a notifiable organism (ONZPR  2020) .  
• New Zealand has country freedom status for A. obliqua  (MPI 2020) . 
Anastrepha obliqua  has potential to establish and spread within New Zealand:  
• A. obliqua  has a tropical and subtropical distribu tion having been recorded from Florida and 
Texas, USA (now absent, eradicated (EPPO 2020) , Southern and Central America and the 
West Indian islands. Some of the areas where A. obliqua  is present (Zucchi and Moraes 
2008; EPPO 2020)  have high climate similar ity with New Zealand (CMI 0.7 –0.9 Phillips et al. 
2018) : 
o Brazil: Santa Cat arina ( CMI 0.7–0.9), Rio Grande do Sul ( CMI 0.7–0.9), Paran á (CMI 
mostly 0.7 –0.8), S ão Paulo (parts have CMI  0.7–0.8); Peru: Piura State (parts have 
CMI 0.7). 
• Anastrepha obliqua  is polyphagous , and suitable hosts include sp ecies grown throughout 
New Zealand both commercially and by home gardeners (Table 9.12.19 ). 
The establishment of Anastrepha obliqua in New Zealand has the potential to cause unwanted 
impacts:  
• The establishment  of A. obliqua  has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , pear ( Pyrus communis , FOB export value: $10.6 million) 
and peach ( Prunus persica , FOB export value: $0.4  million) (Plant & Food Research 2019) . 
• The establishment of A. obliqua  also has the potential to cause significant control costs and to 
impact negatively on national and intern ational trade.  
• It also has the potential to cause sociocultural impacts , as host plants are commonly grown by 
home gardeners.  
• If A. obliqua  was detected in New Zealand, the cost incurred by a response is likely to be high 
(see the Impacts section below).  
Distribution in countries considered in this IRA : Brazil, Mexico, Peru , (absent, eradicated in the US A) 
(EPPO 2020)  
 
Lure: No male lures have yet been identified , but A. obliqua can be captured in traps emitting 
ammonia  (Plant Health Australia 2018; CABI 2 020). 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 278 Table 9.12.19  Anastrepha obliqua citrus hosts and other hosts grown in New Zealand. The type of record 
for the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus limon  Sweet lime  Listing only  White and Elson -Harris (1994)  
Citrus aurantium  Sour orange  Listing only  White and Elson -Harris (1994)  
Citrus paradisi  Grapefruit  Listing only  White and Elson -Harris (1994)  
Citrus sinensis  Sweet orange  Listing only  White and Elson -Harris (1994)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Psidium guajava  Guava  Zucchi and Moraes  (2008)  
Prunus persica  Peach  Zucchi and Moraes  (2008)  
Pyrus communis  Pear  White and Elson -Harris (1994) , CABI  (2020)  
Mangifera indica  Mango  CABI  (2020) , Zucchi and Moraes  (2008)  
Syzygium jambos  Rose apple  White and Elson -Harris (1994) , CABI  (2020)  
 
References  
CABI (2020) Anastrepha obliqua (West Indian fruit fly)  In Invasive Species Compendium . CAB 
International ; Wallingford, UK. https://www.cabi.org/isc/  Accessed 30 October 2020.  
EPPO (2020) EPPO global database. https://gd.eppo.int  Accessed 29  October 2020.  
MPI (2020) Cou ntry freedom status database. https://www.mpi.govt.nz/news -and-
resources/resources/registers -and-lists/country -freedom -status/  Accessed 2 Octob er 2020.  
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database.  
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
Plant Health Australia (2018) The Australian Handbook for the Identification of Fruit Flies. Version 3.1 . 
Plant Health Australia ; Canberra, ACT , Australia . 
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry f or Primary Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
Zucchi, R A; Moraes, R C B (2008) Fruit flies in Brazil – Anastrepha species their host plants and 
parasitoids. http://www.lea.esalq.usp.br/anastrepha/  Updated  30 September 2020 . Accessed 30 
October 2 020. 
   
279 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.20  Anastrepha serpentina  (sapodilla fruit fly)  
 
Scientific name: Anastrepha serpentina  (Wiedemann , 1830 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Urophora vittithorax , Acrotoxa serpentina , Dacus serpentinus , Leptoxys 
serpentina , Trypeta  serpentina , sapote fruit fly, serpentine fruit fly  
 
Hazard identification  
 
Anastrepha serpentina  meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA are a (New 
Zealand), and of potential importance (able to establish and cause harm).  
 
Anastrepha serpentina  is not known to be present in New Zealand:  
• Anastrepha serpentina is not recorded in NZOR (2011)  or PPIN (2020) .  
• Anastrepha serpentina  is a regulated pe st and a notifiable organism (ONZPR  2020) .  
• New Zealand has country freedom status for A. serpentina  (MPI 2020) . 
Anastrepha serpentina has potential to establish and spread within New Zealand:  
• Anastrepha serpentina  occurs in the Americas. Some of the areas where A. serpentina  is 
present (Zucchi and Moraes 2008; EPPO 2020)  have high climate similarity with New 
Zealand (CMI 0.7 –0.9, Phillips et al. 2018) : 
o Brazil: Santa Cat arina (CMI 0.7 –0.9), Paran á (CMI mostly 0.7 –0.8), S ão Paulo (parts 
have CMI 0.7 –0.8); Mexico:  Coahuila (parts have CMI 0.7), Oaxaca (CMI 0.7), 
Puebla (CMI 0.7 –0.8), San Luis Potosí (CMI 0.7).  
• Anastrepha serpentina  is polyphagous , and suitable hosts include species grown in New 
Zealand both commercia lly and by home gardeners ( Table 9.12.20 ).  
The establishment of Anastrepha serpentina in New Zealand has the potential to cause unwanted 
impacts:  
• The establishment of A. serpentina  has the potential to cause economic impacts by directly 
damaging horticul tural crops that are significant to New Zealand, including citrus (Citrus  sp., 
FOB export value: NZ$12.0 million) , apple ( Malus  domestica , FOB export value $828.8 
million), avocado (Persea  americana , FOB export value: $104.3 million), pear ( Pyrus  
communis , FOB export value: $10.6 million) and peach ( Prunus  persica , FOB export value: 
$0.4 million) (Plant & Food Research 2019).  
• The establishment of A. serpentina  also has the potential to cause significant control costs 
and to impact negatively on national an d international trade.  
• It also has the potential to cause sociocultural impacts , as host plants are commonly grown by 
home gardeners.  
• If A. serpentina  was detected in New Zealand, the cost incurred by a response is likely to be 
high (see the Impacts secti on below).  
Distribution in countries considered in this IRA : Brazil, Mexico, Peru (EPPO 2020). Confirmed 
eradicated from the USA in 2003 (NAPPO 2003 , in CABI 2020) , but sporadically captured in the Rio 
Grande Valley of Texas and California (CABI 2020; EPPO  2020) . 
Lure: No male lures have yet been identified , but A. serpentina can be captured using ammonia traps 
(Plant Health Australia 2018; CABI 2020) . 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 280 Table 9.12.20  Anastrepha serpentina citrus hosts and other hosts grown in New Zealand. The type of 
record for the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantium  Sour orange  Listing only  CABI (2020) , White and Elson -Harris (1994)  
Citrus maxima  Pummelo  Listing only  CABI (2020) , White and Elson -Harris (1994)  
Citrus reticulata  Mandarin  Listing only  CABI (2020) , White and Elson -Harris (1994) , 
Zucchi and Moraes  (2008)  
Citrus sinensis  Sweet orange  Listing only  CABI (2020) , White and Elson -Harris (1994) , 
Zucchi and Moraes  (2008)  
Citrus paradisi  Grapefruit  Listing only  CABI (2020) , White and Elson -Harris (1994)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Cydonia oblonga  Quince  CABI (2020) , White and Elson -Harris (1994)  
Malus domestica  Apple  CABI 2020, EPPO (2020) , White and Elson -
Harris (1994)  
Mangifera indica  Mango  CABI (2020) , EPPO (2020) , White and Elson -
Harris (1994)  
Persea americana  Avocado  CABI (2020) , EPPO (2020) , White and Elson -
Harris (1994)  
Prunus persica  Peach  CABI (2020) , White and Elson -Harris (1994)  
Psidium guajava  Guava  CABI (2020) , White and Elson -Harris (1994)  
Pyrus communis  Pear  White and Elson -Harris (1994)  
 
References  
CABI (2020) Anastrepha serpentina (sapodilla fruit fly)  In Crop Protection Compendium . CAB 
International ; Wallingford, UK. https://www.cabi.org/cpc/  Accessed 30 October 2020.  
EPPO (2020) EPPO global database. https://gd.eppo.int  Accessed 29  October 2020.  
MPI (2020) Country freedom status database. https://www.mpi.govt.nz/news -and-
resources/resources/registers -and-lists/country -freedom -status/  Accessed 2 October 2020.  
NAPPO (2003) Phytosanitary Alert System: Lifting of sapote fruit fly, Anastrepha serpentina 
(Wiedemann), quarantine in Texas. 
http://www.pestalert.org/oprDetail.cfm?oprID=80&keyword=ANASTREPHA%20SERPENTINA   
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 Septemb er 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match c limates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
Plant Health Australia (2018) The Australian Handbook for the Identificatio n of Fruit Flies. Version 3.1 . 
Plant Health Australia ; Canberra, ACT , Australia . 
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.   
281 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  White, I M; Elson -Harris, M M (1994 ) Fruit Flies  of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
Zucchi, R A; Moraes, R C B (2008) Anastrepha species their host plants and parasitoids. Fruit Flies 
(Diptera: Tephritidae) in Brazil. Department  of Entomology and Acarology, ESALQ – University of São 
Paulo; Piracicaba, São Paulo, Brazil. http://www.lea.esalq.usp.br/anastrepha/  Updated 30 September 
2020 . Accessed 30 October 2020.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 282 8.12.21  Anastrepha sororcula  (no common name)  
 
Scientific name: Anastrepha sorocula Zucchi, 1979  
Order/Family: Diptera/Tephritidae  
Other names include:  None 
Taxonomic notes:  Anastrepha sororcula  is a member of the Anastrepha fraterculus  complex (White 
and Elson -Harris 1994) . 
 
Hazard identification  
 
Anastrepha sororcula  meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are:  not present in the PRA area (New 
Zealand), and of potential importance (able to establish and cause harm).  
 
Anastrepha sorocula  is not known to be present in New Zealand:  
• Anastrepha sorocula  is not recorded in NZOR (2011)  or PPIN (2020) ; and   
• The regulato ry status of Anastrepha sorocula  is unassessed (not listed in ONZPR  2020) .  
 
Anastrepha sorocula has potential to establish and spread within New Zealand:  
• Anastrepha sororocula  occurs in South America, recorded from Colombia, Paraguay and 
Brazil. Some of the areas where A. sororcula  is present (Zucchi and Moraes 2008; CABI 
2019)  have a high climate similarity with New Zealand  (Phillips et al. 2018) : 
o Brazil: Santa Cat arina ( CMI 0.7–0.9), Paran á (CMI mostly 0.7 –0.8), S ão Paulo (parts 
have CMI  0.7–0.8). 
• Anastrepha sororcula  hosts include species grown in New Zealand both commercially and by 
home gardeners ( Table 9.12.21 ).  
The establishment of Anastrepha sororcula in New Zealand has the potential to cause unwanted 
impacts:  
• The establishment of A. sororcula  has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million)  and peach ( Prunus persica , FOB export value: $0.4 
million) (Plant & Food Research 2019) . 
• The establishment of A. sororcula  also has the potential to cause significant control costs and 
to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural impacts as host plants are grown by home 
gardeners.  
• If A. sororcula was detected in New Zealand, the cost incurred by a response is likely to be 
high (see the Impacts section below).  
Distribution in countries considered in this IRA : Brazil (White and Elson -Harris 1994; Zucchi a nd 
Moraes 2008; CABI 2019; EPPO 2020) .  
 
Lure: No male lures have yet been identified for Anastrepha  spp., but they can be captured using 
ammonia traps  (CABI 2020) . 
 
   
283 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Table 9.12.21  Anastrepha sororcula  citrus hosts and other hosts grown in New Zealand. The type of 
record for the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus sinensis  Sweet orange  Field record  (2 females from 61 fruits)  Souza et al. (2008)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Prunus persica  Peach  Zucchi and Moraes  (2008)  
Psidium guajava  Guava  Zucchi and Moraes  (2008)  
 
References  
CABI (2019) Anastrepha sororcula . In Invasive Species Compendium . CAB International ; Wallingford, 
UK. https://www.cabi.org/isc/  Accessed 30 October 2020.  
CABI (2020) Anastrepha obliqua (West Indian fruit fly) . In Invasive Species Compendium . CAB 
International ; Wallingford, UK. https://www.cabi.org/isc/  Accessed 30 October 2020.  
EPPO (2020) EPPO global database. https://gd.eppo.int  Accessed 29  October 2020.  
NZOR (2011) The New Zealand O rganisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.go vt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool avai lable at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
PPIN (202 0) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
Souza, J F; Souza, S A S; Aguiar -Menezes, E L; Ferrara, F A A; Nascimento, S A; Rodrigues, W C; 
Cassino, P C R (2008) Diversi dade de moscas -das-frutas em pomares de citros no município de 
Araruama, RJ . [Abstract only] Ciência Rural , 38(2): 518 –521. 
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
Zucchi, R A; Moraes, R C B (2008) Fruit flies in Brazil – Anastrepha species their host plants and 
parasitoids. http://www.lea.esalq.usp.br/anastrepha/  Updated on 30 September 2020 . Accessed 30 
October 2020.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 284 8.12.22  Anastrepha striata  (guava fruit fly)  
 
Scientific name: Anastrepha striata  Schiner , 1968   
Order/Family: Diptera/Tephritidae  
Other names include : Dictya cancellaria , Trypeta cancellaria  
 
Hazard identification  
 
Anastrepha striata  meets the criteria to be a quarantine pest for New Zealand.  
 
Criteria for being a quarantine pest relevant to this assessment are: not present in the PRA area (New 
Zealand), and of potential importance (able to establish and cause harm).  
 
Anastrepha stria ta is not known to be present in New Zealand:  
• Anastrepha striata is not recorded in NZOR (2011)  or PPIN (2020) .  
• Anastrepha striata  is a regulated pest and a notifiable organism (ONZPR  2020) .  
 
Anastrepha striata has potential to establish and spread withi n New Zealand:  
• Anastrepha striata is present in the Americas (White and Elson -Harris 1994; Plant health 
Australia 2011) . Some of the areas where A. striata  is present (Zucchi and Moraes 2008; 
CABI 2020; EPPO 2020)  have high climate similarity with New Zea land (Phillips et al. 2018) : 
o Brazil: S ão Paulo ( CMI 0.6–0.8); Mexico:  Aguascalientes ( CMI 0.7). 
• Its presence in southern Brazil has been detected only recently, suggesting that human 
activities may have aided its spread. It has also been intercepted and trapped in the USA 
(Florida, California), indicating its potential for spread via infested fruits (Phillips et al. 2018) . 
• Anastrepha striata  is polyphagous, recorded on hosts from a range of families, with a 
preference for Myrtaceae, and primarily a pest of guava, Psidium guajava  (White and Elson -
Harris 1994; Plant Health Australia 2011; Phillips et al . 2018) . Suitable hosts include species 
grown in New Zealand both commercially and by home gardeners ( Table 9.12.22 ).  
The establishment of Anastrepha striata in New Zealand has the potential to cause unwanted 
impacts:  
• The establishment of A. striata  has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus (Citrus sp., 
FOB export value: NZ$12.0 million) , avocado ( Persea americana , FOB export value: $104.3 
million) and peach ( Prunus persica , FOB export value: $0.4 million) (Plant & Food Research 
2019) . 
• The establishment of A. striata  also has the potential to cause significant control costs and to 
impact negatively on national and international trade.  
• It also has the potential to cause sociocultural impacts , as host plants are commonly grown by 
home gardeners.  
• If A. striata was detected in New Zealand, the cost incurred by a response is likely to be high 
(see the Impacts section below).  
Distribution in countries considered in this IRA : Brazil, Mexico, Peru  (EPPO 2020) . Absent from the 
USA (CABI 2020) , but sporadically captured in the Rio Grande Valley of Texas and California (CABI 
2020; EPPO 2020) . 
 
Lure: No male lures have yet been identified , but the flies can be captured using ammonia traps 
(Plant Health Australia 2011; CABI 2020) . 
  
285 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Table 9.12.22  Anastrepha striata citrus hosts and other hosts grown in New Zealand. The type of record 
for the citrus hosts is given to indicate the strength of association wi th citrus hosts.  
Citrus spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus sinensis  Sweet orange  Listing only  CABI (2020) , White and Elson -Harris (1994) , Zucchi and 
Moraes  (2008)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Psidium guajava  Guava  CABI (2020) , White and Elson -Harris (1994) , Zucchi and Moraes  (2008)  
Mangifera indica  Mango  CABI (2020) , White and Elson -Harris (1994)  
Passiflora edulis  Passionfruit  CABI (2020) , Zucchi and Moraes  (2008)  
Persea americana  Avocado  CABI (2020) , White and Elson -Harris (1994)  
Prunus persica  Peach  CABI (2020) , White and Elson -Harris (1994)  
Syzygium jambos  Rose apple  CABI (2020) , White and Elson -Harris (1994)  
Manihot esculenta  Cassava  CABI (2020) , White and Elson -Harris (1994)  
 
References  
CABI (2020) Anastrepha striata (guava fruit fly)  In Invasive Species Compendium.  Wallingford, UK: 
CAB International. https://www.cabi.org/isc/  Accessed 30 October 2020.  
EPPO (2020) EPPO global database. https://gd.eppo.int  Accessed 29  October 2020.  
NZOR (2011) The New Zealand Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant  & Food Research (2019) Fresh Facts – New Zealand Horticulture . The New Zealand Institute 
for Plant and Food Research Ltd ; Auckland , NZ.  
Plant Health Australia (2011) The Australian handbook for the identification of fruit flies. Version 1.0 . 
Plant Health  Australia ; Canberra, ACT , Australia . 
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economic Significance : Their Identification and 
Bionomics.  CAB International, Wallingford, UK.  
Zucchi, R A; Moraes, R C B (2008) Fruit flies in Brazil – Anastrepha species their host plants and 
parasitoids. http://www.lea.esal q.usp.br/anastrepha/  Updated 30 September 2020 . Accessed 30 
October 2020.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 286 8.12.23  Anastrepha suspensa  (Caribbean fruit fly)  
 
Scientific name: Anastrepha suspensa  (Loew , 1862 ) 
Order/Family: Diptera/Tephritidae  
Other names include: Acrotoxa suspensa , Anastrepha longimacula , Anastrepha unipuncta , Trypeta 
suspensa,  greater Antillean fruit fly  
 
Hazard identification  
 
Anastrepha suspensa  meets the criteria to be a quarantine pest for New Zealand.   
 
Criteria for being a quarantine pest relevant to this assessment are : not present in the PRA area  
(New  Zealand), and  of potential importance (able to establish and cause harm).  
 
Anastrepha suspensa  is not known to be present in New Zealand:  
• Anastrepha suspensa  is not recorded in NZOR (2011)  or PPIN (2020) .  
• Anastrepha suspensa  is a regulated pest and a notifiable organism (ONZPR  2020) .  
• New Zealand has country freedom status for A. suspensa  (MPI 2020) . 
 
Anastrepha suspensa has potential to establish and spread within New Zealand:  
• A. suspensa  has a tropical and subtropi cal distribution having been recorded largely from the 
Caribbean (including Bahamas, British Virgin Islands, Cuba, Dominican Republic, Haiti, 
Jamaica, Puerto Rico) and Florida in the USA (CABI 2020; EPPO 2020) . 
• A. suspensa is indigenous to the West Indies (Weems et al. 2012)  and is considered invasive  
in Florida, USA (CABI 2020; EPPO 2020) . According to Sutton and Steck (2005) , 
A. suspensa  was first detected in South Florida in the 1930s and apparently eradicated. It 
recoloni sed Dade county in 1965 and has since spread widely in Central and South Florida. It 
is occasionally found in northeastern Atlantic coastal counties in Florida (Sutton and Steck 
2005) . Weems et al. (2012)  note isolated records north to Jacksonville (Florida).  
• Some of the areas where A. suspensa  is present have high climate similarity with New 
Zealand (Phillips et al. 2018) : 
o North Florida, including Jacksonville, has a CMI of 0.7.  
• Anastrepha suspensa  is polyphagous , and suitable hosts include species grown throughout 
New Zealand both commercially and by home gardeners ( Table 9.12.23).  
 
The establishment of Anastrepha suspensa in New Zealand has the potential to cause unwanted 
impacts:  
• The establishment of A. suspensa  has the potential to cause economic impacts by directly 
damaging horticultural crops that are significant to New Zealand, including citrus, apple 
(Malus domestica , FOB export value NZ$828.8 million), pear ( Pyrus communis , FOB export 
value: $10.6 million) and peach ( Prunus persica , FOB export value: $0.4 million) (Plant & 
Food Research 2019) . 
• The establishment of A. suspensa  also has the potential to cause significa nt control costs and 
to impact negatively on national and international trade.  
• It also has the potential to cause sociocultural impacts , as host plants are commonly grown by 
home gardeners.  
• If A. suspensa was detected in New Zealand, the cost incurred by a response is likely to be 
high (see  the Impacts section below).  
 
Distribution in countries considered in this IRA : USA (Florida) (EPPO 2020)  
 
Lure: No male lures have yet been identified but can be captured in traps emitting ammonia (Plant 
Health Australi a 2011; CABI 2020) . 
   
287 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Table 9.12.23: Anastrepha suspensa citrus hosts and other hosts grown in New Zealand. The type of 
record for the citrus hosts is given to indicate the strength of association with citrus hosts.  
Citrus  spp. hosts  
Host name  Common name  Type of record  Reference  
Citrus aurantiifolia  Lime  Listing only  White and Elson -Harris (1994)  
Citrus aurantium  Sour orange  Listing only  Weems et al. (2012) , White and Elson -Harris (1994)  
Citrus maxima  Pummelo  Listing only  Weems et al. (2012) , White and Elson -Harris (1994)  
Citrus limon  Sweet lime Listing only  White and Elson -Harris (1994)  
Citrus limon  Lemandarin  Listing only  White and Elson -Harris (1994)  
Citrus paradisi  Grapefruit  Listing only  Weems et al. (2012) , White and Elson -Harris (1994) 
Citrus reticulata  – Listing only  Weems et al. (2012) , White and Elson -Harris (1994)  
Citrus reticulata  Tangerine   White and Elson -Harris (1994)  
Citrus sinensis  Sweet orange  Listing only  Weems et al. (2012) , White and Elson -Harris (1994)  
Citrus reticulata × Citrus paradisi  Tangelo  Listing only  White and Elson -Harris (1994)  
Other hosts grown in New Zealand  
Host name  Common name  Reference  
Psidium guajava  Guava  Weems et al. (2012)  
Prunus persica  Peach  Weems et al. (2012) , White and Elson -Harris (1994)  
Pyrus communis  Pear  CABI (2020) , White and Elson -Harris (1994)  
Mangifera indica  Mango  Weems et al. (2012)  
Malus domestica  Apple  White and Elson -Harris (1994)  
Capsicum annum  Bell pepper  White and Elson -Harris (1994)  
Diospyros kaki  Japanese persimmon  White and Elson -Harris (1994)  
 
References  
CABI (2020) Anastrepha suspensa (Caribbean fruit fly)  In Crop Protection Compendium . CAB 
International ; Wallingford, UK. https://www.cab i.org/cpc/  Accessed 12 November 2020.  
EPPO (2020) EPPO global database. https://gd.eppo.int  Accessed 29  October 2020.  
MPI (2020) Country freedom status database. https://www.mpi.govt.nz/news -and-
resources/resources/registers -and-lists/country -freedom -status/  Accessed 2 October 2020.  
NZOR (2011) The New Zea land Organisms Register. http://nzor.org.nz  Accessed 15 September 
2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. 
https://pierpestregister. mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match too l available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts – New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  
Plant Health Australia (2011) The Australian Handbook for the Identification of Fruit Flies. Version 1.0 . 
Plant Health Australia ; Canberra, ACT , Australia.  
PPIN (2020) Plant Pest Information Network, Version 5.03.01. Ministry for Primary Industries internal 
database. Accessed 15 September 2020.  
Sutton, B; Steck, G (2005) An annotated checklist of the Tephritidae (Diptera) of Florida. Insecta 
Mundi , 19(4): 227 –246. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 288 Weems, J, H. V.; Heppner, J B; Fasulo, T R; Nation, J L (2012) Caribbean Fruit Fly , Anastrepha 
suspensa (Loew) (Insecta: Diptera: Tephritidae). EENY196, UF/IFAS Extension. 
https://edis.ifas.ufl.edu/in353  Accessed 12 November 2020.  
White, I M; Elson -Harris, M M (1994) Fruit Flies of Economi c Significance : Their Identification and 
Bionomics.  CAB International ; Wallingford, UK.  
   
289 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  8.12.24  Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  for the fruit flies in this assessment, the 
likelihood of entry with citrus fruit ranges from low to moderate –high depending on 
the species (with high uncertainty).  
 
All of the fruit fly species in this assessment have been recorded from citrus fruit.  
• The fruit flies in this assessment have been recorded from between one and nine citrus  
species (see individual species sections above  for details) , although some of the associations 
are host listings only.  
Internally feeding fruit pests have a stronger association with fruit than external pests.  
• Fruit-feeding fruit flies complete egg and larval development within fruit flesh (White and 
Elson -Harris 1994) . 
 
The strength of association with citrus fruit for each species included in this assessment is given 
below. The strength of association depends on the  number of citrus hosts a fruit fly species has been 
recorded from, whether those records were only host listings or field records, and the infestation rate 
(where available).  Because of the small number of reliable, field -based host -range studies publishe d 
for all of the species listed below, the uncertainty is rated as moderate  to high in all cases.  
 
• Bactrocera aquilonis  – Weak  to moderate  
• Bactrocera melas  – Weak  
• Bactrocera neohumeralis  – Moderate   
• Bactrocera jarvisi  – Moderate   
• Bactrocera kraussi  – Moderate   
• Bactrocera trivialis  – Weak  
• Bactrocera frauenfeldi  – Moderate to strong  
• Bactrocera melanotus  – Weak  to moderate  
• Bactrocera passiflorae  – Moderate to strong  
• Bactrocera species near  passiflorae  – Weak  
• Bactrocera kirki  – Moderate  
• Bactrocera curvip ennis  – Moderate  
• Bactrocera psidii  – Weak  
• Bactrocera distincta – Weak  
• Bactrocera correcta – Weak  
• Bactrocera latifrons – Weak  
• Bactrocera carambolae – Moderate  
• Zeugodacus tau – Weak  
• Anastrepha obliqua – Weak to moderate  
• Anastrepha serpentina – Weak to moderate  
• Anastrepha sororcula – Weak  
• Anastrepha striata – Weak  
• Anastrepha suspensa – Moderate  
 
Given the arguments and evidence below, basic measures are likely to reduce the 
likelihood of entry of fruit flies by a moderate degree (with moderate to high 
uncertainty) . Consequently , the likelihood of entry is considered low  to moderate 
(with moderate uncertainty).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 290 Fruit fly  infestations may be visually detectable in the field and/or packhouses, leading to the removal 
of infested produce.  
• Puncture holes from oviposition are often visible with the naked eye (White and Elson -Harris 
1994) . Fruits with multiple oviposition punctures and external signs of feeding damage are 
likely to be removed during general handling.  
• Fruit bagging and packhouse culling have been reported to be effective in reducing levels of 
infestation in some citrus commodities in China (Xia et al. 2019) . Fruit bagging is not widely 
practiced due to its labour intensity.  
 
However, there is a chance t hat a small quantity  of infested fruit will not be detected.  
• Low levels of  infestation (fewer oviposition punctures and less external damage) may not be 
obvious enough to be detected during general handling. Low infestation levels may be more 
prevalent in  less preferred hosts such as citrus, which is the case for most of the fruit fly 
species considered here.  
• The volume of the commodities can also affect efficiency of detection. Low levels of 
infestation may not be easily detected, especially if the volum e of commodities is large.  
 
General handling after harvesting is not likely to remove fruit fly larvae inside citrus fruit.  
• General handling after harvesting (e.g. washing and brushing) only treats the surface of fruit. 
These procedures are therefore high ly unlikely to remove fruit fly larvae inside citrus fruit.  
• Fruit will need to be cut open to reveal fruit fly larvae inside. Internally feeding insects are 
likely to be particularly problematic to detect by nondestructive inspection. Even using fruit 
dissection, Gould (1995)  found that detection rates for Caribbean fruit fly ( Anastrepha 
suspensa ) could be as low as 17.9%. In this study, inspectors detected between 17.9% and 
83.5% of fruit infested with Caribbean fruit fly; variables influencing detection r ate were the 
fruit type, its ripeness and the inspector (Gould 1995) . 
 
Larvae of fruit flies may survive transit in citrus commodities.  
• Between 1987 and 2019, live tephritid larvae, pupae or adults, or viable tephritid eggs, were 
intercepted over 1,000 tim es at the New Zealand border (LIMS 2019) . 
 
The level of uncertainty associated with both the degree by which basic measures  reduce the 
likelihood of entry (moderate) and the consequent likelihood of entry (low to moderate) is moderate. 
Firstly, species -specific information about the detectability of low levels of infestation of citrus fruits 
with the fruit flies included in this grouped PRA  is not available. Secondly, there is uncertainty around 
whether standard transit times and storage temperatures of cit rus commodities will be enough to 
prevent survival of eggs and larvae of the fruit flies included in this grouped PRA.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of fruit flies  to transfer from 
imported fruit into a  suitable environment to allow establishment (exposure) is 
considered to be moderate to high (with moderate uncertainty).  
Fruit flies  can survive and develop on the waste of citrus fruit (whole fruit or fruit pieces but probably 
not skin).  
• Fruit-feeding fr uit flies complete egg and larval development within fruit flesh , and most drop 
to the ground to pupate in the soil (White and Elson -Harris 1994) . If citrus fruit is disposed of 
as whole fruit or fruit pieces, it is likely that fruit fly eggs or larvae wil l survive and reach 
adulthood in th is waste.  
  
291 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Most  fruit waste in New Zealand is likely to be disposed of using low -risk methods , so any fruit flies 
present would either be killed or be unable to escape from the citrus host.  
• Most of the waste in New Zeala nd is bagged and disposed of in landfills or run through  
kitchen disposal units, and in these situations, fruit flies are  unlikely to reach a new host (see 
the waste analysis in  section 2.4.1 ). 
 
However, some fruit waste is disposed of using high -risk methods, including composting in gardens , 
using it as animal feed  and discard ing it  directly into the environment.   
• Adults fruit flies  emerging from the soil are likely to be able to find food in the environment if 
citrus fruit waste is disposed of using h igh-risk methods. The typical tephritid adult diet 
includes plant exudates, honeydew, decaying insects and bird droppings (Christenson and 
Foote 1960) . These food sources are common in farms, parks and home gardens , and adult 
fruit flies can fly to locate them.  
• Because the fruit flies in this grouped PRA are polyphagous  or (in the case of B. distincta ) 
oligophagous , hosts for oviposition and larval development are available in most areas of 
New Zealand, either in commercial plantations or in home gardens.  
• If citrus hosts are located near composting sites or animal feeding sites, adult fruit flies are 
likely to locate them (see the waste analysis in section 2.4.1 ). 
 
The level of uncertainty associated with the ability of fruit flies  to move from imported fr uit to a suitable 
host (moderate to high) is moderate. Firstly, waste data may not be very accurate or up to date, and it 
is not known how frequently suitable hosts are present near composting sites or animal feeding 
locations ( see waste analysis in sectio n 2.4.1 ). Secondly, it is uncertain what proportion of composting 
sites are exposed or covered (e.g. in a compost bin). Thirdly, the effect of seasonality on this 
likelihood is uncertain.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for all fruit flies considered in this assessment to establish is considered 
to be low (with high uncertainty) , with the exception of Bactrocera melas,  B. 
correcta, B. latifrons, Anastrepha obliqua, A. serpentina, A. sororcula , A. striata  and 
A. suspensa  where the suitability is moderate to high (with low uncertainty), and B. 
frauenfeldi where the suitability is low (with low uncertainty).  
• Of the fruit flies in this ass essment , B. melas,  B. correcta, B.  latifrons , Anastrepha obliqua, A. 
serpentina, A. sororcula and A. striata  are found in locations with a climate similar to the 
whole of New Zealand (CMI greater than 0.7, Phillips et al. 2018)  (Table 9.12.2 4).   
o The range of B. melas  is in eastern Queensland, particularly in the southeast of the 
state (CMI 0.4 –0.8).  
o Bactrocera correcta  is found in Bhutan, Myanmar, Nepal, Pakistan, Sri Lanka , 
Thailand, and Viet Nam and several regions in India and China (CMI 0.2 –0.8) (Drew 
and Raghu 2002; Kamiji et al. 2014; EPPO 2020; GBIF.org 2020) . 
o Bactrocera latifrons has a broad distribution across southeastern Asia, as well as in 
Kenya, Tanzania and Hawaii (CMI 0.3 –0.8)(EPPO 2020; GBIF.org 2020b) . 
o Anastrepha obliqua , A. serpentina and A. striata have a broad distribution in South 
and Central America, whereas A. sororcula has a more restricted distribution in South 
America (Zucchi and Moraes 2008; CABI 2019, 2020b, 2020a; EPPO 2020) . The 
distributions of these four sp ecies include areas with a similar climate to all of New 
Zealand (CMI greater than 0.7, Phillips et al. 2018) . 
o A. suspens a is found in the West Indies and Florida, USA, and is recorded from the 
North of Florida, USA (CMI 0.5 –0.7), as well as the Dominican Republic (CMI 0.5 –
0.7) (EPPO 2020 ). Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 292 • B. aquilonis  and B. kraussi are restricted to the tropics of northern Australia (Sultana et al. 
2020)  – areas of low climate similarity with the whole of New Zealand (CMI 0.4 –0.6, Table 
9.12.2 4). 
• Bactrocera trivialis is native to Papua New Guinea and West Papua , but it makes seasonal 
incursions into the Torres Strait Islands (Plant Health Australia 2018) . All of these areas have 
a dissimilar climate to the whole of New Zealand (CMI 0.3 –0.6, Table 9.12.2 4). 
• The current dis tribution of B. frauenfeldi includes the Torres Strait Islands and northern 
Queensland, Australia (CMI 0.4 –0.6), Papua New Guinea and West Papua (CMI 0.3 –0.6) and 
Solomon Islands (CMI 0.4 –0.5). The distribution also includes several Pacific islands where 
the CMI is unavailable ; however , the average climate of these islands is likely to be dissimilar 
to that of New Zealand (Leblanc et al. 2012; Sultana et al. 2020)  (Table 9.12.2 4). 
• Bactrocera  passiflorae , B. sp. nr. passiflorae and B. distincta are all found  in Fiji (CMI 0.4) and 
several Pacific Islands where the CMI is unavailable but where the average climate is likely to 
be dissimilar to that of New Zealand (Leblanc et al. 2012)  (Table 9.12.2 4). 
• The distribution of B. melanotus is restricted to the Cook Is lands, that of B. curvipennis and 
B. psidii  to New Caledonia, whereas B. kirki is found in several Pacific Islands – all locations 
where the CMI is unavailable but where the average climate is likely to be dissimilar to that of 
New Zealand (Leblanc et al. 2012)  (Table 9.12.2 4).  
• Bactrocera carambolae is distributed in the north of South America, southeast Asia and East -
Timor in areas of low climate similarity with  the whole of  New Zealand (CMI 0.3 –0.5, Table 
9.12.2 4) 
• Bactrocera  melanotus , B. passiflorae , B. sp. nr. passiflorae , B. kirki, B. curvipennis  and 
B. psidii  are distributed exclusively in the Pacific Islands. The suitability of the New Zealand 
environment for establishment of these species cannot be definitively ruled out , because 
remote island distr ibutions may not be reflective of the fundamental niche of a species but 
rather of geographic isolation. Additionally, although the average temperature found on 
Pacific Islands shows no overlap with New Zealand, there can be considerable temperature 
overlap with equatorial mid -altitude regions, and some months have temperatures similar to 
New Zealand summers (Halloy 2020) . 
• Bactrocera aquilonis , B. kraussi,  B. trivialis, B. frauenfeldi and B. carambolae are unlikely to 
establish in New Zealand in the longer term; however, the transient summer population s in 
the north of New Zealand are possible.  
The level of uncertainty associated with the low suitability of the New Zealand environment for 
Bactrocera aquilonis, B. kraussi, B. trivialis, B. melanotus, B. passi florae, B. sp. nr. passiflorae, B. kirki 
B. curvipennis, B. psidii,  B. distincta and B. carambolae  is moderate, b ecause a detailed assessment 
of the biology of these species  and climate modelling were  not carried out.  
The level of uncertainty associated wi th the low suitability of the New Zealand environment for  B. 
neohumeralis  is moderate to high because the conclusions of different climate models (CLIMEX and 
MAXENT) are conflicting.  
 
   
293 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Table 9.12.2 4  Distribution and climate match index (CMI ) (match to the whole of New Zealand ) (Phillips et 
al. 2018)  of the fruit flies included in this grouped PRA.  
Species  Location  CMI Reference  for 
distribution  
Bactrocera 
aquilonis  Australia – Top end of NT, northern areas of Western 
Australia  0.4–0.5 Sultana et al. (2020)  
Bactrocera melas  Australia – Eastern Queensland, particularly the southeast  0.4–0.8 Hancock et al. (2000)  
Bactrocera 
neohumeralis  Australia – Torres Strait Islands, eastern Queensland, 
northern New South Wales  0.4–0.91 Sultana et al. (2020)  
Papua New Guinea  0.3–0.6 Sultana et al. (2020)  
Bactrocera jarvisi  Australia – NW Australia, Northern Territory, NW 
Queensland, eastern Australia from Cape York to its 
southern boundary near the Queensland -New South Wales 
border  0.4–0.81 Sultana et al. (2020) , 
Dominiak and 
Worsley (2017)  
Bactrocera kraussi  Australia – Torres Strait Islands, northeast Queensland as 
far south as Townsville  0.4–0.6 Sultana et al. (2020)  
Bactrocera trivialis  Australia – Seasonal incursions into Torres Strait Islands  0.4 Plant Health 
Australia (2018)  Indonesia – West Papua  0.3–0.6 
Papua New Guinea  0.3–0.6 
Bactrocera 
frauenfeldi  Indonesia – West Papua  0.3–0.6 
Sultana et al. (2020) 
and Leblanc et al. 
(2012)  Australia – Torres Strait Islands and northern Queensland 
as far south as Townsville  0.4–0.6 
Federated States of Micronesia  N/A 
Kiribati  N/A 
Marshall Islands  N/A 
Nauru  N/A 
Northern Mariana Islands  N/A 
Palau  N/A 
Papua New Guinea  0.3–0.6 
Solomon Islands  0.4–0.5 
Bactrocera 
melanotus  Cook Islands  N/A Leblanc et al. (2012)  
Bactrocera 
passiflorae  Fiji 0.4 
Leblanc et al. (2012)  Niue N/A 
Wallis and Futuna  N/A 
Bactrocera sp. near 
passiflorae  Fiji 0.4 
Leblanc et al. (2012)  Tokelau  N/A 
Tonga  N/A 
Tuvalu  N/A 
Bactrocera kirki American Samoa  N/A 
Leblanc et al. (2012)  Fiji (Rotuma)  N/A 
French Polynesia  N/A 
Niue N/A 
Samoa  N/A 
Tonga  N/A 
Wallis and Futuna  N/A 
Bactrocera 
curvipennis  New Caledonia  N/A Leblanc et al. (2012)  
Bactrocera psidii  New Caledonia  N/A Leblanc et al. (2012)  
Bactrocera distincta  Fiji 0.4 Leblanc et al. (2012), 
White and Elson 
Harris (1994) and 
Drew and Romig 
(1996)  Niue N/A 
Tonga  N/A 
Wallis and Futuna (Futuna)  N/A 
Samoa  N/A 
American Samoa  N/A 
Bactrocera correcta  Bhutan  0.4–0.7 Drew and Raghu 
(2002) , Kamiji et al. China (Hebei, Yunnan)  0.7 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 294 Species  Location  CMI Reference  for 
distribution  
India (Andhra Pradesh, Bihar, Goa, Gujarat, Haryana, 
Himachal Pradesh, Karnataka, Kerala, Madhya Pradesh, 
Maharashtra, Mizoram, Punjab, Tamil Nadu, Uttar 
Pradesh, West Bengal)  0.3–0.8 (2014) , EPPO (2020)  
and GBIF.org 
(2020a)  
Myanmar  0.2–0.7 
Nepal  0.4–0.8 
Pakistan  0.4–0.8 
Sri Lanka  0.4–0.5 
Thailand  0.3–0.5 
Viet Nam  0.4-0.6 
Bactrocera latifrons  Kenya (Nairobi)  0.5–0.8 
EPPO (2020) and 
GBIF.org (2020b)  Tanzania (Arusha, Kilimanjaro)  0.6–0.7 
United States (Hawaii)  0.5–0.8 
Bangladesh  0.4–0.4 
Brunei Darussalam  0.5 
China  (Gansu, Fujian, Guangdong, Guangxi, Hainan, 
Xianggang (Hong Kong), Yunnan)  0.4–0.8 
East Timor  0.4–0.5 
India (Himachal Pradesh, Karnataka, Kerala, Mizoram, 
Tamil Nadu, West Bengal)  0.3–0.8 
Indonesia (Kalimantan, Sulawesi)  0.4–0.6 
Japan (Ryukyu archipelago)  N/A 
Laos  0.3–0.6 
Malaysia (Sabah, West)  0.5 
Myanmar  0.2–0.6 
Pakistan  0.4–0.8 
Singapore  0.5 
Sri Lanka  0.4–0.5 
Taiwan  0.4–0.8 
Thailand  0.3–0.5 
Viet Nam 0.6–0.4 
Bactrocera 
carambolae  Brazil (Amapá, Pará, Roraima)  0.4 
EPPO (2020) and 
GBIF.org (2020c)  French Guiana  0.4 
Guyana  0.4–0.5 
Suriname  0.4–0.5 
Bangladesh  0.3–0.4 
Brunei Darussalam  0.5 
Cambodia  0.3–0.4 
East Timor  0.4–0.5 
India (West Bengal, Andaman and Nicobar Islands)  0.3–0.4 
Indonesia (Java, Nusa Tenggara)  0.3–0.5 
Malaysia (Sabah, Sarawak, West)  0.5 
Myanmar  0.2–0.6 
Singapore  0.5 
Thailand  0.3–0.5 
Viet Nam 0.5 
Zeugodacus tau  Bangladesh  0.3–0.4 
CABI (2020d)  Bhutan  0.4–0.7 
Brunei  0.5 
Cambodia  0.3–0.4 
China ( Chongqing, Fujian, Guangdong, Guangxi, Guizhou, 
Hainan, Hubei, Shaanxi, Sichuan, Yunnan, Zhejiang, Hong 
Kong)  0.4–0.8 
India ( Himachal Pradesh, Kerala, Uttar Pradesh, West 
Bengal)  0.3–0.8 
Indonesia (Sumatra)  0.4  
295 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Species  Location  CMI Reference  for 
distribution  
Laos  0.3–0.6 
Malaysia (Sabah, Sarawak, West)  0.5 
Myanmar  0.2–0.6 
Singapore  0.5 
Taiwan  0.4–0.8 
Thailand  0.3–0.5 
Viet Nam 0.6–0.4 
Anastrepha obliqua  Antigua and Barbuda  N/A 
EPPO (2020) and 
Zucchi and Moraes 
(2008)  Bahamas  0.5 
Barbados  N/A 
Belize  0.3–0.5 
Brazil ( Acre, Alagoas, Amap á, Amazonas, Bahia, Cear á, 
Distrito Federal, Esp írito Santo, Goi ás, Maranh ão, Mato 
Grosso, Mato Grosso do  Sul, Minas Gerais, Par á, Para íba, 
Paran á, Pernambuco, Piau í, Rio de Janeiro, Rio Grande 
do Norte, Rio Grande do Sul, Rond ônia, Roraima, Santa 
Catarina, S ão Paulo, Tocantins)  0.3–0.9 
Colombia  0.3–0.8 
Costa Rica  0.3–0.6 
Cuba  0.5 
Dominica  N/A 
Dominican Republic  0.5–0.7 
Ecuador  0.4–0.8 
El Salvador  0.4–0.5 
French Guiana  0.4 
Grenada  N/A 
Guadeloupe  N/A 
Guatemala  0.3–0.6 
Guyana  0.4–0.6 
Haiti 0.5 
Honduras  0.4–0.6 
Jamaica  0.5–0.6 
Martinique  N/A 
Mexico  0.3–0.8 
Montserrat  N/A 
Netherlands Antilles  N/A 
Nicaragua  0.4–0.6 
Panama  0.4–0.5 
Paraguay  0.5–0.6 
Peru  0.4–0.8 
Puerto Rico  0.5–0.6 
Saint Lucia  N/A 
St Kitts -Nevis  N/A 
St Vincent and the Grenadines  N/A 
Suriname  0.4–0.5 
Trinidad and Tobago  0.5 
Venezuela  0.3–0.8 
Virgin Islands (British)  N/A 
Virgin Islands (US)  N/A 
Anastrepha 
serpentina  Brazil ( Amap á, Amazonas, Bahia, Esp írito Santo, Goi ás, 
Maranh ão, Mato Grosso do Sul, Minas Gerais, Par á, 
Para íba, Paran á, Pernambuco, Piau í, Rio de Janeiro, Rio 
Grande do Norte, Rond ônia, Roraima, Santa Catarina, S ão 
Paula)  0.3–0.9 EPPO (2020) and 
Zucchi and Moraes 
(2008)  
Colombia  0.3–0.8 
Costa Rica  0.3–0.6 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 296 Species  Location  CMI Reference  for 
distribution  
Dominica  N/A 
Ecuador  0.4–0.8 
French Guiana  0.4 
Guatemala  0.3–0.6 
Guyana  0.4–0.6 
Mexico  0.3–0.8 
Netherlands Antilles  N/A 
Panama  0.4–0.5 
Paraguay  0.5–0.6 
Peru  0.4–0.8 
Suriname  0.4–0.5 
Trinidad and Tobago  0.5 
United States of America (California, Texas)84 0.5–0.8 
Venezuela  0.3–0.8 
Anastrepha 
sororcula  Brazil ( Alagoas, Mato Grosso do Sul, Minas Gerais, 
Roraima, Tocantins, Santa Cat arina, Paran á, São Paulo)  0.4–0.9 CABI (2020c) and 
Zucchi and Moraes 
(2008)  Colombia  0.3–0.8 
Paraguay  0.5–0.6 
Anastrepha striata  Bolivia  0.4–0.8 
CABI (2020c) and 
Zucchi and Moraes 
(2008)  Brazil ( Acre, Amap á, Amazonas, Goi ás, Maranh ão, Mato 
Grosso do Sul, Par á, Piau í, Rond ônia, Roraima, Tocantins, 
São Paulo ) 0.3–0.9 
Colombia  0.3–0.8 
Costa Rica  0.3–0.6 
Ecuador  0.4–0.8 
French Guiana  0.4 
Guatemala  0.3–0.6 
Guyana  0.4–0.6 
Honduras  0.4–0.6 
Mexico (Sinaloa, Aguascalientes, Veracrus)  0.5–0.7 
Netherlands Antilles  N/A 
Nicaragua  0.4–0.6 
Panama  0.4–0.5 
Paraguay  0.5–0.6 
Peru  0.4–0.8 
Suriname  0.4–0.5 
Trinidad and Tobago  0.5 
United States of America84 (California, Texas)  0.5–0.8 
Venezuela  0.3–0.8 
Anastrepha 
suspensa  Bahamas  0.5 
CABI (2020d)  British Virgin Islands  N/A 
Cuba  0.5 
Dominican Republic  0.5–0.7 
Haiti 0.5 
Jamaica  0.5–0.6 
Puerto Rico  0.5–0.6 
USA (Florida)  0.5–0.7 
 
1 These species have been reported in regions with high CMIs with all of New Zealand however more detailed climate 
models have produced conflicting predictions so there are moderate to high level of uncertainty.  
 
 
                                                      
84 Confirmed eradicated fr om the USA in 2003 (NAPPO 2003 , in CABI 2020b) , but sporadically captured in the Rio Grande 
Valley of Texas and California (CABI 2020b; EPPO 2020) .  
297 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Impacts in New Zealand : 
 
Given the arguments and evidence below, the level of impact caused by fruit flies i s 
likely to be high (low to moderate uncertainty).  
Fruit flies can cause significant damage to fruit and vegetable commodities.  
• Without control measures, direct damage of fr uit and vegetable commodities by fruit flies 
ranges from 0 –80% but can be as high as 100% depending on host species or variety, 
location and season (EFSA Panel on Plant Health et al. 2020) . 
Fruit flies can cause significant economic impacts due to direct d amage and costs associated with 
control and management.  
• Examples of significant economic impacts of fruit flies include (EFSA Panel on Plant Health et 
al. 2020) : 
o Crop losses and control costs due to fruit flies have been estimated at over US$7.5 
million pe r annum in a single area of South Africa (West Cape).  
o In Brazil, annual economic losses may be as high as US$242 million due to fruit fly 
activity.  
o In Hawaii, the economic losses associated with invasive fruit flies (due to the costs of 
spraying or, where this is ineffective, abandoning crops) exceed US$300 million each 
year.  
If fruit flies are detected in New Zealand, the cost incurred by a response would be high.  
• The typical cost of responses is millions of dollars. For example:  
o The Queensland fruit fly response in 2019 cost approximately NZ$18 million (MPI 
2020) .  
o The eradication of Bactrocera cucurbitae from the Okinawa prefecture of Japan took 
almost 20 years and reached a total cost of US$177.2 million (EFSA Panel on Plant 
Health et al. 2020) . 
o In the mid-1990s , the cost of eradicating Philippine fruit fly (B. philippinensis ) in 
Darwin was estimated at AU$7 million whereas the cost of eradicating B. papayae 
(Leblanc et al. 2012)  from Cairns cost an estimated AU$35 million (Abdalla et al. 
2012) . 
 
The loss of market access due to fruit fly incursions can cause significant economic losses  
• The direct financial impact to the horticultural industry nation -wide (revenue lost due to lost 
market access plus additional costs) of a successfully eradicated Ceratitis capitata incursion 
in New Zealand’s major fruit -growing regions has been estimated at between NZ$24.4 million 
and $71.4  million (Underwood 2007) . 
• The cost due to lost market access in the event of establishment of C. capitata in California 
was es timated at US$564 million (Siebert and Cooper 1995) . 
 
8.12.25  References  
Abdalla, A; Millist, N; Buetre, B; Bowen, B (2012) Benefit –cost analysis of the National Fruit Fly 
Strategy Action Plan . ABARES report to client prepared for Plant Health Australia, Canberra,  
Australia.  
CABI (2019) Anastrepha sororcula . In Invasive Species Compendium . CAB International ; Wallingford, 
UK. https://www.cabi.org/isc/  Accessed 30 October 2020.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 298 CABI (2020a) Anastrepha obliqua (West Indian fruit fly) . In Invasive Species Compendium . CAB 
International ; Wallingford, UK. https://www.cabi.org/isc/  Accessed 30 October 2020.  
CABI (2020b) Anastrepha serpentina (sapodilla fruit fly) . In Invasive Species Comp endium . CAB 
International ; Wallingford, UK. https://www.cabi.org/isc/  Accessed 30 October 2020.  
CABI (2020c) Anastrepha striata (guava fruit fly) . In Invasive Species Compendium . CAB 
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https://www.cabi.org/isc/  Accessed 30 October 2020.  
Christenson, L D; Foote, R H (1960) Biology of fruit flies. Annual Review of Entomology 5(1): 171 –
192.Dominiak, B C; Worsley, P (2017) Review of the southern boundary of Jarvis fruit fly Bactrocera 
jarvisi  (Tryon) (Diptera: Tephritidae: Dacinae) and its li kely southern distribution in Australia. General 
and Applied Entomology 45: 17.  
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October 2020.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 300 9. Insects: Hemiptera,  Pseudococcidae  (mealybugs)  
 
9.1 Nipaecoccus  viridis  (spherical mealybug ) 
 
Nipaecoccus viridis  is a polyphagous mealybug species. It is widespread throughout the tropics and 
subtropics, attacking numerous plant species and often causing considerable damage.  
 
Scientific name: Nipaecoccus viridis (Newstead, 1894)   
Order/Family: Hemiptera/Pseud ococcidae  
Other names include: Dactylopius viridis , Dactylopius vastator , Pseudococcus vastator , 
Pseudococcus viridis , Dactylopius perniciosus , Ripersia theae , Pseudococcus solitaries, 
Pseudococcus perniciosus , Pseudococcus filamentosus corymbatus , Trionymus sericeus , 
Pseudococcus theae , Nipaecoccus vastator , karoo thorn mealybug , lebbeck  mealybug, cotton 
mealybug , globular coffee mealybug  (García et al. 2016; EPPO 2019a )  
 
Taxonomic notes:  The name N. vastator  was commonly used for N. viridis  for ma ny years . It was 
synonymised with N. viridis  by Ali in 1970 (cited in CPC 2020) , but some authors  continue to use  the 
name N. vastator . There are many records of N. viridis  under the name Pseudococcus filamentosus  
(Cockerell ) (it is now included in the genus Nipaecoccus ), but these are based on misidentifications 
(Williams and Watson 1988).  
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Nipaecoccus viridis meets the criteria to be a quarantine pest for New Zealand .  
• Nipaecoccus viridis has a strong association with citrus fruit , with low uncertainty . 
• Basic measure s are likely to reduce the likelihood of entry  of N. viridis  by a moderate degree . 
Consequently , the likelihood of entry is considered to be low , with low uncertainty.  
• Nipaecoccus viridis has low ability (with high uncertainty) to move from imported fruit and into 
a suitable environment to allow establishment, that is, onto a host plant.  
• The suitabil ity of the New Zealand environment to for N. viridis  to establish is considered low  
to moderate (with moderate uncertainty) , but the likelihood of establishment in warmer areas 
and indoor environment s, such as greenhouses, is considered  moderate.  
• The level  of impact caused by N. viridis  is likely to be low  to moderate (with moderate 
uncertainty), but the level of impact to the citrus industry in northern New Zealand is likely to 
be moderate.  
• Nipaecoccus viridis may be considered for additional measures.  
 
Summary of risk assessment against criteria  
Criteria  Rate  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from the imported commodity  onto a suitable host  Low High 
Suitability of the N ew Zealand  environment  Low–moderate  Moderate  
Impacts on the New Zealand economy, environment, health and society  Low–Moderate  Moderate  
  
301 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  9.1.1 Hazard  identification: quarantine status  
 
Given the arguments and evidence below,  Nipaecoccus viridis  meets the criteria to 
be a quarantine pest for New Zealand  
Criteria for being a quarantine pest, relevant to this assessment, are: not present in New Zealand, and 
of potential importance (able to estab lish and cause harm).  
 
Nipaecoccus viridis  is not known to be present in New Zealand:   
• It is not recorded in NZInverts (2020) and NZOR  (2020) . 
• It is not recorded in PPIN (2020).  
• It is listed as ‘Regulated’ in ONZPR  (2020) . 
 
Nipaecoccus viridis  has the potential to establish and spread in New Zealand:  
• Nipaecoccus viridis  is widespread throughout the tropics and subtropics, although it is also 
present in areas with similar or marginally similar climate conditions to New Zealand.  
• Nipaecoccus viridis  is pol yphagous . It has been reported on 140 genera of plants in 52 
families (García et al. 2016 ).  
• Host plants include those commercially grown in New Zealand and those commonly grown in 
gardens and parks, such as Citrus spp., Vitis spp., Solanum lycopersicum , Rosa spp., 
Camellia spp. etc. 
 
Nipaecoccus viridis  has the potential to cause impacts to the economy and environment of New 
Zealand:  
• Nipaecoccus viridis  has the potential to harm plants of eco nomic importance to New Zealand: 
Host plant species of the mealybug  include important agricultural plants in New Zealand, such 
as citrus , grapevine, tomato, apple, pear, apricot and avocado . 
• Nipaecoccus viridis  has the potential to harm the New Zealand environment: The mealybug 
has been reported on plant species u nder genera (e.g. Apium  and Sonchus ) that are native to  
New Zealand.  
 
9.1.2 Hazard identification: commodity association  
 
Nipaecoccus viridis  is associated with citrus fruit  
 
Nipaecoccus viridis  is reported from citrus fruit : 
• Nipaecoccus viridis  infests twigs, s hoots, leaves, flower buds and fruit  on citrus  (García et al. 
2016)  and often settles in cryptic places, such as under sepals of citrus fruits ( Figure 10.1. 1). 
 
9.1.3 Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Nipaecoccus viridis  has a strong  
association with citrus fruit , with low uncertainty . 
Many reports have recorded the damage of N. viridis  on citrus fruits.  
• Nipaecoccus  viridis  infests twigs, shoots, leaves, flower buds and fruit  on citrus  (García et al. 
2016 ), primarily occurring on the foliage and fruit of hosts (Miller et al. 2014).  
• Nipaecoccus viridis  often settles in concealed places, such as under the sepals of citrus fruits 
(Figure 10.1. 1) and under the calyx (CPC 2020).  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 302  
Figure 10.1.1  A portion of t he sepal of a citrus fruit is cut away to reveal the mealybugs ( N. 
viridis ) beneath. Sourced from Diepenbrock and Ahmed (2020).  
 
Although there is a lack of interception data of N. viridis  at the New Zealand border, it has been 
intercepted on citrus fruit in Australia.  
• There are no identification record s of N. viridis  or its synonyms at the New Zealand border 
from 1929 to March 2019 (LIMS 2019 ) or in the EPPO interception database (EPPO 2020c), 
even though it is widespread in many tropical  and subtropical  areas.  
• Adults of Nipaecoccus  filamentosus  (previously known as Pseudococcus filamentosus  
(Williams and Watson 1988 ) have been identified once on fresh orange fruit from Australia at 
the Ne w Zealand border (LIMS 2019).  It is suspected that this record is based on 
misidentification , as N. filamentosus  is not present in Australia. Since N. viridis  is present in 
Australia , and t here are many records of N. viridis  under the name P. filamentosus , it is 
possible that this identification record is actually N. viridis . 
• It is uncertain whether the lack of interception records for N. viridis  is a result of the difficulty in 
detection or because N. viridis  may not be able to survive transit on most commodities. Host 
commodities of fruit flies may have measures that could possibly kill the mealybug, which may 
also contribute to the lack of interception records  for N. viridis in New Zealand . 
• Nipaecoccus virid is has been intercepted on Citrus tangerina  and pomelo fruits at the 
Australian border (DAW E 2019).  
• Nipaecoccus viridis  has been intercepted 37 times at the US border between 1995 and 2012 
(records without commodity types) with specimens originating from B angladesh, Cambodia, 
China, Costa Rica, India, Indonesia, Italy, Laos, Pakistan, the Philippines, Puerto Rico, South 
Africa, Taiwan, Thailand and Viet  Nam (Millers et al. 2014) . 
 
Citrus species/cultivars that are associated with N. viridis are shown in Table 10.1.1.  
 
Table 1 0.1.1  Known citrus plant host association of Nipaecoccus viridis . 
Citrus host scientific name  Citrus host 
common name 
from the reference  Reference  Notes  
Citrus aurantiifolia  Lime García et al. (2016 ), CPC (2020)   
Citrus aurantium  Sour  orange  García et al. (2016 ), CPC (2020)   
Citrus aurantium subsp . bergamia   García et al. (2016 )  
Citrus aurantium var. sinensis   García et al. (2016 )  
Citrus limon  Lemon  García et al. (2016 ), CPC (2020)   
Citrus maxima  Pummelo  García et al. (2016 ), CPC  (2020)   
Citrus maxima   García et al. (2016 )  
Citrus medica   García et al. (2016 )  
Citrus paradisi   García et al. (2016 )  
Citrus reticulata   García et al. (2016 )  
Citrus sinensis  Navels and 
Valencias  Bedford  (1978)  Field fruit infestation  
 
303 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Citrus host scientific name  Citrus host 
common name 
from the reference  Reference  Notes  
Citrus sp. Tangelo Orlando  Germain et al. (2014)   
Citrus reticulata   DAWR (2019)  Interception on fruit  
Citrus paradisi  Grapefruit  CPC (2020)   
Citrus maxima  Pomelo  DAWR (2019)  Interception on fruit  
 
Nipaecoccus viridis  is present in citrus -exporting countries in this IHS:  
• Nipaecoccus viridis  is present in the following citrus -exporting countries in this IHS: Egypt, 
China, Japan, Viet  Nam, Mexico, the USA, Australia, New Caledonia and Solomon Islands  
(García et al. 2016).  
 
Given the arguments and evidence below,  basic measures  are likely to reduce the 
likelihood of entry of N. viridis  by a moderate degree . Consequently , the likelihood of 
entry is considered to be low, with low uncertainty . 
Visual inspection can usually detect infestations of N. viridis  on citrus  fruit. 
• Some typical signs can indicate the presence of N. viridis  on fruit, such as green marks 
occurring on ripe fruit at the point where the mealybugs pierce with their mouthparts, sooty 
mould, ovisac, male cocoon and waxy material produced by the mealy bug. Females produce 
an ovisac with a wax that is sticky when touched. At high levels of infestation , waxy secretions 
may appear as a continuous layer of wax which obscure s individual mealybugs  (Stocks and 
Hodges 2010; Levi -Zada et al. 2019).  
• The reproduci ng females are covered by the buff or whitish, fluffy and stringy ovisac, 
protecting the eggs inside (Bartlett 1987). As such, reproducing adult females and eggs that 
are within the ovisac are likely to be detected.  
 
However, in low population densities or as individuals, or if the commodities have a complex 
structure, detection of N. viridis  citrus fruits can be difficult.  
• Nipaecoccus viridis  often settle in concealed places, such as under sepals of citrus fruits and 
under the  calyx (Figure 10.1. 1; CPC 2020).  This distribution is likely to be the result of 
behaviours  such as thigmotaxis and negative phototaxis t hat have been reported in crawlers 
of other coccoid s pecies  (diaspidids and other pseudococcids) (Nestel  et al. 1995, Geiger and 
Daane 2001).  
• Nipaecoccus viridis  is small. Adult females and males are up to 4  mm and 2.5  mm long 
respectively (Williams 2004), and nymphs and eggs are even smaller (crawlers are 0.4 –
0.5 mm long; Sharaf and Meyerdirk 1987). Adult m ales are up to 2.5 mm long and are 
winged, so they are unlikely to be associate d with commodit ies (Sharaf and Meyerdirk 1987). 
Reproducing females and egg masses are more likely to be detected due to the cottony 
appearance of the ovisac. Nymphs are likely to be more difficult to detect , as they are smaller, 
especially when they are in sheltered places, such as under the sepals and in the calyx. As 
such, detection of N. viridis  require s careful inspection with a good eye or magnifier.  
 
As citrus fruit may h ave protected places for N. viridis  to hide, general handling after harvesting may 
not be able to remove/kill all mealybugs.  
• Nipaecoccus viridis is very difficult to control with insecticides due to its wax -covered body, 
cryptic behaviour, egg masses and m ale cocoon, along with overlapping generations (Sharaf 
and Meyerdirk 1987 ). The wax covering over a mealybug’s body can repel aqueous solutions, 
which reduces the effectiveness of insecticides and the likelihood of removal by washing 
(Hollingsworth and Ham nett 2009).  
• Although early instar nymphs have less wax  covering to protect them from insecticide and 
washing, it is easier for them to hide in sheltered places (e.g. under sepal or calyx and in the 
navel of navel orange) because of their smaller size and higher mobility than other life stages 
(except male adults).  
• In general, except for adult males and the first instar nymphs, other life stages of mealybugs 
tend to be stationary (Kosztarab and Kozár  2012) . As such, they are less likely to get off the 
comm odity during handling, especially when they are in sheltered places.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 304  
Likelihood of establishment:  
 
Given the arguments and evidence below,  Nipaecoccus viridis  has low ability (with 
high uncertainty) to move from imported fruit and into a suitable environment to allow 
establishment, that is, onto a host plant.  (exposure/transfer)  
Nipaecoccus viridis may survive and develop on the waste of citrus  fruit (whole fruit or fr uit pieces).  
• Although there is no specific study on the development of N. viridis  on citrus fruit, a  laboratory 
study in New Zealand (Whyte et al. 1994) showed that the longtailed mealybug, 
Pseudococcus longispinus,  survived up to 49 days on oranges (if wh ole fruit was not 
consumed or decayed). In contrast, desiccation renders orange peel unsuitable as a host.  
• On lemon seedlings at 25±2°C, female and male N. viridis nymphs completed development in 
about 19.3 and 20.3 days (Sharaf and Meyerdirk 1987 ). Shara f and Meyerdirk (1987) did not 
mention which part the mealybug was reared on. There is a moderate to high uncertainty that  
N. viridis  can survive and develop on citrus fruits.   
 
Most of the kitchen  waste in New Zealand is disposed of using methods that pose a low risk of 
transfer to a new host , so the mealybug would either be killed or unable to escape from the citrus  
host.  
• The majority of kitchen  waste in New Zealand is bagged and disposed of in landfills or run 
through  kitchen disposal units, and in these situations, the mealybug is unlikely to reach a 
new host (see waste analysi s, section 2.4.1 ). 
 
However,  some of the waste would be disposed of using methods that pose a higher risk of transfer to 
a new host, including composting in gardens and using  it as animal feed.  
• Nipaecoccus viridis is rather polyphagous, and some host plants are commonly planted in 
home gardens and parks, such as citrus, grapevines, tomatoes, apples, pears, figs, celery, 
cucumbers, asparagus, roses and camellias  (García  et al. 2016 ).  
• Nipaecoccus viridis has been reported on common weed species, including Cynodon 
dactylon (Bermuda grass), Sonchus  spp. and Lantana camara (García et al. 2016). Cynodon 
dactylon is both a lawn grass and weed species ( Breitwieser et al.  2020), common  in warmer 
coastal areas of the North  Island and  some  warmer parts of the South Island; Sonchus 
oleraceus  and S. asper  (sow thistle) are common weeds throughout New Zealand (iNaturalist 
2020); Lantana camara is abundant on the northwest  shore of Hokianga  Harbour and 
occasionally  grows elsewhere in north Auckland and the Bay of Plenty (RNZIH 2014).  If these 
hosts are located near a composting site (see the waste analysis , section 2.4.1 ), N. viridis  
may be able to transfer from the citrus host to the new ho st.  
 
Mealybug species  have relatively limited mobility, and except for the first -instar nymphs (crawlers) and 
adult males, life stages tend to be sessile , meaning they prefer not to move if they are in a suitable 
location .  
• All stages of N. viridis  can move freely, but the crawler is the only life stage that move s 
readily, and they usually settle on the same host ( Sharaf and Meyerdirk 1987 ). This implies 
that dispersal via walking can only result in short -distance dispersal (i.e. within  the original  
host plants or nearby plants). The ovipositing females often remain sedentary (Wakgari and 
Giliomee 2005) . If citrus  fruit waste is disposed of in an environment with suitable hosts 
nearby, for example composting and animal feeding, the crawlers may be ab le to walk to the 
nearby host.  
 
Mealybug species can be dispersed passively , which is also considered an important mechanism 
contributing to the spread of mealybugs, and the polyphagous nature of N. viridis  is likely to increase 
the likelihood of landing o n a suitable host.  
• Mealybugs can be passively dispersed by wind, water, fallen leaves, phoresy (attached to 
birds, ants, other insect s, etc.) and movement of farm equipment, soil and infested plant  
material (although no specific study has been carried out on N. viridis ). However, long -
distance movement of mealybugs is most likely due to the movement of infested nursery 
stock and agricultural commodities (Mani and Shivaraju  2016).  
• Passive dispersal by wind is considered to be an important mechanism contribut ing to the 
colonisation of new areas by mealybugs (Lo et al. 2006). Nymphs (mainly first instars) and  
305 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  adult males (only in insignificant number s) have been reported as able to disperse by wind, 
for short, moderate and presumably long distances:  
o The first - and second -instar nymphs, as well as adult males, of the grape mealybug, 
Pseu dococcus  maritimus , can be dispersed by wind, but there is a marked decline in 
numbers with increasing distance from the source plant (Grasswitz et al. 2008). The 
crawlers were  dispersed up to 8  m in this study. Among the mealybugs being 
dispersed by wind, 86.3% were crawlers, 10.8% were second instars, and 2.9% third 
instars.  
o Lo et al. (2006) conducted a field trial using aerial trapping to catch mealybugs that 
were dispersed by  wind in a New Zealand vineyard. Crawlers and a small number of 
adult males were caught in these traps, and they found that mealybugs can be blown 
at least 5  m and up to 15  m.  
o Based on 24 -hr wind -run values, Barrass et al. (1994) presumed that the crawler s of 
Pseu dococcus  longispinus  could disperse across distances greater than 50  km, 
although this has not been tested in scientific studies.   
o Barrass et al. (1994) also found that the survival rate for the crawlers of Ps. 
longispinus  held at 20 °C and 32% re lative humidity for 48  hours was 75%, suggesting 
that the crawlers are capable of surviving desiccation for long enough to make wind 
currents a viable method of dispersal.  
o In Lo et al. (2006), they also estimated that in the 6 weeks leading up  to mid -April, 
there were 2.5 million crawlers/ha in the air above the mealybug -infested vineyard.  
o Barrass et al. (1994) also found that number of mealybugs caught in aerial traps 
increased directly with wind speed and with the square of the daily temperature 
maximum, which implies that dispersal by winds of mealybugs in areas with high wind 
speeds and temperature are likely to be more frequent.  
o Some coccoid species are known to deliberately move to high points of their host 
plants in order to disperse (Brown 1958, Bear dsley and Gonzalez 1975, Greathead 
1990, Lo et al. 2006). Washburn and Washburn (1984) showed that crawlers of the 
coccid Pulvinariella mesembryanthemi (Vallot ) deliberately entered the air, not only 
by moving up the plant but by orienting their bodies most favourably to the air current 
and standing on their hind legs . However it is important to note that most studies of 
crawler dispersal have been ca rried out u sing insects on their host plants , and that 
information about dispersal of crawlers from situations comparable to a piece of 
discarded fruit is scarce.  
• Rapid and widespread dispersal  of mealybugs  may also  occur  due to the sticky and stringy 
ovisac , which i s well adapted to adhere to the feet of birds (Bartlett et al. 1978).  
• Passive dispersal cannot guarantee N. viridis  will land on a suitable host, but the polyphagous 
nature of N. viridis  is likely to increase the likelihood of landing on a suitable host.  
• However, passive dispersal also means that successful transfer will depend not only on 
whether hosts are present, but also on other factors such as wind speed, whether animals are 
present (i.e. hitchhiking) and the survival rates of the mealybug during pass ive dispersal, 
which are considered uncertain at this stage.  
 
Nipaecoccus  viridis  reproduce s sexually  (Ross et al. 2012, Mendel and Blumberg 2015 ).  Sharaf and 
Meyerdirk (1987) cited one report of asexual r eproduction  by parthenogenesis in Iraq (Al -Ani et al. 
1974) but this is considered to be doubtful (Mendel and Blumberg 2015).  
• Mealybugs are able to mate with their siblings in the laboratory (e.g. Ross et al. 2012, García 
de la Filia et al. 2019) and it is assumed th is also occurs in the field, though there may be 
behavioural or other constraints against sibling mating ( Müller and Müller 2016, Collet et al. 
2019 ).  
• Virgin females  of N. viridis  can produce a sex pheromone to attract males (Levi -Zada et al. 
2019). It is  uncertain how far adult males can fly to locate a mature female, but it is noted that 
the adult males of some well -known mealybug pests are weak fliers (Barrass et al. 1984; 
Chen et al. 2012).  
• Adult male mealybugs  only live for a few days (Williams 2004) . 
 
The level of uncertainty associated with the conclusion  on the transfer ability of N. viridis  is high. First, 
waste data and information may not be very accurate and up to date , and it is not known how 
frequently suitable hosts would be  near composting sites in gardens or animal feeding locations (see 
section 2.4.1,  waste analysis). Second, it is reported that dispersal by wind is an important Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 306 mechanism for the spread of mealybugs, but it is not known how effi cient (compared to dispers al by 
walking) this dispersal method is, and it is uncertain what proportion of composting sites are expos ed 
or covered  (e.g. in a compost bin).  
 
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for N. viridis to establish is considered low to moderate (with moderate 
uncertainty) , but the likelihood of establishment in warmer areas and indoor 
environments , such as greenhouses, is considered  moderate.  
Nipaecoccus viridis  has a wide distribution  that includ es areas with a similar climate to New Zealand.  
• Nipaecoccus viridis  is present in Africa, Asia , North America and Oceania (Table 10.1.2). 
 
Table 10.1.2  Known geographic distribution of Nipaecoccus viridis. Information  compiled 29 May 2020 
from Garc ía et al . (2016) and EPPO ( 2020a ). Country/area with underline  is only recorded in Garcia et al. (2016). 
Country/area in bold  is included in the Citrus IHS project.  
Continent /Region  Country/area  
Africa  Algeria, Angola, Benin, Burkina Faso, Comoros, Cote d ’Ivoire , Egypt , Eritrea, Kenya, 
Madagascar, Malawi, Mali, Mauritius, Niger, Nigeria, R éunion, Rwanda, Senegal, 
Seychelles, South Africa, Sudan, Tanzania, Togo, Uganda, Zanzibar , Zimbabwe  
Asia Afghanistan, Bangladesh, Bhutan , Myanmar , China  (Hainan , Hong Kong, Hunan, 
Henan , Inner Mongolia ), Christmas Island , India, Indonesia, Iran, Iraq, Israel, Japan , 
Jordan, Cambodia, Malaysia, Nepal, Oman, Pakistan, Philippines, Saudi Arabia, 
Singapore , Sri Lanka, Syria , Taiwan, Thailand, Viet Nam 
North America  Bahamas, Mexico , United States  (Florida, Hawaii)  
Oceania  Australia  (Northern Territory, Queensland), Guam, Kiribati, New Caledonia , Northern 
Mariana Islands, Papua New Guinea, Solomon Islands , Tuvalu  
 
Climatically, the distribution of N. viridis  is mainl y in the tropics and subtropics.  
• Nipaecoccus viridis  is widely  distributed in tropical and subtropical areas (Table 10.1.2). 
 
However, N. viridis  is also present in areas with similar climate conditions to New Zealand, although 
these areas only occupy a very small portion of the distribution areas . 
• The current distribution includes a small number of countries/areas with  a climate  match index  
(CMI) (Phillips et al. 2018) over 0.7, which means these areas have 70% –100% similarity of 
climate to the general New Zealand climate . These areas include Henan in China (CMI: 0.7 –
0.8), Hunan in China (CMI: 0.7), Northern Cape of South Africa (CMI: 0.6 –0.8), Him achal 
Pradesh in India (CMI: 0.8) and Rwanda (CMI: 0.7) (García et al. 2016; Phillips et al. 2018; 
CPC 2020).   
 
It is uncertain if the mealybug can survive or complete development in the colder areas of New 
Zealand.  
• Some mealybugs have been reported to be able to survive transit, including cold storage, on 
some commodities (e.g. Pseudococcus longispinus  and Pseudococcus  calceolariae  (Smith et 
al. 1997), implying that these mealybugs are likely to survive cold conditio ns. However, no 
study on the lower temperature developmental threshold or cold tolerance of N. viridis was 
found.  
 
Nipaecoccus viridis  has multiple, overlapping generations in its distribution and a high reproductive 
rate. 
• Nipaecoccus viridis  can quickly develop large populations in its current distribution due to 
multiple and overlapping generations (Bartlett 1978).  
• On lemon seedlings at 25 ±2°C, adult females laid an average of 667 eggs during the 
oviposition period , which lasted from 21 –37 days (Sharaf and Meyerdirk 1987). Bartlett (1978) 
reported that the fecundity of a large female can exceed 1 ,100 eggs.  
 
Host availability is unlikely to be a limiting factor for N. viridis to establish in New Zealand.   
307 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Nipaecoccus v iridis is polyphagous. It has been reported from 140 genera of plants in 52 
families (García et al. 2016).  
• Host plants include those commercially grown in New Zealand and those commonly grown in 
gardens and parks, such as citrus, grapevines, tomatoes, appl es, pears, figs, celery, 
cucumbers, asparagus, Rosa  and Camellia . etc. Common weed species, C. dactylon 
(Bermuda grass), Sonchus  spp. and L. camara , are also reported as hosts (García et al. 
2016).  
 
Nipaecoccus viridis is predominantly distributed in the tropics and subtropics, but it is also present in 
areas/countries (Hunan and Henan in China, Northern Cape of South Africa, Taipei in Taiwan, 
Himachal Pradesh in India and Rwanda) with similar or marginally similar climate conditions to New 
Zealand.  This suggests  that N. viridis  or some populations of the pest may adapt to some areas of 
New Zealand with a colder climate. Also, the lower development threshold and cold tolerance of N. 
viridis  is unknown. Therefore, the level of uncertainty associated with th e conclusion is moderate.  
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by N. viridis  is 
likely to be low –moderate (with moderate uncertainty), but the level of impact to the 
citrus industry in northern New Ze aland is likely to be moderate.  
Damage and symptoms caused by N. viridis  can reduce yield and plant or fruit quality.  
• Nipaecoccus viridis  can feed on the host’s branches, twigs, shoots, leaves, flower buds, fruits 
and root. It sucks up the plant sap, causi ng curling and dwarfing of the terminal growth, 
abortion of flowers, yellowing of leaves, fruit distortion and dropping of fruits. Severe 
infestations can lead to wilt and death of plants (Sharaf and Meyerdirk 1987).  
• Nipaecoccus viridis  injects toxic subst ances into plant tissues , which can lead to dieback of 
the terminal growth. It secretes large amounts of honeydew on the host , which can lead to the 
growth of sooty mould affecting plant photosynthesis. Fruits with sooty mould contamination 
or dust accumul ated due to honeydew become soiled and unmarketable (Sharaf and 
Meyerdirk 1987).  
• The damage caused by N. viridis  on fruits also includes lumpy outgrowths or raised shoulders 
near the stem end. Fruits with this damage have to be culled in the packinghouse ( Hattingh et 
al. 1998,  in CPC 2020).  
 
Nipaecoccus viridis has been reported as a severe pest on a range of economically important plants, 
some of which are also important in New Zealand, such as citrus and grapevine.  
• Nipaecoccus viridis  is a pest on a range of plants that are of economic importance  to New 
Zealand , such as citrus, grapevine, soybean and many ornamental plants (Sharaf and 
Meyerdirk 1987; Thomas and Leppla 2008).  
• In 2019, the domestic and export value of citrus in New Zeal and were NZ$58.5  million and 
$12 million respectively  (Plant & Food Research  2019) .   
• Grapes are high -value crops in New Zealand. In 2019, the export value of New Zealand wine 
was NZ$1.825  billion (Plant & Food Research  2019).  
 
However, while most reports on its impacts were from the tropics and subtropics, severe production 
loss has been reported from South Africa.  
• Citrus:  
o Nipaecoccus viridis has been reported to cause heavy infestations in citrus orchards 
(e.g. orange, acid lime, pomelo, etc.) in South Af rica, Hawaii, Egypt, Jordan, Iraq, 
India and Israel (Bar tlett 1978; Thomas and Leppla 2008; Mani and Shivaraju 2016).  
o In South Africa, N. viridis  is sometimes a serious pest in poorly managed citrus 
orchards in Rustenburg (CMI: 0.7) (Bedford et al. 1978),  and it has been reported to 
cause more than 50% crop loss of navel orange (Hattingh et al. 1998,  in Thomas and 
Leppla 2008). In Rustenburg, N. viridis  (reported as N. vastator ) has three 
generations from September to around April (Bedford et al. 1978). A climate niche 
approach (Halloy 2020) reveals that N. viridis  is active in the wet and warm seasons 
in Rustenburg , with a temperature range overlapping with the temperature rang e of Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 308 the summer months of northern New Zealand ( Figure 10.1. 2), which is New 
Zealand’s main citrus production area. Climate change is likely to increase the 
similarity of the climate between northern New Zealand and Rustenburg  (Figure 
10.1. 2). In addition,  many mealybug species are cold -resistant (DAWR 2019) and 
N. viridis  is present in colder areas with similar climate to  the overall New Zealand  
climate , suggesting that it may be able to overwinter in northern New Zealand. 
Therefore, the consequence s of introducing N. viridis  could potentially be compared 
to the consequences of introduction  in South Africa . 
• Other crops:  
o Nipaecoccus viridis  has been reported to be a pest of grapes in India (Levi -Zada et al . 
2019). It is reported that N. viridis  caused up to 5% damage on grape bunches in two 
vineyards in Bangalore, India (Mani and Thontadarya 1987, in CPC 2020). 
Nipaecoccus  viridis  is not known to occur on grapes in temperate areas.  
o Nipaecoccus viridis  has also been recorded as a pest of soybean s in India. 
Nipaecoccus viridis  feeds on leaves, stems and pods of soybean. An average of 30–
35 mealybugs per soybean plant has been recorded in Rajasthan, India (Babu 2016). 
There is no report of its impact on soybeans in temperate areas. Soybean is 
comme rcially grown in New Zealand, although it is a small industry.  
 
 
Figure 10.1. 2  Climate niches (temperature and precipitation range) of New Zealand (grey ellipse), northern 
New Zealand (including Northland, Auckland and Bay of Plenty; red ellipse), Ruste nburg (pink ellipse), 
active period of N. viridis  in Rustenburg (blue ellipse) and northern New Zealand in a +4 °C climate change 
scenario (red dashes). These ellipses include 95% of climatic sites within the specific area. Northern  
New Zealand includes 68% of the citrus productive area in New Zealand (Halloy 2020).  
 
The i ntroduction of biological control agents has successfully controlled N. viridis  in some areas , and 
one agent (the mealybug ladybird) that is reported to have effectively  controlled the pest is present in 
New Zealand. However, the effectiveness of biological control in New Zealand is uncertain.  
• Nipaecoccus viridis  is very difficult to control with insecticides due to the wax  covering, cryptic 
behaviours, the protection of ovisac s and cocoon s, and overlapping generations (Sharaf and 
Meyerdirk 1987). However, N. viridis  has a long list of natural enemies (García et al. 2016) , 
and introduction of biological agents has successfully controlled the pest in some areas, such 
as the  introduction of Anagyrus dactylopii  (encyrtid wasp) in Hawaii, the introduction of 
A. aegyptiacus  and Leptomastix phenacocci  in Egypt, and the introduction of Cryptolaemus 
montrouzieri  in India  (CPC 2020; Sharaf and Meyerdirk 1987).    
• Cryptolaemus montrouzieri  (mealybug ladybird) is present in warmer areas  in New Zealand, 
mainly in Auckland and Northland (Martin 2018) , and it is commercially produced in New 
Zealand (Bioforce 2012).  However, it is hard to know the effectiveness of this biological 
control agent on N. viridis  in New Zealand due to the complexity and difference s of the 
ecological system in New Zealand compared with other locations.  
 
 
309 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  The e stablishment of N. viridis  may result in increased phytosanitary measures required for export to 
coun tries where the pest is absent  and regulated.  
• Most countries in temperate areas and some areas in the tropics and subtropics have not 
been reported to have the mealybug, such as the whole European area, South America, and 
most areas in North America (Tabl e 10.1.1 ). 
• Nipaecoccus viridis  is a quarantine pest in South Korea (Thomas and Leppla 2008), East  
Africa, Southern Africa, Brazil, Chile, Bahrain and Turday (EPPO 2020).  
 
Nipaecoccus viridis  may cause environmental impacts on native plant species, as it ha s hosts in plant 
genera with native New Zealand plant species, and plant species under some of these genera have 
‘at risk ’ or ‘threatened ’ conservation status.  
• Usually, if a pest attacks species under a genus, it is assumed that the pest may attack other 
species under the same genus. Nipaecoccus viridis  has been recorded on host species 
belonging to genera that have species native to New Zealand . These genera inc luded: 
Avicennia , Apium , Schefflera , Sonchus , Ipomoea , Euphorbia , Geranium , Pelargonium , Vitex , 
Hibiscus , Streblus  and Solanum  (NZPCN 2020; García  et al. 2016 ). It is uncertain what level 
of damage can be caused by the pest on these species .  
• Some of the s pecies under these genera have ‘ at risk’ or ‘threatened’  conservation status  in 
New Zealand , including : Apium prostratum subsp.  denticulatum , Sonchus grandifolius , 
Sonchus kirkii , Sonchus novae -zelandiae , Ipomoea pes -caprae subsp. brasiliensis , Euphorbia 
glauca , Geranium retrorsum , Geranium sessiliflorum var. arenarium , Geranium socolateum , 
Geranium solanderi , Geranium traversii , Hibiscus diversifolius subsp. diversifolius , Hibiscus 
richardsonii , Streblus banksia , Streblus smithii , Solanum avicu lare var. aviculare , Solanum 
aviculare var. latifolium (NZPCN 2020).  
• however it should be noted that relatively few non -indigenous invertebrates and pathogens 
have been recognised as causing serious damage to terrestrial natural ecosystems globally 
(Philli ps et al. 2008), and in the New Zealand context only a few substantial pest and disease 
outbreaks affecting native plants have been documented (Beever et al. 2007 ). 
 
Nipaecoccus viridis  may have impacts on the urban environment and may have indirect health  
impacts to humans . 
• Nipaecoccus viridis  is damaging to a number of plants grown in domestic gardens and parks, 
such as Vitis spp., Prunus  spp., Citrus  spp., Malus  spp., roses and camellias . Therefore, it is 
a potential nuisance pest in urban environment s. Also, it could be more problematic in 
protected environments (e.g. houseplants) where parasitoids do not have easy access to 
them.  
• Nipaecoccus viridis  may indirectly have some impact on human activities. Vespula wasps are 
attracted to honeydew excreted by some insects, and high numbers of wasps in recreational, 
urban or other areas may adversely impact on health (painful stings or allergy to stings) and 
social activities ( MAF  2008). However, as many sap -sucking insects  that can produce 
honeydew  are already present in New Zealand, the impact may  be minor  to negligible .  
 
Most reports on economic or sociocultural impacts of N. viridis  are from the tropics and subtropics, 
except for the report on poorly managed citrus orchards from Rustenburg, South Africa, whe re the 
climate conditions are similar to New Zealand. There is a lack of reports on the environmental impacts 
of N. viridis , but plant genera that have related native species and have ‘at risk’ and “threatened’ 
conservation status in New Zealand have been attacked by N. viridis  overseas. Therefore,  the level of 
uncertainty associated with the conclusion is moderate.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence below,  Nipaecoccus viridis may be considered 
for additional measures . 
• Nipaecoccus viridis  has a strong host association with citrus fruits . 
• Nipaecoccus viridis  is present in several exporting countries . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 310 • Nipaecoccus viridis  is small and cryptic (especially nymphs) . As such, in low population 
densities or as individuals, detection can be difficult if the commodities have sheltered places 
(e.g. under the sepal s or calyx of fruits, in the navel of navel orange s) for them to hide . 
• Nipaecoccus viridis  has relatively limited mobility, but it can disperse passively. It is reported 
that dispersal  of mealybugs by wind is an important mechanism for their spread . 
• Passive dispersal cannot guarantee N. viridis  will land on a suitable host, but the polyphagous 
nature of N. viridis  increases the likelihood of it landing on a suitable host . 
• Disposal to landfill, which is a low -risk disposal method, is the primary  way of disposing of 
kitchen waste in New Zealand, while disposal using high -risk methods (composting and 
animal feeding) is less common . 
• Some kitchen waste is likely to be disposed of using high -risk methods , and the mealybug is 
polyphagous , which increases  the probability that suitable hosts would be present in the 
surrounding environment . 
• Nipaecoccus viridis  is widespread in the tropics and subtropics, but a very small portion of the 
distributi on areas have similar climate conditions to New Zealand . 
• Host availability is unlikely to be a limiting factor for N. viridis to establish in New Zealand . 
• The economic impact is consider ed low to moderate  with moderate uncertainty, because 
there is a lack of report s found on the economic impact s of N. viridis in temperate areas, 
except for South Africa . 
• In South Africa, this mealybug  caused more than 50% crop loss in heavily infested navel 
orange orchards in Rustenburg. The climate conditions of Rusternburg  are similar to those of 
New Zealand based on a climate niche approach . 
• Nipaecoccus viridis  may cause environmental impacts on native plant species, as it has hosts 
in plant genera with native New Zealand plant species, and plant species under some of 
these genera have an ‘at risk’ or ‘threatened’ conservation status . 
 
 
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281–332. 
Washburn, J O; Washburn, L (1984) Active aerial dispersal of minute wingless art hropods: 
exploitation of boundary layer velocity gradients. Science  223 (4640): 1088 –1089.  
 
Whyte, C F; Adams, R L; Richmond, J E; Cowley, J M; Baker, R T (1994) Experimental analysis of 
pest risk factors. An analysis of some biological survival factors us ed in Pest Risk Assessment. 
Lynfield Plant Protection Centre Publications No. 2. 18  pages.  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 314 William, D J; Watson, G W (1988) The Scale Insects of the Tropical South Pacific Region. Part 2. The 
Mealybugs (Pseudococcidae).  CAB International; Wallingford, UK.  
Williams, D J (2004) Mealybugs of Southern Asia. The Natural History Museum Kuala Lumpur: 
Southdene SDN. BHD. Malaysia.  
   
315 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  9.2 Planococcus kraunhiae  (Japanese mealybug ) 
Planococcus kraunhiae  is a species of mealybug. It is believed to be of eastern Asian origi n, and it is 
found in a number of countries.  It damages a variety of fruits (e.g. grapes, pears, figs, citrus etc.), 
especially persimmons in western Japan.  
 
Scientific name: Planococcus kraunhiae  (Kuwana,1902)  
Order/Family: Hemiptera/Pseudococcidae  
Other names include : Dactylopius kraunhiae, Pseudococcus kraunhiae, Planococcus kraunhiae, 
Planococcus siakwanensis  (García et al. 2016 ) 
 
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Planococcus kraunhiae meets the criteria to be a  quarantine pest for New Zealand . 
• Planococcus kraunhiae has a strong association with citrus fruit  with low uncertainty.  
• Basic measure s are likely to reduce the likelihood of entry  of P. kraunhiae  to New Zealand by 
a moderate degree . Consequently , the likelihood of entry is considered low , with low 
uncertainty.  
• Planococcus kraunhiae  has low ability (with high uncertainty) to move from imported fruit and 
into a suitable environment to allow establishment, that is, onto a host plant.  
• The suitability of the New Zealand environment for P. kraunhiae  to establish is considered 
high, with low uncertainty . 
• The level of impact caused by P. kraunhiae is likely to be moderate  (with moderate 
uncertainty) . 
• Planococcus kraunhiae  may be considered  for requiring  additional measures . 
 
Summary of risk assessment against criteria  
Criteria  Rate  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from the imported commodity  onto a suitable host  Low High 
Suitability of the N ew Zealand  environment  High Low 
Impacts on the New Zealand economy, environment, health and society  Moderate  Moderate  
 
9.2.1 Hazard  identification: quarantine status  
Given the arguments and evidence below,  Planococcus kraunhiae  meets the criteria 
to be a quarantine pest for New Zealand . 
Criteria for being a quarantine pest relevant to this assessment are:  not present in New Zealand, and 
of potential importance (able to establish and cause harm).  
 
Planococcus kraunhiae  is not known to be present in New Zealand:   
• It is not recorded in NZInverts (2020) or NZOR  (2020) . 
• It is not recorded in PPIN (2020).  
• It is listed as ‘ regulated’ in ONZPR  (2020) . 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 316 Planococcus kraunhiae  has the potential to establish and spread in New Zealand:  
• Planococcus kraunhiae  is present in China (Shanxi, Yunnan),  India . Iran, Japan, Madeira 
Islands, Philippines, South Korea, Taiwan, Viet  Nam and the United States (California) (Cox 
1989; Hembram et al. 2007; Thuy et al. 2011; García et al. 2016; Wang et al. 2018 ). 
• The current  distribution of the pest includes  areas with similar climate conditions to New 
Zealand: Shanxi ( climate match i ndex (CMI) = 0.7), Yunnan (0.6 –0.8), Japan (0.7 –0.8), South 
Korea (0.6 –0.7) and California (0.5 –0.8) ( Phillips  et al. 2018).  
• Planococcus kraunhiae  is polyphagous. It has been reported on 32 genera of plants in 26 
families  (García et al. 2016 ).  
• The host  list includes species that are commercially planted in New Zealand, including 
kiwifruit  (Actinidia  spp.), pumpkin  (Cucurbita moschata ), persimmon  (Diospyros kaki ), fig 
(Ficus carica ), olive ( Olea europaea ), grapevine  (Vitis vinifera ) and citrus ( Citrus spp.). 
 
Planococcus kraunhiae  has the potential to cause impacts to the economy and environment of New 
Zealand:  
• Planococcus kraunhiae  has the potential to harm plants of eco nomic importance to New 
Zealand . Host species of P. kraunhiae  include important crops i n New Zealand, such as 
Citrus, Actinidia  and Vitis (García et al. 2016; USDA 1995 ). 
• Planococcus kraunhiae  has the potential to harm the New Zealand environment . The 
mealybug has been reported on plant species in genera that are native to  New Zealand  
(NZPCN 2020) . 
 
9.2.2 Hazard identification: commodity association  
Planococcus kraunhiae  is associated with citrus fruit . 
Planococcus kraunhiae  is reported from citrus fruit : 
• It has been reported on citrus fruit in Japan ( Miyashita et al.  2013; Boujo 2020 ). 
• At US ports -of-entry, P. kraunhiae  is most often taken into quarantine on Citrus and Diospyros  
spp. (persimmons) from Japan ( Miller et al.  2014 ), although the authors did  not mention 
whether the commodities were  fresh fruit or plants for planting.  
 
9.2.3 Risk asses sment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Planococcus kraunhiae  has a strong 
association with citrus fruit  with low uncertainty : 
Planococcus kraunhiae  has been reported on citrus fruits.  
• Boujo (2020) reported that P. kraunhiae  is often found on peduncles, branches, fruits and 
leaves  of citrus .  
• Miyashita et al. (2013) conducted a study on the effectiveness of different chemical control 
methods in controlling P. kraunhiae  in lemon orchards, using mealybugs per fruit as one of 
the indices, indicating that P. kraunhiae  can be found on lemon fruits.  
• Planococcus kraunhiae  is reported as an important pest that infests many kinds of fruits, 
including Citrus species in Japan (Kawai 1980 ; Ben-Dov 1994,  in Tabata 2013).  
• Quarantine specime ns of P. kraunhiae  on oranges from Japan to the USA have been 
reported (Miller et al. 2014).  
• At US ports -of-entry, P. kraunhiae  is most often taken into quarantine on Citrus  and Diospyros  
(persimmons) from Japan ( Miller et al.  2014 ), although the authors did not mention whether 
the commodities were  fresh fruit or plants for planting.  
• There has been  only one interception of P. kraunhiae  since 1986 to date at the New Zealand 
border (LIMS interception data). However, there have been  161 interceptions of Plano coccus  
spp. (the identity of species is not always determined) , which may or may not include some P. 
kraunhiae .   
317 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Nymphs of Planococcus kraunhiae  may survive cold storage.  
• Planococcus kraunhiae  can overwinter as first and second -instar nymphs on persimmon in 
Japan (Morishita 2005), which means that they are likely to survive cold storage during 
transit.  
 
Citrus species/cultivars found to be associated with P. kraunhiae are shown in Table 10.2. 1. 
 
        Table 10.2.1  Known citrus plant host association wi th Planococcus kraunhiae . 
Citrus host scientific name  Citrus host common name  
(from the reference ) Reference  
Citrus aurantium   García et al. (2016 ) 
Citrus ichang austera hybrid  Citrus junos  García et al. (2016 ) 
Citrus maxima   García et al. (2016 ) 
Citrus  paradis i* grapefruit  Chen et al. (2003)  
Citrus reticulata  Unshu orange  USDA (1995)  
Citrus limon  lemon  Miyashita et al. (2013)  
Citrus reticulata  mandarin  Venkatesan et al. (2016)  
Citrus sinensis  orange  Miller et al. (2014 ) 
* Reference  is in Chinese, with the  English scientific and common name s not provided . It is assumed that 葡萄柚  refers to  C. paradisi  (grapefruit).  
 
Planococcus kraunhiae  is present in citrus exporting countries in this IHS:  
• Planococcus kraunhiae  is present in the foll owing citrus exporting countries: China, Japan, 
South Korea, Viet  Nam and the USA.  
 
Given the arguments and evidence below,  Basic measure s are likely to reduce the 
likelihood of entry of P. kraunhiae  by a moderate degree, consequently the likelihood 
of entry is considered to be low with low uncertainty:  
Usually, visual inspection can detect infestations of P. kraunhiae on citrus  fruits.  
• Some typical signs can indicate the presence of P. kraunhiae on fruits, such as sooty mo uld 
on fruits and waxy material produced by the mealybug (Thuy et al. 2011 ). 
 
However, in low population densities or as individuals, detection can be difficult if the commodities 
have sheltered places for them to hide.  
• Planococcus kraunhiae  is small. Adul t females are approximately 2.0 –3.3 mm in length and 
2.2–2.0 mm in width, and nymphs and eggs are even smaller than the adult female (Cox 
1989 ). Early instar nymphs are likely to be more difficult to be detected, as they are smaller 
and have less of the waxy covering. As such, detection of P. kraunhiae will require careful 
inspection with a good eye or magnifier.  
• Mealybugs are cryptic and are commonly found in protected places on the plant, such as in 
plant nodes, overlapping leaves, bracts and bark crevic es (Mani and Shivaraju, 2016) . As 
such, P. kraunhiae may be able to hide in the calyx of fruits, underneath sepals, wrinkles 
around the calyx or in the navel of navel orange s if navel orange is a suitable host  (The pest 
has been intercepted on orange from Japan (Miller et al. 2014), but it is not known whether it 
was navel orange).  This reduces the likelihood of detection.  
 
As citrus fruit may have protected places for P. kraunhiae to hide, general handling after harvesting 
may not be able to remove/kill all mealybugs.  
• Mealybugs  are commonly found in protected/sheltered places (Mani and Shivaraju 2016) . 
This distribution is likely to be the result of behaviours such as thigm otaxis and negative 
phototaxis that have been reported in crawlers of other coccoid species (diaspidids and other 
pseudococcids) (Nestel et al. 1995, Geiger and Daane 2001).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 318 • The wax covering over a mealybug ’s body can repel aqueous solutions, which reduces  the 
effectiveness of insecticides and the likelihood of removal by washing (Hollingsworth and 
Hamnett 2009; Teshiba et al. 2015; Venkatesan et al. 2016 ).  
• Although early instar nymphs have less of the wax covering to protect them from washing and 
insectic ides, it is easier for them to hide in sheltered places (such as  the calyx and the navel 
of navel orange s) because of their smaller size and higher mobility than other life stage s.  
• Except for adult males and the first -instar nymphs, P. kraunhiae life stag es have limited 
mobility (Kosztarab and Kozár  2012) . As such, they are less likely to get off the commodity 
during handling.  
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Planococcus kraunhiae  has low ability 
(with high uncertainty) to move from imported fruit and into a suitable environment to 
allow establishme nt, that is, onto a host plant (exposure ). 
Planococcus kraunhiae is likely to survive and develop on the waste of citrus  fruit. 
• Althoug h there is no specific study on the development of P. kraunhiae on citrus fruit, a  
laboratory study in New Zealand (Whyte et al. 1994) showed that the longtailed mealybug, 
Pseu dococcus  longispinus , survived up to 49 days on oranges  (if whole fruit was not 
consumed or decayed) . In contrast, desiccation renders orange peels unsuitable as hosts.  
 
Most of the kitchen  waste in New Zealand is disposed of using methods that pose a low risk of 
transfer to a new host such that the mealybug would either be killed or unable to escape from the 
citrus  host.  
• The majority of kitchen waste in New Zealand is disposed of in landfills and run through  
kitchen disposal units, and in thes e situations, the mealybug is unlikely to reach a new host 
(see section 2.4.1,  waste analysis).  
 
However, some of the waste would be disposed of using methods that pose a higher risk of transfer to 
a new host including composting in gardens and using as an imal feed.  
• Planococcus kraunhiae is polyphagous, and some host plants are commonly planted in home 
gardens, such as Citrus , Pyrus  and fig.  It has been reported on a weed species, Digitaria 
sanguinalis  (summer grass ) (García et al. 2016 ), which is very common in northern  and 
coastal regions of the North Island of New Zealand (AgPest 2020) . If these hosts are located 
near the composting site or animal feeding site (see section 2.4.1,  waste analysis), some life 
stages of P. kraunhiae  may be able to transfe r from the citrus host to the new host.  
 
Mealybug species  have relatively limited mobility, and other than  the first -instar nymphs (crawlers) 
and adult males, life stages tend to be sessile.  
• The primary dispersal stage of mealybug species  is the crawlers . Crawlers have been found 
to possess characteristics that are considered adaptations for dispersal behaviour, including 
relatively well -developed legs and  antennae (Gullan and Kosztarab  1997). This implies that 
dispersal via walking can result in short -distance dispersal (i.e. within the original host plants 
or nearby plants). While other life stages  of mealybugs  are usually mobile, they tend to be 
stationary  or may only move limited distances (Kosztarab and Kozár  2012 ). For P. kraunhiae , 
it is reported that all life stages can walk and move (Boujo 2020), but no reports have been 
found mentioning how far the different life stages of P. kraunhiae  can move specifically. If 
citrus  fruit waste is disposed of in an open environment with suitab le hosts nearby (for 
example , composting and animal feeding ), the crawlers may be able to walk to the nearby 
host.  
 
Mealybug species can be dispersed passively , which is also considered an important mechanism 
contributing to the spread of mealybugs, and th e polyphagous nature of P. kraunhiae  is likely to 
increase the likelihood of landing on a suitable host.  
• Mealybugs can be passively dispersed by wind, water, fallen leaves, phoresy (attached to 
birds, ants, other insects , etc.) and movement of farm equipment, soil and infested plant 
material (although no specific study has been carried on P. kraunhiae ). However, long -
distance movement of mealybugs is most likely due to the movement of infested nursery 
stock and agricultura l commodities (Mani and Shivaraju  2016).   
319 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Passive dispersal by wind is considered  an important mechanism contributing to the 
colonisation of new areas by mealybugs (Lo et al. 2006). Nymphs (mainly first instars) and 
adult males (only in insignificant number) of mealybugs have been reported to be able to 
disperse by wind for short, moder ate and presumably long distances:  
o The first - and second -instar nymphs, as well as adult males, of the grape mealybug, 
Pseu dococcus  maritimus , can be dispersed by wind, but there is a marked decline in 
numbers with increasing distance from the source plan t (Grasswitz et al. 2008). The 
crawlers were  dispersed up to 8  m in this study. Among the mealybugs being 
dispersed by wind, 86.3% were crawlers, 10.8% were second instars, and 2.9% third 
instars.  
o Lo et al. (2006) conducted a field trial using aerial trap ping to catch mealybugs in a 
New Zealand vineyard that were dispersed by wind. Crawlers and a small number of 
adult males were caught in these traps, and they found that mealybugs can be blown 
at least 5  m and up to 15  m.  
o Based on 24 -hr wind -run values, B arrass et al. (1994) presumed that the crawlers of 
Pseu dococcus  longispinus  could disperse across distances great er than 50  km, 
although this has not been tested in scientific studies.   
o Barrass et al. (1994) also found that the survival rate for the crawl ers of 
Ps. longispinus  held at 20 °C and 32% relative humidity for 48  hours was 75%, 
suggesting that the crawlers are capable of surviving desiccation for long enough to 
make wind currents a viable method of dispersal.  
o In Lo et al. (2006), they also estimated that in the 6 weeks leading up  to mid -April, 
there were 2.5 million crawlers/ha in the air above the mealybug -infested vineyard.  
o Barrass et al. (1994) also found that number of mealybugs  caught in aerial traps 
incre ased directly with wind speed and with the square of the daily temperature 
maximum, which implies that dispersal by winds of mealybugs in areas with high wind 
speeds and temperature are likely to be more frequent.  
o Some coccoid species are known to delibera tely move to high points of their host 
plants in order to disperse (Brown 1958, Beardsley and Gonzalez 1975, Greathead 
1990, Lo et al. 2006). Washburn and Washburn (1984) showed that crawlers of the 
coccid Pulvinariella mesembryanthemi (Vallot) deliberatel y entered the air, not only 
by moving up the plant but by orienting their bodies most favourably to the air current 
and standing on their hind legs . However it is important to note that most studies of 
crawler dispersal have bee n carried out using insects on their host plants, and that 
information about dispersal of crawlers from situations comparable to a piece of 
discarded fruit is scarce.  
• Passive dispersal cannot guarantee P. kraunhiae  will land on a suitable host, but the 
polyphagous nature of P. kraunh iae is likely to increase the likelihood of landing on a suitable 
host.  
• However, passive dispersal also means that the successful transfer will depend not only on 
whether hosts are present, but also on other factors, such as wind speed, whether animals 
are present (i.e. hitchhiking) and the survival rates of the mealybug during passive dispersal, 
which are considered uncertain at this stage.  
 
Successful establishment of P. kraunhiae requires at least one mature female and one male 
successfully transferring  to the same host, or a female carrying fertilised eggs.  
• Planococcus  specie s are able to mate with their siblings in the laboratory (e.g. Ross et al. 
2012, García de la Filia  et al. 2019) and it is assumed this also occurs in the field, though 
there may be behavioural or other constraints against sibling mating (Müller  and Müller  2016 , 
Collet et al. 2019 ). 
• Planococcus kraunhiae is known to be biparental (Teshiba 2013 ), which m eans s uccessful 
establishment requires at least one female and one male located at the same host or in a 
close distance , or a female carrying fertilised eggs .  
• Females can produce sex pheromone to attract males (Sugie et al.  2008), but it is uncertain 
how far an adult male can fly to locate a mature female.  
• Parthenogenesis (reproduction without a male) has not been observed in this species.  
• Adult males of mealybug species can only live for a few days (Williams 2004).  
 
The level of uncertainty associated wit h the conclusion is high. First, waste data and information  may 
not be very accurate and up to date , and it is not known how frequently suitable hosts would be near Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 320 composting sites in gardens or animal feeding locations (see section 2.4.1,  waste analysis). Second , 
it is reported that all life stages of P. kraunhiae  can walk and move, but no reports have studied the 
mobility of this species specifically.  Third , it is reported that dispersal by winds is an important 
mechanism for the spread o f mealybugs, but it is not known how efficient (compared to dispersal  by 
walking) this dispersal method is, and it is uncertain what proportion of composting sites are exposed  
or concealed (e.g. in a compost bin).  
 
Given the arguments and evidence below, t he suitability of the New Zealand 
environment for P. kraunhiae  to establish is considered high with low uncertainty . 
Planococcus kraunhiae lives in  both tropical and temperate areas with similar climate conditions to 
New Zealand.  
• Planococcus kraunhiae  is present in both tropical and temperate areas. It has been reported 
in China (Shanxi, Yunnan), Iran, Japan, Madeira Islands, Philippines, South Korea, Taiwan, 
Viet Nam (Thuy et al. 2011), United States (California) (García et al. 2016 ) and India 
(Hembram  et al. 2007) .  
• Its current  distribution includes  areas with similar climate conditions to New Zealand: Shanxi 
(CMI = 0.7), Yunnan (0.6 –0.8), Japan (0.7 –0.8), South Korea (0.6 –0.7) and California (0.5 –
0.8) (Phillips  et al.  2018) .  
• It is common in Japan, China and Korea, and it is known in the USA on numerous host plants 
(Williams 2004).  
 
Multiple generations of P. kraunhiae  occur per year in areas  with similar climate conditions to New 
Zealand.  
• Three to four generations of P. kraunhiae  per year have  been reported in  the Shimane, 
Hiroshima, Gifu and Fukuoka prefectures in Japan (Sawamura et al. 2015). Except for the 
Fukuoka prefecture , which has a CMI ranging from 0.6 –0.7, other named prefectures have 
CMI = 0.7.  
 
Development temperature thresholds of P. kra unhiae  implies that it is likely to survive and develop at 
least in the North Island.  
• Planococcus kraunhiae  was reared on citrus leaves in Japan at five constant -temperature 
regimes to determine developmental thresholds (Arai 1996). The upper developmental  
threshold was estimated to be around 30 °C, as no mealybugs developed to oviposition at 
30°C. Lower developmental threshold for the entire nymphal stage and preovipositional 
period were 8 °C and 11.7 °C respectively.  The other study which reared P. kraunhiae  on 
germinated broad bean seeds found that the estimated lower developmental threshold for the 
nymphal developmental period (from egg -hatching to adult) and the preovipositional period 
were 12.2°C and 8.1°C (Sawamura and Narai 2008).  
• Monthly average data f or the period 1971 –2000 (NIWA  2016)  show that most areas of the 
North Island have monthly mean temperatures higher than 8°C, including northern areas 
(Kaitaia, Whangarei, Auckland and Tauranga), Hamilton in the c entral North Island, the 
southwest North Island (New Plymouth, Palmerston North and Wellington), and Gisborne and 
Napier in the eastern North Island, indicating that P. kraunhiae  is likely to survive , or even 
develop, in winter in these areas.  
 
Host availability is unlikely to be a  limiting factor for the mealybug to establish in New Zealand.  
• Planococcus kraunhiae  is polyphagous. It has been reported on 26 families and 32 genera of 
plants (García et al. 2016 ).  
• The host  list includes those that are commercially planted in New Zealan d, including kiwifruit, 
squash/pumpkin , persimmon, fig, olive , pear ( Pyrus spp.) , grapevine and citrus . Many of 
these hosts are also common in home gardens.  
• Some ornamental plants that can be found in parks and gardens are host s of P. kraunhiae , 
such as  holly ( Ilex sp.) and southern magnolia ( Magnolia grandiflora ). Summer grass  
(Digitaria sanguinalis ), which is very common in northern  and coastal regions of the North 
Island of New Zealand  (AgPest 2020),  is also a host of P. kraunhiae . 
 
Impacts in New Zealand:  
  
321 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Given the arguments and evidence below, the level of impact caused by P. 
kraunhiae is likely to be moderate (with moderate uncertainty).  
Damage and symptoms caused by P. kraunhiae  can reduce yield and plant or fruit quality.  
• Like other mealybug s pecies, P. kraunhiae is a sap-sucking insect . Nymphs and adult 
females feed on branches, leaves and fruits (Boujo 2020).  
• Planococcus kraunhiae excretes honeydew that can lead to the growth of sooty moulds , 
which  build up on the leaves, shoots and  fruits.  These moulds interfere with the plant’s normal 
photosynthetic  activity, which  affects plant growth. If the infestation level is high, it can stop 
new growth of shoots , and branches can die (Boujo 2020).  
 
Production loss caused by P. kraunhiae  has been reported from countries with similar climate 
conditions to New Zealand, and yield losses associated with P. kraunhiae  have been observed 
overseas in a variety of fruit crops that are also grown commercially in New Zealand.  
• Impact on persimmons:  
o Many studies from Japan, especially in the last decade, have reported the damage of 
and control methods for P. kraunhiae  on persimmon plants and fruits (e.g. Morishita 
2005; Miyashita et al.  2013 ; Teshiba and Tabata 2017; Teshiba 2018), implying that it 
is a serious pest on persimmons in Japan.  
o A field experiment conducted in Ukiha  city, Fukuoka Prefecture, Japan, to investigate 
the effectiveness of mating disruption (mating dispensers containing a sex 
pheromone component) in controlling P. kraunhiae , reveal ed that the mean injured 
fruit rate of persimmon ranged from approximately 1% to 2% in field trials with mating 
disruption, while 13% to 20% injured fruit rate was observed for the control treatment 
(Teshiba 2018).  
o Three to four generations of P. kraunhiae  per year have been reported in Shimane, 
Hiroshima, Gifu and Fukuoka prefectures in Japan (Sawamura et al. 2015). Except 
for Fukuoka prefecture which has a CMI ranging from 0.6 – 0.7, other named 
prefectures have CMI = 0.7.  
o In New Zealand, the domestic val ue (2018/19) of persimmons is NZ$1.5 million, and 
the export value (2019) is $10  million  (Plant & Food Research  2019).  
• Impact on pears:  
o A survey on three mealybug species, P. kraunhiae , Pseudococcus comstocki  and 
Crisicoccus matsumotoi , in Korea in 1990 –1991 found that 80.6% of the mealybugs 
collected from pears were P. kraunhiae . The degree85 of damage caused  by these 
mealybugs on different pear varieties, Singo, Poongsoo and Haengsoo, were 21.2, 
18.2 and 13.3%. The population density of the pests began to increase from mid -
June and peaked in mid -July (with 48% damage), mid -August (with 50.6% damage) 
and early October  (Park and Hong 1992).  
o In New Zealand, the export value of pear in 2019 was NZ$10.6  million (Plant & Food 
Research  2019).  
• Impact on other plant  species that are of economic importance in New Zealand.  
o Planococcus kraunhiae  has been reported as one of the most harmful mealybugs that 
attack many kinds of fruit crops in Japan, including persimmons, grapes, pears, citrus 
and figs (Kawai 1980 ; Shibao a nd Tanaka 2000 ; Ueno 1963, in Teshiba and Tabata 
2017). However, reports on  the economic impact on grapes, citrus and figs could not 
be found or the full text of the report was not accessible (e.g. Shibao 2000 on P. 
kraunhiae  on figs in Japan).  
 
Cryptolae mus montrouzieri  (mealybug ladybird),  one of the natural enemies of P. kraunhiae , is 
present in New Zealand, but the effectiveness of control by this natural enemy in New Zealand is 
unknown.  
• Smith and Armitage (1931,  in Mani and Shivaraju  2016) reported that an isolated infestation 
of P. kraunhiae  on citrus disappeared following the release of Cryptolaemus montrouzieri  
(mealybug ladybird) in Southern California. Cryptolaemus montrouzieri  is present in New 
Zealand as an exotic species (NZOR  2020). However, it is hard to know the effectiveness of 
this biological control agent on P. kraunhiae  in New Zealand due to the complexity of the 
                                                      
85  In Park and Hong (1992), Degree of damages (%) = 100[(4A + 3C +2B + D)/4(total fruits investigated)], where A: above 16, 
B: 11 –15, C: 6 –10, D: 1 –5 individuals per pear fruit.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 322 ecological system in New Zealand and how different New Zealand’s ecosystem is from other 
locations.  
 
Establi shment of P. kraunhiae may result in increased phytosanitary measures required for export to 
countries where the pest is absent  and regulated.  
• The known distribution of P. kraunhiae  includes China (Shanxi, Yunnan), Iran, Japan,  
Madeira Islands, Philippine s, South Korea, Taiwan, United States (California) (García et al. 
2016 ) and India (Hembram et al. 2007) .  
• Planococcus kraunhiae  is considered a quarantine pest in Australia ( Department of 
Agriculture and Water Resources 2019 ). 
• Although it is recorded that P. kraunhiae  is present in California (Ben -Dov 1994), Park et al . 
(2010) reported that due to strict quarantine controls, fruit could not enter the US A if 
P. kraunhiae was discovered, and P. kraunhiae  was a regulated pest at the time of this 
assessment (USDA 2020).  
• Planococcus kraunhiae  is absent in European countries, but it is not in the EPPO A1 or A2 list 
of pests recommended for regulation as quarantine pests  (EPPO 2020a  and 2020 b). 
 
Planococcus kraunhiae  has been reported on a plant species under a genus  that has a native 
representative  in New Zealand  (NZPCN 2020) ; the native  species under th is genus ha s an ‘at risk ’ 
conservation status.  
• Digitaria sanguinalis  (family: Poaceae) is a host of P. kra unhiae  (García et al. 2016 ). In New 
Zealand, the indigenous plant species Digitera  setigera , has ‘at risk -naturally uncommon’ 
conservation status (NZPCN 2020). It is locally common in the northern Kermadec Islands, 
but has only been collected on the mainland islands  once some  time between 1838 and 1840 
from the Bay of Islands. The impact of P. kraunhiae  on this plant species is likely to be low.  
 
Planococcus kraun hiae may have an impact on the urban environment and may have indirect health 
impacts for humans.  
• Planococcus kraunhiae is damaging to a number of plants grown in domestic gardens  (e.g. 
Vitis spp., Citrus  spp., persimmons , figs) and ornamentals in parks . Therefore, it is a potential 
nuisance pest in the urban environment.  Also, it could be mor e problematic in protected 
environments (e.g. houseplants and nurseries) where parasitoids do not have easy access to 
them.  Parasitoids known to affect P. kraunhiae  are not known to be released in nurseries in 
New Zealand.  
• Planococcus kraunhiae may indirectly have some impact on human activities. Vespula wasps 
are attracted to honeydew excreted by some insects, and high numbers of wasps in 
recreational, urban or other areas may adversely impact on health (painful stings or allergy to 
stings) and soci al activities ( MAF  2008).  However, as many sap -sucking insects are already 
present in New Zealand that can produce honeydew, the impact maybe minor  to negligible .  
 
The level of uncertainty associated with the conclusion is considered moderate. Many studie s from 
Japan have reported its impacts on persimmons , and low to moderate fruit damage has been 
reported. There is one report from 2010 from South Korea on its severe impact on pears. Most of 
these reports are either in Japanese/Korean or not accessible. A lthough most key information was 
extracted from English abstracts, machine translation (Google Translat e) has been used to interpret 
the content  of some texts , and as such, very high accuracy in interpretation cannot be guaranteed.  
 
 
Risk assessment summar y: 
 
Given the arguments and evidence below,  Planococcus kraunhiae may be 
considered  for additional measure s. 
 
• Planococcus kraunhiae  has a strong host association with citrus fruit . 
• Planococcus kraunhiae  is present in exporting countries . 
• Planococcus kraunhiae is small and cryptic . As such, in low population densities or as 
individuals, detection can be difficult if the commodities have sheltered places for them to hide  
(e.g. under the calyx or potentially in the navel of navel oranges).   
323 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • The ability of  P. kraunhiae to move from imported fruit and into a suitable environment to 
allow establishment is limited . 
• Disposal to landfill, which is a low -risk disposal method, is the major way of disposing of 
kitchen waste in New Zealand, while dispos al using high -risk methods (composting and 
animal feeding) is less common.  
• Some kitchen  waste is likely to be disposed of using high -risk methods , and the mealybug is 
polyphagous , which increases  the probability that suitable hosts would be present in the 
surrounding environment.  
• Planococcus kraunhiae is distributed in both tropical and temperate areas including areas 
with similar climate conditions to New Zealand.  
• The climate suitability of the New Zealand environment for the establishment of P. kraunhiae  
is high.  
• The level of impact is considered moderate, because there are many reports on its damage 
and control methods in persimmon orchards in Japan, and a low-to-moderate level of fruit 
damage on pears has been reported from Korea. No report has been found on product ion 
loss of citrus due to this mealybug species.  
 
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Southdene SDN. BHD. Malaysia.   Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 328 9.3 Planococcus  minor  (Pacific mealybug ) 
Planococcus minor  is a species of mealybug of Asian origin, but it is the most widespread mealybug 
in the South Pacific area as an exotic species. Adult females are  wingless and oval,  about  1.3–
3.2 mm long and 0.8 –1.9 mm wide, and they are covered in a white, powdery, waxy  secretion. Males 
are minute and winged, without functional mouthparts.  
 
Scientific name: Planococcus minor  (Maskell, 1897)  
Order/Family: Hemiptera/Pseudococcidae  
Other names include: Dactylopius calceolariae  minor , Pseudococcus calceolariae minor , 
Planococcus pacificus , Planococcus psidii , passionvine mealybug , guava mealybug  (EPPO 2020; 
García et al. 2016 )  
 
Taxonomic notes:  Planococcus minor  is very similar to P. citri  and has been routinely misidentified 
due to similarity in appearance, host plan t range and geographic distribution (Roda et al. 2013).  
Distinction usually requires the expertise of a taxonomist, and good preparations are needed to count 
the oral collar tubular ducts at the anterior end of the body (Williams  2004) . Williams (1982,  in Cox 
1989)  comments that most records of P. citri  from the South Pacific Islands are misidentifications of P. 
minor . 
 
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Planococcus minor  meets the criteria to be a quarantine pest for New Zealand .  
• Planococcus minor  has a strong association with citrus fruit  with low uncertainty . 
• Basic measure s are likely to reduce the likelihood of entry  of P. minor  by a moderate degree . 
Consequently , the likelihood of entry is considered to be low with low uncertainty . 
• Planococcus minor  has low ability (with high uncertainty) to move from imported fruit and into 
a suitable environment to allow establishment, that is, onto a host plant.  
• The suitability of the New Zealand environment for P. minor  to establish is considered low –
moderate (with moderate –high uncertainty) , and establishment is likely to be limited to 
warmer areas . 
• The level of impact caused by P. minor  is likely to be low  to moderate (with high uncertainty) . 
• Planococcus minor  may be considered for requiring  additional measure s. 
 
Summary of risk assessment against criteria  
Criteria  Rate  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from the imported commodity  onto a suitable host  Low High 
Suitability of the N ew Zealand  environment  Low–moderate  Moderate –high 
Impacts on the New Zealand economy, environment, health and society  Low–moderate  High 
 
9.3.1 Hazard  identification: quarantine status  
Given the arguments and evidence below,  Planococcus minor  meets the criteria to 
be a quarantine pest for New Zealand .   
329 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause harm86). 
 
Planococcus minor  is not known to be present in New Zealand:   
• It is not recorded in NZInvert s (2020), NZOR  (2020) or PPIN (2020) . 
• It is listed as ‘Regulated’ in ONZPR  (2020) . 
 
Planococcus minor  has the potential to establish and spread in New Zealand:  
• Planococcus minor  is present in Africa, Asia, North America, Central America and Caribbean, 
South America, Europe (only Madeira, Portugal) and Oceania  (CPC 2020).  
• Planococcus minor is predominantly distributed in tropical and subtropical areas, but its 
distribution has extended to temperate areas. The current distribution includes areas (e.g. 
Uruguay  and New South Wales, Australia)  with similar climatic conditions to New Zealand.  
• Planococcus minor  is polyphagous. It has been reported on 73 families and 196 genera of 
plants (García et al. 2016 ).  
• Host plants include those commercially grown in New Zealand and those commonly grown in 
gardens and parks, which include but are not limited to  citrus ( Citrus  spp.) , capsicums 
(Capsicum  spp.), tomatoes ( Solanum lycopersicum ), potato ( S. tuberosum ), sweet c orn (Zea 
mays ), cucumber ( Cucumis sativus ), fig (Ficus carica ), camellias ( Camellia sinensis ) (CPC 
2020; García et al. 2016 ) 
 
Planococcus minor  has the potential to cause impacts on the economy and environment of New 
Zealand:  
• Planococcus minor  has the pote ntial to harm plants of eco nomic importance to New Zealand . 
Host plant species of the mealybug  include important agricultural plants in New Zealand, such 
as citrus , sweet corn, tomato, potato, cucumber, squash and grapevine.  
• Planococcus minor has the potential to harm the New Zealand environment . The mealybug 
has been reported on plant species in genera that are native to  New Zealand.  
 
9.3.2 Hazard identification: commodity association  
 
Planococcus minor  is associated with citrus fruit . 
Planococcus minor  is reported from citrus fruit : 
• It has been intercepted on citrus fruit 44 times (38 live) at the New Zealand border (LIMS 
2019).  
• Planococcus minor is considered a major pest on Citrus  in Taiwan (Ho et al.  2007) . 
 
9.3.3 Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below,  Planococcus minor  has a strong 
association with citrus fruit , with low uncertainty : 
Planococcus minor  has been intercepted on citrus  fruit at the border.  
• It has been identified 321 ti mes at the New Zealand border, among these records, 44 records 
were on citrus  fresh produce (lime, Tahitian lime, orange, grapefruit and pomelo) from various 
exporting countries (Australia, Ecuador, New Caledonia, Samoa, the USA and Vanuatu) from 
1929 to March 2019 (LIMS 2019). Of these 44 records, 29 records were from the last decade.  
• Of these 44 border identifications on citrus fresh produce, 38 identifications were live 
P. minor , indicating that it can survive post -harvest and transit process es on these  citrus  
fruits . 
                                                      
86 Refer to ISPM 5  for the definition of a quarantine pest under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 330 • The most intercepted life stage is adults, but eggs and nymphs have also been intercepted at 
the border.  
 
Planococcus minor  has been recorded as a major pest of Citrus . 
• It has been recorded as a major pest of a range of crops in Taiwan, including Citrus  (Ho et al.  
2007) , although the reference does not mention whether the pest was on fruit.  
 
Citrus species/cultivars found to be associated with P. minor  are shown in Table  10.3.1. 
 
            Table 10.3. 1  Known citrus fruit host association with Planococcus minor  
Citrus host scientific 
name  Citrus host common 
name from the reference  Reference  Notes  
Citrus aurantiifolia   García et al. (2016)   
Citrus aurantium   García et al. (2016)   
Citrus reticulata  Mediterranean mandarin  CPC (2020)   
Citrus hystrix   Chen et al. (2013)   
Citrus latifolia   LIMS (2019)  Interception on fruit  
Citrus limon   García et al. (2016)   
Citrus maxima   García et al. (2016)   
Citrus reticulata   García et al. (2016)   
Citrus paradisi   LIMS (2019)  Interception on fruit  
Citrus maxima  Pomelo  LIMS (2019)  Interception on fruit  
Citrus sinensis  Orange  / Navel orange  LIMS (2019)  Interception on fruit  
Citrus paradisi  Grapefruit  LIMS (2019)  Interception  on fruit  
 
 
Given the arguments and evidence below,  basic measure s are likely to reduce the 
likelihood of entry of P. minor  by a moderate degree . Consequently , the likelihood of 
entry is considered low, with low uncertainty : 
Usually, visual inspection can  detect infestations of P. minor  on citrus  fruits.  
• Some typical signs that indicate the presence of P. minor  on fruit can be wet patches (of 
honeydew) and sooty mould, and waxy material produced by the mealybug (Roda et al.  
2013) . 
 
However, in low population densities or as individuals, if the commodities have a complex structure, 
detection of P. minor  on citrus fruit can be difficult.  
• Planococcus minor  is small. Adult females are approximately 1.3 –3.2 mm, and nymphs and 
eggs are even smaller  than the adult female (Roda et al.  2013) . Early instar nymphs are 
pinkish and likely to be more difficult to detect as they have less waxy covering. As such, 
detection of P. minor  will require careful inspection with a good eye or magnifier.  
• Mealybugs ar e cryptic. In the field, Planococcus minor  are rarely found in direct sunlight, and 
they are often found on the underside of leaves, inside the calyx of sepals, in axils or under 
bark (Roda et al.  2013) . As such, P. minor  may be able to hide in the calyx o f fruit, wrinkles 
around the calyx or in the navel of navel oranges.  
 
General handling after harvesting may not be able to remove and detect all mealybugs if commodities 
have protected places for P. minor  to hide.  
• Planococcus minor  is commonly found in protected places (Mani and Shivaraju 2016) , which 
reduces the likelihood of detection and the effectiveness of insecticides.  This distribution is 
likely to be the result of behaviours such as thigmotaxis and negative phototaxis that have 
been reported in crawlers of other coccoid species (diaspidids and other pseudococcids) 
(Nestel et al. 1995, Geiger and Daane 2001).   
331 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • The wax covering over a mealybug ’s body can repel aqueous solutions,  which reduces the 
likelihood of removal of the mealybu g during commodity handling (e.g. washing and 
pesticides) (Hollingsworth and Hamnett  2009) .  
• Although early instar nymphs have less of the wax covering to protect them from insecticide s 
and washing, it is easier for them to hide in sheltered places because of their smaller size and 
higher mobility than other life stages (except male adults , which are winged (Roda et al. 
2013)).   
• Adult  males are winged and the first instar nymphs  are very  mobile. Other  life stages are less 
mobile when they are on suitable food sources (Williams 2004) . As such, they are less likely 
to get off the commodity during handling.  
• Planococcus minor  has been identified over 44 times at the New Zealand border on citr us 
fresh produce (LIMS 2019). It has also been identified over 1990 times on various hosts from 
over 30 countries between 1995 and 2012 at the US border (Wistermann et al. 2016).  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Plano coccus minor  has low ability (with 
high uncertainty) to move from imported fruit and into a suitable environment to allow 
establishment, that is, onto a host plant  (exposure) . 
Planococcus minor  may survive on the waste of citrus  fruits (whole fruit or frui t pieces).   
• A laboratory experiment showed that P. minor  can survive when reared on orange s. The 
duration of the nymphal stage of female P. minor  is approximately 22.8 days at approximately 
25°C; the number of eggs per adult female is approximately 49.4; nymphal mortality is 33.3% 
(de Souza et al. 2018 ). 
• Although not specifically for P. minor , other mealybug species have been reported to be able 
to resist desiccation and starvation (Abbs 2010; Barrass et al. 1994).  
 
Most of the kitchen  waste in New Zealand  would be disposed of using low -risk methods , so the 
mealybug would either be killed or be unable to escape from the citrus  host.  
• The majority of kitchen waste in New Zealand is bagged and disposed of in landfills or run 
through kitchen disposal units, an d in these situations, the mealybug is unlikely to reach a 
new host (see the waste analysis , section 2.4.1 ). 
 
However, some waste is disposed of using high -risk methods, including composting in gardens and 
using as animal feed.  
• Planococcus minor  is polyphagous, and some host plants are commonly planted in home 
gardens, such as tomato, citrus , grapevine and pear.  Planococcus minor  has been reported 
on a common weed species, Saccharum officinarum (García et al. 2016) . If these hosts are 
located near the composting site (see the waste analysis , section 2.4.1 ), some life stages of 
P. minor  may be able to transfer from the citrus host to the new host.  
 
Planococcus minor has relatively limited mobility, and excep t for the first -instar nymphs (crawlers) and 
adult males, life stages tend to be sessile  while they are on a suitable food source .  
• The primary dispersal stage of P. minor  is the crawlers. Crawlers of P. minor  are very mobile, 
and may disperse over the pla nt host, especially toward tender , growing parts. This implies 
that dispersal via walking can only result in short -distance dispersal (Roda et al. 2013) (i.e. 
within original host plants or nearby plants). While other life stages are able to move, they 
tend to be stationary  or may move limited distances (Kosztarab and Kozár 2012).  If citrus  fruit 
waste (whole fruit or fruit pieces) (see the waste analysis , section 2.4.1 ) is disposed of in an 
environment with suitable living hosts nearby, for example compost  and animal feed, the 
crawlers may be able to walk to the nearby host after the fruit is no longer a suitable food 
source.  
 
Mealybug species can be dispersed passively , which is also considered an important mechanism 
contributing to the spread of mealybugs, and the polyphagous nature of P. minor  is likely to increase 
the likelihood of landing on a suitable host.  No species specific data are available for P. minor , but it s 
dispersal capacity is likely to be similar to other Pseudococcidae.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 332 • Mealybugs can be passively dispersed by winds, water, fallen leaves, phoresy (attached to 
birds, ants, other insect s, etc.) and movement of farm equipment, soil and infested plant 
materi al (although no specific study has been carried on P. minor ). However, long -distance 
movement of the mealybug is most likely due to the movement of infested nursery stock and 
agricultural commodities (Mani and Shivaraju  2016).  
• Passive dispersal by wind is considered an important mechanism contributing to the 
colonisation of new areas by mealybugs (Lo et al. 2006). Nymphs (mainly first instars) and 
adult males (only in insignificant number s) of mealybugs have been recorded to be able to 
disperse by wind for short, moderate and presumably long distances:  
o The first - and second -instar nymphs, as well as adult males, of the grape mealybug, 
Pseu dococcus  maritimus , can be dispersed by wind, but there is a marked decline in 
numbers with increasing distance from the  source plant (Grasswitz et al. 2008). The 
crawlers can be dispersed up to 8  m in this study. Among the mealybugs being 
dispersed by winds, 86.3% were crawlers, 10.8% were second instars and 2.9% third 
instars.  
o Lo et al. (2006) conducted a field trial usi ng aerial trapping to catch mealybugs in a 
New Zealand vineyard that were dispersed by wind. Crawlers and a small number of 
adult males were caught in these traps, and they found that mealybugs can be blown 
at least 5  m and up to 15  m.  
o Based on 24 -hour wind-run values, Barrass et al. (1994) presumed that the crawlers 
of Pseu dococcus  longispinus  could disperse across distances greater than 50  km, 
although it has not been tested in scientific studies.  
o Barrass  et al. (1994) also found that the survival rate for the crawlers of 
Ps. longispinus  held at 20 °C and 32% relative humidity for 48  hours was 75%, 
suggesting that the crawlers are capable of surviving desiccation for long enough to 
make wind currents a viab le method of dispersal.  
o Lo et al. (2006) also estimated that in the six  weeks befre  mid-April, there were 2.5 
million crawlers/ha in the air above the mealybug -infested vineyard.  
o Barrass et al. (1994) also found that the numbers of mealybug s caught in aeri al traps 
increased directly with wind speed and with the square of the daily temperature 
maximum, which implies that dispersal of mealybugs by wind in areas with high wind 
speeds and temperature is likely to be more frequent.  
o Some coccoid species are known  to deliberately move to high points of their host 
plants in order to disperse (Brown 1958, Beardsley and Gonzalez 1975, Greathead 
1990, Lo et al. 2006). Washburn and Washburn (1984) showed that crawlers of the 
coccid Pulvinariella mesembryanthemi (Vallot)  deliberately entered the air, not only 
by moving up the plant but by orienting their bodies most favourably to the air current 
and standing on their hind legs . However it is important to note that m ost studies of 
crawler dispersal have been ca rried out us ing insects on their host plants , and that  
information about dispersal of crawlers from situations comparable to a piece of 
discarded fruit  is scarc e. 
• Passive dispersal cannot guarantee P. minor  will land on a suitable host, but the polyphagous 
nature of P. minor  is likely to increase the likelihood of landing on a suitable host.  
• However, passive dispersal also means that successful transfer will depend on other factors 
in addition to the presence of  hosts, such as wind speed, whether animals are present a nd 
the survival rates of the mealybug during passive dispersal, which are considered uncertain at 
this stage.  
 
Successful establishment of P. minor  requires at least one mature female and one male successfully 
transferring to the same host, or a female ca rrying fertilised eggs.  
• Planococcus  specie s are able to mate with their siblings in the laboratory (e.g. Ross et al. 
2012, García de la Filia et al. 2019) and it is assumed this also occurs in the field, though 
there may be behavioural or other constraint s against sibling mating (Müller  and Müller  2016 , 
Collet et al. 2019 ).  
• Planococcus minor  is known to be biparental (CPC 2020 ), which means s uccessful 
establishment requires at least one female and one male located at the same host or in a 
close distance , or a female carrying fertilised eggs .  
• Females can produce sex pheromone to attract males (Ho et al. 2007), but it is uncertain how 
far adult male s can fly to locate a mature female.  
• Adult males of mealybug species only live for a few days ( Williams 2004 ).  
333 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
The level of uncertainty associated with the conclusion is high. First, waste data may not be very 
accurate and up to date , and it is not known how frequently suitable hosts would be present near 
composting sites in gardens or animal feeding locations (see Chapter 2 waste analysis).  Second , it is 
reported  that dispersal by wind is an important mechanism for the spread of mealybugs, but it is not 
known how efficient (compared to dispers al by walking) this dispersal method is, and it is uncertain 
what proportion of composting sites are expose d or concealed (e.g. in a compost bin).  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for P. minor  to the establish is considered low  to moderate (with 
moderate  to high unce rtainty), and establishment is likely to be limited to warmer 
areas . 
Planococcus minor is mainly distributed in tropical and subtropical areas, but its distribution has 
extended to temperate areas.  
• Planococcus minor is predominantly  distributed in tropical and subtropical areas (Table 
10.3. 2). 
 
Table 10.3. 2  Known geographic distribution of Planococcus minor. Information compiled 29 May 
2020 from Garc ía et al . (2016) and EPPO (2020), unless specified. Country/area with underline  is only 
recorded in Garc ía et al. (2016). Country/area in bold is included in the Citrus  IHS project.  
Continent /Region  Country/area  
Africa  Ascension Island , Comoros, Madagascar, Mauritius, Seychelles  
Asiaa Bangladesh, Brit. Indian Ocean Terr., Brunei, Burma (=Myanmar) , China  (Hong Kong) , 
Christmas Island , Hong Kong, India, Indonesia, Kampuchea, Malaysia, Maldives, 
Philippines, Singapore, Sri Lanka, Taiwan, Thailand, Viet Nam 
North America  Bermuda, Guadeloupe, Mexico , United States  (Florida , Californiab) 
Central America 
and Caribbean  Barbuda, Bahamas, Costa Rica, Cuba, Dominica, Grenada, Guatemala, Guadeloupe, 
Haiti, Honduras, Jamaica, Saint Lucia, Trinidad and Tobago, United States Virgin 
Islands  
South America  Argentina , Brazil , Colombia, Ecuador (Gal apagos Islands), Guyana, Suriname, Uruguay  
Europe  Portugal ( Madeira ) 
Oceania  American Samoa , Australia  (New South Wales, No rthern Territory, Queensland, 
South Australia (including Adelaidec), Australian Capital Territoryc), Cook Islands , 
Fiji, French Polynesia, Kiribati,  New Caledonia , Papua New Guinea,  Samoa , Solomon 
Islands , Tokelau, Tonga, Vanuatu , Wallis and Futuna Islands  
a Japan is recorded as “CABI Data Mining (Undated)” (CPC 2020) but is not recorded in Garcia et al (2016) and EPPO (2020). A se arch was 
conducted in CAB Abstract, no report indicates that P. minor  is present in Japan. There is one literature reporting that P. minor  was intercepted 
in Japan during import inspection (Suqimoto 1994).  
b This record is from Wistermann et al. (2013).  
C The records of Adelaide and Australian Capital Territory are from ALA (2020).  
 
• Planococcus minor  is of Asian origin, and it is the most widespread mealybug in the South 
Pacific area.  
• The current distribution includes countries and areas with climate match index  (CMI) (Phillips  
et al.  2018) of 0.7–1, which means these areas have a 70%–100% similarity of climate to the 
general New Zealand climate. These areas include  Argentina (CMI ranges from 0. 6 to 0.9), 
Uruguay (0.7 –0.9), California (0.6 –0.8), New South Wales (0.7 –1), Adelaide (0.8 –0.9), 
Australian Capital Territory (0.9 ) and South Australia (0.5 –0.8). This implies that the mealybug 
species or some populations of the mealybug may adapt to colder temperate climate s.  
 
It is uncertain if the mealybug can survive or complete development in the colder areas in New 
Zealand.  
• Cold tolerance and overwintering mechanisms for P. minor  are uncertain. The only 
information found on it is a laboratory experiment, which  reported that no eggs of P. minor  
hatched at 15 °C (Francis et al. 2012).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 334 • As P. minor  is present in areas with similar  climate conditions to New Zealand, it may have an 
overwintering strategy. Planococcus minor  is very similar to P. citri  in terms of  appearance, 
host plant range and geographic distribution . Planococcus citri  overwinters primarily as eggs 
on the upper root s, trunk and lower branches of the host plant. Some mealybug species are 
known to overwinter in the soil or on the host plant (Roda et al. 2013) . In addition, many 
mealybug species are cold -resistant (DAWR 2019).  
 
Host availability is unlikely to be a limi ting factor for the mealybug to establish in New Zealand.  
• Planococcus  minor  is polyphagous. It has been reported from 73 families and 196 genera of 
plants (García et al. 2016 ). 
• Host plants include those commercially grown in New Zealand and those commonly grown in 
gardens and parks, such as citrus , capsicums , tomato , potato , pears , sweet corn , cucumber , 
grapevine , fig, camellia s, eucalypts  (Eucalyptus spp.) , roses ( Rosa  spp.). Common weed, 
Saccharum officinarum , is also a reported host (García et al.  2016) .  
 
Planococcus minor is predominantly distributed in warmer areas, but it is also present in 
areas/countries (Argentina, New South Wales , Adelaide  and Australian Capital Territory ) with similar 
climate conditions to New Zealand. These areas occupy a very small proportion of the known 
distribution. Also, the cold tolerance and overwintering strategy of P. minor  is unknown. Therefore, the 
level of uncertainty associated with the conclusion is moderate  to high.  
 
Impac ts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by P. minor  is 
likely to be low  to moderate (with high uncertainty).  
Damage caused by P. minor  can reduce yield and plant or fruit quality.  
• Planococcus minor  is sap -sucking insect . Damage due to the feeding can reduce yield and 
plant or fruit quality and causes stunted growth, discoloration/yellowing and leaf loss ( Venette 
and Davis 2004 , in Roda 2013 ). High density of the mealybug can even kill perennial plants 
(Krishnamoorthy and Singh  1987 ; Walton et al.  2006 in Roda 2013; Ben -Dov 1994 ). However, 
high density of P. minor  is less likely to occur in cooler areas such as much of New Zealand.  
• During low infestation, the mealybug can still be a serious pest, as it is a vector of virus  
diseases (e.g. Piper yellow mottle virus  and Banana streak virus ) that could cause plant death 
(Cox 1989; de Sousa et al.  2011; Francis 2011 ). Piper yellow mottle virus  and Banana streak 
virus  are badnaviruses that are transmitted by mealybugs in a semi -persistent manner (Bhat 
et al. 2016).  
• Planococcus minor  excretes honeydew , which  can lead to growth of sooty mould that build s 
up on the leaves, shoots, fruits and  other plant parts ( Mittler and Douglas 2003 , in Roda 
2013 ). These moulds interfere with the plant’s normal photosynthetic  activity, which  affects 
plant growth. Honeydew and sooty mould also cause cosmetic  defects to plants and their 
fruits . 
 
Reports on the economic impact or damage caused by P. minor  are focused on crops grown in 
warmer areas, while there is a lack of reports on the quantified economic impact of P. minor  in 
temperate areas or countries with similar climate conditions to New Ze aland or quantifying the impact.  
• Reports on the economic impact or damage caused by P. minor  are focused on crops grown 
in warmer areas, such as coffee ( Coffea  sp.), cacao, cotton and custard apple from Brazil, 
Taiwan, Papua New Guinea, Trinidad and India. Stevens (1996 , in Williams and Watson 
1988) recorded P. minor  as P. citri , which formed over 90% of a mixed population of 
Coccoidea, caus ed a 70–75% reduction in yield on coffee.  
• It is considered as a major pest of banana, citrus , mango, celery, guava, melon ( Benincasa  
spp.), pumpkin ( Cucurbita  spp.) and passionvine ( Passiflora  spp.) in Taiwan (Ho et al.  2007) , 
where has CMI from 0.4 –0.8. It is also found on grape vine in Uruguay (CMI: 0.7 –0.9) 
(Wistermann et al. 2016 ). It is also reported as a serious  pest of grapevine in California and 
occasional pest of citrus ( Wistermann et al. 2016 ). However, no reports have been found 
quantif ying the incidence and yield loss d ue to the mealybug on these hosts.   
335 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Some of the hosts are important commercial crops planted in New Zealand, such as citrus , 
grapevine, tomato and pear.  
• A couple of predatory ladybird beetles ( Cryptolaemus  and Scymnus ) that can prey on 
P. minor  are present in New Zealand.  
 
Planococcus minor  can transmit Banana streak virus  (BSV) (absent from New Zealand) , which can 
cause serious damage to banana crops, which in turn  may cause impact on banana s grown in New 
Zealand. BSV may also attack Heliconia  in gardens and parks.  
• A banana plantation is under development in Northland, New Zealand (Kissun 2019), but no 
report s were  found on the potential  value of this crop in New Zealand , although it is likely to 
be low in terms of  the overall econom y. 
• BSV is ab sent from New Zealand (PPIN; Veerakone  et al. 2015 ). The transmission efficiency 
of P. minor  is 17.2% (Arias and Miranda 2002).  
• In Australia, infection  of BSV  can result in an 18 -day delay in harvest and a 6% loss of yield 
annually ( Daniells et al.  2001 ). 
• BSV has the potential to impact Heliconia  in gardens and parks (CPC 2019).  
 
Establishment of P. minor  may result in increased phytosani tary measures required for export to 
countries where the pest is absent.  
• Most of the countries in temperate areas have not been reported to have the mealybug.  
 
Planococcus minor  has hosts in plant genera with native New Zealand plant species, and plant 
species under some of these genera have at risk or threatened conservation status.  
• Some  of the species in these genera are native to New Zealand, such as Apium prostratum 
subsp.  prostratum var. filiforme , Schefflera digitat a, Cyperus ustulatus, Isolepis prolifera, 
Pelargonium inodorum , Vitex lucens , Dysoxylum spectabile , Piper excelsum  subsp. excelsum  
and Solanum opacum  (NZPCN 2020 ). 
• Some of the s pecies in these genera have ‘ at risk’  or ‘threatened’  conservation status  in New 
Zealand , including Apium prostratum subsp.  denticulatum, Ipomoea cairica, Ipomoea 
pescaprae subsp.  brasiliensis, Corynocarpus laevigatus, Cyperus in sularis, Euphorbia glauca, 
Hibiscus diversifolius  subsp. diversifolius , Hibiscus richardsonii , Syzygium maire , Piper 
excelsum  subsp. delangei , Piper excelsum  subsp. peltatum , Piper excelsum  subsp. 
psittacorum , Piper melchior , Solanum americanum , Solanum aviculare  var. aviculare , 
Solanum aviculare  var. latifolium  and Solanum laciniatum  (NZPCN  2020). 
• As no report was found on the impact of the mealybug on native plants, the damage level on 
New Zealand native plant species is uncertain.  It should be noted th at relatively few non -
indigenous invertebrates and pathogens have been recognised as causing serious damage to 
terrestrial natural ecosystems globally (Phillips et al. 2008), and in the New Zealand context 
only a few substantial pest and disease outbreaks affecting native plants have been 
documented (Beever et al. 2007 ). 
 
Planococcus minor  may have sociocultural and human health consequences.  
• Planococcus minor  is damaging to a number of plants grown in domestic gardens and parks, 
such as Vitis spp., Prunus  spp., Citrus  spp. and Malus  spp. Therefore, it is a potential 
nuisance pest in urban environment.  Also, it could be more problematic in protected 
environments (e.g. houseplants and nurseries) where parasitoids do not have easy access to 
them.  
• Planococcus minor  may indirectly have some impact on human activities. Vespula wasps are 
attracted to honeydew excreted by some insects, and high numbers of wasps in recreational, 
urban or other areas may adversely impact on health (painful stings or allergy to stings ) and 
social activities ( MAF  2008). However, as many sap -sucking insects are already present in 
New Zealand that can produce honeydew, the impact may be minor  to negligible .  
 
Due to the lack of reports quantifying the economic and environmental impact of P. minor , and the 
uncertainty of whether the pest is present outdoors or indoors in those areas with similar climate 
condition to New Zealand, the level of uncertainty associated with the conclusion is high.  
 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 336 Risk assessment summary : 
 
Given the arguments and evidence below,  Planococcus minor  may be considered for 
additional measures . 
 
• Planococcus minor  has a strong host association with citrus fruit.  
• Planococcus minor  is present in several exporting countries.  
• Planococcus minor  is small and cryptic . As such, low infestation would be difficult to detect.  
• The ability of P. minor  to move from imported fruit and into a suitable environment to allow 
establishme nt is low , but with high uncertainty.  
• Planococcus minor  have relatively low mobility: except for the  crawler stage and male adult, 
life stages tend to be stationary.  
• Disposal to landfill, which is a low -risk disposal method, is the primary way of disposing of 
kitchen  waste in New Zealand, while disposing using high -risk methods (composting and 
animal fee ding) is less common.  
• Some kitchen  waste is likely to be disposed of using high -risk methods , and the mealybug is 
polyphagous , which increase s the probability that suitable hosts would be present in the 
surrounding environment.  
• Planococcu s minor  is predominantly distributed in tropical/subtropical areas, but also present 
in areas with similar climate conditions to New Zealand. The suitability of the New Zealand 
environment for P. minor  to the establish is considered low  to moderate , with moderate  to 
high uncertainty, and establishment is likely to be limited to warmer areas . 
• The economic impact is considered low  to moderate with high uncertainty, because there is a 
lack of reports found on quantified economic impact of P. minor  in temperate areas .  
 
9.3.4 References  
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of cotton mealybug ( Phenacoccus Solenopsis ; Hemiptera: Pseudococcidae). International Journal of 
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Arias, G G; Font, C; Miranda, E (2002) Planococcus Minor  (Markell), vector del virus estriado del 
plátano (BSV). Fitosanidad , 6(2): 47 –48. 
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mealybug, Pseudococcus longispinus  (Targioni Tozzetti) (Pseudococcidae: Hemiptera). Australian 
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Beever, R E; Harman, H; Waipara, N; Paynter, Q; Barker, G; Burns, B (2007) Native Flora Biosecurity 
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Entomologist  90: 658 –690. 
Chen, S P; Wu, W Z; Weng, Z Y (2013) Mealybugs (Hemiptera: Coccoidea: Pseudococcidae) 
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Collet, M ; Amat, I ; Sauzet, S ; Auguste, A Fauvergue, X ; Mouton, L ; Desouhant, E (2019) Insects and 
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Cox (1989) The mealybug genus Planococcus (Homoptera: Pseudococcidae).  Bulletin of the British 
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https://www.cabi.org/cpc/datasheet/8548  Accessed 22 May 2020 . 
CPC ( 2020 ) Planococcus minor  (passionvine mealybug). Crop Protection Compendium . 
https://www.cabi .org/cpc/datasheet/41892  Accessed 22 May 2020 . 
Daniells, J W; Geering, A D W; Bryde, N J; Thomas, J E (2001 ) The effect of Banana streak virus  on 
the growth and yield of dessert bananas in tropical Australia. Annals of Applied Biology , 139(1):  51–
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DAWR (2019) Final group pest risk analysis for mealybugs and the viruses they transmit on fresh fruit, 
vegetable, cut -flower and foliage imports . CC B y 3.0. Department of Agriculture and Water 
Resources ; Australia.  
de Sousa, C M; Pantoja, K d F; Boari, A d  J (2011) Detecção de piper yellow mottle virus em 
espécimes de cochonilhas de pimenteira -do-reino por meio de PCR. Embrapa Amazônia Oriental -
Artigo Em Anais De Congresso (ALICE).  
de Souza, A L V; Costa, M B; Souza, B; Santa -Cecília, L V C; Lima, R R (2018 ) Host preference and 
biology of two cryptic species, Planococcus citri (Risso) and Planococcus minor (Maskell) (Hemiptera: 
Pseudococcidae). Scientia Agraria , 19(2): 71 –77.  
EPPO (2020) EPPO Global Database. https://gd.eppo.int/  Accessed 22 May 2020.  
Francis, A W (2011) Investigation of Bio -Ecological Factors Influencing Infestation by the Passionvine 
Mealybug, Planococcus Minor (Maskell) (Hemiptera: Pseudococcidae) in Trinidad for Application 
towards its Mana gement. PhD thesis. University of Florida ; Florida, USA.  
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  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 340 10. Insects: Hemiptera, Psyll oidea  (psyllids)  
 
10.1 Diaphorina citri  (Asian citrus psyllid ) 
Diaphorina citr i is a small (around 3 mm long) psyllid that damages plant tissues directly through its 
feeding activities and indirectly through vectoring ‘ Candidatus  Liberibacter asiaticus’ and other 
liberibacter species that cause huanglongbing (HLB) (also known as citrus greening) (Grafton -
Cardwell et al. 2006, CABI 2020).  
 
Scientific name: Diaphorina citri  Kuwayama, 1908  
Order/Family: Hemiptera/Liviidae  
Other names include: Asian citrus psyllid (ACP), citrus psyllid  
 
Taxonomic inf ormation: Diaphorina citri  is one of the psyllid vectors of the causal agents of the 
serious citrus disease HLB, also known as citrus greening.  
 
HLB is associated with three liberibacter species, ‘ Candidatus  Liberibacter africanus’, ‘ Ca. 
americanus’ and ‘ Ca. L. asiaticus’ (Gottwald 2010). ‘ Ca. L. asiaticus’, which is the most prevalent 
bacteria , is associated with Asian HLB which is the most widespread form of the disease. ‘ Ca. L. 
africanus’ is associated with the African form of HLB and ‘ Ca. L. americanus’  with the American form 
of HLB. Recently, a new strain provisionally named ‘ Ca. L. caribbeanus’ has been reported that may 
cause HLB -like symptoms in citrus (Keremane et al. 2015). The liberibacter are found in the phloem 
of the plant host. They are transm itted naturally by two psyllid vectors: Diaphorina citri  and Trioza 
erytreae  (Bove 2006). D. citri  vectors ‘ Ca. L. americanus’ and ‘ Ca. L. asiaticus’ naturally and is 
capable of transmitting ‘ Ca. L. africanus’, experimentally at least (Gottwald 2010 ; Bove 2006). Trioza 
erytreae  transmits ‘ Ca. L. africanus’ under natural conditions, and it has been shown experimentally 
that T. erytreae  is able to transmit ‘ Ca. L. asiaticus ’ (Gottwald 2010).  
 
Note:  
A related species, Diaphorina communis  (Mathur 1975) occurs o ccasionally on citrus (Halbert and 
Manjunath 2004). It was first described from Murraya koenigi  in Uttar Pradesh in norther n India and 
has since been reported in Bhutan , where it was found on mandarin trees that showed symptoms of 
huanglongbing (HLB) cause d by ‘ Candidatus  Liberibacter asiaticus’ (Donovan et al. 2012). The 
presence of ‘ Ca. L. asiaticus’ in adult D. communis  was confirmed by conventional and real -time 
PCR , indicating the potential for this species to act as a vector of the disease , but transm ission has 
not yet been confirmed (Donovan et al. 2012). However, this psyllid species is not known to occur in 
any of the potential citrus -exporting countries considered in this import risk assessment.  
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Diaphorina citri  meets the criteria to be a quarantine pest for New Zealand.  
• Diaphorina citri  has a strong association with citrus, but a weak association with citrus fruit  
(with low uncertainty) . 
• Basic measures  are likely to reduce th e likelihood of entry by a high degree  (with low 
uncertainty);  consequently, the likelihood of entry is considered to be low  (with low 
uncertainty).  
• The ability of D. citri  to move from imported fruit to a suitable host plant is high (with low 
uncertainty) . 
• The suitability of the New Zealand environment for D. citri  to establish is considered moderate  
(with low uncertainty) . 
• The level of impact caused by D. citri  is likely to be low to moderate for New Zealand overall  
(with low uncertainty),  but moderate to  high for the citrus industry  (with low uncertainty),  
depending on the presence of the citrus disease HLB , with at least two of the causal agents 
being  vectored by D. citri . 
• Diaphorina citri  may be  considered  for additional measures .  
341 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Summary of risk assessment against criteria:  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Weak  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from the imported commodity  onto a suitable host  High Low 
Suitability of the N ew Zealand  environment  Moderate  Low 
Impacts on the New Zealand economy, environment, health and society , 
depending on presence of HLB  Low-moderate  Low 
 
10.1.1  Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Diaphorina citri meets the criteria to be a 
quarantine pest for New Zealand  
Criteria for being a quarantine pest relevant to this assessment are : not present in New Zealand, and 
of potential importance (able to establish and cause harm).  
 
Diaphorina citri is not known to be present in New Zealand . 
• Diaphorina citri  is not recorded in NZInverts (2020), NZOR (2020) or PPIN (2020).  
• The quarantine statu s of D. citri  in New Zealand is ‘regulated’ , and it is an unwanted organism 
(ONZPR  2020).  
 
Diaphorina citri has the potential to establish and spread in New Zealand . 
• Diaphorina citri  is widespread throughout Asia and occurs in North, Central and South 
America, Africa and Oceania (Table 11.1. 2) (Halbert and Nunez 2004 ; Grafton -Cardwell et al. 
2006 ; EPPO 2020 ; CABI 2020).  
• Some of the areas where  D. citri  occurs have a high climate match  with New Zealand, with a 
climat e match index (CMI) of 0.7 or greater (Phillips et al. 2018), indicating the potential to 
establish in New Zealand:  
o For example, Yunnan and Sichuan (mostly 0.7 -0.8 CMI) in China; Uruguay (0.8 –0.9 
CMI).  
• There are suitable hos t species ( Citrus  spp.) present in areas of New Zealand that are likely 
to be climatically suitable for D. citri .  
 
Diaphorina citri has the potential to cause economic impacts in New Zealand . 
• Diaphorina citri  has the potential to damage citrus, which is o f economic importance to New 
Zealand, both through direct feeding damage and by vectoring liberibacter species that cause 
the citrus disease huanglongbing (HLB).  
• Losses relating to establishment of D. citri  are likely to result from loss of market access f or 
Citrus  in those countries free from HLB.  
 
10.1.2  Hazard identification: commodity association  
Diaphorina citri  is associated with citrus fruit . 
 
Diaphorina citri is reported from citrus fruit:  
• A study by Halbert et al. (2010) showed that D. citri can be transp orted with harvested citrus 
fruit. Live adults (509 psyllids) were collected from seven trailers, from the tops and sides of 
the loads up to 30 cm below the surface of the oranges, suggesting they were distributed 
throughout the loads. The psyllids were se en resting on the fruit itself rather than on the 
minimal amount of foliage that was present (Halbert et al. 2010).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 342 • High numbers of D. citri  adults were intercepted in boxes of fresh unprocessed citrus fruit 
(grapefruit) picked in the Bahamas and shipped t o Ft. Pierce, Florida, for processing in 2001 
(Halbert and Nunez 2004).  
 
10.1.3  Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below,  Diaphorina citri  has a strong association 
with citrus, but a weak association with citrus fruit.  
 
Although the life stages of D. citri  feed on young tender foliage, adults that have been disturbed may 
seek refuge on citrus fruit.  
• All life stages of D. citri  are found on foliage. Females oviposit within 2 -cm lengths of the 
terminal tissue in leaf folds,  on petioles, axillary buds, upper and lower surfaces of young 
leaves and tender stems (Tsai and Liu 2000). Nymphs undergo five instar stages, feed only 
on soft, young plant tissue and excrete wax and honeydew. They are found on immature 
leaves, stems and flowers of citrus and are sedentary, but will move if disturbed or 
overcrowded. Adults feed on both new growth and mature citrus flush (Grafton -Cardwell and 
Daugherty  2018 ; Childers and Rogers 2005). Mature fruits are not considered suitable 
feeding sites for any life stage of D. citri.  
• Adults are easily disturbed and will jump or fly a short distance (Tsai and Liu 2000). Adults of 
D. citri  that have been disturbed may seek refuge on citrus fruit. Live adults have been 
intercepted on harvested citrus fruit being transported by trailer and by ship for processing 
(Halbert and Nunez 2004 ; Halbert et al. 2010).  
 
Diaphorina citri  infests many citrus species and varieties:  
• Host plants for D. citri  are confined to the Rutaceae and include Citrus  spp. (Table 1 1.1.1) 
and many close citrus relatives. Well -known hosts include Murraya paniculata  (orange 
jasmine) and Murraya koenigii  (curry leaf) (Halbert and Manjunath 2004).  
• Based on Aubert (1987) , there are at least 21 species on which D. citri  can feed, but egg -
laying and nymphal development are restricted to 15 and 14 hosts, respectively (Biosecurity 
Australia 2011).  
 
Table 1 1.1.1. Citrus  spp. recorded as hosts for Diaphorina citri  by EPPO (2020) and Halbert and 
Manjunath (2004)  
Botanical name  English common name as gi ven in 
EPPO (2020)  Reference  
Citrus reticulata  Djeruk lime, Nasnaran mandarin  EPPO 2020: Westbrook et al . 2011  
Citrus aurantiifolia  Key lime , Lime , Mexican lime, West 
Indian lime  EPPO 2020: Aubert 1990 ; Westbrook et al . 2011  
Citrus aurantium  Bigarade, Bitter orange, Seville 
orange, Sour orange  EPPO 2020: Tsai and Liu 2000 ; Westbrook et al . 2011  
Citrus australasica  Australian finger lime  EPPO 2020: Westbrook et al . 2011  
Citrus australis  Australian round lime  EPPO 2020: Westbrook et al . 2011  
Citrus reticulata  _ Halbert and Manjunath 2004  
Citrus halimii  _ EPPO 2020: Westbrook et al . 2011  
Citrus paradisi  Hassaku orange  EPPO 2020: Westbrook et  al. 2011  
Citrus hystrix  Kaffir lime,  Kieffer lime, Leech lime, 
Limau purut, Mauritius bitter orange  EPPO 2020: Aubert 1990  
Citrus inodora  Russel river lime  EPPO 2020: Westbrook et al . 2011  
Citrus latifolia  Persian lime, Tahiti lime  Ramirez -Godoy et al. 2018; Casique -Valdes et al. 
2015   
343 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Botanical name  English common name as gi ven in 
EPPO (2020)  Reference  
Citrus limon  Rough lemon  EPPO 2020: Tsai and Liu 2000 ; Westbrook et  al. 2011  
Citrus latipes  - EPPO 2020: Westbrook et al . 2011  
Citrus limon  Palestine sweet lime  EPPO 2020: Westbrook et al . 2011  
Citrus limon  Lemon  EPPO 2020: Westbrook et al . 2011  
Citrus aurantiifolia  Alemow, Colo  EPPO 2020:  Westbrook et al . 2011  
Citrus reticulata   Halbert and Manjunath 2004  
Citrus maxima  Bali lemon, Pummelo, Shaddock  EPPO 2020:  Westbrook et al . 2011  
Citrus medica  Buddha’s hand, Cidran, Citron, Etrog  EPPO 2020: Westbrook et al . 2011  
Citrus limon  - Halbert and Manjunath 2004  
Citrus paradisi  Kinkoji  Halbert and Manjunath 2004  
Citrus paradisi  Grapefruit, Pomelo  EPPO 2020: Tsai and Liu 2000 ; Westbrook et al . 2011  
Citrus reticulata var. 
austera  Cleopatra mandarin  EPPO 2020: Tsagkarakis et al . 2010  
Citrus reticulata  Clementine, Mandarin, Tangerine  EPPO 2020: Westbrook et al . 2011  
Citrus sinensis  Sweet orange  EPPO 2020: Westbrook et al . 2011  
Citrus reticulata var. 
austera  Sour mandarin  EPPO 2020: Westbrook et al . 2011  
Citrus aurantium  - EPPO 2020: Westbrook et al . 2011  
Citrus limon  Volkameriana  EPPO 2020: Westbrook et al . 2011  
Citrus aurantiifolia  Kalpi  EPPO 2020: Westbrook et al . 2011  
Citrus limon  Canton lemon, Mandari n lime, 
Rangpur lime  EPPO 2020: Westbrook et al . 2011  
Citrus reticulata  Kjing orange, Tangor  EPPO 2020: Westbrook et al . 2011  
 
Diaphorina citri  is present in several citrus -export ing countries considered in this import risk 
assessment.  
• Diaphorina citri  is widespread throughout Asia and occurs in North, Central and South 
America, Africa and Oceania (Table 11.1.2) (Halbert and Nunez 2004, Grafton -Cardwell et al. 
2006 ; EPPO 2020 ; CABI 2020).  
• Diaphorina citri  is present in the following citrus -export ing countries under consideration for 
this assessment:  
o Brazil, China, Japan, Mexico, USA, Viet  Nam (EPPO 2020)  and Samoa (MPI 2020a).  
 
Table 11.1. 2. Known geographic distribution of Diaphorina citri.  Information is compiled as at 31 August 
2020 (from EPPO 2020, except where indicated). Countries in bold  are included in the scope of this risk 
assessment.  
Continent/Regi on Country (province/state)  
Africa  Ethiopia, Kenya, Mauritius, Nigeria, Réunion , Tanzania  
North America  Mexico , USA (Alabama, Arizona, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, 
South Carolina, Texas ) 
Central America and 
Caribbean  Antigua and Barbuda, Bahamas, Barbados, Belize, Cayman Islands, Costa Rica, Cuba, 
Dominica, Dominican Republic, Guadeloupe, Haiti, Jamaica, Martinique, Puerto Rico, Saint 
Lucia, St Vincent and the Grenadines, US Virgin Islands  
South America  Argentina, Brazil (Amazonas, Bahia, Cear á, Par á, Pernambuco, Rio de Janeiro, Santa 
Catarina, S ão Paulo ), Colombia, Paraguay, Uruguay, Venezuela  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 344 Continent/Regi on Country (province/state)  
Asia Afghanistan, Bangladesh, Bhutan, Cambodia, China (Aomen , Fujian, Guangdong, Guangxi, 
Guizhou, Hainan, Henan, Hunan, Jiangxi, Sichuan, Xianggang, Yunnan, Zhejiang ), East Timor, 
India, Indonesia, Iran, Japan (Kyushu, Ryukyu Archipelago ), Laos, Malaysia, Maldives, 
Myanmar, Nepal, Oman, Pakistan, Philippines, Saud i Arabia, Singapore, Sri Lanka, Taiwan, 
Thailand, United Arab Emirates, Viet Nam, Yemen  
Oceania1 American Samoa, Samoa  (MPI 2020), Guam, Northern Mariana Islands, Papua New Guinea  
1 Australia  – absent, pest no longer present  
 
Given the arguments and evidence below, basic measures are likely to reduce the of 
entry of D. citri  by a high degree; consequently, the likelihood of entry is considered 
to be low.  
General handling after harvesting is expected to remove the majority of small mobile external 
organisms such as adult D. citri . 
• Eggs and immature stages of D. citri  are unlikely to be associated with the harvested fruit 
commodity in the packhouse as they f eed on young, soft plant tissues and tend not to move 
from their feeding sites. However, any leaf material contaminating the commodity may carry 
eggs or larvae.  
• Although adult D. citri  do not feed on citrus fruit, they are very mobile and have been recorde d 
on unprocessed harvested citrus fruit that is being transported for processing. Therefore, 
adults may be associated with the commodity when it reaches the packhouse.  
• Washing, brushing and other activities in packhouse are expected to remove most 
contamin ants and small mobile organisms from the outside of the fruit.  
• Adults are brownish in colour and around 3  mm in length (the average size was 3.3  mm in 
length and 1.0  mm in width for adult females, 2.7  mm long and 0.8 mm wide for adult males in 
a study by T sai and Liu , 2000) and are therefore visually detectable on the commodity.  
 
The export production system may not remove all D. citri  present on the fruit commodity.  
• Adults move readily if disturbed and can fly and resettle. They are also attracted to brigh t 
lights , which  may be used in the packhouse. There is potential for adult D. citri  to settle on 
fruit again after disturbance , and fruit may be infested during packhouse processing or if not 
stored separately from fruit that has not yet been through the e xport production system.  
• Small amounts of leaf contaminants harbouring life stages of D. citri  may be overlooked 
during routine inspection.  
• There is potential for D. citri  adults or other life stages to become hidden in crevices such as 
the navel of an ora nge. 
• There have been previous interceptions at the New Zealand border of other mobile Hemiptera 
(e.g. Aphididae) on fruit of Citrus  spp. (MPI LIMS 2014 –2016) , indicating that packhouse 
systems may not always remove all organisms present on fruit.  
 
Diaphorina citri  can survive transit in citrus commodities.  
• Storage and transport of citrus consignments from exporting countries to New Zealand are 
likely to occur at cool temperatures, with the length of time for shipment depending on the 
exporting count ry. For example, transport of fruit by sea may take up to three weeks from 
Korea and more than three weeks from Brazil.  
• Overwintering adults, especially females, have a much longer lifespan than females in other 
generations and can live for 8 –9 months. The re is no complete diapause or dormancy. Some 
overwintering adults are able to survive temperatures as low as -12°C for short periods of 
time (Yang et al. 2006).  
• D. citri  can survive, without food or water, for increasing periods as temperature decreases 
and humidity increases. Under laboratory conditions, adult D. citri  are able to survive up to 
94.5 hours at 25°C without feeding if suitable foliage is not available (McFarland and Hoy 
2001). Therefore, psyllids packed with fruit could survive for longer per iods at lower 
temperatures (Biosecurity Australia 2011).  
• Interceptions of live psyllids on unprocessed fruit (Halbert and Nunez 2004) show that D. citri  
can survive transportation and storage in some conditions.  
  
345 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Likelihood of establishment:  
 
Given the arguments and evidence below,  Diaphorina citri  has a high ability (with low 
uncertainty) to move from imported fruit and into  a suitable environment to allow 
establishment, that is, onto a host plant.  
 
Diaphorina citri is easily disturbed and may disperse to a host plant:  
• Adults are easily disturbed and will jump a short distance or fly (Tsai and Liu 2000 ; Grafton -
Cardwell et al. 2006). Therefore, an adult D. citri  is able to fly off the fruit at any stage in the 
pathway to consumption or disposal . 
• Diaphor ina citri  uses both olfactory and visual cues to orient to host plants (Wenninger et al. 
2009).  
• D. citri  has been recorded dispersing away from host plants to nearby citrus groves (Boina et 
al. 2009). Arakawa and Miyamoto (2007) calculated flight distances  of up to 978 m for 
females and 1 ,241 m for males using a flight mill.  
 
Most D. citri  are likely to be disturbed off fruit in an environment with limited access to host plants . 
• Most imported citrus fruit is displayed and handled inside retail buildings , and therefore , any 
adults that fly off fruit in these settings would fly into an environment with limited access to 
host plants. Nymphs and pupae associated with imported citrus fruit may also be dislodged 
during fruit handling; however, unless they are near  suitable host plants , there is no 
opportunity for exposure.  
• Potential for transfer exists if infested fruit is unpackaged in an environment containing 
suitable host plants or if adults can easily reach environments containing host plants . In these 
instanc es, adult D. citri  may be able to disperse to a new host.  
 
Citrus  spp. are present throughout New Zealand, especially in residential environments.  
• Citrus  spp. are present in commercial groves throughout Northland, Auckland, Bay of Plenty, 
and Gisborne, and in domestic gardens in warmer regions. C. limon  (one of the main hosts of 
D. citri ) is particularly prevalent in domestic gardens through much of the country.  Therefore, 
if disturbed off fruit in or near an outdoor environment, D. citri  could reach a suitable host 
plant particularly in a residential environment with Citrus  present.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for D. citri  to establish is considered moderate . 
New Zealand’s climate in some citrus -growing regions is likely to be suitable for D. citri  to establish, 
especially in the north of New Zealand.  
• Some of the areas where D. citri  has been recorded (T able 11.1. 2) have similar climate to 
New Zealand, as indicated by climate match ind ex (CMI)  values  >7 (Phillips et al. 2018), for 
example:  
o Argentina (0.7 –0.9); Brazil: Santa Cat arina (0.7 –0.9), S ão Paulo (parts are 0.7 –0.8); 
China: Sichuan (0.7 –0.8), Yunnan (0.7 –0.8); Uruguay (0.8 –0.9); USA: Alabama (0.7 –
0.8), Georgia (0.7 –0.8), South Carolina (0.7 –0.8), Texas (mostly 0.7 –0.8) 
• Two models to assess the global climate suitability of citrus huanglongbing and its vector D. 
citri predict that the northern N orth Island (both models) and southern North Island (one 
model) are climatically suitable for the establishment of D. citri  (Narouei -Khandan et al. 2016).  
• Therefore, D. citri  is likely to be able to establish in warmer areas of northern New Zealand.  
 
Poten tial hosts are available, especially in warmer northern regions , where most commercial citrus is 
grown.  
• Citrus  is commercially produced in both the North and South Island , with most production 
taking place in the North Island (see section 2.4.2 ). The main citrus -growing areas in New 
Zealand are Northland, Auckland, Bay of Plenty, Hawke’s Bay and Gisborne ( Plant & Food Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 346 Research  2019). Citrus  is also commonly grown in domestic gardens in warmer regions. 
Lemon ( C. limon ), one of the main hosts of D. citri , is grown in domestic gardens through 
much of the country.  
• Other hosts, such as Murraya paniculata (a preferred host), M. koenigi  and Choisya ternata , 
are cultivated in gardens.  
 
Diaphorina citri  is likely to find mates and has a high reproductive rate.  
• D. cit ri reproduces sexually , and adults locate mates through pheromones (Wenninger et al. 
2008) and vibrational communication (Wenninger et al. 2009b). If several individuals were to 
be disturbed off fruit in the same environment, either outdoors or near outdoo rs, males and 
females would be capable of locating each other.  
• D. citri  mate and lay eggs almost exclusively on young foliage (Wenninger and Hall 2007) and 
the timing of reproduction in D. citri  is related to the emergence of new growth on the host 
plants (Halbert and Manjunath 2004).  
• The number of eggs laid by D. citri  females varies in the literature, with as many as 1 ,000–
2,000 eggs laid by a female psyllid in three weeks (Aubert 2008) to as f ew as 180 –520 eggs 
(Pande 1971). Egg -laying capacity may vary on different hosts (Tsai and Liu 2000).  
• There are multiple generations per year, the number depending on regional climates, with up 
to 11 –12 generations possible when suitable flush growth is pr esent (Husain and Nath 1927).  
• Adults of D. citri  can live for several months. They do not diapause but are able to overwinter 
on vegetation to wait for more favourable breeding conditions (Gottwald et al. 2007).  
 
Diaphorina citri  can disperse locally to enable initial establishment.  
• Adult psyllids are very mobile and can move from tree to tree in the field . D. citri  uses both 
olfactory and visual cues to orientate to host plants and has been recorded dispersing away 
from host plan ts to nearby citrus orchards (Boina et al. 2009 ; Wenninger et al. 2009a).  
 
Diaphorina citri  can spread over longer distances.  
• There is some evidence that high winds and storms can move psyllids considerable distances 
(Gottwald 2010).  
• An important means o f long -distance dispersal to new areas is through the movement of 
infested host plant material (Halbert and Manjunath 2004).  
• Adults can hitchhike on unprocessed fruit consignments (Halbert and Manjunath 2004, 
Halbert et al. 2010) and , in the absence of fr uit, are likely to hitchhike with various forms of 
transport to new locations.  
 
 
Impacts in New Zealand  
 
Given the arguments and evidence below, the level of impact caused by D. citri  is 
likely to be low to moderate for New Zealand overall but moderate to high for the 
citrus industry, depending on the presence of HLB in New Zealand . 
 
The potential economic consequences of D. citri  are considered low to moderate for New Zealand, 
but mod erate to high for the citrus industry, depending on the presence of HLB . 
• D. citri  typically causes defoliation and dieback. Serious damage to growing points can occur, 
which can lead to dwarfing , as well as lack of juice and taste in fruit. Heavy D. citri  populations 
can cause blossom and fruitlet drop. The honeydew excreted by D. citri  promotes the growth 
of sooty mould , which affects the photosynthetic activity of the tree (CABI 2000).   
347 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Little direct economic loss has been reported as a result of D. citri  alone (Biosecurity Australia 
2011).  
• However, the main economic impact of D. citri  is as a vector of huanglongbing (HLB) disease, 
also referred to as citrus greening. HLB is regarded as one of the most devastating diseases 
of citrus in the world. Premature  fruit drop on infected trees results in decreased production. 
Infected fruit that remains on the tree can be small, hard, discoloured and misshapen with a 
bitter unpleasant taste that makes it commercially useless. Trees become stunted and have a 
much sho rter life. Nearly all commercial citrus species and cultivars are susceptible to the 
disease , regardless of rootstock (Bove 2006). HLB is associated with three liberibacter 
species, ‘ Candidatus  Liberibacter africanus’, ‘ Ca. L. americanus’ and ‘ Ca. L. asiat icus’. The 
liberibacter are found in the phloem of the plant host. They are transmitted naturally by two 
psyllid vectors: Diaphorina citri  and Trioza erytreae  (Bove 2006). D. citri  vectors ‘ Ca. L. 
americanus’ and ‘ Ca. L. asiaticus’ naturally and is capable  of transmitting ‘ Ca. L. africanus’, 
experimentally at least (Gottwald 2010 ; Bove 2006). The liberibacter can be found in the 
salivary glands and haemolymph of D. citri  (da Graca 1991 ; Gottwald 2010) , and once the 
psyllid has acquired the bacteria, as a nymph or adult, it is maintained in the psyllid for its 
lifetime.  
o ‘Candidatus  Liberibacter africanus’ is not known to be present in any of the countries 
in the IRA  (EPPO 2020) . It has been recorded as a bsent, confirmed by survey  in 
Spain (EPPO 2020);  
o ‘Candidatus  Liberibacter a mericanus ’ is known to be present in one of the IRA 
countries : Brazil (EPPO 2020);  
o ‘Candidatus  liberibacter asiaticus’  is known to be present in several of the IRA 
countries : Brazil , China , Japan , Mexico , USA, Viet Nam (EPPO 2020). It has been 
recorded as absent, confirmed by survey, in Fiji, Cook Islands, Samoa  and Spain , 
and absent (invalid record) in Egypt  (EPPO 2020).  
• The introduction of D. citri  to New Zealand is very likely to mean the introduction of HLB if 
infected psyllids come from a location where the disease is present. On the other hand, if D. 
citri arrives in New Zealand in the absence of the disease, then establishment of psyllid 
popula tions that are capable of vectoring HLB would be of concern should the disease be 
introduced at a later date.  
• In areas where both the vector and HLB are present , the damage to citrus production can be 
very high (Biosecurity Australia 2011). For example, HL B destroys 10 –15% of tangerine trees 
in Thailand annually (Bové 2006) . In Réunion, an eight -year survey conducted in the 1980s 
and 1990s determined that 65% of trees were infected and became unproductive within 
seven years of planting (Gottwald et al. 1989 ; Gottwald et al. 2007).  
• Both D. citri  and HLB affect many Citrus  species and commercial citrus varieties including 
those in the New Zealand citrus industry (see section 2.5.2 ).  
• The discovery of the presence of D. citri  in New Zealand as an incursion or an established 
population is likely to have an immediate impact on exports of citrus countries free from 
huanglongbing and D. citri .  
• If D. citri  were detected in New Zealand, the cost incurred by a response would be high . It is 
likely that a response would be undertaken given the ability of D. citri  to vector HLB, 
regardless of the presence of HLB. The typical cost of a response is millions of dollars. For 
example, the Queensland fruit fly response in 2019 cost approximat ely NZ$18 million (MPI 
2020b).  
• Establishment of D. citri  is likely to increase phytosanitary measures required for export of 
citrus fresh produce to countries where D. citri  and HLB are not present, such as the 
European Union.  
• Models predict that the clima te in the northern North Island (both models) and southern North 
Island (one model) are climatically suitable for the establishment of D. citri  (Narouei -Khandan 
et al. 2016). Therefore, D. citri  is likely to be able to establish in warmer areas of northern  
New Zealand where much of the country’s commercial Citrus  production takes place , 
especially in areas such as Northland , where it could have a large impact on the local 
economy.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 348  
It is likely that D. citri  will cause a low to moderate level of sociocultur al impacts in New Zealand, 
depending on the presence of HLB.  
• Citrus  spp. and Murraya paniculata  are common in domestic gardens in New Zealand, 
especially in the northern regions, although C. limon  is grown more widely through out the 
country. If D. citri  became established in New Zealand , it could impact home gardeners 
directly through feeding damage to host plants , which  can result in leaf distortion and 
abscission, and blossom and fruit drop. Excreted honeydew promotes the growth of sooty 
mould , affecting both appearance and photosynthetic activity of the plant (CABI 2000).  
• Greater impacts would occur if any of the liberibacter species that cause HLB were present in 
New Zealand, given the role of D. citri  as a vector for HLB. Symptomatic infected citrus tre es 
would have blotchy mottled and yellowing leaves, small lopsided and bitter -tasting fruit with 
aborted seeds, with branches and eventually whole plants dying after a few years (Garnier 
and Bove 2000 ; CABI 2000). Symptoms of HLB may not be expressed on Murraya 
paniculata , but there is potential for this species to act as a reservoir for the disease 
(Darmsteegt et al. 2010).  
 
It is likely that D. citri  will have a very low level of impact on the environment.  
• Citrus  species are members of the Rutaceae  family. There are two endemic genera within 
Rutaceae in New Zealand (NZPCN 2020), Melicope  and Leionema . Neither genus is 
considered threatened (NZPCN 2020) , and they are usually restricted to native forest 
environments. Although neither of these genera a re known to be hosts for D. citri , heavy 
psyllid infestations can cause leaf, blossom and fruit abscission; however, the main risk 
associated with D. citri  is from transmission of the disease HLB , which only affects Rutaceae, 
primarily Citrus  spp. 
 
It is likely that D. citri  will have negligible impacts on human health.  
• No evidence was found that D. citri has an impact on human health.  
 
 
Risk assessment summary : 
 
Given the arguments and evidence below, Diaphorina citri  may be considered for 
additional meas ures. 
 
• Diaphorina citri  has a strong association with citrus, but a weak association with citrus fruit.  
• Basic measures  are likely to reduce the entry of D. citri  by a high degree (with low 
uncertainty) . Consequently, the likelihood of entry is considered low (with low uncertainty) .  
• The ability of D. citri to move from imported fruit to a suitable host plant is  high (with low 
uncertainty).  
• The suitability of the New Zealand environment for D. citri  to establish is considered moderate 
(with low uncertainty) . 
• The level of impact caused by D. citri  is likely to be low to moderate (with low uncertainty) for 
New Zealand overall but moderate to high (with low uncertainty)  for the citrus industry, 
depending on the presence of HLB in New Zealand , with at least two of the causal agents 
being vectored by D. citri . 
• Diaphorina citri  is present in the following citrus -export ing countries under consideration for 
this assessment: Brazil, China, Japan, Mexico, the USA, Viet  Nam and Samoa.  
 
10.1.4  References  
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Psyllid. Oakland, California: University of Calif ornia. ANR Publication 8205. 
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disease of citrus: a literat ure review and assessment of risk in Florida. Florida Entomologist , 87(3): 
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transporting oranges to processing plants move Asian citrus psyllids. Florida En tomologist , 93(1): 33 –
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Halbert, S E; Nunez, C A (2004) Distribution of the Asian citrus psyllid, Diaphorina citri Kuwayama 
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Husain, M A; Nath, D (1927) The citrus psylla  (Diaphorina citri  Kuw.) [Psyllidae: Homoptera]. Memoirs 
of the Department of Agriculture India, Entomology Series , 10: 5 –27. (Cited in Biosecurity Australia 
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Keremane, M L; Ramadugu, C; Castaneda, A; Diaz, J. E; Penaranda, E A; Chen, J; Duan, Y P; 
Halbert, S E; Lee, R F (2015) Report of Candidatus  Liberibacter caribbeanus, a new citrus - and 
psyllid -associated Liberibacter from Colombia, South America. In American Phytopathological Society 
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parasitoids, Tamarixia radiata  (Hymenoptera: Eulophidae) and Diaphorencyrtus aligarhensis  
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suitability of citrus huanglongbing and its v ector, the Asian citrus psyllid, using two correlative species 
distribution modeling approaches, with emphasis on the USA. European Journal of Plant Pathology , 
144: 655 –670. 
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Accessed October 2020.  
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of Entomology . 6: 307 –311. (cited in Biosecurity Australia 2011)   
351 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Phillips, C B; Kea n, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
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Botanicae Horti Agrobotanici  46(2): 546 –552. 
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Diaphorina citri  (Hemiptera: Psyllidae). Florida Entomologist , 90: 715 –722. 
Wenninger, E J; Hall, D G; Mankin, R W (2009b) Vibrational communication between the sexes in 
Diaphorina citri  (Hemiptera: Psyllidae ). Annals of the Entomological Society of America , 102(3): 547 –
555. 
Wenninger, E J; Stelinski, L L; Hall, D G (2008) Behavioral evidence for a female -produced sex 
attractant in Diaphorina citri . Entomologia Experimentalis et Applicata , 128: 450 –459. 
Wennin ger, E J; Stelinski, L L; Hall, D G (2009a) Roles of olfactory cues, visual cues, and mating 
status in orientation of Diaphorina citri  Kuwayama (Hemiptera: Psyllidae) to four different host plants. 
Environmental Entomology , 38: 225 –234. 
Westbrook, C J; Hal l, D G; Stover, E; Yong Ping Duan; Lee, R F (2011) Colonization of Citrus  and 
Citrus -related germplasm by Diaphorina citri  (Hemiptera: Psyllidae). HortScience , 46(7): 997 –1005.  
Yang, Y; Huang, M; Beattie, G A C; Xia, Y; Ouyang, G; Xiong, J (2006) Distribu tion, biology, ecology 
and control of the psyllid Diaphorina citri  Kuwayama, a major pest of citrus: A status report for China. 
International Journal of Pest Management , 52: 343 –352. 
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 352 10.2 Trioza erytreae  (African citrus psyllid ) 
 
Trioza erytreae  is a small psyllid (about 2 mm long) that damages plant tissues directly through its 
feeding activities and indirectly through vectoring liberibacter  that cause huanglongbing (HLB), a very 
destructive disease of citrus (van den Berg 1990 ; CABI 2020).  
 
Scientific name: Trioza erytreae  (Del Guercio , 1918 ) 
Order/Family: Hemiptera/Triozidae  
Other names include: Aleurodes erytreae , Spanioza eritreae , Spanioza erythreae , Spanioza 
erytreae , Spanioza merwei , Trioza citri , Trioza erythreae , Trioza merwei , African c itrus psyllid, citrus 
psylla, African citrus psylla,  two-spotted citrus psyllid  
 
Note:  
Trioza erytreae  is one of the psyllid vectors of the causal agents of the serious citrus disease HLB, 
also known as citrus greening . 
HLB is associated wit h three liberibacter species, ‘ Candidatus  Liberibacter africanus’, ‘ Ca. 
americanus’ and ‘ Ca. L. asiaticus’  (Gottwald 2010) . ‘Ca. L. asiaticus’ , which is the most prevalent 
bacteria , is associated with Asian HLB , which is the most widespread form of the disease. ‘ Ca. L. 
africanus’ is associated with the African form of HLB and ‘ Ca. L. americanus’ with the American form 
of HLB. Recently, a new strain provisionally named ‘ Ca. L. caribbeanus’ has been reported that may 
cause HLB -like symptoms in citrus (Keremane et al.  2015) . The liberibacter are found in the phloem 
of the plant host. They are transmitted naturally by two psyllid vectors: Diaphorina citri  and Trioza 
erytreae  (Bove 2006). D. citri  vectors ‘ Ca. L. americanus’ and ‘ Ca. L. asiaticus’ naturally and is 
capabl e of transmitting ‘ Ca. L. africanus’, experimentally at least (Gottwald 2010, Bove 2006).  Trioza 
erytreae  transmits ‘Ca. L. africanus’  under natural conditions, and it has been shown experimentally 
that T. erytreae  is able to transmit ‘ Ca. L. asiaticus ’ (Gottwald 2010 ). 
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Trioza erytreae  meets the criteria to be a quarantine pest for New Zealand . 
• Trioza erytreae  has strong association with citrus, but a weak association with citrus fruit  (with 
low uncertainty) . 
• Basic measures  are likely to reduce the likelihood of entry by a high degree  (with low 
uncertainty) . consequently, the likelihood of entry is considered low (with moderate 
uncertainty).  
• The ability of T. erytreae  to transfer from imp orted fruit to suitable host plants is high  (with low 
uncertainty) . 
• The suitability of the New Zealand environment for T. erytreae  to establish is considered high 
(with moderate uncertainty).  
• The level of impact caused by T. erytreae  is likely to be low to  moderate for New Zealand 
overall  (with low uncertainty) , but moderate to high for the citrus industry  (with low 
uncertainty) , depending on the presence of the citrus disease HLB , with a least one of the 
causal agents being  vectored by T. erytreae.  
• Trioza erytreae  may be considered  for additional measures . 
 
Summary of risk assessment against criteria:  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Weak  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Moderate  
The ability to move from the imported commodity  onto a suitable host  High Low 
Suitability of the N ew Zealand  environment  HIgh  Moderate  
Impacts on the New Zealand economy, environment, health and society , 
depending on presence  of HLB  Low–moderate  Low  
353 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  10.2.1  Hazard identification: quarantine status  
Given the arguments and evidence below,  Trioza erytreae  meets the criteria to be a 
quarantine pest for New Zealand . 
Criteria for being a quarantine pest relevant to this assessment are:  not present in New Zealand, and 
of potential importance (able to establish and cause harm).  
 
Trioza erytreae is not known to be present in New Zealand.  
• Trioza erytreae  is not recorded in NZInverts (2020), NZOR (2020) or PPIN (2020).  
• The quarantine status of T. erytreae  in New Zealand is ‘regulated’ , and it is an unwanted 
organism ( ONZPR 2020).  
 
Trioza erytreae has the potential to establish and spread in New Zealand.  
• T. erytre ae largely occurs in Africa and nearby Asian countries, Sau di Arabia and Yemen. 
However, it has been recently recorded in Europe (Portugal and Spain) (EPPO 2020 ; CABI 
2020) (Table 11.2. 2). 
• Some of the areas where T. erytreae  occurs have a high climate match with New Zealand, 
with a climat e match index (CMI) of 0.7  or greater (Phillips et al. 2018), indicating the potential 
to establish in New Zealand, for example:  
o Spain (0.7 –0.9) and Portugal (0.8 –0.9). 
• There are suitable host species ( Citrus  spp.) present in areas of New Zealand that are likely 
to be climatically suitable for T. erytreae . 
 
Trioza erytreae has the potential to cause economic impacts in New Zealand.  
• T. erytreae  has the potential to damage citrus , which is of economic importance to 
New Zealand,  both through direct feeding damage and by vectoring liberibacter species that 
cause the citrus disease huanglongbing (HLB).  
• Establishment of T. erytreae  is likely to affect market access for Citrus  to those countries free 
from T. erytreae  and HLB.  
 
10.2.2  Hazard identification: commodity association  
Trioza erytrea e is associated with citrus fruit  
• Trioza erytreae  (African citrus psyllid) is a similar organism to Diaphorina citri  (Asian citrus 
psyllid) , which also has a host range confined to the Rutacaeae , including Citrus  and other 
close relatives (Halbert and Manj unath 2004) , and is also a vector for at least two of the 
pathogens that cause HLB . 
• A study by Halbert et al. (2010) showed that D. citri  can be transported with harvested citrus 
fruit. Live adults (509 psyllids) were collected from seven trailers, from th e tops and sides of 
the loads up to 30 cm below the surface of the oranges, suggesting they were distributed 
throughout the loads. The psyllids were seen resting on the fruit itself rather than on the 
minimal amount of foliage that was present (Halbert et al. 2010).  
• High numbers of D. citri  adults were intercepted in boxes of fresh unprocessed citrus fruit 
(grapefruit) picked in the Bahamas and shipped to Ft. Pierce, Florida, for processing in 2001 
(Halbert and Nunez 2004).  
• Therefore, it is assumed that adu lts of T. erytreae  can similarly be associated with citrus fruit 
as hitchhiker s. 
10.2.3  Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below,  Trioza erytreae  has a strong association 
with citrus but a weak association with citrus fruit.  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 354 Although the life stages of T. erytreae  feed on foliage, adults that have been disturbed may seek 
refuge on citrus fruit.  
• All life stages of T. erytreae  are found on citrus host foliage (van den Berg 1990). Eggs are 
laid on the margins of actively growing leaves. Nymphs live in individual depressions or open 
galls they produce on the undersides of leaves and remain there until they become adult s. 
Nymphs and adults prefer to feed on young plant tissues, generally foliage (van den Berg 
1990) . They are not kno wn to feed on mature fruit (Biosecurity Australia 2011).  
• T. erytreae  adults wander leaves and fly readily to areas of citrus flush (van den Berg 1990). It 
is assumed here that, in a similar fashion to D. citri , adult T. erytreae  will jump or fly short 
distances and seek refuge on citrus fruit when disturbed.  
• Live D. citri  adults have been intercepted on harvested citrus fruits being transported by trailer 
and by ship , in boxes of unprocessed fruit shipped from the Bahamas to Florida, USA , for 
processing (Ha lbert and Nunez 2004, Halbert et al. 2010).  
 
Trioza erytreae  infests many citrus species and varieties.  
• All known hosts of T. erytreae  are members of the Rutaceae. The original hosts are probably 
Vepris lanceolata  (=undulata ) and Clausena anisata , with Citrus spp., and other close 
relatives such as Murraya paniculata  and Poncirus trifolliata  recorded as hosts (Cocuzza et al. 
2017).  
• T. erytreae  has been recorded infesting many citrus species and varieties. Table 11.2. 1 lists 
Citrus  species/taxa that are confirmed hosts (EPPO 2020). Some of these hosts are preferred 
over others (Biosecurity Australia 2011).  
 
Table 11.2. 1. Citrus  host plant records for Trioza erytreae  
Botanical name  Common name  Comments  
Citrus aurantiifolia  Lime  EPPO  2020: confirmed host (Aubert 1987)  
Aubert (1987): a preferred host plant  
Citrus australasica  
(Microcitrus australasica ) Australian finger lime  EPPO 2020: confirmed host, incidental (Aubert 1987)  
Aubert (1987): an occasional host plant  
Citrus reticulata  _ EPPO 2020: confirmed host (Aubert 1987)  
Aubert (1987): a common host plant  
Citrus limon  Rough lemon  EPPO 2020: confirmed host (Aidoo et al. 2019)  
Citrus limon  Lemon  EPPO 2020: confirmed host (Moran 1968)  
Aubert (1987): a preferred host plant  
Citrus maxima  Pummelo  EPPO 2020: confirmed host (Aubert 1987)  
Aubert (1987): a common host plant  
Citrus medica  Citron  EPPO 2020: confirmed host (Aubert 1987)  
Aubert (1987): a preferred host plant  
Citrus reticulata  Tangor  EPPO 2020: confirmed host (Aubert 1987)  
Aubert (1987): a common host plant  
Citrus paradisi  Grapefruit  EPPO 2020: confirmed host (Aubert 1987)  
Aubert (1987): a common host plant  
Citrus reticulata  Mandarin  EPPO 2020: confirmed host (Aubert 1987)  
Aubert (1987): a common host plant  
Citrus sinensis  Sweet orange  EPPO 2020: confirmed host (Aubert 1987. Aidoo et al 2019)  
Aubert (1987): a common host plant  
Citrus reticulata  Tangerine  EPPO 2020: confirmed host (Aidoo et al. 2019)  
 
Trioza erytreae  is present in one citrus -export ing country consi dered in this import risk assessment.  
• The geographic range of T. erytreae  is largely African , but it occurs in some nearby Asian 
countries and more recently in Europe (Table 11.2. 2).  
355 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • T. erytreae  is present in the following citrus -export ing country under consideration:  
o Spain (EPPO 2020)  
 
Table 11.2.2. Known geographic distribution of Trioza erytreae . Information  compiled  31 October 2020 from 
EPPO (2020). Countries in bold  are included in the scope of this risk assessment.  
Continent/Region  Country/State  
Africa  Angola, Cameroon, Comoros, Congo (Democratic Republic of the), Eritrea, Eswatini, Ethiopia, 
Gabon, Kenya, Madagascar, Malawi, Mauritius, R éunion, Rwanda, Saint Helena, S ão Tom é 
and Principe, South Africa, Sudan, Tanzania, Uganda, Zamb ia, Zimbabwe  
Asia Saudi Arabia, Yemen  
Europe  Portugal (mainland and Madeira), Spain (mainland and Canary Islands ) 
 
Given t he arguments and evidence below, basic measures are likely to reduce 
likelihood of entry of T. erytreae  by a high degree . Consequently, the likelihood of 
entry is considered to be low (with moderate uncertainty).  
General handling after harvesting is expected to remove the majority of small mobile external 
organisms , such as adult T. erytreae . 
• Eggs and immature stages of T. erytreae  are unlikely to be associated with the harvested fruit 
commodity in the packhouse as they feed on young, soft plant tissues and tend not to move 
from their feeding sites. However, any leaf material contaminating the commodity may carry 
eggs or lar vae. 
• Although adult T. erytreae don’t feed on citrus fruit, they are mobile. Given D. citri  has been 
recorded as hitchhiker on unprocessed harvested citrus fruit that is being transported for 
processing, it is assumed that T. erytreae  could also hitchhike on fruit. Therefore, adults may 
be associated with the commodity when it reaches the packhouse.  
• Washing, brushing and other activities in packhouse are expected to remove most 
contaminants and small mobile organisms from the outside of the fruit.  
• Adults ar e brownish in colour and around 2  mm in length (adult males 2.17 mm, adult females 
2.24 mm (van den Berg 1990)) and are therefore visually detectable on the commodity.  
 
The export production system may not remove all T. erytreae present on fruit . 
• Adults mo ve if disturbed and can fly and resettle. They are also attracted to bright lights that 
may be used in the packhouse (Biosecurity Australia 2011). There is potential for adult 
T. erytreae  to settle on fruit again after a disturbance , and fruit may be infes ted during 
packhouse processing or if not stored separately from fruit that has not yet been through the 
export production system.  
• Small amounts of leaf contaminants harbouring life stages of T. erytreae  may be overlooked 
during routine inspection.  
• There i s potential for T. erytreae  adults or other life stages to become hidden in crevices such 
as the navel of an orange.  
• There have been previous interceptions at the New Zealand border of other mobile Hemiptera 
(e.g. Aphididae) on fruit of Citrus  spp. (MPI LI MS 2014 –2016) , indicating that packhouse 
systems may not always remove all organisms present on fruit.  
 
Adult T. erytreae may be able to survive transport times and temperatures for some citrus 
commodities.  
• Storage and transport of citrus consignments from exporting countries to New Zealand are 
likely to occur at cool temperatures, with the length of time for shipment depending on the 
exporting country. For example, transport of fruit by sea may take up to th ree weeks from 
Korea and more than three weeks from Brazil.  
• The threshold the temperature for nymphal development is between 10 °C and 12 °C, and the 
psyllid overwinters as an adult (van den Berg 1990).  
• Trioza erytreae  adults can live up to 55 hours without  feeding if suitable foliage is not 
available or 85 hours in the absence of a suitable host plant in the field . The death of the 
psyllids under field conditions, where temperatures reached 27°C and relative humidity 
dropped to 37%, was attributed to desicc ation rather than starvation ( van den Berg and 
Deacon 1988). Therefore, psyllids associated with fruit could survive for longer periods during Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 356 transportation and storage under low temperatures and high humidity (Biosecurity Australia 
2011).  
 
The level of u ncertainty in relation to entry is rated as moderate , because it has been assumed that 
T. erytreae will behave in a similar manner to D. citri , there is no specific information on the conditions 
of transit, including temperature and duration, and there is a lack of interception data for T. erytreae . 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Trioza erytr eae has a high  ability (with low 
uncertainty) to move from imported fruit and into a suitable environment to allow 
establishment, that is, onto a host plant.  
 
Trioza erytreae  is mobile and may disperse from fruit to a new host.  
• Adult T. erytreae  associated with imported  fruit are able to move independently from imported 
fruit to a suitable host.  
• Adults can readily locate and invade isolated areas of flush over several hundred metres (van 
den Berg 1990)  
• T. erytreae able to disperse via wind currents up to 1.5 km (van den  Berg and Deacon 1988).  
 
Most T. erytreae  are likely to be disturbed off fruit in an environment with limited access to host plants.  
• Most imported citrus fruit is displayed and handled inside retail buildings , and  therefore , any 
adults that fly off fruit in these settings would fly into an environment with limited access to 
host plants. Nymphs and pupae associated with imported citrus fruit may also be dislodged 
during fruit handling; however, unless they are near suitable ho st plants , there is no 
opportunity for exposure.  
• Potential for transfer exists if infested fruit is unpackaged in an environment containing 
suitable host plants or if adults can easily reach environments containing host plants . In these 
instances, adult T. erytreae  may be able to disperse to a new host.  
 
Citrus  spp. are present throughout New Zealand, especially in residential environments.  
• Citrus  plants  are present in commercial groves throughout Northland, Auckland, Bay of Plenty 
and Gisborne, and in dome stic gardens in warmer regions. C. limon  (a preferred host of 
T. erytreae ) is particularly prevalent in domestic gardens through out much of the country. 
Therefore, if disturbed off fruit in or near an outdoor environment, T. erytreae  could reach a 
suitable  host plant , particularly in a residential environment with Citrus  present.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for T. erytreae  to establish is considered high (with moderate 
uncertainty).  
 
New Zealand’s climate is likely to be suitable for establishment of T. erytreae . 
• Trioza erytreae  is adapted to relatively cool environments, often at higher altitudes, and is 
sensitive to high temperatures combined with low humidity (Bove 2006).  
• The distri bution of the psyllid in Africa, Saudi Arabia and Yemen show that it has been able to 
adapt and settle under a variety of ecological conditions such as in equatorial, arid, and warm 
temperate climates with different temperatures and rainfall (Cocuzza et al . 2017).  
• Some of the areas where T. erytreae  has been recorded (Table 11.2. 2) have similar climate 
to New Zealand, as indicated by climate match ind ex (CMI)  values  >0.7 (Phillips et al. 2018), 
for example:  
o Spain (0.7 –0.9): location records in Galicia (0.9)  (EPPO 2020)  
o Portugal (0.8 –0.9): mainland Norte (0.9) and Centro (0.8 –0.9) regions, Porto (0.9), 
Area Metropolitana de Lisboa (0.8) (EPPO 2020)  
o Eswatini (Swaziland) (0.7 –0.8 CMI): found in cool moist upland regions (EPPO 2020)  
• New Zealand’s climate is like ly to be more suitable for T. erytreae  than D. citri , which is more 
heat tolerant (Bove 2006). Two models to assess the global climate suitability of citrus 
huanglongbing and the vector D. citri  predict that the northern North Island (both models) and  
357 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  southern North Island (one model) are climatically suitable for the establishment of D. citri 
(Narouei -Khandan et al. 2016). Therefore, D. citri  is likely to be able to establish in warmer 
areas of northern New Zealand. It is likely that T. erytreae  will be ab le to establish more 
widely in New Zealand than D. citri . 
Potential hosts are available , especially in warmer northern regions where most commercial citrus is 
grown:  
• Citrus  fruit is commercially  produced in both the North and South Island , with most production 
taking place in the North Island (see section 2 .4.2). The main citrus -growing areas in 
New Zealand are Northland, Auckland, Bay of Plenty, Hawke’s Bay and Gisborne ( Plant & 
Food Research 2019). Citrus is also commonly grown in domesti c gardens in warmer regions. 
Lemon ( C. limon ), a preferred host for T. erytreae , is grown in domestic gardens through 
much of the country.  
• Other hosts, such as Murraya paniculata  (a preferred host ), Casimoa edulis  and Choisya 
ternat a (Cocuzza et al . 2017) , are cultivated in gardens.  
T. erytreae  has a high reproductive rate.  
• Trioza erytreae  reproduces sexually. It is not clear if males find females using pheromones , 
but evidence suggests that D. citri adults locate each other through pheromones ( Wenninger 
et al. 2008) and vibrational communication (Wenninger et al. 2009). If T. erytreae  use similar 
mechanisms, this would increase the ability for males and females to locate each other if 
several individuals were to be disturbed off fruit in the sam e environment, either outdoors or 
near outdoors  
• Trioza erytreae  females  lay eggs almost exclusively on soft young tissues, often along the 
margins of young leaves , and the timing of reproduction is related to emergence of new 
growth on host plants.  
• Trioza erytreae  is a highly  fecund species, with females laying an average of 827 eggs during 
their lifetime (van den Berg 1990). Trioza erytreae  is capable of rapid population expansion 
when hosts with new shoot growth are available (Gottwald et al. 2007). And u nder ideal 
conditions up to eight generations may occur in a year (van den Berg 1990).  
• Trioza erytreae  does not undergo diapause. During winter, when conditions are not suitable 
for reproduction, the psyllid will continue to feed and survive until conditio ns become 
favourable for breeding (van den Berg 1990 ; Gottwald et al. 2007 ; Biosecurity Australia 2011). 
Adults may live for 2 –3 months (van den Berg 1990).  
Trioza  erytreae  can disperse locally to enable initial establishment . 
• Adults can readily  locate and invade isolated areas of flush over several hundred metres (van 
den Berg 1990).  
• Trioza  erytreae  is able to disperse via wind currents up to 1.5 km (van den Berg and Deacon 
1988).  
Trioza erytreae  can spread over longer distances.  
• An important  means of long -distance dispersal to new areas is through the movement of 
infested host plant material (Bove 2006). Adults can hitchhike on unprocessed fruit 
consignments and , in the absence of fruit , have the potential to hitchhike  with various forms of 
transport to new locations.  
• Trioza erytreae  has been demonstrated to be invasive, having recently been detected in 
mainland Portugal and Spain , where it is spreading in the northwest (Cocuzza et al . 2017).  
The level of uncertainty for suitability of the New Zealand environment is rated as moderate , because 
a comparison has been made with predictions from models for D. citri, although evidence indicates 
T. erytreae  does better than D. citri  in climates that are more similar to New Zealand . 
 
Impacts in New Zeal and:  
Given the arguments and evidence below, the level of impact caused by T. erytreae  
is likely to be low to moderate (with low uncertainty) for New Zealand overall , but 
moderate to high (with low uncertainty) for the citrus industry, depending on the 
presence of HLB in New Zealand . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 358 The potential economic consequences of T. erytreae  considered to be low to moderate for New 
Zealand, but moderate to high for the citrus industry, depending on the presence of HLB.  
• T. erytreae  feeding can severely distort le aves, which become stunted and galled. Leaves 
may become yellowed (CABI 2020). However, little direct economic loss has been reported 
as a result of T. erytreae alone , and it is considered a minor pest by itself (van den Berg 1990 ; 
Biosecurity Australia 20 11).  
• The main economic impact of T. erytreae  is as a vector of huanglongbing (HLB) disease, also 
referred to as citrus greening. HLB is regarded as one of the most devastating diseases of 
citrus in the world. Premature fruit drop on infected trees results  in decreased production. 
Infected fruit that remains on the tree can be small, hard, discoloured and misshapen , with a 
bitter unpleasant taste that makes it commercially useless. Trees become stunted and have a 
much shorter life. Nearly all commercial cit rus species and cultivars are susceptible to the 
disease regardless of rootstock (Bove 2006). HLB is associated with three liberibacter 
species, ‘ Candidatus  Liberibacter africanus’, ‘ Ca. L. americanus’ and ‘ Ca. L. asiaticus’. The 
liberibacter are found in the phloem of the plant host. They are transmitted naturally by two 
psyllid vectors: Diaphorina citri  and Trioza erytreae  (Bove 2006). Trioza  erytreae  vectors 
‘Ca. L. africanus’ naturally and is capable of transmitting ‘ Ca. L. asiaticus’, experimentally at  
least (Gottwald 2010, Bove 2006).  
o ‘Candidatus  Liberibacter africanus’ is not known to be present in any of the countries 
in the IRA  (EPPO 2020). It has been recorded as absent, confirmed by survey  in 
Spain (EPPO 2020);  
o ‘Candidatus  Liberibacter a mericanus ’ is known to be present in one of the IRA 
countries: Brazil (EPPO 2020);  
o ‘Candidatus  liberibacter asiaticus’  is known to be present in several of the IRA 
countries: Brazil , China , Japan , Mexico , USA, Viet Nam  (EPPO 2020). It has been 
recorded as absent, co nfirmed by survey, in Fiji, Cook Islands, Samoa and Spain, 
and absent (invalid record) in Egypt (EPPO 2020).  
• The introduction of T. erytreae to New Zealand is likely to mean the introduction of HLB if 
infected psyllids come from a location where the diseas e is present. On the other hand, if 
T. erytreae arrives in New Zealand in the absence of the disease, then establishment of 
psyllid populations that are capable of vectoring HLB would be of concern should the disease 
be introduced at a later date.  
• In areas  where both the vector and HLB are present, the damage to citrus production can be 
very high (Biosecurity Australia 2011). For example, HLB destroys 10 –15% of tangerine trees 
in Thailand annually (Bove 2006) and in Réunion, an eight year survey conducted i n the 
1980s and 1990s found that 65% of trees were infected and became unproductive within 
seven years of planting (Biosecurity Australia 2011).  
• Both T. erytreae  and HLB affect many Citrus  species and commercial citrus varieties 
including those in the New Zealand citrus industry (see  section 2.5.2 ).  
• The discovery of the presence of T. erytreae  in New Zealand as an incursion or an 
established population is likely to have an immediate impact on exports of citrus to countries 
free from huanglongbing and T. erytreae  where these organisms are quarantine pests. 
Countries and areas that have these organisms as quarantine pests are listed in the EPPO 
Global Database (EPPO 2020) .  
• If T. erytreae were detected in New Zealand, the cost incurred by a response would be high. It 
is likely that a response would be undertaken , given the ability of T. erytreae to vector HLB, 
regardless of the presence of HLB. The typical cost of a response is millions of dollars. For 
example, the Queensland fruit fly response in 2019 cost ap proximately NZ$18 million (MPI 
2020b). 
• Establishment of T. erytreae is likely to increase phytosanitary measures required for export 
of citrus fresh produce to countries where T. erytreae  and HLB are not present  and where 
these organisms are quarantine pes ts. 
• New Zealand’s climate is likely to be more suitable for T. erytreae  than D. citri , which is more 
heat tolerant (Bove 2006 ). Models predict that the climate in the northern North Island (both 
models) and southern North Island (one model) are climaticall y suitable for the establishment  
359 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  of D. citri  (Narouei -Khandan et al. 2016). Therefore, D. citri  is likely to be able to establish in 
warmer areas of northern New Zealand where much of the country’s commercial Citrus  
production takes place; especially in ar eas such as Northland , where it could have a large 
impact on the local economy.  It is likely that T. erytreae  will be able to establish more widely 
in New Zealand than D. citri , potentially affecting directly more of the country’s commercial 
citrus product ion. 
 
It is likely that T. erytreae  will cause a low to moderate level of sociocultural impacts in New Zealand, 
depending on the presence of HLB.  
• Citrus  spp. and Murraya paniculata  are common in domestic gardens in New Zealand, 
especially in the northern regions, although C. limon  is grown in more widely through the 
country. If T. erytreae  became established in New Zealand , it could impact home gardeners 
directly through feeding dam age to host plants that can result in leaf distortion and yellowing 
(CABI 2000).  
• Greater impacts could occur if the liberibacter species that cause HLB were present in New 
Zealand, given the role of T. erytreae  as a vector for HLB. Symptomatic infected cit rus trees 
would have blotchy mottled and yellowing leaves, small , lopsided and bitter -tasting fruit with 
aborted seeds, with branches and eventually whole plants dying after a few years (Grafton 
Cardwell et al. 2018 ; CABI 2000).  
 
It is likely that T. erytreae  will have a very low level of impact on the environment.  
• Citrus  species are members of the Rutaceae family. There are two endemic genera within 
Rutaceae in New Zealand, Melicope  and Leionema (NZPCN 2020). Neither genus is 
considered threatened (NZ PCN 2020) , and they are usually restricted to native forest 
environments. Although neither of these genera are known to be hosts for T. erytreae , heavy 
psyllid infestations can cause leaf distortions and yellowing; however, the main risk 
associated with T. erytreae  is from transmission of the disease HLB , which only affects 
Rutaceae, primarily Citrus  spp. 
 
It is likely that Trioza erytreae  will have negligible impacts on human health.  
• No evidence was found that T. erytreae  has an impact on human health.  
 
Risk assessment summary:  
 
Given the arguments and evidence below  Trioza erytreae may be considered for 
additional measures . 
• Trioza erytreae has a strong association with citrus, but a weak association with citrus fruit.  
• Basic measures  are likely to reduce the of entry of T. ertyreae  on citrus fruit, by a high degree  
(with low uncertainty) . Consequently, the likelihood of entry is considered to be low  (with 
moderate uncertainty) . 
• The ability of T. erytreae  to transfer from imported fruit to suitable host plants is high  (with low 
uncertainty) . 
• The suitability of the New Zealand environment for T. erytreae  to establish is considered high 
(with moderate uncertainty).  
• The level of impact caused by T. erytreae is likely to be low to moderate (with  low uncertainty)  
for New Zealand overall , but moderate to high for the citrus industry  (with low uncertainty) , 
depending on the presence of HLB in New Zealand.  
• T. erytreae is present in the one citrus -exporting country considered in this import risk 
asses sment, Spain.  
 
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algorith m for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  https://www.freshfacts.co.nz/files/freshfacts -2019.pdf  
PPIN (2020) Plant Pest Information Network. MPI internal database.  
van den Berg, M A (1990) The citrus psylla, Trioza erytreae  (Del Guercio) (Hemiptera: Triozidae): A 
review. Agriculture, Ecosystems and Environment , 30: 171 –194. 
van den Berg, M A ; Deacon, V E (1988) Flight activities of the citrus psylla, Trioza erytreae  
(Hemiptera: Triozidae). Phytophylactica , 21: 391 –395. 
Wenninger, E J; Hall, D G; Mankin, R W (2009) Vibrational communication between the sexes in 
Diaphorina citri  (Hemiptera: Psyllidae). Annals of the Entomological Society of America , 102(3): 547 –
555. 
Wenninger, E J; Stelinski, L L; Hall, D G (2008) Behavioral evidence for a female -produced sex 
attractant in Diaphorina citri. Entomologia Experimentalis et Applicata , 128: 450 –459. 
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 362 11. Insects:  Lepidoptera (moths, butterflies)  
 
11.1 Gymnandrosoma aurantianum  (citrus fruit borer)  
Gymnandrosoma aurantianum , the citrus fruit borer, is a polyphagous  moth native to  tropical South 
America, which has spread to Central America and the Caribbean islands . Formerly a minor pest, it 
became a major pest of citrus due to the indiscriminate use of chemical pesticides (Parra et al. 2004). 
Internal feeding by larvae causes fruit  to rot and drop prematurely and, thus, become unmarketable. 
Other affected crops include macadamia, avocado, peach, banana and lychee (CABI 2020).  
 
Scientific name: Gymnandrosoma aurantianum Lima, 1927  
Order/Family: Lepidoptera/Tortricidae  
Other names: Ecdytolopha aurantiana, E. aurantianum, E. torticornis, Tortrix citriana , macadamia nut 
borer (CABI 2020 ) 
 
Notes on taxonomy : Gymnandrosoma aurantianum  was first identified and reported in 1915  by 
Gregorio Bondar as Tortrix citriana  Fernald . In 1927, the species  was redescribed and relocated 
taxonomically as Gym nandrosoma aurantianum  (Lima), but was transferred  again,  in 1995, to the 
genus Ecdytolopha  as Ecdytolopha aurantiana  Adamski & Brown (2001) . Following a  taxonomic 
revision of the genera Ecdytolopha  (Zeller), Gymnandrosoma  (Dyar) and Pseudogalleria  (Ragonot) of 
America , it was concluded that the species aurantianum  (Lima 1927) belonged to the genus 
Gymnandrosoma , not to the genus Ecdytolopha  (see Noboa et al. 2018 for all taxonomic references 
used in  this section).  
 
Summary of c onclusion s 
 
Given the arguments and evidence presented : 
• Gymnandrosoma aurantianum  meets the criteria to be a quarantine pest for New Zealand.  
• G. aurantianum  has a strong association with citrus fruits  with low uncertainty . 
• The pest is present in a range of countries , including Brazil, Peru (and Mexico , where its 
current status is uncertain ). These are among the countries being considered in the current 
citrus fresh produce import risk analysis.  
• Basic measures  will reduce the  likelihood of entry of G. aurantianum  on citrus fruit by a high 
degree (with moderate uncertainty) . Consequently, the likelihood of entry is low  with low 
uncertainty . 
• The ability of G. aurantianum  to transfer from imported fruit onto a suitable host plant to 
enable establishment is low (with moderate uncertainty).  
• The suitability of the New Zealand environment (especially the citrus -growing areas) for the 
establishment of G. aurantianum  is rated  moderate  to high (with moderate uncertainty).  
• Gymnandrosoma aurantianum is likely to cause moderate impacts in New Zealand  (with 
moderate uncertainty).  
• Gymnandrosoma  aurantianum  may be considered for additional measures on citrus fruit . 
 
Summary of risk assessment against criteria  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from the imported commodity  onto a suitable host  Low Moderate  
Suitability of the N ew Zealand  environment  Moderate –high Moderate  
Impacts on the New Zealand economy, environment, health and society  Moderate  Moderate   
363 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  11.1.1  Hazard  identification: quarantine status  
Given the arguments and evidence below,  Gymnandrosoma aurantianum  meets the 
criteria to be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are : not present in New Zealand, and 
of potential importance (able to esta blish and cause harm).  
 
There are no records of G. aurantianum  from New Zealand .  
• The pest is not recorded in PPIN (2020), NZOR (2020) or NZ Inverts  (2020).  
• It is a regulated pest for New Zealand; ‘regulated’ as Ecdytolopha  aurantiana in ONZPR  
(2020).  
 
Gymnandrosoma aurantianum has the potential to establish in New Zealand . 
• The geographical distribution of the pest is mostly within the New World tropics , but it occurs 
in some areas  with a subtropical climate , e.g. S ão Paulo in Brazil and Tucuman in Argen tina 
(CABI 2020) . 
• Currently, it is widely distributed in South America:  Argentina, Brazil  (Minas Gerais, São 
Paulo, Santa Catarina, Rio Grande do Sul), Colombia, Ecuador, Peru and Venezuela; Central 
America : Costa Rica and Nicaragua; and in some Caribbean islands : Dominican Republic, 
Haiti, Puerto Rico, and Trinidad and Tobago (C ABI 2020; EPPO 2020) . 
• When compared with New Zealand, sub -tropical /temperate  areas in Brazil where the pest 
occurs  (São Paulo, Santa Catarina and Rio Grande do Sul) have climate  match index (CMI) 
values of 0.7, 0.8 –0.9 and 0.8 –0.9 respectively . These values indicate a 70 –90% climate 
match, which suggests that the New Zealand climate would be suitable for establishment of 
the pest (Phillips et al. 2018) , even though CMI values for the  Caribbean and Central 
American countries where the pest occurs, which range from 0.4 –0.6, suggest otherwise.  
 
Gymnandrosoma  aurantianum has the potential to cause impacts in New Zealand . 
• In Brazil, G. aurantianum  is considered to be one of the most important pests of citrus , as 
infesting larvae render the fruit uns uitab le for both fresh consumption and industrial 
processing  (Parra et al. 2004).  
• It emerged as one of  the main citrus pests in Brazil in the 1990s, and depending on the 
degree of infestati on, yield losses  ranged from 5–50% (Parra et al . 2004 ; Fundecitrus 20 07). 
• The pest causes economic damage to citrus i n regions of Brazil (São Paulo, Santa Catarina 
and Rio Grande do Sul ) that have a similar climate (CMI values of 0.7 –0.9) to New Zealand, 
especially warmer northern areas (Phillips et al. 2018) , where most commercial citrus 
production takes place .  
• Gymnandrosoma aurantianum damage to citrus in the State of São Paulo , which produces 
most of Brazil’s export citrus (Passos et al. 2018) , was esti mated at US$50 million per year 
during the 1990s  (CABI 2020; Garcia 1998 in Parra et al. 2004).  
• The pest is known to attack other economically important hosts, such as avocado ( Persea 
americana ), peach ( Prunus persica ) and macadamia ( Macadamia  spp.)  (CABI 2020), which 
are grown in the warmer northern regions of New Zealand ( Plant & Food Research  2019).  
 
11.1.2  Hazard identification: commodity association  
Given the arguments and evidence below,  Gymnandrosoma aurantianum  is 
associated with citrus fruit and is recor ded in countries under consideration for export 
of citrus fresh produce to New Zealand . 
• Gymnandrosoma  aurantianum was first described in 1915 causing damage to citrus trees in 
the state of São Paulo , Brazil (CABI 2020; EPPO 2017).   
• The pest has been found infesting mandarin  (Citrus reticulata ) (Noboa et al. 2018).  
• Citrus species on the EPPO (2020) host list for  G. aurantianum  include mandarin  
(C. reticulata ), orange  (Citrus sinensis ) and grapefruit  (Citrus paradisi ).  
• The NPPO  of Spain  has intercepted the pest on several occasions, in consignments of 
oranges ( C. sinensis ) imported from Brazil  (EPPO 2017) . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 364 • The pest is recorded in a number of countries, including three being considered in the citrus 
fresh produce import risk analysis for New Zealand (Brazil, Peru and Mexico) (Adamski and 
Brown 2011 , in CABI 2020; GBIF 2020).  
• Note that although the presence of the pest in Mexico is validated by identifications of 
specimens collected from Colima state in 1923 –1924 (Adamski and Brown 2011 , in CA BI 
2020), its current status in Mexico is uncertain, due to the absence of recent records.  
 
11.1.3  Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below,  Gymnandrosoma aurantianum  has a 
strong association with citrus fruit , with low uncertainty.  
There are  reliable records of G. aurantianum  on citrus fruit:  
• The earliest record of G. aurantianum  is when it was first identified in 1915 , as a pest of c itrus 
trees in the state of São Paulo , Brazil (EPPO 2020).   
• Each a dult female G. aurantianum  lays a single egg on the surface of citrus fruit , and first -
instar larvae burrow into the fruit within two to seven hours of emerging from the egg (Parra et 
al. 2001).  
• The pest has been found infesting mandarin  (C. reticulata ) fruit in Ecuador (Noboa et al. 
2018).  
• The named citrus hosts of the pest include orange  (C. sinensis ), tangerines/mandarins 
(C. reticulata ), lemon  (C. limon ), lime ( C. aurantiifolia ) and pomelo ( C. paradisi ), but all types 
of citrus are considered likely to be susceptible hosts  (EPPO 2020; CABI 2020).  
• The pest has been intercepted on several occasions at the border of Spain on oranges 
(C. sinensis ) imported from Brazil  (EPPO 2017).  
 
Given the arguments and evidence below, basic measures are likely to reduce the 
likelihood of entry of G. aurantianum  on citrus fruit by a high degree  (with moderate 
uncertainty) . Consequently, the likelihood of entry is low, with low uncertainty.  
Internally feeding larvae of G. aurantianum  cause externally visible signs of infest ation, although early 
infestations may not be detected:  
• On mature fruit, the larval penetration hole is evident, and as the larva feeds within the fruit, it 
throws out frass (excrement and food scraps) that hardens on the skin of the fruit around the 
entry  hole (Fundecitrus 2007; Parra et al. 2004).  
• In addition, infested fruits often turn bright yellow prematurely ( distinct from healthy fruit ) and 
fall off the tree before they can be picked (Parra et al. 2004); such fruit would not meet basic 
measures  and a re likely to be culled and excluded from consignments meant for export.  
• Signs of infestation may, however, not be as obvious on mature fruit picked shortly after 
becoming infested, and interception of the pest (not stated if alive or dead) on fresh oranges  
from Brazil at the border of Spain (EPPO 2018) may be an indication that some infestations 
escape detection during post -harvest processes and pre -export inspections.  
• In green/immature fruit, which are attacked almost at the same rate as mature fruit when pest 
population levels are high, larval development takes longer (Parra et al. 2001) , and as such, 
visible signs of infestation may also take longer to develop on such fruit.  
• The length of time it takes for external signs of infestation to become obvious on fruit is 
uncertain, but this will depend on larval feeding and development rates.  
• Note that eggs, which are 1–1.3 mm long and laid singly on the surface of fruit (Blanco -
Metzler 1994), may be difficult to detect, but they could be dislodged from fruit or damaged by 
post-harvest measures such as washing, cleaning and waxing. Therefore, it is unlikely (but 
possible) that viable eggs would remain associated with exported fruit.  
 
Larvae may not survive transit conditions and duration on fruit shipped from South America:  
• Cold storage of fruit has been shown to effectively reduce the viability of pupae or larvae in 
fruit that is in transi t (CABI 2020), and r ecommended storage and s hipping temperature  
365 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  ranges for orange ( C. sinensis ), which is a major host of G. aurantianum , are within the range 
0 to 8°C depending on the variety/cultivar/origin (BMT 2020).  
• Given that transit times are 58 and 65 days respectively from the Santos and Ri o Grande 
ports in Brazil to the Tauranga port, 61 days from the Paita port  in Peru to the Auckland port 
and 42 days from the Mazatlán port  in Mexico to the Tauranga port  in New Zealand (MSC 
Cargo 2020), larvae of G. auranti anum may not be alive/viable when  infested oranges arrive 
in New Zealand.  
• However, lack of data on how long the larvae of G. aurantianum  can survive at low 
temperatures, and what those exact low temperatures are, creates some uncertainty as to 
whether or not larvae would be viable on arri val. There is also some uncertainty around transit 
times, which may be shorter if the ships are chartered and if routes are direct, with no trans -
shipment.  
• Some citrus commodities, e.g. grapefruit, lime and lemon, which are also hosts of 
G. aurantianum , are normally shipped at between 10 °C and 14 °C because they are damaged 
by lower temperatures (BMT 2020). Hence, larvae of G. aurantianum,  which have an 
estimated lower development threshold of 9.8 °C (Garcia 1998 in Parra et al. 2004), could 
survive  transit  on such commodities; these three commodities are among those for which 
Brazil and Peru are requesting market access to New Zealand.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of G. aurantianum to transfer 
from imported fruit onto a host plant to allow establishme nt (exposure), is rated as 
low (with moderate uncertainty).  
The pest needs to complete development to the adult stage for transfer to occur:  
• Immature stages of G. aurantianum are non -disper sing and only adults can transfer to host 
plants (Blanco -Metzler 1994; CABI 2020).  
 
Infested fruits that arrive in New Zealand are likely to contain mostly young larvae:  
• Fruit containing older larvae usually have detectable signs of infestation (Fundecitr us 2007; 
Parra et al. 2004), and thus, are likely to have been detected and culled prior to export.  
• Young larvae are unlikely to develop during transit in fruits (especially oranges) stored and 
shipped at temperatures below the estimated lower development threshold of G. aurantianum  
larvae, which is 9.8 °C (Garcia 1998 in Parra et al. 2004).  
• However, it is uncertain whether low in -transit temperatures would kill the larvae or simply 
prevent them from developing.  
• Some development may occur in larvae infesting grapefruit, lemons and limes, which are 
usually shipped at temperatures between 10 °C and 14 °C (BMT 2020).  
 
Young larvae may be able to complete development in infested fruit disposed of in open environments 
in warmer parts of New Zealand:  
• In a la boratory study conducted at 27 °C, G. aurantianum  completed its four stages of larval 
development on two varieties ( Natal  and Pera ) of orange ( C. sinensis ) in 18 and 22 days 
respectively, while the pupal stage took about 10 days (Garcia 1998 in Parra et al.  2004).  
• At constant temperatures of 18 °C, 20°C and 22 °C respectively, mean duration of larval 
development on an artificial diet was 30.6, 30.3 and 25.9 days, while mean duration of the 
entire life cycle at those temperatures was 61.8, 56.5 and 50.2 days re spectively (Garcia 
1998 in Parra et al. 2004).  
• In most of the upper North Island (where hosts are also more available), average summer 
temperatures  are between 18°C and 2 1°C (NIWA 2020) . In these areas, larval development 
of G. aurantianum in discarded imported fruit could be completed in 26 –30 days (or slightly 
less, since larvae may have undergone some development in the fruit before it was exported 
and since the  temperature in the field will not be constant).  
• It is likely that fruit may decay before c ompletion of larval development, since the  postharvest 
life of citrus fruit, especially if it has  been stored for several months or shipped for long 
distances  at low temperatures, is severely reduced by saprophytic and pathogenic fungi  
(Strano et al. 2017) . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 366 • Another estimated 18 –20 days may be required for pupal development and adult emergence, 
as mean duration of pupal development took 17.2, 18 and 20 days respectively, at 18 °C, 
20°C and 22 °C (Garcia 1998 in Parra et al. 2004).  
• Larvae in fruit arriving New Zealand at cooler times of the year are unlikely to complete 
development.  
 
Adults of both sexes may need to emerge close to fruiting host plants for transfer to be completed : 
• Gymnandrosoma aurantianum  has separate male and female sexes  (Blanco -Metzler 1994 ), 
and in Brazil,  adults of the pest mostly mate on the third and fourth nights after emergence , 
between  6:00 p.m. and 9:00 p.m., in the upper crown of citrus trees  (Bento et al.  2001 ). 
• As females usually lay a single egg per fruit, several infested fruit may need to be dis carded 
close to each other for both sexes to co -occur, leading to mating. However, females produce 
a sex pheromone, which facilitates  the long-distance attraction of males (Bento et al. 2001), 
although the exact distance or radius of attr action is not stated.  
• After mating, most adult movement has been observed to occur within the same host tree, 
although some moths flew to adjacent trees (Bento et al. 2001).  
• Therefore, transfer is more likely if several infested fruits are discarded near  orchards of citrus 
and other host plants, or within home gardens with fruiting citrus trees, so that mating can 
occur and newly emerged mated adult females can find suitable oviposition sites.  
• Although the pest is often cited as having poor flight ability  (Blanco -Metzler 1994; CABI 2020; 
EPPO 2020), its exact flight range or dispersal rate is not reported, which creates uncertainty 
around the argument about successful transfer of adults to suitable hosts.  
 
Uncertainty:  
There is moderate uncertainty around the conclusion on the ability of the pest to transfer:  
• The time required to complete larval development on discarded fruit and pupal development 
in the soil in New Zealand are estimates, based on data from laboratory experiments at 
constant temperatures an d using an artificial diet.  
• Infested fruit may or may not be dis carded near suitable hosts, and there are no up -to-date 
data on composting of food waste in New Zealand . In particular, the proportion of fruit waste 
that is composted in home gardens or in op en areas where suitable hosts may be available is 
unknown.  
 
 
Given the arguments and evidence below,  the suitability of the environment of the 
North Island and upper South Island of New Zealand for the establishment of G. 
aurantianum is moderate  to high ( with moderate uncertainty), but most of the colder 
South Island is unlikely to be suitable.  
 
The current geographical distribution of G. aurantianum  is mainly tropical, but some locations where it 
occurs have a subtropical climate similar to parts of northern New Zealand:  
• Gymnandrosoma  aurantianum  is widely distributed in South America : Argentina ( Tucumán 
and Entre Ríos ), Brazil  (Minas Gerais, São Pau lo, Santa Catarina), Colombia, Ecuador, Peru , 
and Venezuela; Central America : Costa Rica and Nicaragua; and in some Caribbean islands : 
Dominican Republic, Haiti, Puerto Rico, and Trinidad and Tobago.  
• The climate match index (CMI) for  the climate of the sta te of São Paolo (Brazil), where G. 
aurantianum is a major citrus pest, is 0.8 when compared to the Northland and Auckland 
regions (Phillips et al. 2018).  
• Analysis of 50 location records for the pest in the Global Biodiversity Information Facility  
(GBIF 202 0) shows that there is considerable temperature overlap between New Zealand’s 
citrus -growing areas and equatorial mid -altitude and subtropical locations, particularly coastal 
subtropical areas (Halloy 2020).  
• The pest is capable of surviving and reproducing  at temperatures ranging from 18 –32°C, with 
optimum survival and development occurring between 25 –29°C. 
• The lower development threshold estimated, by linear regression, is 9.81 °C, with an 
estimated 579.05 degree days required for the completion of the life  cycle from egg to adult 
(Garcia 1998 in Parra et al. 2004).   
367 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Based on the above, the pest is likely to be able to establish and could potentially complete 
2–4 generations each year in the main citrus -growing areas of New Zealand’s North Island 
(see Table 12.1.1 below, which compares climatic variables for locations  where the pest 
occurs in Brazil and Argentina, with citrus -producing areas of New Zealand).  
• Compared to the Brazil sites, temperatures in the Argentina locations are more similar to 
those in New Zealand’s citrus -growing areas (Table 1 2.1.1 ) and if data on the number of 
generations completed by the pest in the Argentina sites were available, they would provide 
more reliable estimates for New Zealand.  
• More uncertainty is created by the absence of da ta on the lowest temperatures that the pest 
can tolerate, and since it is not known to diapause, there is some uncertainty as to whether or 
not the pest would survive winter temperatures, which occasionally drop to 0 °C in some parts 
of the main citrus -growing areas of New Zealand (NIWA 2020).  
 
Table 12.1. 1. Locations in São Paulo, Brazil, with climate and number of annual generations completed 
by G. aurantianum  on citrus, and two locations in Argentina where the pest has been recorded, 
compared with th e main citrus production regions in New Zealand.  
Location  Köppen -Geiger  
climate classification * Mean annual 
temperature 
(°C) Mean 
temperature 
of coldest 
month (°C)  Annual 
rainfall 
(mm)  G. aurantianum  
generations/year  
São Paulo, Brazil       
Barretos  Aw (tropical savanna ) 22.8 19 1,309 8.3 
Sao Jose do Rio Preto  Aw (tropical  savanna ) 22.8 19.4 1,268 8.2 
Bebedouro  Aw (tropical  savanna ) 22.3 19 1,337 7.3 
Limeria  Cwa (temperate , hot summer ) 20.5 16 1,284 7.2 
Araraquara  Cwa (temperate , hot summer ) 20.4 16 1,352 7.1 
Argentina       
Entre Ríos  Cfa (humid subtropical)  17.7 11.4 989 No data  
Tucumán  Cfa (humid subtropical)  19.4 12.7 997 No data  
Main citrus -growing regions of New Zealand     
Northland  Cfb (temperate , warm summer ) 15.6 11.7 1,658 3.0–3.6 
Auckland  Cfb (temperate , warm summer ) 15.2 10.6 1,284 2.9–3.8 
Bay of Plenty  Cfb (temperate , warm summer ) 14.4 9.6 1,426 2.1–3.2 
Gisborne  Cfb (temperate , warm summer ) 14.2 9.4 1,071 2.7–3.1 
 
* For further detail, see, e.g. Beck et al. (2018) ( https://www.nature.com/articles/sdata2018214 ). The Köppen -Geiger climate classification  is based on five 
major climate types: A, C, D & E are defined by temperature  (A the warmest, E the coldest) , B by dryness.  The major climate types are divided into 
subtypes with an additional ore or two letters : w = dry winter, a = hot summer, f = without dry season, b = warm summer.  
Climate information from Climate -Data.org ( https://en.climate -data.org/ ), accessed 23  September 2020.  
Data on number of annual generations of G. aurantium  in Brazil locations obtained from Garcia (1998) in Parra et al. (2004) . 
Degree -day (10°C) data for New Zealand citrus -growing regions obtained from NIWA https://niwa.co.nz/our -science/climate/publications/regional -
climatologies , accessed 23  September 2020 . 
The number of G. aurantianum generations i n New Zealand regions are estimates based on estimated lower development threshold (9.8°C) and thermal 
requirement of 579.05 degree days for completion of one generation from Garcia (1998) , cited in Parra et al. (2004).  
The l ocations in Argentina where occ urrence of the pest is reported have a more similar temperature to New Zealand’s major citrus -growing area than the 
Brazil sites. However, no data was found on the number of annual generations completed by the pest in the Argentina locations .  
 
 
Citrus  and other host species of G. aurantianum are widely available in the northern regions of 
New Zealand ’s North Island . 
• All citrus species are likely to be hosts of G. aurantianum . The main citrus -producing areas of 
New Zealand, in terms of area planted and weight of produce , are in the North Island : 
Gisborn e (56% of production), Northland (34%), Auckl and (9%) and Bay of Plenty (1%) 
(Citrus NZ 2020).  
• Other hosts of the pest (peach ( Prunus  persica ), avocado ( Persea americana ), macadamia 
(Macadamia integrifolia ) and banana ( Musa  spp.) ) are also grown in the warmer parts of the 
North Island ( Plant & Food Research  2019) and in the case of peach, down to Otago and 
Southland, where the colder climate may, however, be a limitation to establishment.  
• Citrus plants, esp ecially lemons, are also commonly grown in home gardens throughout New 
Zealand.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 368 Therefore, host availability is unlikely to be a barrier to establishment of G. aurantianum , especially in 
the North Island.  
 
 
Impacts  in New Zealand  
 
Given the arguments and evidence below,  Gymnandrosoma aurantianum  is likely to 
cause moderate impacts in New Zealand, with moderate uncertainty . 
 
Gymnandrosoma aurantianum  causes economic impacts in citrus hosts . 
• Citrus  species, especially oranges ( C. sinensis ), are the main host s of G. aurantianum , and 
once  infested, fruit is rendered unsuitable for consumption as fresh produce or for processing 
(Fundecitrus 2007; Parra et al. 2004).  
• The pest prefers to attack mature fruit, but at high populations, immature (green) fruit is also 
attacked , even though larval development is slower and mortality is high (29 –50%) due to the 
high acidity of such fruit (Parra et al. 2001).  
• In citrus orchards in São Paulo , Brazil, the moth can complete seven to eight annual 
generations, and with ea ch female laying approximately 200 eggs, fruit losses  can range from 
5–50% depending on citrus varieties (Fundecitrus 2007; Garcia 1998 in Parra et al. 2004).  
• However, the development and application of synthetic pheromone trapping (1 trap/10 
hectares)  have significantly reduced fruit losses  caused by G. aurantianum  in São Paulo  and 
south Minas Gerais  (Brazil) to an average of 0.6–1 fruit/plant  (Bento et al. 2001; Carvalho 
2003 in Parra et al. 2004), compared with 1 to 2 boxes (around 350 fruits /plant) with out this 
strategy ( references cited in Parra et al. 2004) . 
• According to Parra et al. , in 2004 , the pheromone trap, including a tablet containing synthetic 
pheromone, cost about US$7. Therefore, the cost per hectare was 70 cents, c onsidering that 
a trap covers a citrus area of 10  ha. Trapping also led to about 50% reduction in the use of 
chemical pesticides against the pest (Parra et al. 2004) . 
• Temperatures in New Zealand’s main citrus production areas are lower than in Brazil, and 
hence, the pest is like ly to complete fewer annual generations (see the section on 
establishment above and Table 12.1. 1) and cause lower  impacts in New Zealand, compared 
to areas of Brazil with a similar but warmer climate.  
• No data were found on the number of generations and dam age caused by G. aurantianum  to 
citrus in areas of Argentina that have even more similar climate to citrus -growing areas of 
New Zealand . The reason(s) for the absence of such data is unclear, but it could  be that 
impacts caused in Argentina are much lower than in Brazil, and as such, impacts in New 
Zealand may be even lower, although this is uncertain.  
 
Gymnandrosoma aurantium may cause low economic impacts in non -citrus hosts . 
• Although G. aurantianum  is polyphagous and attacks plant species in multiple fam ilies (CABI 
2020), most of its non -citrus hosts are tropical species that are either not present in New 
Zealand, or limited to very small areas, and therefore of little importance to New Zealand’s 
economy.  
• Of the non -citrus hosts of the pest grown in the N orth Island, avocados, with an export value 
of NZ$104.3 million, have the highest economic value to New Zealand ( Plant & Food 
Research  2019). Other less -valued minor hosts are peach and macadamia.  
• However, the pest prefers Citrus species, especially orange s (C. sinensis ) and , to a lesser 
extent, mandarins and other citrus varieties (CABI 2020; Parra et al. 2004). Thus, non -citrus 
hosts in New Zealand are less likely to be attacked if citrus hosts are available.  
 
The pest is likely to spread, but its distribution is likely to be limited to the upper North Island . 
• The pest can spread within and between nearby orchards, but the rate of spread is likely to be 
slow, because the pest is known to undertake only short flights  (Bento et al. 2001; Blanco -
Metzle r 1994). However, there is some uncertainty , as its actual flight range is not known.  
• If long -distance spread is to occur (to citrus orchards and other hosts), it is likely to be via the 
distribution of infested fruit, as the pest is not known to be migrat ory (Blanco -Metzler 1994; 
CABI 2020; Parra et al. 2004).   
369 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Spread may also be limited to orcharding areas and home gardens in New Zealand’s North 
Island (and possibly Nelson in the upper South Island), as cooler temperatures in most of the 
South Island are u nlikely to support long -term establishment of the pest.  
 
The pest is likely to have a low impact on access  to export markets for host commodities . 
• The main New Zealand exports likely to be affected are avocado and citrus fruit exports, 
which are mainly to Australia and countries in Asia (Japan and Korea) ( Plant & Food 
Research  2019), where the pest is not present (CABI 2020; EPPO 2017).  
• In 2019, the export value for New Zealand of fresh avocado and citrus (orange, mandarin and 
tangelo) were NZ$ 104.3  million  and $2.2 million  respectively ( Plant & Food Research  2019).  
• However, G. aurantianum  is not listed as a quarantine pest for Australia or any of the 
countries that are export destinations for host commodities from New Zealand . It is on the 
EPPO alert list , and it is a quarantine pest for Morocco and Chile (EPPO 2020).  
• Also, as natural dispersal of the pest is likely to occur slowly and since an effective and 
relatively cheap (US $0.70/ha) pheromone lure is available (Parra et al. 2004), eradication 
may be po ssible, but would incur added costs.  
• The cost of eradication is highly uncertain, as the pest has not established , and therefore has 
not needed to be eradicated outside the neotropics.  
 
Gymnandrosoma aurantianum  may cause environmental impacts, but these are likely to be negligible, 
with low uncertainty . 
• In its native range and most of South America, G. aurantianum occurs in native forests, 
orchards and urban landscapes, usually below 500 -m elevation , with primary hosts being in 
the Rutaceae and Sapindaceae  plant families (CABI 2020) . 
• New Zealand has three endemic species in the Rutaceae: Leionema nudum  (in the northern 
half of North Island), Melicope simplex  and Melicope  ternata  (in lowland areas of both the 
North and South Island) (NZPCN 2020).  
• Indigenous Sapindaceae include Dodonaea viscosa  (lowland forest in the North, South and 
Chatham Islands), Alectryon excelsus  subsp. grandis  (endemic; Three Kings Islands) and 
Alectryon excelsus  subsp. excelsus  (endemic; North and South Islands from Te Pak i to Banks 
Peninsula  (NZPCN 2020) . 
• None of the above native species is considered threatened (de Lange et al. 2018; NZPCN 
2020).  
 
Gymnandrosoma aurantianum  may cause  some social  impacts, but it is unlikely to cause any health 
impacts . 
• The pest may establis h on citrus plants in private gardens.  
• Surveillance and eradication activities may have social impacts, due to the likely restrictions 
placed on the movement of host commodities, and the potential need to access and spray 
chemical pesticides on private properties.  
• Gymnandrosoma aurantianum  is a plant pest and has not been reported to affect human or 
animal health.  
 
11.1.4  References  
Bento , J M S; Parra , J R P; Vilela , E F; Walder , J M; Leal, W S (2001) Sexual behaviour and diel 
activity of citrus fruit borer Ecdytolopha aurantiana . Journal of Chemical Ecology , 27(10) : 2053 –2065.  
Blanco -Metzler, H (1994)  Biology and ecology of the macadamia nut borer Ecdytolopha torticornis  in 
Costa Rica . PhD Thesis. University of Edinburgh ; Edinburgh, UK ; 131 pages. 
https://era.ed.ac.uk/handle/1842/15091  Accessed 18 September 2020.  
BMT (2020) Oranges. Cargo Handbook . https://cargohandbook.com/Oranges  Accessed 22 
September 2020.  
BRAD (2020) Biosecurity Risk Analysis Database. Ministry for Primary Industries internal database. 
Accessed 7 September 2020.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 370 CABI (2020) Gymnandrosoma aurantianum  (citrus fruit borer) . Invasive Species Compendium . CAB 
International; Wallingford, UK.  https://www.cabi.org/isc/datasheet/20360#a1c28f1e -86d4 -4eb3 -a64d -
9c9896ba2aab  Accessed 24 September 2020.  
Citrus New Zealand (2020) https://www.citrus.co.nz/faq/how -big-is-the-citrus -industry -in-new-zealand/  
Accessed 24 September 2020.  
Climate -Data.org https://en.climate -data.org/oceania/new -zealand -9/ Accessed 23 September 2020.  
De Lange et al. (2018) Conservation status of NZ indigenous vascular plants 2017. 
https://www.nzpcn.org.nz/site/assets/files/0/13/654/nztcs_vascular_plants_2017.pdf   
EPPO (2017) Gymnandrosoma aurantianum : addition to the EPPO Alert List . EPPO Reporting 
Service  03–201 (2017/057).  https://gd.eppo.int/reporting/article -6025  Accessed 17 September 2020.  
EPPO (2020) EPPO Global database – Gymnandrosoma aurantianum . 
https://gd.eppo. int/taxon/ECDYAU/  Accessed 24 September 2020.  
EPPO (2020) Gymnandrosoma aurantianum  EPPO Global Database. 
https://gd.eppo.int/taxon/ECDYAU  Accessed 23 September 2020.  
Fundecitrus (2007) Manual Técnico do Bic ho Furão . Fundecitrus (Fundo de Defesa da Citricultura) ; 
Araraquara, Brazil . http://www.citrusbr.com/manuaistecnicos/fundecitrus_bichofurao.pdf  Accessed 21  
September 2020.  
GBIF (2020) Occurrence records for Gymnandrosoma aurantianum . 
https://www.gbif.org/occurrence/search?taxon_key=9897370  Accessed 23  September 2020.  
Halloy, S (2020) Climate suitabilit y for New Zealand , of Gymnandrosoma aurantianum , citrus fruit 
borer . Ministry for Primary Industries (MPI) Internal technical advice document . 
MSC Cargo (2020) Mediterranean Shipping Company shipping schedules 
https://www.msc.com/search -schedules  Accessed 22 September 2020.  
NIWA (2020) New Zealand Regional Climatologies https://niwa.co.nz/our -
science/climate/publica tions/regional -climatologies  Accessed 24 September 2020.  
Noboa, M; Medina, L.; Viera, W (2018) First report of Gymnandrosoma aurantianum  (Lepidoptera: 
Tortricidae) in mandarin (Citrus reticulata) in the inter -Andean valleys of Ecuador. Florida 
Entomologist , 101(4): 699 –701. 
NZInverts (2020) New Zealand Land Invertebrates https://nzinverts.landcareresearch.co.nz/  
Accessed 20 July 2020.  
NZOR (2020) New Zealand Organisms Register http://www.nzor.org.nz/  Accessed 7 September 
2020.  
NZPCN (2020) New Zealand Plant Conservation Network https://www.nzpcn.org.nz/flora/species/  
Accessed 24 Septemb er 2020.  
ONZPR (2020) Official New Zealand Pest Register. MPI public database. 
https://pierpestregister.mpi.govt.nz/  
Parra, J R P; Bento, J M S; Garcia, M S; Yamamoto, P T; Vilela, E F; Leal, W S (2004)  Development 
of a control alternative for the citrus fruit borer, Ecdytolopha aurantiana  (Lepidoptera, Tortricidae): 
from basic research to the grower. Revista Brasileira de Entomologia , 48(4): 561 –567.   
371 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Parra, J R P; Kasten Júnior, P; Molina, R M da S; Ha ddad, M de L (2001) Effect of pH on the 
development of the citrus fruit borer (Efeito do pH no desenvolvimento do bicho -furão). Laranja , 22(2): 
321–332. 
Passos, O S; Souza, J da S; Bastos, D C; Girardi, E A; Gurgel, F de L; Bastos Garcia, M V; de 
Oliveira,  R P; Soares Filho, W dos S (2018) Citrus industry in Brazil with emphasis on tropical areas. 
In Sajid , M; Amanullah  (eds) Citrus – Health Benefits and Production Technology . 
https://www.intechopen.com/books/citrus -health -benefits -and-production -technology/citrus -industry -
in-brazil -with-emphasis -on-tropical -areas  Accessed 9 September 2020.  
Phillips, C  B; Kean, J M ; Vink, C J ; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’  
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3) : 777–791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) Fresh Facts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ.  https://www.freshfacts.co.nz/files/freshfacts -2019.pdf  
Accessed 24 September 2020.  
PPIN (2020) Plant Pest Information Network. MPI internal database. Accessed 7 September 2020.  
Strano, M C; Altieri,  G; Admane,  N; Genovese , F; Di Renzo , C G  (2017) Advance in citrus postharvest 
management: Diseases, cold storage and quality evaluation . In Harsimran G; Garg, H (eds) Citrus 
Pathology . https://www.intechopen.com/books/citrus -pathology/advance -in-citrus -postharvest -
management -diseases -cold-storage -and-quality -evaluation  Accessed 8 September 2020.  
Blanco -Metzler, H (1994)  Biology and ecology of the macadamia nut borer Ecdytolopha torticornis  in 
Costa Rica . PhD Thesis. University of Edinburgh ; Edinburgh, UK ; 131 pages.  
https://era.ed.ac.uk/handle/1842/15091  Accessed 18  September 2020.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 372 11.2 Marmara gulosa  (citrus peelminer ) 
The citrus peelminer  is a 4-mm-long, dark -grey moth  with mottled white and brown markings  (Guillén 
et al. 2001). Females lay eggs on citrus fruit, and larvae cause cosmetic damage by mining just under 
the peel, forming serpentine mines that render fruit unacceptable for the fresh market (Gibson et al. 
1997). The pest causes economic damage to commercial citrus fruit in California, Arizona, Northern 
Mexico and Cuba (Jones 2001).  
 
Scientific name: Marmara gul osa Guillèn and Davis  2001  
Order/Family: Lepidoptera/ Gracillariidae  
Other names:  none  
 
Note on taxonomy : In California and Arizona, this pest was originally thought to be Marmara  
salictella , but was later described as Marmara gulosa . Earlier publications i n which M. salictella  was 
recorded as a pest of citrus probably refer to Marmara gulosa  (Gracilliridae.net  2016).   
 
Summary of c onclusion s 
 
Given the arguments and evidence presented : 
 
• Marmara  gulosa  meets the criteria to be a quarantine pest for New Zealand . 
• Marmara gulosa  has a strong association with citrus fruit , with low uncertainty . 
• Basic measures  reduce the likelihood of introduction of M. gulosa  on citrus fruit  by a high 
degree , with low uncer tainty; therefore, the likelihood of entry is rated low . 
• The ability of M. gulosa  to transfer from imported fruit to suitable host plants is low, with 
moderate uncertainty . 
• The suitability of the New Zealand environment for the establishment of M. gulosa  is 
moderate,  with moderate uncertainty.  
• Marmara  gulosa is likely to cause moderate impacts in New Zealand, with moderate 
uncertainty; there may be sporadic high  impacts (with moderate uncertainty) in years when 
average summer temperatures in the main citrus -growing areas exceed 26°C, allowing  the 
pest to complete more generations and rapidly build up populations.  
• Marmara  gulosa  may be considered for  additional measures on citrus fruit . 
 
Summary of risk assessment against criteria  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from the imported commodity  onto a suitable host  Low Moderate  
Suitability of the N ew Zealand  environment  Moderate  Moderate  
Impacts on the New Zealand economy, environment, health and society  Moderate  Moderate  
 
11.2.1  Hazard  identification: quarantine status  
Given the arguments and evidence below,  Marmara gulosa  meets the criteria to be a 
quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause harm).  
 
There are no records of M. gul osa from New Zealand . 
• The pest is not recorded in PPIN (2020), NZOR (2020) or NZ Inverts  (2020).  
• It is not a regulated pest for New Zealand; it is not recorded in ONZPR  (2020) or BRAD 
(2020).   
373 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Marmara gulosa  has the potential to establish  in New Zealand . 
• The pest  is native to the southwestern US A (California, Arizona and Texas) and has been 
reported in the southeastern US state of Florida, northern Mexico and Cuba  (Guillén et al. 
2001).   
• Climate match index (CMI) values for most areas of California, Arizon a and Texas are 
between 0.7 and 0.8, which indicates sufficient similarity to the New Zealand climate  (Phillips 
et al. 2018)  to allow establishment of M. gulosa .  
 
Marmara  gulosa  has the potential to cause  impacts  in New Zealand . 
• Larvae of M. gulosa  mine a nd damage only the peel of grapefruit ( Citrus paradisi ), pomelo 
(Citrus maxima ) and susceptible varieties of navel oranges ( Citrus sin ensis ). Although 
damage is cosmetic, fruit with as few as two to three mines is not acceptable for the fresh fruit 
market (Gibson et al.  1997; Jones 2001; Stelinski 2013).  
• In 1995, an outbreak of M. gulosa  in the Coachella Valley, California, caused 80 % to 90% fruit 
loss (due to severe mining of the peel) in some grapefruit groves (J ones 2001).  
 
11.2.2  Hazard identification: commodity association  
Marmara gulosa  is associated with citrus fruit . 
• Reports of M. gulosa from the peel of citrus fruits in southwestern USA date back to early in 
the 20th century ; the earliest known record is  of a mine d orange peel collected 23 July 1915 
from Pasadena, California (Vinal 1917 , in Semet 2010).  
• Larvae of M. gulosa  mine and damage the peel of grapefruit ( C. × paradisi ), pomelo 
(C. maxima ) and susceptible thin -skinned varieties (Fukumoto, Thompson Improved a nd 
Atwood) of navel oranges ( C. sinensis ) (Gibson et al. 1997; Jones 2001; Stelinski 2013).  
• There are laboratory and field studies (e.g. Guillén et al. 2001; Guillén et al. 2003 ; Guillén et 
al. 2004; O’Neal et al. 2011) of M. gulosa  developing on grapefruit.  
• All citrus and their hybrids are considered  hosts of M. gulosa , but grapefruit ( C. × paradisi ), 
orange ( C. sinensis ), pomelo ( C. maxima ), lemon ( C. limon ) and lime ( C. aurantiifolia ) have 
been specifically reported in the scienti fic literature (Gibson 1997; Guillén et al. 2001; Guillén 
et al. 2003, University of California 2008; Semet 2010; Stelinski 2013).  
 
11.2.3  Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below,  Marmara  gulosa  has a strong association with 
citrus, but a weak  association with commercially traded (export) citrus fruit , with low 
uncertainty : 
There are  reliable records of M. gulosa  from citrus fruit .  
• M. gulosa  occurs on citrus throughout the southern United States, mostly attacking grapefruit 
(C. paradisi ), navel oranges ( C. sinensis ) and pomelo  (C. maxima ), but lemons ( Citrus limon ) 
and limes ( Citrus × aurantiifolia ) are also affected  (Gibson et al.  1997; Guillén et al. 2001; 
Guillén et al. 2003, Guillén et al. 2004; O’Neal et al. 2011).  
• Adult female M. gulosa  lay their eggs on the surface of citrus fruit, or on the stems of new 
flush growth (Gibson et al. 1997; Guillén et al. 2001; Guillén et al. 2003).  
• Across its current geographical distribution  (southwestern USA : California, Arizona an d 
Texas, southeastern USA (Florida), northern Mexico ** and Cuba), M. gulosa  has been 
reported on citrus (Guillén et al. 2001; Jones 2001; Semet 2010).  
• Between 1988 and 2014, dead larvae of Marmara spp. were intercepted at the New Zealand 
border on citrus fruit from the USA: M. salictella (dead larvae) twice on grapefruit ( C. 
paradisi ); M. gulosa  (two dead larvae)  once on grapefruit and pomelo ( C. paradis i / 
C. maxima ); and Marmara sp. (dead larva) t wice on grapefruit (LIMS 2019).  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 374 **Note : There is some uncertainty regarding the presence of M. gulosa in Mexico; references to the 
pest’s presence in Mexico were likely based on  the assumption that the species of peelminer in 
Mexico is M. gulosa.  However,  from morphological examination of specimens collected from citrus in 
Sonora, northwest Mexico, Semet (2010) confirmed that citrus fruit in Mexico is attacked by a 
distinctly different and undescribed species of Marmara  that was also present in Riverside a nd, 
possibly, Coachella in California, USA. In 2018, the NPPO of Mexico added M. gulosa to its 
quarantine pest list (EPPO 2020) and had earlier (October 2007) rejected a shipment of peelminer -
scarred fruit from California, with the claim that M. gulosa  was not a documented species in Mexico 
(Semet 2010). More precise molecular genetic studies are needed to resolve the taxonomy of the 
citrus peelminer species in Mexico and California (Semet 2010).  
 
Basic measures  reduce the likelihood of entry of M. gulosa  on citrus fruit by a high degree , 
with low uncertainty . Therefore, the likelihood of entry is rated low (with low uncertainty) . 
Larvae of M. gulosa  and the mining damage they cause are visually detectable on fruit . 
• Live larvae of M. gulosa  are active and visible within their mines on citrus fruit, and they cause 
highly visible damage (serpentine mines) on the peel (Guillén et al. 2001;  O’Neal et al. 2011, 
Stelinski 2013 ; University of California 2008). As such, signs of infestation can be d etected in 
the field, at harvest and  during post -harvest practices in packing  houses.  
• Packing  houses usually reject peelminer -damaged fruit; especially fresh fruit for export 
markets (Gibson et al. 1997; Stelinski 2013).  
• Eggs of M. gulosa  are laid externa lly on the surface of fruit (Guillén et al. 2001; Guillén et al. 
2003; O’Neal et al. 2011; University of California 2008), and they are likely to be removed or 
damaged during post -harvest processes such as washing, brushing, cleaning and waxing of 
fruit.  
• Any remaining undamaged eggs may not be detected due to their small size (0.41 mm long 
and 0.28 mm wide) (Kerns et al. 2004) and could remain associated with fruit after post -
harvest and packhouse processes.  
 
Larvae of M. gulosa  may not survive pre -shipme nt cooling and transit conditions on citrus fruit .  
• In a laboratory study, O’Neal et al. (2011) reported that at 17 °C, cumulative mortality of 
M. gulosa  reached 70% after 27 days, with mortality of egg s, first-instar larvae  and second -
instar larvae being 13%, 16% and 18% respectively. Based on these results, O’Neal et al. 
inferred that there would be high mortality of M. gulosa eggs and early -instar larvae at 
temperatures below the lower development threshold, which was determined to be  12.2°C. 
• Given that citrus fruits are usually shipped at low temperatures (0 °C to14°C depending on 
citrus variety) and the minimum duration of shipping from North America to New Zealand is 
18–20 days (BMT 2020), eggs and early -instar larvae of M. gulosa  on citrus consignments 
can be expected to suffer high rates of mortality.  
• The r ecommended storage and shipping temperatures for orange ( C. sinensis ), which is a 
major host of M. gulosa , range from 0 °C to 8°C, while grapefruit ( the most preferred host) , 
limes  and lemons (minor hosts), are normally shipped at between 10 °C and 14 °C because 
they are damaged by lower temperatures (BMT 2020). Hence, larvae of M. gulosa will have a 
slightly better chance of surviving transit on the latter commodities.  
• However, betwe en 1999 and 2019, only dead larvae of Marmara gulosa, M. salictella  and 
Marmara sp. were  intercepted at the New Zealand border  – five times on grapefruit 
(C. paradisi ) and once on pomelo ( C. maxima ) from the USA (LIMS 2019).  
• Taken together, the above evidence suggests that if undetected M. gulosa eggs hatch after 
post-harvest handling and packing of fruit, early -instar larvae are not likely to survive transit 
conditions.  
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of M. gulosa to transfer from 
imported fruit onto a host plant to allow establishme nt is rated  low, with moderate 
uncertainty . 
  
375 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Eggs and larvae of M. gulosa  are non -dispersing and, thus, cannot transfer from fruit to host plants . 
• The stages (eggs and larvae) of  M. gulos a that are likely to be present on imported citrus fruit 
are non -dispersing (Guillén et al 2001) and need to complete development into adults to 
transfer.  
• Eggs of M. gulosa hatch and pass through four or five sap -feeding larval instars and one or 
two non -feeding larval instars on the fruit, after which the non -feeding larvae leave the fruit to 
pupate, before the emergence of adults, which can fly to find suitable host plants (Guillén et 
al. 2001; Guillén and Heraty 2004).  
 
It is possible (but unlikely) that early -instar larvae of M. gulosa  can complete development to mobile 
adults on  peel or whole fruit  discarded as waste in New Zealand:   
• Optimum development of M. gulosa  occurs between 26 °C and 29 °C (Guillen et al. 2 003; 
Guillén and Heraty 2004; O’Neal et al. 2011) , while its lower and upper development 
thresholds were determined to be 12.2 °C and 33 °C respectively (O’Neal et al. 2011).  
• In laboratory studies, average d evelopment time from egg to adult was 29 days at 2 6°C, on 
grapefruit  that is a preferred host (Guillén et al. 2001; Guillén & Heraty 2004), while  on 
Cucurbita pepo  (squash), which is an alternate host, it took 40.71 days at 21 °C and 23. 7 days 
at 25 °C (O’Neal et al.  2011).  
• Development of the feeding and n on-feeding larval instars, which must be completed on fruit, 
required a minimum of 14.1 days on grapefruit at 2 6°C (Guillén et al. 2001) and 18.6 days at 
21°C and about 17.6 days at 25 °C on squash (O’Neal et al. 2011).  Maurer et al. (1998), 
discussing the moth’s life cycle under field temperatures during late summer in Arizona, 
stated that larvae complete their development cycle in 20 –28 days.  
• During the southern hemisphere summer when citrus fruits from the USA and Mexico are 
likely to begin arriving in New Zealand , mean daily maximum temperatures across most of 
New Zealand are between 20 °C and 25 °C (NIWA 2020) . At these lower temperatures , based 
on the studies cited above, it is estimated that M. gulosa  early instars on discarded fruit would 
require  17–18 days (at the least) to complete larval development , after which pupation and 
subsequent adult emergence could occur in another 10 –15 days.  
• It is uncertain if infested fruit and/or peel will contain enough sap and remain fresh to support 
development of th e larvae for 18 days ; in the laboratory study of the pest’s development on 
squash ( O’Neal et al. 2011), the fruit was kept fresh with moist vermiculite , misting and a 
covering of paper towels. Temperatures were also held constant in the laboratory studies,  but 
will fluctuate in the open environments, e.g. open fields and compost heaps in home gardens 
where citrus waste may be discarded.  
• However, the possibility of larvae completing development before the fruit decays cannot be 
ruled out, and adults could em erge following successful larval development and pupation.  
 
If development is completed, adult female M. gulosa must mate to produce  offspring:  
• Marmara  gulosa  has separate male and female sexes (Guillén et al. 2001), and no evidence 
was found in the litera ture to show that unmated females can lay eggs that lead to the 
establishment of a viable population.  
• However, exported fruit that is infested with M. gulosa is likely to bear both sexes, as f emale 
M. gulosa  usually lay more than one egg on each fruit ( Guillén et al. 2001; O’Neal et al. 2011) 
and sex ratios are approximately 1:1 or slightly biased toward males between 17°C and 29 °C 
(O’Neal et al. 2011).  
• Female M. gulosa  produce sex pheromones that attract males (McElfresh et al. 2009) , 
although there is  no information on the distance over which the pheromones are effective.  
 
Uncertainty:  
There is moderate uncertainty  regarding the ability of M. gulosa  to transfer from imported fruit to host 
plants . The uncertainty is mainly due to insufficient informatio n to determine if early -instar larvae can 
complete development on discarded peel or whole fruit , which may require at least 18 days at 
average summer temperatures in  New Zealand . It is also uncertain if the discarded fruit will be fresh 
enough to allow com pletion of the larval stages. The possibility of transfer is also highly dependent on 
the disposal of unprocessed infested fruit waste in the vicinity of suitable hosts (see details in the 
section on waste disposal in section 2.4.1 ). 
 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 376 Given the arguments and evidence below, the suitability of the New Zealand 
environment (especially in the warmer parts of the North Island where citrus is grown  
commercially)  for the establishment of M. gulosa  is rated  moderate, with moderate 
uncertainty . 
 
The current geographical distribution of M. gulosa  includes some locations with a similar climate to 
New Zealand . 
• The known distribution of M. gulosa  includes southwestern USA (California, Arizona and 
Texas), southeastern  USA (Florida), northern Mexico and Cuba (Guillén et al. 2001; Jones 
2001; Semet 2010).  
• Climate match index (CMI) values for most areas of northern Mexico, California, Arizona and 
Texas are between 0.7 and 0.8, which indicates enough similarity to the New Zealand climate  
(Phillips et al. 2018)  to allow establishment of M. gulosa . As they are more tropical, Florida 
(CMI: 0.5 -0.7) and Cuba (CMI 0.5) have less similar climate s to New Zealand.  
• The optimum temperature range for the development of M. gulosa  is 26–29°C (Guillén and 
Heraty  2004). Its lower and upper development thresholds were estimated, by linear 
regression  of experimental data , to be 12.2 °C and 33 °C respectively (O’Neal et al.  2011). As 
such, the pest is more likely to establish in the warmer parts of the North Island of New 
Zealand, which are also the main citrus -growing areas.  
 
Host plants of M. gulosa are widely available in New Zealand, especially in northern areas where th e 
climate is more suitable for the pest . 
• Citrus species, especially grapefruit, navel oranges and pomelo, are major hosts of M. gulosa , 
and the main citrus -producing areas of New Zealand (ranked in terms of area planted and 
weight of produce): Gisborn e (56% of production), Northland (34%), Auckl and (9%) and Bay 
of Plenty (1%) (Citrus NZ 2020), are in the North Island, which has a warmer climate than the 
South  Island (NIWA 2020).  
• Oranges cover the largest area (783 hectares), whereas there are only 15 hecta res of 
grapefruit, which is the most preferred host (Citrus NZ 2020).  
• Nevertheless, the pest  is polyphagous, with hosts in more than 31 different plant families 
(Guillén et al., 2001; Semet, 2010). Some of the non -citrus hosts  of M. gulosa include 
avocado  (Persea americana ), grapevine ( Vitis vinifera ), plum ( Prunus  domestica ) and pepper 
(Capsicum  spp.)  (Gibson et al. 1997; Guillén et al. 2001), which are cultivated in New 
Zealand, and willow ( Salix  spp.) , which  is planted on riverbanks for erosion control i n New 
Zealand (Bay of Plenty Regional Council).  
 
Marmara  gulosa  is likely to spread within the main citrus production areas of New Zealand . 
• Adult M. gulosa can disperse by flying and are likely to spread within and between citrus 
groves.  
• In 1999, a field biologist working with the Tulare County (California) Agricultural 
Commissioner’s office observed citrus fruit with peelminer damage discarded outside packing 
houses, and peelminer damage soon appeared in orchards around the packing  houses  
(Haines 2002 , in Semet 2010).  
• Subsequently, infestations were noted in orchards at a greater distance (not specified) from 
the initial sightings , and a wave of infestation moved northward, so that by summer 2001, 
peelminer infestation  had increased drama tically, with some orchards sustaining as much as 
80% damage (Grafton -Cardwell 2003).  
• Spread beyond citrus -growing areas is likely to occur as infested fruit are distributed  to other 
parts of New Zealand. However, outside of the upper North Island, the coo ler climate may 
limit the pest’s establishment.  
 
Impacts  in New Zealand  
 
Given the arguments and evidence below,  Marmara  gulosa  is likely to cause 
moderate impacts in New Zealand, with moderate uncertainty around the magnitude 
of impacts.   
377 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Marmara gulosa  is a cyclical pest in its native range and mainly causes high economic impact in citrus 
hosts during periodic outbreaks . 
• In southern California where it is endemic, M. gulosa  is a cyclical pest, and only periodically 
damages >5% of citrus fruit due to lar vae mining just beneath the surface of fruit, with 2 –3 
mines per fruit render ing fruit unacceptable for the fresh market  (Jones 2001; Stelinski 2013).  
• In the central San Joaquin Valley (California) , M. gulosa  had been a minor pest of grapefruit 
(C. paradis i) for many years, but since 1999, it expanded its host range to include pomelo 
(C. maxima ) and smooth -skinned navel orange ( C. sinensis ) varieties such as Fukumoto, 
Atwood, T hompson Improved , and Barnfield , which were especially susceptible. These and 
other crops, such as walnuts, grapes, cotton and beans,  have been attacked to a greater 
extent than observed previously, with losses in grapefruit ranging from 10 –80% (University of 
California 2008).  
• In the Coachella Valley, California, an outbreak of M. gulo sa in 1995 caused 80 to 90% fruit 
loss (due to the appearance of the mined rind) in some grapefruit groves (Jones 2001). Such 
huge losses have not been reported in the area since then, and this may be due to improved 
pest management practices.  
• In other types of citrus, e.g.  C. sinensis  (orange), C. limon  (lemon) and C. aurantiifolia 
(Mexican lime), fruit damage is reported to be usually less than 5% (University of California 
2008).  
• Outbreaks of M. gulosa  in Arizona in 1994 and 1995, which resulted in economic damage in 
grapefruit, were most likely caused by excessive use of insecticides for whitefly control in 
adjacent fields of cotton; an alternate host from which M. gulosa  dispersed to infest citrus 
crops (Maurer et al. 1998). It is believed that the pesticides reduced the populations of larval 
parasitoids of M. gulosa  in the cotton fields, allowing it to quickly build up populations in the 
adjacent citrus crops. No reports were found of further outbreak s in Arizona.  
• Marmara  gulosa  is likely to cause economic impacts in the main citrus -producing areas of 
New Zealand (ranked according to production area and weight): Gisborn e (56% of 
production), followed by Northland (34%), Auckl and (9%) and Bay of Plenty (1%) (Citrus NZ 
2020).  
• Impacts may be high in grapefruit , which is a preferred host of M. gulosa  in the USA (Guillén 
et al. 2003; O’Neal et al. 2011). However, as of 2019, only 15 hectares in New Zealand were 
planted with grapefruit ( Plant & Food Research  2019).  
• In non -citrus hosts such as avocado, peppers, grapes and plums, M. gulosa  mainly mines 
twigs, rather than fruit, and causes little to no economic impact in these crops (Gibson et al. 
1997; University of California 2008).  
 
Marmara  gulosa  is unlikel y to cause environmental impacts . 
• The pest mines twigs of Salix  species , which are considered  its native hosts  in the US A 
(Guillén et al. 2001; University of California 2008) , and several cultivars of Salix  are used for 
erosion control,  shelterbelts and, sometimes, as a fodder source for bees or livestock in New 
Zealand (Bay of Plenty Regional Council).  
• However, no evidence was found indicating that mining of twigs of Salix  species by M. gulosa  
causes any economic damage , and the pest is  not known to attack any plants that are native 
to New Zealand.  
 
Marmara  gulosa  is unlikely to cause any health impacts, but may cause  some social  impacts : 
• M. gulosa  is a plant pest and has not been reported to affect  human or animal health  
• The production of home -made marmalade from citrus fruits may be affected if people 
consider the peel of mined fruit to be unsuitable. However, such impacts have not been 
reported in the literature . 
• Damage to fruit from home gardens may make such fruit unattractive; altho ugh the damage is 
limited to the peel and is not known to affect the quality or taste of the fruit itself . 
 
Climate is likely to limit the overall impacts of M. gulosa  in New Zealand (with moderate uncertainty) .  
• In the San Joaquin Valley, California, M. gulosa  survives throughout the year on Salix  
species, and infests pomelo ( Citrus maxima ) from June to October (summer to autumn) , 
during which it completes six to seven generations. The pest then attacks oranges, on which 
it completes three generations, fr om August to October (late summer  to mid-autumn).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 378 • The citrus -growing areas of New Zealand have lower average summer temperatures (18 –
20°C) (NIWA 2020) compared to (23 –27°C) in the San Joaquin Valley (NOAA 2020) and as 
such, M. gulosa  is unlikely to be able  to complete as many generations in New Zealand like it 
does in the USA, which would limit its impacts.  
• However,  impacts may be high (with moderate uncertainty) in years when average summer 
temperatures in the main citrus growing areas exceed 26°C, allowin g the pest to complete 
more generations and rapidly build up populations . 
 
There is moderate uncertainty in the conclusion regarding impacts, as there is not enough evidence to 
accurately predict the extent to which climate will limit the pest’s distributi on and impacts in New 
Zealand. Presumably, impacts will likely increase with rising temperatures  as a consequence of 
climate change.  
 
11.2.4  References  
Bay of Plenty Regional Council. Factsheet on willow. 
https://www.boprc.govt.nz/media/29173/LandManagement -090526 -Factsheet21.pdf  Accessed 18 
June 2020.  
BMT (2020)  Oranges.  Cargo Handbook . https://cargohandbook.com/Oranges  Accessed 22 
September 2020.  
BRAD (2020) Biosecurity Risk Analysis Database. Ministry for Primary Industries internal database. 
Accessed 18 June 2020.  
Chappell, P  R (2013 ) The climate and weather of Northland. NIWA Science and Technology Series , 
59. 40 pages . https://niwa.co.nz/static/Northland%20ClimateWEB.pdf  Accessed 22 July 2020.  
Citrus New Zealand (2020) How big is NZs citrus industry? https://www.citrus.co.nz/faq/how -big-is-
the-citrus -industry -in-new-zealand/  Accessed 25 May 2020.  
EPPO (2020) EPPO Global database https://gd.eppo.int/taxon/MARMGU/categorization  Accessed 22 
October 2020 . 
Gibson, R; Bacon, D; Langston, D; Gibson, R (1997) The citrus peel miner, Marmara sali ctella , in 
Arizona grapefruit. Citrus Research Report . https://repository.arizona.edu/handle/10150/220558  
Accessed 04 June 2020.  
Gracillariidae.net - Global taxonomic Database of Gracillariidae (Lepidoptera) (2016) Marmara gulosa . 
Guillén & Davis, 2001 http://www.gracillariidae.net/species/show/1828  Accessed 04 June 2020.  
Guillén, M; Davis,  D R; Heraty , J M (2001 ) Systematics and biology of a new, polyphagous species of 
Marmara  (Lepidoptera: Gracillariidae) infesting grapefruit in the southwestern United States. 
Proceedings of the Entomological Society of Washington , 103: 63 6–654. 
Guillén, M; Heraty, J M (2004) Instar d ifferences in Marmara gulosa  Guillén and Davis (Lepidoptera: 
Gracillariidae). Annals of the Entomological Society of America , 97(6): 1227 –1232.  
Guillén, M; Heraty , J M; Luck , R F (2003 ) Seasonal variation and infestation incidence by Marmara 
gulosa  (Lepido ptera: Gracillariidae) on grapefruit in the Coachella Valley, California. Journal of 
Economic Entomology , 96(3): 577 –583. 
Jones, J (2001) Citrus peelminer fact sheet. Cotton Cooperative Extension. 
https://cals.arizona.edu/crops/cotton/insects/other/peelminer.html  Accessed 26  May 2020.   
379 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Kerns, D; Wright, G; Loghry , J (2004) Citrus peelminer ( Marmara gulosa ). Citrus Insect s Coopera tive 
Extension. https://cals.arizona.edu/crops/citrus/insects/peelminer.pdf  Accessed 25 May 2020.  
LIMS (2020) Laboratory Information Management System. Ministry for Primar y Industries internal 
database. Accessed 8 June 2020.  
Maurer, M A; Kens, D L; Tellez, T (1998) Citrus peel miner Marmara salictella  monitoring techniques 
and control measures 1996 –1997. Citrus and Deciduous Fruit and Nut Research Report . AZ1051  
McElfresh, S J; Moreira, J A ; Grafton -Cardwell, E E ; Headrick, D H ; Heraty, J M ; Guillén, M ; Millar, J 
G (2009) Novel lepidopteran sex pheromone components from Marmara gulosa  (Lepidoptera: 
Gracillariidae). Journal of Economic Entomology , 102(2) : 574–584. 
National Oc eanic and Atmospheric Administration (2020) Central and Southern San Joaquin Valley 
Climate Graphs. https://www.weather.gov/hnx/Cliplot  Accessed 22 July 2020.  
NIWA (2020) The National Climate Database. https://cliflo.niwa.co.nz/  Accessed 8 June 2020.  
NZOR (2020) New Zealand Organisms Register. http://www.nzor.org.nz/  Accessed 8 June 2020.  
O’Neal, M  J; Headrick, D H ; Montez, G H ; Grafton -Cardwell, E E (2011) Temperature thresholds and 
degree -day model for Marmara gulosa  (Lepidoptera: Gracillariidae).  Journal of Economic Entomology , 
104(4): 1286 –1293.  
ONZPR (2020) Official New Zealand Pest Register. MPI public database . 
https://pierpestregister.mpi.govt.nz/  
Phillips, C B ; Kean, J  M; Vink, C J ; Berry, J  A (2018) Utility of the CLIMEX ‘match climates regional’  
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3) : 777–791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) Fresh Facts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , New Zealand.  https://www.freshfacts.co.nz/files/fresh facts -
2019.pdf  Accessed 10 June 2020.  
PPIN (2020) Plant Pest Information Network. Ministry for Primary Industries internal database. 
Accessed 8 June 2020.  
Semet, P (2010) Taxonomy, biogeography and pest status of Marmara sp. in Northern Mexico and 
Californ ia citrus production . MSc thesis. California Polytechnic State University; California, USA.  
Stelinski, L (2013) Citrus peelminer : Marmara gulosa  Guillèn and Davis (Insecta: Lepidoptera: 
Gracillariidae). EDIS, 2013(4). https://journals.flvc.org/edis/article/view/120770  Accessed 27 May 
2020.  
University of California (2008 ) Citrus leafminer and Citrus peelminer . 
https://anrcatalog.ucanr.edu/pdf/8321.pdf  Accessed 9 June 2020.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 380 11.3 Spodoptera littoralis  (African cotton leafworm ) 
Spodoptera littoralis  is a grey-brown moth, 15 –20 mm long, with  grey-reddish brown wings. It  is one of 
the most destructive agricultural moths w ithin its subtropical and tropical range . The larvae feed 
extensively on leaves, fruit and seeds of many economically important crops, often complete ly 
stripping the plants  (CABI 2020; EPPO 2020) . 
 
Scientific name: Spodoptera littoralis  (Boisduval 1833 ) 
Order/Family: Lepidoptera/ Noctuidae  
Other names: African cotton leafworm,  Egyptian cotton leafworm , Mediterranean brocade  moth 
(EPPO 2020)  
 
Note on taxonomy : Prior to 1962,  Spodoptera  littoralis  and S. litura  were treated as a single species 
under the scientific name  Prodenia litura . However, Viette (1962) demonstrated that S. littoralis  is a 
speci es separate from S. litura . It is g enerally  accepted that S. littoralis  is found in Africa, 
Madagascar, Europe and the Middle East, whereas S. litura  is found in Asia, Australia and the Pacific 
Islands  (CABI 2020; EPPO 2020) . 
 
Summary of c onclusion s 
 
Given the arguments and evidence presented : 
 
• Spodoptera littoralis meets the criteria for being a quarantine pest . 
• Spodoptera littoralis  has a weak association with citrus  and is not reported to be associated 
with the fruit of any Citrus  species (with low uncertainty) . 
• Basic measures  are likely to reduce  the likelihood of entry of S. littoralis  on citrus fruit by a 
high degree . Consequentl y, the likelihood of entry is considered  very low, with low 
uncertainty.  
• The ability of S. littoralis  to transfer from imported fruit to suitable host plants, leading to 
establishment, is moderate (with moderate uncertainty).  
• The s uitability of the New Zea land climate for establishment of the pest is moderate (with 
moderate uncertainty) . The pest may be able to establish outdoor populations in parts of the 
North Island and South Island, with transient populations in glasshouses.  
• The pest is likely to cause  moderate or sporadic ally high impacts in glasshouse and field 
crops, and it may cause environmental and social impacts by attacking native species.  
• It is recommended that  Spodoptera littoralis  does  not require  consider ation  for additional 
measures, due to the lack of evidence of association with citrus fruit and the degree by which 
minimum measures reduce the likelihood of entry on the commodity.  
 
Summary of risk assessment against criteria  
 
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Weak  Low 
Likelihood of entry on the commodity, given the application of basic measures  Very low Low 
The ability to move from the imported commodity  onto a suitable host  Moderate  Moderate  
Suitability of the N ew Zealand  environment  Moderate  Moderate  
Impacts on the New Zealand economy, environment, health and society  Moderate  Moderate  
 
11.3.1  Hazard  identification: quarantine status  
Given the arguments and evidence below,  Spodoptera littoralis meets the criteria to 
be a quarantine pest for New Zealand .   
381 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause harm).  
 
There are no records of S. littoralis from New Zealand , and the pest is regulated . 
• Spodoptera littoralis is not recorded in PPIN (2020), NZOR (2020) or NZ Inverts (2020).  
• The regulatory status of S. littoralis in New Zealand is “regulated” ( ONZPR  2020).  
 
Spodoptera littoralis  has the potential to establish in New Zealand . 
• The pest is mostly restricted to tropical and subtropical Africa, but occurs in southern France, 
Spain, Italy and parts of Portugal (EPPO 2020) in areas  that have similar climates to parts of 
both the North and So uth Islands of New Zealand: climate match index (CMI) values of 0.7 –
0.9 (Phillips et al. 2018).  
• The pest also has the potential to establish in glasshouses (CABI 2020; EPPO 2020).  
 
Spodoptera littoralis  has the potential to cause impacts in many field and glasshouse crops . 
• The pest is highly polyphagous, with host species in 44 plant families , and is capable of 
completely defoliating crops (CABI 2020; EPPO 2020).  
• Hosts of S. littoralis  include t omato  (Solanum lycopersicum ), eggplant ( S. melongena ), potato 
(S. tuberosum ), kumara ( Ipomoea  batatas ), peppers  (Capsicum  spp.), grapevine ( Vitis 
vinifera ), apple ( Malus domestica ), corn ( Zea mays ), clover ( Trifolium spp.), Cucurbitaceae 
and Brassicaceae (CABI 2020; EPPO 2020), which are economically important crops 
cultivated either in fields or glasshouses across New Zealand (Horticulture NZ 2017; Plant & 
Food Research 2019).  
 
11.3.2  Hazard  identification: commodity association  
Given the arguments and evidence below,  Spodoptera littoralis  has a weak 
association with citrus (with low uncertainty) and has not been reported from citrus 
fruit.  
There  are few and somewhat conflicting records of S. littoralis from citrus species, and non e from 
citrus fruit . 
• Citrus  aurantium (sour orange) is listed as a host in the Crop Protection Compendium  
datasheet on S. littoralis (CABI 2020), but details of the plant parts affected are not provided.  
• Guerrero et al. (2012) list Citrus  spp. and their hybrids as hosts of S. littoralis , but no 
supporting primary literature was found in which S. littoralis  is associated with citrus fruit.  
• Citrus  is not included on the host list for S. littoralis  on the UK Plant Health and EPPO 
databases (D EFRA 2020; EPPO 2020).  
• Spodoptera littoralis is not recorded as a pest of citrus in Egypt (Biosecurity Australia 2002), 
which is within the native geographic range of the pest.  
 
11.3.3  Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below,  Spodoptera littoralis has a weak 
association with citrus plants and no known association with citrus fruit:  
Records of S. littoralis on citrus are few and somewhat in conflict with each other . 
• CABI (2020) lists Citrus  aurantium (sour orange) as a host of S. littoralis, and Citrus  spp. and 
their hybrids are named as hosts of S. littoralis  in Guerrero  et al. (2012).  
However, citrus is not included on the host list for S. littoralis  in the UK Plant Health and 
EPPO databases (DEFRA 2020; EPPO 2020).  
• No suppor ting primary literature in which S. littoralis  is associated with citrus plants or fruit 
could be found , and it is not recorded as a pest of citrus in Egypt  (Biosecurity Australia 2002), 
where it is a native species, nor in the south of Spain , the only oth er country being considered 
in this risk assessment, where it  is known to occur . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 382 • Nearly 80% of interceptions of S. littoralis  at EU borders have been on shipments of cut 
flowers of Rosa  spp., with other interceptions on Aster , Begonia , Chrysanthemum , Diant hus, 
Eryngium , Eustoma , Lisianthus , Pelargonium , Petunia , Ranunculus , Mentha  and Ocimum, 
and a few on Solanum melongena  and Solidago  spp. (EFSA 2015).  
• Interception records show that S. littoralis  has not been intercepted on Citrus  fruit or nurse ry 
stock  at the New Zealand border (LIMS 2020). This could be because the pest is not present 
in countries from which New Zealand has previously imported citrus commodities. However, 
neither has the pest been intercepted on any host commodities imported into New Ze aland. 
There is one record for S. litura  intercepted on nursery stock of Gypsophila  sp. from Israel 
(LIMS 2020). This may  or may not have been S. littorali s, as S. litura is not known to be 
present in Israel, whereas S. littoralis is (CABI 2020; EPPO 2020) . 
 
Feeding and egg -laying behaviour of S. littoralis  make it highly unlikely  that the pest would  be 
associated with citrus fruit:  
• Larvae of the pest are defoliators , and adult f emales lay egg masses (20 –1,000 eggs) on the 
lower surface of younger leaves on  upper parts of host plants ( Khalifa et al . 1982 , in CABI  
2020; Sadek 2011 ). Sadek (2011) states that: “o f 1,082 egg batches found in 2 years (2007 –
2008) in cotton fields in Egypt, 1 ,035 batches (96.5%) were found on the underside of leaves, 
28 (2.6%) on the upper side of leaves and 10 batches (0.9%) on petioles and leaf axillae ”. 
• No literature  was found , in which S. littoralis  is reported to feed or lay eggs  on citrus  fruit.  
• Plants for planting and cut flowers and branches, but not fruits, are listed as the main risk 
commodities for the international spread of S. littoralis  (CABI 2020; EPPO 2020).  
• Incursions of S. littoralis  in UK glasshouses in the 1960s, were found to have occurred via 
entry of the pest’s eggs  on imported cuttings, especiall y chrysanth emums and carnations 
(CABI 2020). There are no records of introduction on citrus fruit.  
 
Despite the conflicting information regarding the association of S. littoralis  with citrus, there is low 
uncertainty around the conclusion that the pest has a weak ass ociation with citrus and that it is 
unlikely to be present on citrus fruit.  This is  because the conclusion is supported by reliable data on 
the pest’s biology and the fact that no primary sources in support of a contrary conclusion were found.  
 
Given the a rguments and evidence below, basic measures are likely to reduce the 
likelihood of introduction  of S. littoralis on citrus fruit by a high degree . Consequently, 
the likelihood of entry is considered very low . 
The l ife stages of S. littoralis  that may incidentally be on citrus fruit  (eggs and larvae) can be visually 
detected . 
• Eggs are laid on leaves , and larvae feed mainly on leaves and occasionally fruit (capsicums 
and tomatoes), whereas pupation usually takes place in soil , and adult moths are ve ry mobile 
and unlikely to remain associated with fruit (Ellis 2004; EPPO 2020).  
• Eggs, though tiny (0.6 mm in diameter), are laid in batches of 20 –1,000 and covered with 
hairy scales from the adult female’s body (CABI 2020; EPPO 2020), which makes them lik ely 
to be detected, if present on fruit.  
• Egg masses are also likely to be damaged or dislodged during fruit handling and packing 
house processes such as washing, brushing, cleaning and waxing.  
• Larvae measure 1 –45 mm long (increasing in size as they develo p from young instars to older 
instars) and feed externally, with young instars often in aggregations (EPPO 2015; CABI 
2020; EPPO 2020), and are therefore likely to be detected and removed during harvest, post -
harvest handling and packing house processes su ch as washing, brushing, waxing and 
culling.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of S. littoralis to transfer from 
imported citrus fruit onto a suitable host plant to allow establishment 
(transfer/exposure) is rated moderate (with moderate uncertainty) .  
383 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Climatic conditions during summer in northern parts of New Zealand may be suitable for eggs and 
early instar larvae to complete development:  
• Eggs of S. littoralis  need to develop (at least to second - or third-instar larvae) for  transfer  to 
occur . Eggs are not mobile  and first -instar larvae are not known to disperse , but second - and 
third-instar larvae are able to move to different parts of a host plant , and older larvae can 
disperse to nearby plants (Sadek 2011 ). 
• Eggs of S. littoralis  reared on leaves of preferred host plants (cotton, clover, cowpea, cabbage 
and maize)  at 25 ± 2°C, 70 ± 2% RH and 16:8 h (L:D) photoperiod took an average of 35 
days to become adults ( Thoming et al. 2013).  At a constant temperature  of 18°C,  the life 
cycle from egg to adult took about 70 days on lucerne ( Medicago sativa ) (Ocete Rubio 1984  
cited by CABI 2020 ). 
• Given the above temperature requirements and the fact that the citrus export season in Egypt 
(late November – February) coincides with New Zealand’s summer, when average 
temperatures, especially in the northern parts of the country (Auckland, Northland, Gisborne, 
Hawkes’ Bay) are between 18 –21°C (NIWA 2020) , eggs of S. littoralis  on citrus fruit discarded 
in open environmen ts may be able to complete development into adults, but this would take 
considerably longer than 35 days .  
• The fruit material is likely to rot  before the pest completes development , as saprophytic and 
pathogenic fungi severely reduce the post -harvest life of citrus fruit, especially if it has  been 
stored for several months or shipped for long distances  at low temperatures  (Strano et al. 
2017).  However, older larvae are likely to disperse away from rotting fruit in search of 
alternative hosts, b ased on the observation that older larvae can disperse to nearby plants 
(Sadek 2011).  
 
If development is completed, S. littoralis  adults could transfer to a suitable host and produce offspring:  
• Adults are mobile and can disperse to find hosts . The flight r ange during a 4 -hour period can 
be up to 1.5 km (Salama and Shoukry 1972) . 
• It is also possible that the pest undertakes long -distance migrations, as adults, which may be 
genuine migrants rather than those emerging from imported eggs/larvae, have been 
occas ionally trapped in the UK (CABI 2020; Clancy 2020).  
• Although the moth has separate sexes and mating is required for females to lay viable eggs, 
females produce a sex pheromone that effectively attracts males (Tamaki and Yushima 
1974).  
• Females can attract males from about 90 m downwind, and the attractive radius is about 10 m 
(El-Sayes 1977  and Ellis 1980 , both in Ellis 2004).  
• Most females m ate on the first night of emergence , and a pproximately 50% of mated females 
lay their eggs on the same night of mating, before sunrise (Hassan et al. 1960 , in CABI 2020 ). 
• However, the likelihood of finding a mate may be low, given the low numbers of adults that 
would arise from one incursion incident, and this may further reduce likelihood of transfer 
leading to est ablishment.  
There is uncertainty around the conclusion on the pest’s ability to transfer from imported citrus, mainly 
due to lack of information on whether the pest feed s on and can complete development on citrus fruit 
or if the larvae can disperse from de caying citrus fruit in search of other sources of food.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for the establishment of S. littoralis  is rated  moderate (with moderate 
uncertainty) . 
Spodoptera littoralis  is a tropical and subtropical species, and a warm climate is critical to its 
development and persistence . 
• Spodoptera littoralis  is native to Africa and Israel , and its current geographic distribution is 
limited to tropical countries in Africa , the Middle East  and Mediterranean Europe : Africa : 
Algeria, Angola, Benin, Botswana, Burkina Faso, Burundi, Cameroon, Cape Verdi, Central 
African Republic, Chad, Comoros, Congo, Congo Democratic Republic, C ôte d’Ivoire, Egypt,  
Equatorial Guinea, Ethiopia, Eritrea, Gambia, Ghana, Guinea, Kenya, Libya, Madagascar, 
Malawi, Mali, Mauritania, Mauritius, Morocco, Mozambique, Namibia, Niger, Nigeria, R éunion, 
Rwanda, St Helena, Senegal, Seychelles, Sierra Leone, Somalia, South Africa,  Sudan, 
Swaziland, Tanzania, Togo, Tunisia, Uganda ; Middle East/Asia : Bahrain, Iran, Iraq, Israel, 
Jordan, Lebanon, Oman, Pakistan, Saudi Arabia, Syria, Turkey, United Arab Emirates, Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 384 Yemen ; Europe : Cyprus, Greece (Crete), Italy (Sicily), Malta, Portugal , France and  Spain  
(CABI 2020; EPPO 2020) . 
• The northern distribution limit of S. littoralis  in Europe  (eastwards into Turkey and north into 
eastern Spain, southern France and northern Italy ) corresponds to the climatic zone in which 
winter frosts are infreque nt, and is probably the extent of migrant activit y, because  the pest 
overwinters in southern parts of Greece and Spain, but not in northern Italy or Franc e (CABI 
2020; Miller 1977).  
• Miller (1977) demonstrated that exposure of S. littoralis pupae to 13 ± 0.5°C for 70 days 
resulted in the emergence of only a few adults, all of which were deformed and none of which 
mated or laid fertile eggs. Eggs and early - and late -instar larvae were also shown to be 
susceptible to low temperatures ( 1°C, 4°C, 7°C , 10°C an d 13°C) , and 30 -day-old larvae, 
which were the most cold -resistant, suffered 100% mortality after 65 days at 13 °C. 
• The findings of Miller (1977) explained why, without being able to enter a state of diapause, 
the pest does not overwinter in northern Spain,  Italy and France.  
• Ocete Rubio (1984), cited in CABI (2020), reported that the minimum constant temperature 
required for normal development of all stages was between 13–14°C  and showed that egg, 
larval and pupal stages took 2, 10 and 8 days respectively  at 36°C,  whereas at 18°C, 
development of these stages  took 9, 34 and 27 days  respectively . 
• In a laboratory study in Egypt, El Malki (2000) reported that eggs of S. littoralis  kept at 10°C 
failed to hatch; the lower temperature threshold for the completion of development of egg, 
larva, pupa and adult maturation (pre -oviposition and oviposition) was estimated to be 
11.8°C, 12.5°C, 11.3°C, 10.7°C, 10.8 °C respectively and 12.6°C f or the completion of a 
generation.  
• Yones et al. (2012) , on the other hand, considered the lower developmental threshold to be 
9.9°C and based on this, determined that, on average, the thermal requirements for 
completing a generation (egg to adult) were about 524 degree  days in the laboratory and 545 
in the fie ld (calculated from air temperatures) in Egypt.  
 
Spodoptera littoralis may be able to establish outdoors in most of the North Island and in northern 
parts of the South Island with transient seasonal populations in glasshouses . 
• The pest overwinters outdoors  in parts of southern Greece  (Crete) and southern Spain  up to 
Barcelona (CABI 2020; EPPO 2020) , which have similar enough climate (CMI: 0.7 –0.8) to the 
Auckland and Northland regions  in the North Island  of New Zealand.   
• The p redicted distribution of S. littoralis  in the US A (based on modelling) includes parts of 
Tennessee, North and South Carolina, northern Florida, northern parts of Georgia, Missouri 
and Oklahoma (Venette and Davis 2003 in Ellis 2004), which also have CMI values of 0.7–
0.8, when compared to the Auckland and Northland regions of New Zealand.  
• In Kaitaia, which is in the Northland region, the monthly average maxima never drop below 
15°C. Auckland drops below 15°C for only one month and never below 13°C monthly average 
maxima (NIWA 2020).  
• On the above criterion, Spodoptera littoralis  could breed in much of the North Island, from 
Kaitaia to Taranaki, Gisborne and Napier, and possibly Blenheim, which covers most of the 
principal citrus growing areas of New Zealand.  
• Degree days required to complet e a life cycle were estimated, from laboratory physiological 
thresholds, at between 366 and 490 by El-Malki (2000) , and between 544 to 641 degree days 
above 9.89 °C  by Yones et al. (2012) ; although recogni sing that laboratory data suggest fewer  
degree days , Yones et al. (2012) based their estimates on remote sensing information.  
• Assuming mid -point estimates of 428 and 593 d egree days, Spodoptera littoralis  could 
complete 3 –5 generations per year in Whangarei, 2 –3 in Nelson and, potentially, 1 in 
Invercargi ll (Halloy 2020).  
• The pest can establish in glasshouses and has been detected and eradicated from 
glasshouses in the UK, following its introduction as eggs  on cuttings, especiall y 
chrysanthemum and carnation  cuttings , imported into glasshouses (CABI 2020).  
• Occasional outbreaks  in glasshouses, which were also successfully eradicated, have also 
been reported from Sweden, Switzerland, Finland and Germany (Bartlett and Macdonald 
1993 , in EFSA 2015).  
• The pest is highly polyphagous (CABI 2020), and many of its host plants, e.g. cabbage, 
broccoli, cauliflower, lettuce, tomato, potato, kumara, onion, clover and maize, are cultivated  
385 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  in parts of the South Island and especially in the North Island (Horticul ture New Zealand 
2017), where the climate is likely to be more suitable for the pest to establish.  
 
There is uncertainty in the conclusion about the suitability of the New Zealand environment for 
establishment of S. littoralis , because although the pest is  mostly tropical , requires high temperatures 
for survival and development and does not overwinter in parts of Europe with similar climate to New 
Zealand, degree -day models suggest that the New Zealand climate is likely to be suitable for the 
pest’s establi shment.  
 
 
Likelihood of impact:  
 
Given the arguments and evidence below,  Spodoptera littoralis is likely to cause 
moderate impact (with moderate uncertainty) .  
Spodoptera  littoralis  can cause economic impacts in outdoor and glasshouse crops:  
• Spread of th e pest in outdoor areas is likely to occur mainly via the dispersal of adults, which 
can fly up to 1.5 km during a 4 -hour period (Salama and Shoukry 1972) , and the pest could 
be introduced into glasshouses on infested plants for planting.  
• The Auckland and Northland regions of New Zealand where the pest is more likely to be able 
to establish have similar climate (CMI: 0.7 –0.8) to the southern areas of the European 
countries where the pest occurs (Phillips et al. 2018), and as such, the pattern of damage 
likely to be caused by the pest in these regions of New Zealand, may be similar to what 
occurs in southern Europe.  
• Many of the field crops affected in southern Europe are grown outdoors in the North Island of 
New Zealand: lettuce, onions, cabbage, broccoli an d cauliflower are grown in New Zealand’s 
northern and mid -regions, with warmer climate conditions allowing year -round production 
(Horticulture New Zealand 2017). Tomato, eggplant and peppers are important hosts mainly 
grown in glasshouses in New Zealand (V egetables New Zealand 2020).  
• The s ize of production area, domestic value in 2018 and export value in 2019 for New 
Zealand tomatoes and capsicums were 120 ha ( NZ$176 million  domestic, $11.2  million  
export) and 95 ha ( NZ$25 million domestic, $20.6 million  export)  respectively ( Plant & Food 
Research  2019), and chrysanthemums, which are important ornamental hosts of the pest, are 
also grown in New Zealand glasshouses for domestic and export trade as cut flowers 
(Markham 2017).  
• In Europe, damage caused by S. littoralis  was minimal until about 1937 , but in 1949, a 
population explosion of the pest in southern Spain severely affected lucerne, potatoes and 
other vegetable crops (EPPO 2020). At present, S. littoralis  is considered an economically 
important pest in Cyprus, Malta and parts of southern Greece, Italy, France and Spain, with 
damage in these areas being mostly sporadic, but occasionally severe, in a wide variety of 
outdoor vegetable, salad and ornamental crops (CABI 2020; EFSA 2015).  
• In 2009, in France ( Corsica), crops of vegetables (chard, lettuce) and ornamentals (calla lilies 
and buttercups) were seriously damaged by S. littoralis (Fredon Corse 2014), and pheromone 
traps had to be deployed in 2013 and 2014 because of serious damage to lettuce and chard  
(Jean -Marie Ramel, personal communication cited in EFSA 2015).  
• In Silicia and Liguria (southern Italy), S. littoralis  is an important pest of horticultural crops 
(and floriculture); having spread gradually since the 1980s to coastal areas characterised by  
intensive cultivation of protected crops (Sannino 2003).  
• In Greece, specifically Crete, S. littoralis  causes slight damage on lucerne ( Medicago 
sativum ) and clover ( Trifolium  spp.) only (CABI 2020; EPPO 2020), which are important 
legumes used in New Zeala nd dairy pastures.  
• The number of generations completed by the pest each year would determine the level of 
impact, and Halloy (2020) estimates that Spodoptera littoralis  could complete 3 –5 generations 
per year in Whangarei, 2 –3 in Nelson and, potentially, 1 in Invercargill; based on degree days 
required for the completion of a generation calculated by El -Malki (2000) and Yones et al. 
(2012).  
• Studies in Egypt show  that S. littoralis  has seven overlapping generations per annum when 
feeding on cotton  (El-Shafei et al. 1981  and Khalifa et al. 1982 , both cited in CABI 2020 ). Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 386 • Spodoptera litura , a related species that is established in parts of the North Island of New 
Zealand, only causes sporadic economic impacts in pasture crops following occasional 
outbreak s (Gerard et al. 2011).  
• Based on the foregoing, overall, economic impacts may be expected to be very low to low in 
most years, but they could be high in glasshouses, and moderate  to high outdoors in years 
when temperatures are higher than normal, allowing  the pest to complete more generations.  
 
Spodoptera littoralis  may cause low environmental and social impacts, but is unlikely to cause health 
impacts:  
• There are New Zealand native species in the plant families  to which known hosts of the pest 
belong. Few  examples of native plants that could be affected include Hibiscus richardsonii  
and Hoheria  spp.: family Malvaceae, found in parts of the north Island; Streblus banksia : 
Moraceae, an endemic species of coastal forest on the North Island (University of Auck land 
2020); two species of Clianthus  (kakabeak or kōwhai ngutukākā in Māori): Fabaceae, one of 
which is endangered and the other of which is critically endangered (Hee nan 2000) .  
• Kumara ( Ipomoea batatas ), which is a culturally significant food plant for Māori , is a known 
host of the pest that is grown exclusively in the North Island (90% in Northland) (Vegetables 
New Zealand 2019). The bark of Hoheria  populnea (houhere, lacebark) , found in lowland 
forest in the upper half of the North Island, contains a l ace-like sheet that is highly prized for 
weaving decorative items (University of Auckland 2020).  
• Many vegetable hosts of the pest, e.g. tomato, capsicum and cabbage, are grown in private 
gardens.  
• No reports of human or animal health impacts from S. littora lis were found . 
 
Effective p est management measures are available, but will lead to added costs:  
• Incursions in glasshouses are likely to be detected early, due to the pest’s voracity, allowing 
for eradication; sporadic o utbreaks of the pest in northern European glasshouses have been 
successfully eradicated (Bartlett and Macdonald 1993 in EFSA 2015). Outdoor populations 
may be more difficult to eradicate, especially if the infestation is spread out over a wide area.  
• Long -term i nsecticidal control is possible and effective, although there have been many cases 
of resistance , and biological control methods  are not always effective (EPPO  2020 ), which 
means that introduction of S. littoralis  into glasshouses could necessitate i nsecticide 
treatments that may interfere with existing biological control of other pests .  
• The synthetic sex pheromone cis 9 -trans -11-tetradecadien -1-y1 acetate is highly effective at 
trapping male moths of S. littoralis  (Kehat  and Dunkelblum 1993 ). 
• Successful control of the pest and resistance management can be obtained with mass 
trapping, mating disruption and attract -and-kill methods, but these methods are expensive to 
implement (Guerrero et al. 2014).  
• In Spain, S. littoralis  is controlled effectiv ely using entomopathogenic nematodes, such as  
Steinernema feltiae  and Heterorhabditis bacteriophora , in IPM systems (Galeano et al. 2009). 
Steinernema feltiae is recorded as present and indigenous in New Zealand, while the latter is 
not known to be present  (NZOR 2020).  
• The pest has many other known natural enemies; pathogens ( Beauveria  bassiana , Bacillus 
thuringiensis ), parasitic wasps ( Apanteles spp., Brachymeria  spp., Cotesia  spp.) and 
predatory beetles ( Coccinella undecimpunctata , Euborellia annulipes ) (CABI 2020), which are 
present in New Zealand (NZOR 2020) and could contribute to mitigating impacts.  
 
Uncertainty:  
Uncertainty regarding the level of impact stems from the fact that damage caused by the pest in areas 
of Europe with similar climate to some parts of New Zealand has been described using terms such as 
slight, severe or serious, but is not quantified in terms of production or yield losses. Additionally, 
cropping practices are not the same across all locations and between those places and New Zea land, 
which creates uncertainty around the estimate of the potential level of economic damage. Also, with 
climate change resulting in higher average temperatures, more areas of New Zealand could become 
more suitable for the pest to establish, which could l ead to increased impacts.  
  
387 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  11.3.4  References  
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to control Spodoptera  spp. (Lepidoptera: Noctuidae). Journal of Pest Science , 87: 231–247. 
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2020.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 388 Halloy, S (2020). Climate suitability of New Zealand for Spodoptera littoralis , Cotton leaf worm . 
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Accessed 2 September 2020.  
Kehat M ; Dunkelblum E (1993 ) Sex pheromones: achievements in monitoring and mating  disruption 
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August 2020.  
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temperatures. Bulletin of Entomological Research , 67(1) : 142–152.  
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Phillips, C B ; Kean, J M ; Vink, C J ; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’  
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  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 390 12. Insects: Thripidae (thrip s) 
 
12.1 Caliothrips fascia tus (bean thrips ) 
Caliothrips fasciatus  was once  a significant pest of many commercial crops (lucerne, beans , 
cantaloupes, cotton, lettuce, pears, peas and walnuts ) in California, but its status as a crop pest has 
waned, due to improv ed pest and crop management systems. However, this thrips remains a major 
quarantine issue for the export of fresh navel oranges ( Citrus sinensis ) and mandarins/tangerines 
(C. reticulata ) from California, because adults overwinter in the navels of the oranges, posing an 
incursion threat to importing countries (Hoddle et al. 2006).  
 
 
Scientific name: Caliothrips fasciatus (Pergande  1895)  
Order/Family: Thysanoptera/Thripidae  
Other names:  Heliothrips fasciat us, Hercothrips fasciatus , Caliothrips woodworthi , North American 
bean thrips, California bean thrips (Bailey 1933)  
 
Summary of c onclusion s 
 
Given the arguments and evidence presented : 
 
• Caliothrips fasciatus meets the criteria to be a quarantine pest for New Zealand.  
• Caliothrips fasciatus has a strong association with fruits of Citrus sinensis  (navel orange); 
particularly, navel oranges from California, USA.  
• Basic measures  are likely to reduce the likelihood of entry of C. fasciatus by a low  to 
moderate degree (with moderate uncertainty) ; consequently, likelihood of entry is moderate  to 
high.  
• The ability of C. fasciatus  to transfer from imported fruit to suitable host plants i s low , with 
moderate uncertainty.  
• The suitability of the New Z ealand climate for establishment of C. fasciatus  is rated as high . 
• Caliothrips fasciatus  is likely to cause moderate impacts, overall; impacts on crop hosts  is 
likely to be low , but establishment in citrus -growing areas could lead to long-term costs for 
phytosanitary measures to ensure access to foreign markets, for citrus exports . 
• Caliothrips fasciatus may be considered for additional measures on citrus fruit . 
 
Summary of risk assessment against criteria  
 
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Moderate –high Low 
The ability to move from the imported commodity  onto a suitable host  Low Moderate  
Suitability of the N ew Zealand  environment  High Low 
Impacts on the New Zealand economy, environment, health and society  Low Low 
 
12.1.1  Hazard  identification: quarantine status  
Given the arguments and evidence below,  Caliothrips fasciatus meets the criteria to 
be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential importance (able to establish and cause harm).  
  
391 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  There are no records of Caliothrips fasciatus from Ne w Zealand87. 
• The pest is not recorded in PPIN (2020), NZOR (2020) or NZ Inverts (2020).  
• Caliothrips fasciatus is a regulated pest for New Zealand , recorded as “regulated” in ONZPR  
(2020).  
 
Caliothrips fasciatus has the potential to establish  in New Zealand . 
• Caliothrips fasciatus  is native to the United States of America  (USA ) and is found in Alabama, 
Arizona, California, Florida, Idaho, Louisiana, Nevada, Texas, South Carolina and Wyoming.  
• Compared with New Zealand, some of the locations in the USA where C. fasciatus  occurs 
have a climate match index (CMI) value ≥ 0.7, which indicates enough climate similarity to 
allow establishment of the pest in New Zealand (Phillips et al. 2018).  
 
Caliothrips fasciatus has the potential to cause  impacts  in New Zealand . 
• The pest is of major quarantine concern as a contaminant of navel oranges from California 
(Hoddle et al. 2006), and its establishment in New Zealand (especially in citrus -growing areas 
of the North Island) is likely to affect access to export of citrus fruits,  especially navel oranges  
to Australia . 
• The pest has also been reported on more than 60 genera of plants in the state of California, 
including more than forty cultivated crops (Bailey 193 3; Hoddle 2020 ). Some host plants of 
C. fasciatus  that are economically important to New Zealand include pear ( Pyrus  spp.), 
lettuce ( Lactuca  sativa ), watermelon ( Citrullus lanatus ), onion ( Allium  cepa ) and brassicas 
(Plant & Food Research  2019; Vegetables New Zealand 2020).  
 
12.1.2  Hazard identification: commod ity association  
Caliothrips fasciatus  is associated with citrus fruit . 
• Although C. fasciatus  does not feed on citrus , adults of the thrips overwinter in the navel of 
navel oranges in California from November to March, which coincides with the harvest seaso n 
for citrus fruits in California.  
• The pest is frequently intercepted on citrus fruit from the USA at the borders of Australia and 
New Zealand (EPPO 2020; Hoddle et al. 2006; LIMS 2020).  
• The pest is reported as present in USA and Mexico , two of the exporti ng countries being 
considered in the citrus fresh produce import risk analysis.  
 
12.1.3  Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below,  Caliothrips fascia tus has a strong 
association with citrus  commodities, especially fresh fruit of navel oranges ( Citrus 
sinensis ) from the USA (California) . 
There are reliable record s of Caliothrips fasciatus  on citrus  plants and traded citrus fruit from 
California : 
• The first published record of this thrips , in 1895 , was of two specimens colle cted from  an 
orange leaf  in Yuba County, California, in November 1894  (Bailey 1933).  
• Bailey (1933) cites Russell (1925) as having recovered hibernating adult bean thrips  from the 
navel end of oranges sent from California to Lincoln, Nebraska and Urbana, Il linois.  
• Whitney (1930) reported that in Hawaii in December 1929, hibernating adults of Hercothrips 
fasciatus  (syn. Caliothrips fasciatus ) were found on shipments of persimmons, tangerines and 
oranges from California.  
• Between 1988 and 2020, there were 157 interceptions of C. fasciatus  at the New Zealand 
border, 99%  of the them  on fresh oranges, with the remaining 1% shared between lemons, 
                                                      
87 The CABI Invasive Species Compendium  datasheet on C. fasciatus  https://www.cabi.org/isc/datasheet/112877  includes New 
Zealand in distribution table, but there is no supporting evidence from any other sources (database or primary literature).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 392 tangerines, mandarins, tangelos, pears and apples . All commodities on which the pest was 
intercepted were from the USA (LIMS 2019).  
• Hibernating adult bean thrips were collected from leaves of orange ( Citrus sinensis ) infested 
with soft brown scale ( Coccus hesperidum ) at Davis, California . The thrips were huddled 
among the scales, with  some hiding in the emergence holes of the parasiti sed scales (Bailey 
1933).  
 
Given the arguments and evidence below, basic measures are likely to reduce the likelihood 
of entry of C. fasciatus on citrus fruit  by a low-moderate degree . Consequently, the likelihood 
of entry is moderate  to high. 
Caliothrips fasciatus  may be visually detect able in the field  and in packing houses, leading to its 
removal from produce, but some individuals are likely to be undetected:  
• Only adults of C. fasciatus  are known to over winter (usually in aggregations) in the navels of 
navel oranges (Bailey 1933; Hoddle et al. 2006), and such aggregations are likely to be 
detected and removed during harvest and post -harvest processes.  
• Due to the high level of awareness in California of th e phytosanitary risk posed by 
C. fasciatus  in association with citrus exports, a rigorous systems approach  for pre -export 
management of the pest has been developed and includes in -field monitoring using sticky 
traps, post -harvest inspections and packhouse processes (Harman et al. 2007a, 2007b).  
• However, Harman et al. (2007b) suggest that despite the systems approach, the usually low 
infestation levels (less than 0.5% ) of C. fasciatus on citrus fruit  in California, coupled with the 
pest’s small size, w ould b e likely to make detection of all infested fruit difficult.  
• Laboratory experiments by Harman et al. (2007b) showed that washing  navel oranges  using 
either of five spray rinses, including distilled water, resulted in close to 90% recovery of thrips , 
leaving  about 10% of the pest population in the fruit.  
• Thus, post -harvest processes such as washing, brushing, cleaning and waxing are likely to 
dislodge some of the hibernating C. fasciatus  adults from fruit, but individuals deep inside the 
fruit navel may rema in associated with the fruit.  
• Frequent interceptions of live, adults of C. fasciatus  on navel oranges from the USA at the 
New Zealand border (LIMS 2019) indicates that basic measures  do not prevent entry of the 
pest into New Zealand.  
• Therefore, additional measures may be required to adequately reduce the likelihood of entry 
of the pest.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of C. fasciatus to transfer from 
imported fruit onto a host plant (exposure) to allow establishme nt, is rated  low (with 
moderate uncertainty) .  
 
Overwintering adults of the pest on imported fruit that arrive in summer can come out of hibernation . 
• Only adults of the pest, which can fly, are likely to be associated with imported citrus fruit,  
since only adults overwinter in citrus fruits (Bailey 1933; Hoddle 2020; Hoddle et al 2016).  
• Bailey (1933) observed that entrance into and emergence from hibernation was gradual and 
that in the field during winter, hibernating adults became active on very  warm days when 
temperatures rose to between 23.9 °C and 26 °C. 
• The citrus harvest season in California is November – May, and as such, the pest is likely to 
arrive New Zealand on citrus shipments in the summer . 
• Average summer temperatures across New Zealand  are usually between 18–21°C (NIWA 
2020) , but daily maxima can be as high as 27 °C, which may allow the pest to come out of 
hibernation and become active. Bailey (1933) reported that adults of C. fasciatus  were usually 
active at temperatures between 10 –47°C, with optimum activity between 23 –32°C, and adults 
can be made to become inactive and to resume activity by respectively, lowering and raising 
temperature.  
  
393 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Adult C. fasciatus  may be able to fly from fruit onto host plants, but this is highly uncertain and 
dependent on where the fruit is disposed of or displayed and their proximity to host plants . 
• Thrips on fruit discarded along with other food waste are often stimulate d (by th e deteriorating 
materials) to search for a suitable host on which to feed (Lewis 1997).  
• Individuals of most thrips species can launch themselves into the air from flat plant surfaces 
such as petals or leaf blades , but they often choose a protruding narrow edge from which to 
jump  (Lewis 1997).  
• However, the absence of information on adult  C. fasciatus  or other thrips launching into flight 
from dis carded waste, creates some uncertainty . Presumably, the pest would need to crawl or 
climb to a sufficiently high level above ground to enable it to launch into flight, a nd this is not 
likely to be possible from waste discarded in landfills, but could be possible from open 
compost heaps in gardens and even more likely from  a roadside fruit stall or market.  
• If a launch site  is found , the takeoff of thrips ’ flight is strongly influenced by weather  factors , 
especially temperature, light and wind ; most thrips from temperate climate s are able to take 
off at a minimum temperature  of 17°C to 21°C, with most takeoffs occur ring during the 
warmest part of the day  (Lewis 1997).  
• Although thrips are regarded as weak flyers, their finely fringed wings enable them to remain 
airborne long enough for the wind to blow them to great heights an d for long distances (Lewis 
1991) .  
• There is abundant circumstantial evidence that, at least when they are near the level of 
vegetation during a long distance wind -assisted flight, th rips exercise a  sufficient degree of 
control  that allow s them to choose t o alight on host crops ; even on individual plants  (Lewis 
1991). There is also experimental evidence that thrips in flight can respond to the scent of 
host plants and flowers , using them as visual and olfactory cues to recognise and land on 
suitable hosts  (Kirk 1985).  
• Many known hosts of the pest are present in New Zealand and include outdoor crops (e.g. 
clover, lucerne, lettuce, onion, corn, pear, peach, apple, grapes) and common weeds: field 
bindweed ( Convolvulus arvense ), sow thistle ( Sonchus oleraceus ) and prickly lettuce 
(Lactuca serriola ) (Bailey 1933),  which increases the likelihood of the pest landing on a 
suitable host plant.  
  
Unmated female C. fasciatus  are not likely to establish a breeding population . 
• Rugman -Jones et al. (2012)  showed that virgin females (n=90) from three distinct 
populations, kept individually and allowed to oviposit on a bean leaf for 11 days, failed to 
produce any offspring , and v irgin females isolate d in groups of five only produced males.  
• Bailey (1933) show ed that after 10 days, female C. fasciatus  mated once and lived naturally 
for 20 days, only laid eggs that hatched into male offspring, with repeated mating required to 
produce females.  
• In California, adults coming out of hibernation began to feed, mate an d lay eggs in March 
(early spring) when average daily temperatures were about 13 –15°C (Bailey 1933).  
• It is uncertain  if previously mated females coming out of hibernation in New Zealand will able 
to lay viable eggs without mating or if they can find males with which to mate .  
• There is no evidence that the species produces a sex pheromone, although its ability to form 
overwintering aggregations inside the navels  of oranges  is thought to be mediated by a male -
produced aggregation pheromone, which is yet to be  identified (Hoddle 2020).  
 
Cumulative cold stress, from cooling before and during transit, may render hibernating female C. 
fasciatus  incapable of producing viable offspring, but this is highly uncertain . 
• Hoddle et al. (2006) report that navel oranges are shipped from California at a temperature of 
2.78°C to Australia ( the same probably applies to New Zealand) and hypothesize that 
exposure to this low temperature for the duration of transit (18 –24 days to Australia) could be 
rendering female C. fasciatu s incapable of laying viable eggs.  
• Hoddle (2020) suggest s that bean thrips surviving harvest, washing/waxing, cool storage and 
refrigerated shipping are not “fit” when they arrive in a new locale  and that this may partly 
explain the pest’s failure to esta blish outside its native range despite being exported from 
California inside the navels of oranges since at least 1899 – a view shared by Mound et al. 
(2011).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 394 • Hoddle (2020) concludes that c ompounding cold stress resulting from winterization, storage, 
and s hipping may have a significant negative impact on fitness,  i.e. the longevity and 
fecundity, of surviving thrips.  
• Simply put, cold -debilitated thrips that make it to Australia and New Zealand alive and escape 
into the wild are unable to found viable popula tions of sufficient size to overcome additional 
establishment barriers posed by natural enemies, competition from other thrips species and 
unpredictable  environmental effects (e.g. a heat wave).  
• However, Bailey (1933) observed that hibernating C. fasciatu s in the field did not appear to be 
affected by temperature s as low as -8°C, without stating the duration of exposure to this low 
temperature.  
• It is likely that duration of exposure  to cold temperature is important for the negative effect on 
fitness  of C. fasciatus females  that has been suggested by Hoddle et al . (2006) and Mound et 
al. (2011).  
• The cold -stress hypothesis about C. fasciatus  is plausible but uncertain , because it has not 
yet been tested and proven experimentally.  
 
 
Given the arguments and evidence below,  the suitability of New Zealand’s 
environment for the establishment of C. fasciatus  is high . 
The native geographic range of C. fasciatus  includes some locations with similar climate s to New 
Zealand . 
• Caliothrips fasciatus  is native to western North America; United States of America  (USA) : 
Alabama, Arizona, California, Florida, Idaho, Louisiana, Nevada, Texas, South Carolina and 
Wyoming ; and Mexico  (Bailey 1933; Hoddle 2020; Hoddle et al.  2006) . 
• Outside of North America, C. fas ciatus has been reported on strawberry plants in Rio Grande 
do Sul, Brazil  (Pinent et al. 2011), Argentina (Bailey 1933) and China  (Steinweden and 
Moulton 1930) . However, these records are considered to be unreliable; t he record s from 
Brazil (and Argentina ) are thought to be “a likely misidentification of Caliothrips phaseoli  by 
non-specialists” (Hoddle 2020), while the record of a single female on citrus in Foochow, 
China, is also considered a likely misidentification of a novel species, which was later 
described as Caliothrips tongi  (Mound et al. (2011). No other records of C. fasciatus  from 
Brazil or China were found . 
• A comparison of the climate of all of New Zealand with the US states where the pest occurs 
using the climate match index (CMI) of Phillips et al. (2018) shows a range of climate 
similarity from low to high (Arizona: 0.5 –0.8; Florida and Texas: 0.6 –0.7; California: 0.6 –0.8; 
Idaho, South Carolina, Louisiana, Wyoming: 0.7 –0.8).  
• CMI ≥ 0.7 indicates that the climate of at least some parts of New Zealand would be suitable 
for the pest to establish (Phillips et al. 2018).  
• Hibernation is a strategy used by the pest to survive cold temperatures, and in California, this 
begins from the start of November (late autumn) and is terminated at the end of Mar ch (early 
spring) after about 5 months; temperatures as low as -8°C appeared to have little effect on 
hibernating adults in the field in California, although the duration of exposure to this 
temperature is not stated (Bailey 1933).  
• The above observation s uggests that climate (even in the colder southern regions of the 
South Island) is not likely to be a barrier to establishment of the pest in New Zealand.   
 
Host availability is unlikely to be a barrier to the pest’s establishment:  
• Many known hosts of the p est are present in both the North and South Islands of New 
Zealand; they include outdoor crops (clover, lucerne, lettuce, onion, corn, pear, peach, apple, 
grape) and weeds: field bindweed ( Convolvulus arvense ) and prickly lettuce ( Lactuca 
serriola ), which increases the likelihood of the pest finding suitable host plants on which to 
establish (Hoddle 2020).  
 
  
395 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Impacts  in New Zealand:  
 
Given the arguments and evidence below,  Caliothrips fasciatus is likely to cause low 
impacts . The  impacts in crop hosts are li kely to be very low to low, but the pest could 
lead to added costs for eradication or long -term phytosanitary measures to prevent 
contamination of citrus fruit for export . 
 
Caliothrips fasciatus  could lead to long -term costs for phytosanitary measures to ensure continued 
access to export markets for navel oranges . 
• The pest is not reported to cause loss of yield or quality in citrus, but it has been a perennial 
problem for California citrus export s, due to its habit of hibernating in the navels of citrus fruit 
such as n avel oranges and pomelo s, necessitating the development of a systems approach of 
phytosanitary measures to maintain access to export markets (Hoddle et al. 2006; Harman et 
al. 2007a ; Hoddle 2020).  
• Given  that the pest is likely to be able to establish in New Zealand, especially in the warmer 
citrus -growing areas, eradication may be necessary, and if not possible, long -term 
management and application of phytosanitary measures would be r equired to maintain 
access to foreign markets for fresh citrus fruit (especially navel oranges) , even if the value of 
citrus exports to New Zealand is currently low  (2019 export sales (free -on-board value) of 
New Zealand oranges were worth NZ$1.7 million  (Plant & Food Research  2019).  
• Sticky traps and many other monitoring and management tools have been developed for use 
in California (Harman et al. 2007a , 2007 b; Hoddle 2020) and could be used in New Zealand 
to reduce infestation of citrus fruits.  
• Hoddle (20 20) states that the severity of bean thrips infestations of citrus in California may be 
driven, in part, by weed abundance and suggests that good weed management within and 
around orchards may reduce the risk of infestation.  
• Therefore, the most likely eco nomic consequences for New Zealand could come from 
attempting to eradicate the pest or establish control systems to ensure continued market 
access for oranges to Australia, where C. fasciatus  is a regulated pest.  
 
Caliothrips fasciatus may cause minor feed ing damage on hosts other than citrus . 
• Like most thrips that attack plants, the injury done by the bean thrips is the direct result of the 
feeding of the larvae and adults on plant tissue, with larvae causing more damage by feeding 
gregariously (Bailey 1933). The pest is, however, unlikely to c ause feeding damage to citrus, 
as it has not been reported to feed on citrus (Hoddle et al.  2006).  
• Bailey (1933) reported that in California, the thrips caused damage on pear, mainly by early 
and excessive defoliation, which weakened the tree for the ensui ng season and exposed both 
the new growth and the fruit to “sun scalding ” in the hottest part of the summer.  
• The thrips only attacked pears  when leaves of infested pear trees became unsuitable for food. 
The attacked pears  were left with ugly scars and minute oily drops of excrement that lowered 
the grade and  marketability  (Bailey 1933). It was noted that such injury only occurred at high 
average temperatures (25 –32°C) in very heavily infested local areas where early defoliation 
was present, with about 1 5% of fruit affected.  
• Although the pest has been reported on a wide range of hosts (in California) , some of which 
are economically important to New Zealand , it has not been reported as causing production 
losses in California or elsewhere since the 1930s (H oddle et al. 2006; Harman et al. 2007a; 
Mound et al. 2011; Hoddle 2020).  
• The pest feeds on many hosts in the legume family (Fabaceae) , e.g. Vicia faba  (broad 
beans), Phaseolus  spp. (beans), Pisum sativum  (peas), Medicago sativa  (lucerne) and 
Trifolium rep ens (clover). Lucerne is a minor crop in New Zealand, but along with clover, it is 
important because of its use as fodder for livestock.  
• Other host plants of C. fasciatus  that are economically important to New Zealand include 
avocado ( Persea americana ), lettuce ( Lactuca  sativa ) watermelon ( Citrullus lanatus ), onion 
(Allium cepa ) and brassicas ( Plant & Food Research  2019;  Vegetables New Zealand 2020) , 
but the damage to these crops has not been quantified.  
• Bailey (1933) stated that in nearly every case of cro p injury in California, the source of 
infestation was local weed growth, particularly the prickly lettuce and the annual sow thistle, Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 396 which suggests that good weed management practice is likely to significantly limit damage in 
crops.  
• The pest is likely to spread naturally, through short hops and flights aided by wind, but the 
rate of natural spread is likely to be slow. The pest may also be spread via the distribution of 
infested fruit.  
• Therefore, although the thrips may spread and feed on commercially grow n plants in New 
Zealand, the damage is likely to be minor and have few impacts for the relevant industries or 
for the New Zealand economy.  
 
Caliothrips fasciatus  may cause low soci ocultural impacts, but  is unlikely to cause environmental and 
health impacts . 
• The pest may cause social impacts, as some of its vegetable hosts, e.g. broad beans, peas 
and lettuce, are grown in private gardens.  
• Efforts to eradicate the pest may require access to private gardens for surveillance, removal 
of host plants, or the appl ication of pesticides to kill the pest, which would cause social 
impacts.  
• None of the recorded hosts are native New Zealand species or species of particular cultural 
significance.  
• There is no evidence that C. fasciatus  causes human or animal health impacts .  
 
 
12.1.4  References  
Bailey , S F (1933 ) The biology of the bean thrips. Hilgardia , 7(12):  467–522. 
BRAD (2020) Biosecurity Risk Analysis Database. Ministry for Primary Industries internal database. 
Ministry for Primary Industries; Wellington, NZ.  Accessed 20  July 2020.  
CABI (2020) Caliothrips fasciatus . Invasive Species Compendium . CAB International; Wallingford, 
UK. https://www.cabi.org/isc/datasheet/112877  Accessed 8 September 2020.  
EPPO (2020) EPPO Glo bal database. Datasheet on Caliothrips fasciatus . 
https://gd.eppo.int/taxon/THRIPL  Accessed 28 July 2020.  
Harman, J A; Mao, C X; Morse, J G (2007a) Selection of colour of sticky trap for monitoring adult 
bean thrips, Caliothrips fasciatus (Thysanoptera: Thripidae) . Pest Management Science , 63(2): 210 -
216. 
Harman, J A; Mao, C X; Robinson, L J; Morse, J G (2007) Evaluation of two non -destructive sampling 
methods for bean thrips (Thysanoptera: Thripidae) dete ction in navel oranges. Crop Protection , 26: 
1747 –1754.  
Hoddle, M  S (2020 ) North American bean thrips - Caliothrips fasciatus  (Pergande) (Thysanoptera: 
Thripidae: Panchaetothripinae) : a perennial export problem for California citrus growers . 
https://biocontrol.ucr.edu/bean -thrips  Accessed 11 September 2020.  
Hoddle, M S; Stosic, C D; Mound, L A (2006) Populations of North American bean thrips, Caliothrips 
fasciatus  (Pergande) (Thysanoptera: Thripidae: Panchaetothripinae) not detected in Australia. 
Australian Journal of Entomology, 45: 122 –29. 
Kirk, W  D J (1985 ) Effects of some floral scents on host finding by thrips (Insecta: Thysanoptera) . 
Journal of Chemical Ecology , 13(1): 35–43. 
Lewis, T (1991 ) Feeding, flight and dispersal in thrips . In Bruce , L; Parker , M S (eds) Towards 
Understandin g Thysanoptera . General technical report  NE-147, US Department of Agriculture, 
Radnor . http://www.treesea rch.fs.fed.us/pubs/4216  Accessed 10 September 2020.   
397 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Lewis, T  (ed) (1997) Thrips as Crop Pests . CAB International; Wallingford, UK.  
LIMS (2019) Laboratory Information Management System. Ministry for Primary Industries internal 
database. Accessed 27 July 202 0. 
Moulton, D; Steinweden, J B (1930) Thysanoptera from China. Proceedings of the Natural History 
Society of the Fukien Christian University , 3: 19 –30. 
Mound , L A; Zhang , H-R; Bei, Y-W (2011) Caliothrips tongi  sp. n. (Thysanoptera, Thripidae) from 
China, and a dubious record of North American Bean Thrips. Zootaxa , 2736: 57 –62 
NIWA (2020) The National Climate Database. https://cliflo.niwa.co.nz/  Accessed 27 July 2020.  
NZInve rts (2020) NZ Land Invertebrates. https://nzinverts.landcareresearch.co.nz/  Accessed 7 
September 2020.  
NZOR (2020) New Zealand Organisms Register. http://www. nzor.org.nz/  Accessed 20 July 2020.  
ONZPR (2020) Official New Zealand Pest Register. https://www.mpi.govt.nz/ne ws-and-
resources/resources/registers -and-lists/biosecurity -organisms -register -for-imported -commodities  
Accessed 20 July 2020.  
Phillips, C B ; Kean, J M ; Vink, C J ; Berry, J A (2018). Utility of the CLIMEX ‘match climates regional’  
algorithm for pest risk an alysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3) : 777–791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Pinent , S M J ; Nondillo , A; Botton , M; Redaelli , L R; Pinent , C E da C (2011 ) Species of thrips 
(Insecta, Thysanoptera) in two strawberry production systems in Rio Grande do Sul State, Brazil. 
Revista Brasileira de Entomologia , 55 (3) : 419–423. 
Plant & Food Research (2019) Fresh Facts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ. https://www.freshfacts.co.nz/files/freshfacts -2019.pdf  
Accessed 14 September 2020.  
PPIN (2020) Plant Pest Information Network. Ministry for Primary Industries internal database. 
Ministry for Primary Industries; Wellington, NZ. Accessed 20 July 2020.  
Rugman -Jones, P F; Hoddle, M S; Amrich, R; Heraty, J M; Stouthamer -Ingel, C E; Stouthamer , R 
(2012) Phylogeographic structure, outbreeding depression, and reluctant virgin oviposition in the bean 
thrips, Caliothrips fasciatus (Pergande) (Thysanoptera: Thripidae), in California . Bulletin of 
Entomological Research , 102(6): 1 –12. 
Vegetables New Z ealand (2020) Covered crops. https://www.freshvegetables.co.nz/crops/covered -
crops/  Accessed 14 September 2020.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 398 12.2 Chaetan aphothrips  orchidii  (orchid thrips)  
 
Chaetanaphothrips orchidii  adult females are about 0.8 –1.0 mm long, pale yellow with two dark bands 
on the wings. This thrips is polyphagous and damaging to some economic crops/ornamentals.  
 
Scientific name: Chaetanaphothrips orchidii  (Moulton, 1907)  
Order/Family: Thysanoptera/Thrip idae 
Other names include: Euthrips orchidii  Moulton,1907; Euthrips marginemtorquens  Karny, 1914 
(Mound et al. 2017); Anthurium thrips (Hara et al. 2002), orchid thrips, citrus rust thrips 
(http://www.ces.csiro.au/aicn/system/c_4149.htm ) 
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Chaetanaphothrips orchidii  meets the criteria to be a quarantine pest for New Zealand.  
• Chaetanaphothrips orchidii  has a strong association with citrus fruit.  
• Basic measures  are likely to reduce the likelihood of entry  of C. orchidii  to a moderate  to high 
degree . Consequently, the likelihood of entry is considered  low to moderate (with low 
uncertainty).  
• Chaetanaphothrips  orchidii  has a moderat e ability to move from imported fruit and into a 
suitable environment to allow establishment, that is, onto a host plant (with low uncertainty).  
• The suitability of the New Zealand environment for C. orchidii  to establish is considered  
moderate  (with low un certainty).  
• The level of impact caused by C. orchidii  is considered low  to moderate (with low uncertainty).  
• Chaetanaphothrips  orchidii  may be considered for additional measures . 
 
Summary of risk assessment against criteria  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Low 
The ability to move from the imported commodity  onto a suitable host  Moderate  Low 
Suitability of the N ew Zealand  environment  Moderate  Low 
Impacts on the New Zealand economy, environment, health and society  Low–moderate  Low 
 
12.2.1  Hazard  identification: quarantine status  
 
Given the arguments and evidence below,  Chaetanaphothrips orchidii  meets the 
criteria to be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: not present in PRA area (New 
Zealand), and of potential importance (able to establish and cause harm).  
 
Chaetanaphothrips or chidii is not known to be present in New Zealand .  
• It is recorded as not present in New Zealand in PPIN (2020 ). 
• It is not listed in NZOR (2020 ). 
• It is listed as ‘regulated’ in ONZPR  (2020 ). 
 
Chaetanaphothrips orchidii  has the potential to establish and spr ead in New Zealand . 
• C. orchidii  is present in countries with regions that have a climate match  index (CMI)  of at 
least 0.7 or greater with New Zealand (Phillips et al. 2018), e.g. Australia, Spain, Japan, USA.   
399 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • C. orchidii  is polyphagous and is reported  to feed on a wide range of plants , including fruit, 
vegetables, ornamentals, herbs, grasses and weed species in at least 32 genera across 20 or 
more families (Childers and Stansly 2005). Some hosts are commonly grown in New Zealand 
such as citrus, sweet pota to and corn/maize (see impacts below).  
• C. orchidii is mobile  and able to walk short distances , and adults are capable of flight. 
Dispersal and spread can be active and/or human assisted through movement of infested 
plant material.  
 
Chaetanaphothrips orchid ii has the potential to cause impacts on the economy and environment of 
New Zealand : 
• C. orchidii  is recognised as a pest of plants of economic concern to New Zealand, including 
fruit crops of oranges, grapefruit (Childers and Stansly 2005), lemons (Goane e t al 2013), 
avocado (Izhar 1997; Argov 2003) and ornamentals such as anthuriums and orchids (Hara et 
al. 2002), Acer (maples) , Adiantum  (maidenhair fern), Croton , Dracaena , Monstera  and 
Rhododendron  (Childers and Stansly 2005).  
• C. orchidii has hosts overse as in genera that have species native to New Zealand, such as 
Ipomoea , Sonchus , Alternanthera  (Childers and Stansly 2005; Breitwieser et al. 2010), and 
has the potential to damage them.  
 
12.2.2  Hazard identification: commodity association  
 
Chaetanaphothrips orchi dii is associated with citrus fruit . 
 
Chaetanaphothrips orchidii  is reported from citrus fruit . 
• Childers and Stansly (2005) report feeding damage to citrus fruit by C. orchidii . 
 
12.2.3  Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Chaetanaphothrips orchidii  has a strong 
association with citrus fruit . 
 
There are several published reports of C. orchidii  on citrus fruit.  
• C. orchidii  has the specific habit of feeding where fruit in clusters are touching each other or 
where some o ther part of the plant (leaves, branches) are in contact with fruit (Childers and 
Stansly 2005).  
• C. orchidii  was identified as the primary cause of rind blemish damage to clustered citrus 
fruits in Florida. C. orchidii is found on citrus fruit throughout t he whole year in Florida’s citrus -
growing areas. It is found mostly on grapefruit, more so on the red grapefruit, and has been 
found on oranges (Childers and Stansly 2005).  
• C. orchidii  was detected in lemon orchards in northwest Argentina causing high levels of 
damage to fruit (Goane et al. 2013)  
• C. orchidii  is reported from orange fruit in Spain (Campos Rivela et al. 2017) and from citrus 
fruit in Israel (Argov 2015).  
• C. orchidii inser ts its eggs in the epidermis of leaves and fruit. Adults and larvae are 
associated with fruit but there are no reports of pre -pupae or pupae remaining on the fruit or 
tree. (Catal án et al. 2019).  
 
Chaetanaphothrips  orchidii  has been intercepted at the New Zealand border, but not on citrus fruit.  
• Between 2001 and 2013 there have been six separate occasions where C. orchidii  has been 
detected live on cut flowers, ( e.g. Anthurium  from Mauritius C2013/217900), and also on an 
unrecorded commodity from Fiji [2003 /27494] (MAFBNZ Interception database1988 –2014)  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 400 • EPPO interception data (1 Sept ember  1999 to 2 July 2020) has no records of detections for 
C. orchidii  on citrus fruit.  
• It is uncertain why there do not appear to be records of C. orchidii  on imported citrus, though 
it is possible it may not survive in -field treatments or pre -export treatments, especially if 
coming from fruit fly inhabited areas. Dead -on-arrival invertebrates are seldom recorded if 
detected. Alternatively, New Zealand is not currently importing  citrus fruit from some areas or 
countries where C. orchidii  is most commonly infesting citrus fruit, e.g. Israel, Spain, Florida 
(Quancargo 2020).  
 
 
Given the arguments and evidence below, basic measures are likely to reduce the 
likelihood of entry of Chaetanaphothrips orchidii  to a moderate  to high degree . 
Consequently, the likelihood of entry is low  to moderate (with low uncertainty) . 
Usually, visual inspection should detect C. orchidii  on citrus fruit.  
• Often , damage by C. orchidii  to fruit begins at the onset of the fruit coming into contact with 
other fruit or some part of the citrus tree. High levels of infestation would be readily detectable 
as C. orchidii  causes very obvious damage to citrus fruit which should be a cue to its 
presence. Feeding damage signs are  almost circular, tan -coloured areas at the points of 
contact with other fruit or parts of the tree. The thrips is present on citrus throughout the 
fruiting season to harvest (Catal án et al. 2019), indicating it can be foun d on fruit ready for 
harvest.  
• The thrips are small and pale yellow with cryptic behaviour , but their movement may make 
them more likely to be detected.  
• However, low levels of infestation are less detectable , and very early feeding damage may be 
mistaken for branch rub. Individuals are harder to detect, especially as the hiding behaviour  
appears characteristic of this species (Childers and Stansly 2005; Goane et al. 2013).  
 
General post -harvest handling may not dislodge some C. orchidii . 
• In most cases , harve sting and grading is expected to reveal damaged fruit , which is likely to 
be excluded from export.  
• However, if damage is minor  or mistaken  for branch rub  then those fruits may still be sent for 
export. Although it is not reported if this species  of thrips  will hide under the calyx of citrus 
fruit, there is the opportunity for occasional individuals to remain and eggs are likely to remain 
embedded  in fruit. Calyces are not taken off fruit , as this hastens fruit decay (Cronje et al . 
2005).  
 
 
Likelihood of es tablishment:  
 
Given the arguments and evidence below,  the ability of Chaetanaphothrips  orchidii  to 
move from imported fruit and into a suitable environment to allow establishment, that 
is, onto a host plant  is considered moderate  (exposure) . 
Most waste in New Zealand is disposed of by low -risk methods.  
• Collection of bagged waste for landfill or putting food waste into a kitchen disposal unit are 
common methods of disposing of food waste. Thrips on imported fruit are very unlikely to 
survive either method (w aste analysis , section 2.4.1 ). 
 
Some waste from citrus fruit is likely to be disposed of in proximity to host plants.  
• A proportion of unavoidable waste generated from imported citrus fruit will end up exposed to 
the environment, e.g. in open composts in ho me gardens.  
• Some hosts of C. orchidii  are commonly grown in home gardens, such as lemons, begonias, 
chrysanthemums, maples, parsley and sow thistle (puha).  
• A proportion of the thrips that survive to this point are likely to seek a new host plant.  
 
C. orchi dii is moderately mobile.  
• Immature thrips have not yet developed their wings but are capable of walking short distances 
between leaves, flowers and fruits and between close plants.   
401 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Adults are winged and can fly short distances between different plants, or  walk between plant 
parts and very close plants.  
• Wind is known to assist in dispersal of adult thrips and carry them long distances (Lewis 
1997; Lo et al. 2000). As C. orchidii  is highly polyphagous , it is likely to find suitable hosts.  
 
 
Given the argume nts and evidence below, the suitability of the New Zealand 
environment for establishment of Chaetanaphothrips  orchidii  is considered moderate  
(with low uncertainty) . 
The geographic distribution of C. orchidii  is largely tropical and subtropical, but also i ncludes some 
areas of temperate climates.  
• It is thought that C. orchidii  may have its origins in South East Asia, as many other species of 
the genus do (Hoddle et al. 2012).  
• Table 13.2.1 provides the current geographical distribution. Countries or areas that are 
underlined have a climate match index (CMI) with New Zealand of at least 0.7 or greater 
(Phillips et al. 2018).  
• Climate matches of 0.7 or greater indicate there are parts of New Zealand where our climate 
is similar enough to be suitable for C. orchidii  establishment.  
• C. orchidii  has spread throughout the citrus -growing region of Spain , and those areas show a 
70% to 80% climatic similarity with New Zealand  (CMI 0.7 – 0.8), in parti cular, with the 
northern half of the North Island (i.e.: Hawke ’s Bay, Gisborne, Bay of Plenty, Auckland, 
Northland) , where most of the citrus production is. This is the more likely area for outdoor 
establishment.  
• In Israel , C. orchidii is reported from areas on the Northern Coastal Plain (e.g. Ga’ton, Bet 
HaEmek)  and the Central Coastal Plain (e.g. Herzliyya) (Izhar 1997), which have a climate 
match of 0.7 with New Zealand.  
• Sakimura (1975) notes that C. orchidii  is well established in the wet, native fores t areas in 
Hawaii and has been collected from plants ( Cyrtandra  sp., Hedyotis  sp., Pisonia  sp., 
Spath oglottis  plicata , Zingiber zerumbet ) found at below 1 ,000-m elevation.  
• In northwest Argentina88, the thrips is found in the northern region of Tucum án provi nce ( e.g. 
La Ramada, CMI 0.6; El Sunchal, CMI 0.7) and in the centre -south region of Tucum án 
province (e.g. Monte Grande and Caspinchango, CMI 0.7; Aguilares, CMI 0.8). These two 
regions in Tucum án have different climatic and ecological conditions , and the citrus trees 
perform differently. Both regions have a warm, humid climate , but the rainfall and water deficit 
vary. The north has an average rainfall of 700 –900 mm with a water deficit of 0 –200 mm 
between winter and spring , and the risk of frost e xtends from June to August. In the centre -
south , the citrus -growing areas are on the mountainside with creeks, streams and rivers 
crossing it. The average rainfall is 900 –1,700  mm with little rainfall in winter and spring, but no 
soil water deficit. The ri sk of frosts is rare. The lemon trees of the centre -south have higher 
vegetative growth, a larger canopy and a higher density of leaves than those of the north, and 
also produce larger fruits earlier (Goane et al. 2013). C. orchidii  is found in higher numb ers 
and causing greater damage in the centre -south of Tucum án, suggesting the conditions are 
more suitable there than in the north. In New Zealand , the main citrus -producing areas have a 
relative humidity between about 73% and 87% over the year, and a comp arable rainfall with 
centre -south Tucum án, but, it occurs mainly during the winter months , as do the highest 
number of ground frost days; this information is based on data giving mean monthly values 
from 1981 –2010 (NIWA 2020), but doesn’t reflect the chang e in climate trends.  
• Climate trends for New Zealand were reported in October 2020  (Ministry for the Environment 
and StatsNZ 2020). The current trends for 30 sites throughout New Zealand during 1972 to 
2019 show an overall increase in minimum and maximum da ily temperatures in many of the 
major horticultural growing areas. There is also an increasing trend in growing degree days. 
Frosts are less common, e.g. Nelson and Tara Hills averaged a loss of 5 days per decade, 
one of the fastest decreases in frost days . Whangarei never recorded more than 2 frost days 
per year, but since 1994 , there has not been a temperature below zero recorded at this site. 
Rainfall is also changing, with one third of the sites getting less, many of these are in the 
northern half of th e North Island. Annual rainfall decreased by 4.3% per decade in Whangarei 
                                                      
88 C. orchidii may be elsewhere in Argentina, but Goane et al. (2013) only rep orted on the thrips in relation to the lemon trees of 
specific areas in Tucum án. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 402 and by 3.2% per decade in Tauranga, relative to the average rainfall over the entire period. 
Winter and spring rainfall is decreasing in a number of sites in northern North Island. 
Conversely, the southern South Island and West Coast sites showed increased annual rainfall 
(Ministry for the Environment and StatsNZ 2020).  
• This high -level comparison of climate suggests there are areas in New Zealand, particularly 
within the northern Nor th Island , that are likely to be suitable for C. orchidii  establishment.  
 
Table 13.2.1  Known geographic distribution of Chaetanaphothrips orchidii  as at July 2020. Countries in 
bold  are those considered as current or potential exporters of citrus fruit to New Zealand, and those underlined  
have regions with a CMI of 0.7 or greater with New Zealand.  
 
Continent  /region  Country  /area  
Africa  Mauritius, S ão Tom é and Principe (CPC 2019).  
Asia India, Indonesia, Japan  (Honshu , Kyushu), Malaysia, Nepal, Sri Lanka, Taiwan  
(CPC 2019) , Israel (Izhar 1997); China  (Guizhou Province ) (Yan et al. 2018) , 
Philippines (Mituda -Sabado and Calilung 2000) , Israel (Argov 2003)  
North America  Mexico , USA  (California , Florida , Hawaii , Illinois , Louisiana , Massachusetts  
(CPC 2019) and Kentucky , Washington DC  and New York  (Hara et al. 2002) ) 
Central and South 
America  Costa  Rica, Cuba, Dominica, Dominican Republic, Grenada, Guadeloupe, 
Honduras, Jamaica, Puerto Rico, Saint Lucia, Trinidad and Tobago, Argentina 
(Tucum án), Brazil  (Minas Gerais, Rio Grande do Sul ), Ecuador , Suriname 
(CPC 2019)  
Europe  Italy*, Poland * (CPC 2019) , Spain  (Alcanar -Tarragona , El Baix Maestrat , La 
Safor , La Costera , La Ribera and the Marina Alta ) (Catal án et al. 2019)  
(* are Greenhouse records)  
Oceania  Australia  (New South Wales, Queensland ), Tonga (CPC 2019) , Fiji 
(interception data C2003/27494, MPI internal d atabase). 
 
Host availability is not a barrier to the establishment of C. orchidii . 
• C. orchidii  is polyphagous, feeding on at least 32 genera across 20 or more families , including 
ornamentals, herbs, fruits, vegetables, grasses and several weed species. The following are 
plants that C. orchidii  is reported from overseas and are found growing in New Zealand:  
Acer (maple), Adiantum  (maiden hair ferns), Alternanthera, Amaranthus , Begonia , Bidens 
pilosa, Cattleya labiata  (orchid), Cyclamen , Citrus  spp., Dracaena, Ficaria, Hypoxis, 
Monstera, Musa, Paspalum paniculatum, Philodendron, P ortulaca oleracea,  Rhododendron 
simsii , Saintpaulia ionantha, Sonchus oleraceus  (sow thistle/puha), Spathoglottis  and 
Tradescantia  (Childers and Stansly 2005). Other plants listed by CPC (2019) that are found in 
New Zealand include Allium, Anthurium andrea num, Bougainvillea, Chrysanthemum, 
Euphorbia (spurges), Ipomoea batatas  (sweet potato), Lycopersicon, Passiflora, Petroselinum 
crispum  (parsley), Piper, Pisonia  and Zea mays  (corn).  
 
Greenhouses are suitable environments for C. orchidii  to live in.  
• There are records of C. orchidii  infesting greenhouses throughout the USA and parts of 
Europe (Hara et al . 2002). In Poland , this thrips was found in flowers and leaf buds of 
Anthurium  andraeanum  plants in glasshouses and was eliminated after several spray  
treatments (Labanowski 1999). In Italy , the first record for C. orchidii  was on Piper  in a 
glasshouse of a tropical plant collection in Florence (Bene and del Gargani 2001). 
Establishment in greenhouses would enable C. orchidii  to increase its range withi n New 
Zealand.  
 
Chaetanaphothrips  orchidii  has biological traits that can assist its establishment in new environments.  
• Males of C. orchidii  have not been reported (Sakimura 1975; Hara et al. 2002; Childers and 
Stansly 2005; Goane et al. 2013; Catal án et al. 2019). Hara et al. (2002) comment that 
“reproduction occurs without mating and is continuous throughout the year” in Hawaii . This 
infers reproduction is  thelytokous parthenogenesis , which means the offspring are females. 
This provides an advantage to e stablishment as a single adult female does not need to find a  
403 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  mate in order to be fertilised and lay eggs. This increases the likelihood that a single female 
could initiate a new population.  
• No information was found (that was available and in English) to g ive lower developmental 
thresholds for this species, which is one factor that can contribute to assessing how likely 
establishment in New Zealand is. However, developmental duration is reported. At 25 °C on 
anthurium leaves eggs take about 11 days to hatch , the time from egg to adult is about 34 
days, the time from egg to egg is about 37 days, adult longevity is about 28 days , and the 
total eggs per female is about 75 (Argov 2003, in Childers and Stansly 2005). It is likely this 
species would have several ov erlapping generations per year. No mention of diapause or  
overwintering  was found in the literature .  
 
 
Impacts  in New Zealand : 
 
Given the arguments and evidence below, the level of impact caused by 
Chaetanaphothrips  orchidii  is likely to be low  to moderate (with low uncertainty).  
 
Chaetanaphothrips orchidii  is likely to cause economic impacts within New Zealand.  
Citrus  
• Citrus that C. orchidii  is reported from overseas include lemons, oranges, red grapefruit and 
grapefruit.  
• Adults and larvae feed d irectly on citrus fruit causing rind blemish on maturing fruit. Damage 
occurs at the point of contact between fruit and presents as brown rings or smooth russeting. 
(Childers and Stansly 2005). In Spain, C. orchidii  is a key pest of oranges and is “active on 
fruits throughout the cycle of cultivation” (Catal án et al. 2019).  
• In the Tucum án region of Argentina high levels of damage were reported on lemon fruit 
resulting in rejection of fruit for export. When fruit was sampled as part of a 4 year in -field 
study the population levels varied from 0.6 ± 0.29 individuals per fruit in the northern part of 
the region to 8.2 ± 1.52 individuals per fruit in the centre -south of Tucum án. About 70% of the 
population comprised larvae and about 30% were adults. Winter fruit  had higher levels of 
thrips than summer fruit. In the north, less than 12% of winter fruit had feeding and oviposition 
damage from C. orchidii . In the centre -south, damage was seen in at least 62% of fruit , with 
more than half this amount (27% to 47% depe nding on orchard) considered unacceptable for 
the fresh fruit market. Damage distribution was not uniform through the lemon tree canopy , 
and this was noticed in each orchard sampled. There was a higher proportion of damaged 
fruit in the lower section of th e tree (Goane et al. 2013). This is obviously a characteristic of 
the thrips , as it was also seen in grapefruit crops in Florida. It was suggested that C. orchidii  
prefers humid and shaded microhabitats , given the greater damage was reported from fruit 
clusters within the canopy as opposed to fruit clusters that were more exposed (Childers and 
Frantz 1994 , in Goane et al. 2013).  
• The majority of New Zealand citrus crops are grown in the northern half of the North Island, 
which is also the area more likely for outdoor establishment of C. orchidii . This thrips species 
appears to favour grapefruit, lemon and orange fruits. Domestic sa les for New Zealand in 
2019 for these three fruit crops were NZ$30.3  million,  and export sales were $11.5  million 
(Plant & Food Research  2019).  
Other crops  
• In Bet HaEmek and subsequently 11 other sites on the Northern Coastal Plain  in Israel, 
damage to av ocado reached 74.7% in extreme cases (Izhar 1997). Immatures and adults will 
settle under the sepals or at points of contact between clustered avocado fruit, fruit and 
leaves or branches. Star -shaped feeding blemishes occur around the sepals; at points whe re 
fruit touch each other , circular or oval patches or rings of russeting are found. Similarly to 
citrus in Israel and other countries, only females and larvae were found on avocado (Izhar 
1997). Avocado crops are common in Northland and Bay of Plenty. Avo cado exports earned 
New Zealand about NZ$104.3  million in 2019 and $56.5  million domestically ( Plant & Food 
Research  2019).  
• Banana is a new crop being established in Gisborne and Northland , which could be affected 
by C. orchidii  establishment. As yet , there are no costings available for this fledgling industry.  
• Sweet potato and Allium  are noted as ‘other’ hosts, indicating they are not main hosts of this 
thrips (CPC 2019). Onions earned NZ$170  million in exports during 2019. Sweet potato is Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 404 grown mainl y in the northern regions and in 2019 earned $55.0  million on the domestic 
market ( Plant & Food Research  2019).  
• Overall, a proportion of these horticultural industries may experience a low to moderate level 
of impact from C. orchidii  should it establish. D amage to outdoor crops may be less severe in 
New Zealand than experienced overseas due to inhibiting factors from our climate, such as 
higher rainfall and a shorter duration of high temperatures. Population growth of C. orchidii  
may be slower, not reaching  levels that cause severe damage.  
Greenhouse plants  
• Greenhouse crops that could be affected by C. orchidii  are largely cut flowers (orchids, 
chrysanthemums, anthuriums) and/or ornamentals as in nursery plants and potted indoor 
plants (e.g. bidens , chrysanthemums, orchids, anthuriums, begonias, monstera, maidenhair 
ferns, maples, cyclamen). Damage to anthuriums initially occurs from C. orchidii  feeding 
within the unopened spathe (‘flower’) soon after the bud emerges from the leaf axil. White 
streak s and scarring can be found on both sides of the spathe , and with age , injured tissue 
becomes bronzed looking. Spathes can become deformed and in severe cases fail to open. 
Feeding damage to foliage causes scarring, streaking, bronzing and deformation. Pla nt 
growth can be reduced (Hara et al. 2002).  
• Feeding damage would certainly cause economic losses , as cut flowers and potted 
ornamentals rely on an unblemished appearance in order to obtain the highest available 
prices. Depending on the level of infestatio n plants are likely to be too sickly for sale or may 
be sufficiently damaged as to warrant price reduction in order to sell them. The cut 
flower/foliage sector earned NZ$20 million in exports in 2019  (Plant & Food Research 2019); 
however, that amount inclu ded several different species, some of which are not known to be 
hosts of this thrips. The cut flower/foliage sector earned NZ$20 million in exports in 2019  
(Plant & Food Research 2019) ; however, that amount included several different species , 
some of which  are not known to be hosts of this thrips.  
• Generally protected crops are well monitored , and so once a thrips is detected , most growers 
are likely to spot -spray for control. Labanowski (1999) noted that a few chemical spray 
treatments managed to eradicate C. orchidii  from a greenhouse in Poland. However, each 
spray treatment can be costly to a grower , and sometimes reinfestation can occur from 
outside , causing another cycle of damage and treatments.  
 
Establishment of  C. orchidii may result in increased phyt osanitary measures on exports from New 
Zealand to countries where it is absent.  
• C. orchidii  is on the EPPO A1 quarantine pest list.  Currently, host plants of C. orchidii  do not 
appear to be exported to Chile.  
 
Chaetanaphothrips orchidii  may cause impacts to sociocultural values of New Zealand, and 
potentially to the natural environment, but is unlikely to have impacts upon human health.  
• Ipomoea  batatas  (kumara) and Sonchus olearaceus  (puha) are reported as hosts of 
C. orchidii . Kumara and puha are treasure d plants (taonga) to M āori, and so damage to these 
plants would be considered significant.  
• A number of plants that are C. orchidii  hosts are grown in domestic gardens and amenity 
plantings, such as citrus, cyclamen, maples, rhododendrons, chrysanthemums an d are likely 
to suffer feeding and oviposition damage from C. orchidii  establishment.  
• There are genera native to New Zealand that are reported hosts of C. orchidii overseas, such 
as Adiantum  (maidenhair ferns), Alternanthera, Dracaena , Passiflora  and Sonch us species . 
Beever et al. (2007) stated that most exotic pests that attack native plants are polyphagous, 
but highly damaging polyphagous species appear to be exceptional , and it has been 
postulated that the impact of relatively specialised organisms is li kely to be greater than highly 
polyphagous species . However, there are three introduced thrips species that can reach large 
populations on native plants in native ecosystems (pers. comm. N. Martin , 12 Sept ember  
2013). For instance, the introduced thrips Heliothrips haemorrhoidalis , which is found 
outdoors in central and southern Florida and southern California but in greenhouses 
elsewhere in the USA (Denmark and Fasulo 2010), is known to cause damage to the 
seedlings of native trees in New Zealand (pers. comm. N. Martin , 12 Sept ember  2013). The 
northern areas of the North Island have a number of locally endemic plant species that may 
be at risk from young -growth herbivory, though whether they are likely hosts of C. orchidii  is 
unknown.  
  
405 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  12.2.4  References  
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407 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  12.3 Scirtothrips dorsalis  (yellow tea thrips)  
Scirtothrips  dorsalis  is a small (0.7  mm–1.2 mm long) polyphagous thrip s that causes economic 
damage to many crops by feeding and vectoring viruses . 
 
Scientific name: Scirtothrips  dorsalis  Hood , 1919  
Order/Family: Thysanoptera/Thripida e 
Other names include: Heliothrips  minutissimus  Bagnall,1919; Anaphothrips  andreae  Girault,1925;  
Neophysopus  fragariae  Girault,1927; Scirtothrips dorsalis  var. padmae  Ramakrishna, 1942  (Mound et  
al. 2017) ; chilli thrips, yellow tea thrips, Assam thrips, strawberry  thrips (EPPO 2020)  
 
Taxonomy  
Scirtothrips dorsalis  is now recognised as a species complex, comprising at least  9 cryptic species 
and 2 morphologically distinguishable species ( S. oligochaetus and S. aff. dorsalis ), most of which are 
regionally e ndemic (Dickey et al. 2015) . This has some influence on host plants associated with a 
species in the complex, on its vector potential, on its climate tolerance based on its native range and 
its level of invasiveness (Dickey et al. 2015). For the purposes o f this pest risk assessment the 
complex is considered as a whole, i.e. S. dorsalis sensu lato . 
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Scirtothrips dorsalis  meets the criteria to be a quarantine pest for New Zealand ; 
• Scirtothrips dorsali s has a moderate association with citrus fruit (with moderate uncertainty) ; 
• Basic measures  are likely to reduce the likelihood of entry of S. dorsalis  to a moderate  to high 
degree; consequently, the likelihood of entry is considered low  to moderate (with low 
uncertainty) ; 
• Scirtothrips dorsalis  has a moderate ability to move from imported fruit and into a suitable 
environment to allow establishment, that is, onto a host plant (with low uncertainty) ; 
• The suitability of the New Zealand envi ronment for S. dorsalis  to establish is considered  
moderate (with low uncertainty) ; 
• The level of impact caused by S. dorsalis is considered  low to moderate (with low 
uncertainty) ; and  
• Scirtothrips dorsalis  may be considered for additional measures.  
 
Summary of risk assessment against criteria  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Moderate  Moderate  
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Low 
The ability to move from the imported commodity  onto a suitable host  Moderate  Low 
Suitability of the N ew Zealand  environment  Moderate  Low 
Impacts on the New Zealand economy, environment, health and society  Low–moderate  Low 
 
12.3.1  Hazard identification: quarantine status  
 
Given the arguments and evidence below,  Scirtothrips dorsalis  meets the criteria to 
be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are:  not present in the PRA area (New 
Zealand), and of potential importance (able to establish and cause harm).  
 
Scirtothrips dorsalis is not known to be present in New Zealand .  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 408 • It is recorded as ‘not in New Zealand’ in PPIN (2020 ).  
• It is not listed in Gordo n (2010 ) or NZOR (2020 ). 
• It is listed as ‘ regulated ’ in ONZPR  (2020 ). 
 
Scirtothrips dorsalis  has the potential to establish and spread in New Zealand . 
• S. dorsalis  is established in countries with regions that have a climate match  index (CMI) of 
0.7 or high er with New Zealand (Phillips et al. 2018), e.g. Australia, Japan and USA.  
• S. dorsalis  is very polyphagous and is reported to feed on 225 plant taxa across 72 families 
and 32 orders (Kumar et al. 2013). Hosts of S. dorsalis , such as citrus and roses, are 
commonly grown in New Zealand (see Impacts  in New Zealand, section  13.3.3 ). 
• S. dorsalis  is mobile , as it can walk small distances and adults are able to fly. Spread can be 
active or human -assisted through distribution of infested plant material.  
 
Scirtothrips dorsalis  has the potential to cause impacts on the economy and environment of New 
Zealand.  
• S. dorsalis  can feed on and damage crops of economic concern to New Zealand which 
include grapevine (Tatara 1994), bean, tomato and onion (in Meissner e t al. 2005).  
• S. dorsalis  has the potential to vector three tospoviruses that are not reported from 
New Zealand (Veerekone et al. 2015; PPIN 2020) and potentially are able to damage plants 
of value to New Zealand.  
• S. dorsali s has hosts overseas in genera th at have species native to New Zealand , such as 
Schefflera  and Pittosporum , to which the thrips is reported as causing severe damage 
(Ludwig and Bogr án 2007).  
 
12.3.2  Hazard identification: commodity association  
Scirtothrips dorsalis  is associated with citrus frui t. 
Scirtothrips dorsalis  is reported from citrus fruit . 
• Tatara (1994) reports that S. dorsalis  oviposits into the epicarps of mandarin s and oranges in 
Shizuoka, Honshu, Japan.  
 
12.3.3  Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Scirtothrips dorsalis  has a moderate 
association  with citrus fruit  (with moderate uncertainty) . 
 
There are published reports documenting damage by S. dorsalis  to citrus fruit.  
• In Japan, S. dorsalis  is reported to lay its eggs into the epicarp of mandarins  and oranges 
(Tatara 1994), often under the calyx (Collins et al. 2006). The larvae feed upon the fruit 
(Tatara 1994).  
• Minaei et al. (2016) report that in southern Iran , S. dorsalis  feeds on citrus fruit, piercing and 
sucking out the contents of the epider mal cells causing scarring and scabbing to the rind.  
• S. dorsalis  pupates in sheltered places including under the calyces of flowers and fruits 
(Collins et al. 2006).  
But: 
• S. dorsalis  is usually (but not always) associated with young fruit.  
• In Japan, overw intering females oviposit in young leaves of viburnum and tea in the spring, 
and later generations oviposit into the outer layer of citrus rinds. The author noted that 
satsuma mandarin might not be a suitable host for S. dorsalis , as adult female longevity and 
fecundity was reduced compared to tea and viburnum plants (Tatara 1994).   
409 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Ookubo (2001) noted that S. dorsalis  preferred the young shoots of  podocarp and viburnum 
trees that enclosed citrus orchards, and would only move to ci trus at two periods in the year 
(July and late August to early September) when there were few or no suitable host plants.  
• On Jeju Island, South Korea, S. dorsalis  was observed to migrate from kiwifruit and mango 
orchards to citrus (Hwang et al. 2016).  
However:  
• The above authors and Kang et al. (2015) note that S. dorsalis  is a serious pest on citrus in 
Japan, Taiwan and Korea.  
 
Scirtothrips  dorsalis  has been intercepted frequently at the New Zealand border, but has not been 
detected on citrus fruit.  
• S. do rsalis  has been detected in cut flowers often, particularly roses from India and Colombia, 
e.g. C2019/256691 (LIMS 2020 MPI internal database).  
• It has also been identified on basil leaves from Fiji [C2016/343900] (MAFBNZ Interception 
database 1988 –2014).  
Overseas, all life  stages of S. dorsalis  have been intercepted on mature Momordica  fruit and 
vegetable consignments at the UK and USA borders from Africa and Asia (McLeod and Collins 2006; 
Meissner et al. 2005). Information on the transit conditions was not  provided ; however, there is a 
record of live S. dorsalis  on live plant material intercepted in airmail from Viet  Nam to the USA prior to 
2005 (Meissner et al. 2005), indicating this thrips species will survive the duration of transit and 
obviously some ha ndling on that pathway.  
 
There is moderate uncertainty regarding how likely the thrips would be associated with harvested 
citrus fruit. It has not been intercepted on fresh citrus fruit in New Zealand or the United Kingdom but  
Meisner et al. (2005) report it has been found on citrus fruit carried by passengers at the USA border. 
Given the level of damage it can cause , it is most likely those fruits would be prevented from being 
exported. However, individuals of S. dorsalis  may escape the grading process if  they have  newly 
arrived on fruit and are sheltering under the calyx . 
 
 
Given the arguments and evidence below, basic measures are likely to reduce the 
likelihood of entry of Scirtothrips  dorsalis  by a moderate  to high degree . 
Consequently, the likelihood of entry is considered low  to moderate (with low 
uncertainty ). 
Generally, visual inspection should detect S. dorsalis  on citrus fruit.  
• If thrips have been feeding on the fruit , there is likely to be visible damage, particularly around 
the calyx (Minaei et al. 2015).  
But: 
• If the feeding damage from the thrips is minor , it can sometimes be mistaken for branch -rub 
or wind damage , in which case the thrips may miss detection.  
• S. dorsalis  immatures, adults or pupae can shelter under the calyx of citrus fruit and thus be 
undetectable.  
• Eggs are laid into the rind, often under the calyx and will not be visible.  
 
Low numbers of thrips in a consignment are more difficult to detect.  
• Individual thrips are less likely to be found in a consignment and therefore remain unde tected.  
 
Common post -harvest activities may not remove all thrips.  
• Most thrips are expected to be removed during the usual post -harvest activities. However, as 
eggs are embedded into the rind, often under the calyx , they are less likely to be removed. 
Other life stages that can shelter under the calyx are also less likely to be removed. Calyces 
are not taken off fruit , as this hastens fruit decay (Cronje et al . 2005).  
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Scirtothrips  dorsalis  has moderate ability 
to move from imported fruit and into a suitable environment to allow establishment, 
that is, onto a host plant  (exposure/transfer) . Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 410 Most waste in New Zealand is disposed of  using  low-risk methods.  
• Sending b agged food waste to the landfill or  running waste through  kitchen disposal units are 
common methods of food waste  disposal  (see section 2.4.1) . Thrips on imported fruit are very 
unlikely to survive either method.  
 
Some waste from citrus fruit is likely to be disposed of in p roximity to host plants.  
• A proportion of unavoidable waste generated from imported citrus fruit will end up exposed to 
the environment, e.g. in open composts in home gardens.  
• Some hosts of S. do rsalis are commonly grown in home gardens, such as begonias, r oses, 
chrysanthemums, alstroemerias, cucurbits, beans, tomatoes and strawberries.  
• A proportion of the thrips that survive to this point are likely to seek a viable host plant.  
 
Scirtothrips dorsalis  is moderately mobile.  
• Immature (larvae, prepupae, pupae) thrips have not yet developed their wings but are 
capable of walking short distances between leaves, flowers and fruits and between close 
plants. Adults are winged and can fly short distances between different plants or walk 
between plant parts and close p lants. Dev (1964) observed  that the adults are fast moving 
and will jump at  a slight disturbance , then fly a short distance.  
• Masui (2007) states females have been recorded 50  m from their source and can be wind -
assisted to further distances. Lewis (1997) a nd Lo et al. (2000) also note that wind can assist 
in adult dispersal and carry adults long distances. As S. dorsalis  is highly polyphagous , it is 
likely to find suitable hosts.  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for establishment of Scirtothrips  dorsalis  is considered moderate  (with 
low uncertainty).  
Scirtothrips dorsalis  has a mostly tropical to subtropical geographic distribution with some temperate 
areas.  
• The Indian subcontinent was originally thought to be the native range of S. dorsalis . However , 
the work by Dickey et al. (2015) infers the native range is wider, including South Asia, East 
Asia, South Africa and Australia. This covers a wide range of altit udes and climatic conditions.  
• S. dorsalis  has subsequently invaded the Caribbean, parts of South America, North America, 
and the Middle East, causing severe problems throughout (Seal et al. 2010; Venette and 
Davis 2004; Minaei et al. 2015).  
• Table 13.3.1 shows the current distribution of S. dorsalis . The countries and areas that are 
underlined  have a 70% or greater climate match  (CMI 0.7 or higher)  with New Zealand 
(Phillips et al. 2018).  
• A CMI of 0.7 or higher  indicates there are parts of New Zealand that a re suitable for the 
establishment of S. dorsalis . 
• S. dorsalis  was identified on hydrangea from a nursery near Aquebogue on Long Island, New 
York, early in 2012. The plants were growing in containers that had overwintered in an 
unheated hoop house protected  with a thin layer of plastic. Winter temperatures can reach -
12.2°C to -17.8°C for a few days to a week or so in this region. S. dorsalis  was found in 
subsequent years , and damage on plants in the landscape was attributed to S. dorsalis  (pers. 
comm. D. Gilrein, 2016) , which indicates there was an established population in the area.  
• Climate modelling  showed that most of the North Island is suitable for S. dorsalis  
establishment , and potentially the thrips could have 8 generations/yr in the Northland regio n. 
There is a low degree of uncertainty about the ‘presence data’ that can affect the model . For 
two records , it was uncertain if the thrips was reported from greenhouses or was found 
outdoors.  
• Beever et al.  (2007) state , “Although some … introduced thrips  are pest species overseas, 
they are rarely pests in New  Zealand because the prolonged dry weather they require to 
produce large populations occurs infrequently (Mound and Walker 1982) .” However, this is 
unlikely to be the case today with the current globa l and local warming.  
• Climate trends for New Zealand were reported in October  2020  (Ministry for the Environment  
and StatsNZ 2020) . The current trends for 30 sites throughout New Zealand during 1972 to 
2019 show an overall increase in minimum and maximum da ily temperatures in many of the 
major horticultural growing areas. There is also an increasing trend in growing degree days.  
411 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Frosts are less common, e.g. Nelson and Tara Hills averaged a loss of 5 days per decade, 
one of the fastest decreases in frost days . Whangarei never recorded more than 2 frost days 
per year, but since 1994 , there has not been a temperature below zero recorded at this site. 
Rainfall is also changing, with one third of the sites getting less, many of these are in the 
northern half of th e North Island. Annual rainfall decreased by 4.3% per decade in Whangarei 
and by 3.2% per decade in Tauranga, relative to the average rainfall over the entire period. 
Conversely, the southern South Island and West Coast sites had increased rainfall (Ministry 
for the Environment  and StatsNZ 2020) .  
• This brief overview of the increase of warmer, drier areas indicates there is the potential for 
thrips pest species to produce larger populations in those areas.  
 
Table 13.3.1  Known geographic distribution of Scirtothrips dorsalis  as at July 2020. Countries in bold are 
those considered as current or potential exporters of citrus fruit to New Zealand, and those underlined  have 
regions with a CMI of 0.7 or greater with New Zealand (Phi llips et al. 2018).  
Continen t /region  Country  /area  
Africa  Ivory Coast, Kenya , Uganda (EPPO 2020) , West Coast (Ghana, suggested 
from interception data , McLeod and Collins 2006) , South Africa (Dickey et al. 
2015)  
Asia Bangladesh, Brun ei, Cambodia, China , Hong Kong, India, Indonesia  (EPPO 
2020) , Iran (Minaei et al. 2015) , Israel, Japan , Malaysia, Myanmar, Pakistan, 
Philippines,  South Korea , Sri Lanka,  Taiwan , Thailand, Viet Nam (EPPO 
2020) , Singapore  (Dickey et al. 2015).  
North America  USA  (Florida , Georgia, Hawaii , Texas  (EPPO 2020) , Long Island, New York 
(pers. comm D. Gilrein 2016) ) 
Central and South 
America  Barbados, Guadeloupe, Jamaica, Puerto Rico, Saint Lucia, Saint Vincent and 
The Grenadines, Trinidad and Tobago (EPPO 2020) , Brazil  (Dias -Pini et al . 
2018) , Colombi a (Ravelo et al. 2018) , Suriname, Venezuela (EPPO 2020)  
Europe  Netherlands * (few occurrences), Spain , England * (few occurrences) (EPPO 
2020)  
Oceania  Australia  (New South Wales, Northern Territory , Queensland) , Papua New 
Guinea, Solomon Is lands  (EPPO 2020) , Fiji (intercepted at NZ border , LIMS 
2020)  
* These were possibly reports from greenhouses.  
 
Availability of host plants is unlikely to be a barrier to the establishment of Scirtothrips  dorsalis . 
• S. dorsalis  is highly polyphagous . Using infor mation from the Global Pest and Diseases 
Database, Kumar et al.  (2013) report that S. dorsalis  is recorded feeding on (not necessarily 
reproducing on) 225 plant taxa worldwide in 72 different families and 32 orders of plants.  
• As well as citrus, S. dorsalis  has been reported from: kiwifruit ( Actinidia chinensis ) 
(Sakakibara and Nishigaki 1988,  in McLeod and Collins 2006); onion ( Allium cepa ), 
Asparagus  officinalis , cucumber and melon ( Cucumis  spp.), pumpkin ( Cucurbita  moschata ), 
beans ( Phaseolus  vulgaris ), tomato ( Solanum lycopersicon ) (In: Meissner et al.  2005);  sweet 
peppers ( Capsicum  annuum ), avocado ( Persea  americana ) (Kumar et al. 2013); pear (Pyrus  
spp.) (Masui 2007); common fig ( Ficus  carica ) (Ludwig & Bogran 2007 ); strawberry ( Fragaria  
x ananassa ) (Mound and Palmer 1981); sweet potato ( Ipomoea batatas ) (Venette and Davis 
2004); cherry ( Prunus  spp.) (Collins et al. 2006); eggplant ( Solanum  melongena ) (Raizada 
1965); grapevine ( Vitis vinifera ) (Tatara 1994) , which are all economically important crops 
grown in New Zealand.  
• Also, there are numerous economically important ornamentals and cut flowers that are hosts 
for S. dorsalis  that are grown in New Zealand and are common as landscape, amenity and 
home garde n plants , for instance , poinsettia, gerbera, alstroemeria, rose, begonia, 
snapdragon, crape myrtle, azalea, viburnum, Schefflera  and Pittosporum  (Kumar et al. 2013).  
 
Greenhouses are likely to be suitable environments for Scirtothrips dorsalis , based on ov erseas 
occurrences.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 412 • S. dorsalis  has been reported from greenhouses overseas, e.g. on tomatoes in a plastic 
greenhouse in Ibaraki, Honshu, Japan (Nakagaki et al . 1984,  in Vierbergen and van der Gaag 
2009); as overwintering life  stages from a greenhouse growing grapes in Okayama (Shibao et 
al. 1991) and on potted Hydrangea  in Saitama and Chiba (Kuriyama et al.  1991).  
• Small numbers of S. dorsalis  found in a Dutch greenhouse in Hoek van Holland were 
eradicated by chemical treatment (Vierbergen and van der G aag 2009). A population of S. 
dorsalis  established in a botanical glasshouse in southern England in May 2008 and was still 
ongoing in 2012 (EFSA 2012) . EPPO 2020 refers to occasional recurrences of presence in 
both the Netherlands and England.  
• S. dorsalis  was found on hydrangea grown in an unheated tunnel house on Long Is land, New 
York, USA.  
 
Scirtothrips  dorsalis  has biological characteristics that can assist its establishment in new 
environments.  
• S. dorsalis  can reproduce both sexually and by arrhenotokous parthenogenesis (unfertilised 
eggs produce only male offspring) (Amin and Palmer 1985). This can be advantageous in a 
new environment , as the male is not essential to the production of offspring. One or two  
unfertilised females or a single mated female may be capable of founding a population.  
• S. dorsalis  overwinters in Japan as non -diapausing adults in leaf litter or soil or on branches 
or leaves (Okada and Kudo 1982). The lifespan for overwintering adults appears to be about 
5 months. Larvae, prepupae and pupae also hibernate over the winter if young leaves are 
available in a mild winter (Okada and Kudo 1982). Similarly, the population on Long Island 
appears to successfully overwinter and is thought to have  originated from Japan (Dickey et al. 
2015).  
• The lower developmental threshold of S. dorsalis  has been calculated at 8.5 °C on grape 
(Shibao 1996) and 9.7 °C on sweet viburnum (Tatara 1994), which would enable it to establish 
in parts of New Zealand.  
 
Impac ts in New Zealand : 
 
Given the arguments and evidence below, the level of impact caused by Scirtothrips 
dorsalis  is likely to range from low to moderate  (with low uncertainty) . 
Scirtothrips dorsalis  can cause damage that reduces the yield and quality of the  affected crops  (see 
Figure 13.3.1 for examples) . 
• Citrus  
o Feeding by S. dorsalis  causes significant leaf and flower deformities, scarring of fruit 
and yield reduction (Chiu et al. 1991). Although there are several different authors 
who report serious damage  to citrus from this thrips in Asia, there is no quantitative 
information regarding percent yield loss/damage or economic cost.  
o The image in Figure 13.3.1  of oranges from the Fars region of Iran shows S. dorsalis  
feeding damage (Minaei et al. 2016).  
o The citrus industry in New Zealand earned $58.5  million in domestic sales and $12  
million in exports during 2019. Damaged citrus fruit might be able to go for 
processing, but this would still result in reduced income for growers. Most citrus 
production occurs in areas of the North Island which are suitable for S. dorsalis  
establishment.  
• Other crops  
o On grapes heavy feeding damage to flower clusters and developing fruit caused 
reduced fruit set and reduced saleability of the fruit (Ananthakrishnan 1971). Shibao 
(1997) observed that plots of grapes that were sprayed with insecticide had 60% of 
the fruit clusters damaged compared to unsprayed plots that had 90% of the fruit 
clusters damaged in Japan. The New Zealand wine industry export earnings for 2019 
were more t han NZ$1.8 billion  (Plant & Food Research 2019). A reduction in fruit set 
would result in a reduction in grape yield and therefore reduced income. Only a 
proportion of the wine grape production is in areas suitable for S. dorsalis  
establishment.  
o Feeding da mage to onion, chilli, castor and cotton can wilt, stunt and distort young 
shoots and leaves, and cause premature leaf, bud or flower drop. Yield losses in chilli 
attributed to S. dorsalis  have ranged from 20% to almost 50% (in Venette and Davis  
413 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  2004). The  New Zealand onion industry had export earnings of NZ$170  million in 
2019. The bulk of the crop is grown in areas of the North Island where S. dorsalis  
could establish ( Plant & Food Research 2019).  
o In India , S. dorsalis  is a major pest of rose production, distorting or destroying leaves 
buds and flowers, reducing the marketability (Gahukar 1999). The cut flower and 
foliage export earnings for New Zealand in 2019 were NZ$20.0  million (Plant  & Food 
Research  2019). Some of this production is outdoors and some is under protection . 
Both situations have  been shown to be adequate for S. dorsalis  survival , which could 
result in damage to the crop.  
o Economic damage to economically important crops does not always occur. For 
instance, multiple generations of S. dorsalis  were observed between May and 
October on kiwifruit in Japan, but no economic damage resulted (Sakakibara and 
Nishigaki 1988, in McLeod and Collins 2006). However, presence within a crop may 
have an adverse effect regarding S. dorsalis -free export markets.  
 
Establishment in glasshouses is likely to have a considerable  but short -term impact .  
• There would be costs associated with any eradication attempts. Chemical control for 
S. dorsalis  on crops in glasshouses is likely to result in disruption of IPM programmes , 
disruption to the growing season and costs associated with crop or yield loss and control.  
 
 
 
Fig 13.3.1  Images of feeding damage by Scirtothrips dorsalis : top left on capsicum fruit and leaves; top 
right on oranges; bottom left, rosebud  and bottom right shows stunted, damaged (left) and normal rose 
leaves.  
 
Scirtothrips dorsalis  has the potential to vector viruses that are not present in New Zealand.  
• Viruses most commonly vectored by thrips are in the genus Orthot ospovirus, family 
Tospo viridae  and order Bunyavirales . Orthotospoviruses are transmitted in a persistent, 
propagative manner and are trans -stadially passed in their insect vector  (Whitfield et al. 
2005). Tospoviruses are not known to be transmitted congenitally to the offspring o f the 
vector (ICTVdB 2013) . Early -instar larvae acquire a virus and retain it for their lifetime. 
Sometimes adults can acquire but not transmit a virus for reasons not entirely clear (Wijkamp 
1996).  
• S. dorsalis  is reported to vector Groundnut bud necrosis virus  (GBNV), Groundnut chlorotic 
fan-spot virus  (GCFSV) and Groundnut yellow spot virus  (GYSV) (Riley et al. 2011), which 
are not known to be in New Zealand (Veerekone et al. 2015; PPIN 2020). No evidence of 
these viruses affecting citrus fruits  was found  during the literature review , but some weed 
Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 414 species are natural hosts, e.g. Solanum  nigrum  is a natural host of GBNV (Bhat et al. 2020) 
and is quite common in or on the edge of cultivated crops.  
 
Establishment of S. dorsalis  may result in increased phytosanitary measures on exports from New 
Zealand to countries where it is absent.  
• Most of Europe does not have populations of S. dorsalis , and it is considered an A1 
quarantine pest in Europe (EPPO 2019). New Zealand exports host s of S. dorsalis  to 
continental Europe, e.g. onions, kiwifruit.  
• S. dorsalis  is on the A1 list for Brazil and Chile, and Mexico considers it a quarantine pest.  
 
Scirtothrips dorsalis  may cause impacts to New Zealand sociocultural values and potentially to t he 
natural environment, but is unlikely to have impacts upon human health.  
• Ipomoea sp. is a reported host of S. dorsalis. It is assumed that Ipomoea batatas  (kumara) 
could be affected by S. dorsalis. Kumara is a taonga or  treasured plant to M āori, and so 
damage to this plant would be considered significant.  
• Roses, alstroemeria, begonia, azaleas, viburnum and various pittosporums are among the 
many hosts of S. dorsalis  that are common in home gardens and amenity plantings. These 
are likely to suffer from fee ding and oviposition damage should S. dorsalis  establish.  
• There are genera native to  New Zealand that are hosts of S. dorsalis  overseas.  
Dwarf Schefflera  and Pittosporum  species are frequently attacked by S. dorsalis  in Florida 
and Texas (Ludwig and Bogran 2007).  New Zealand species in these genera may also be 
vulnerable to S. dorsalis . Beever et al . (2007) state that most exotic pests that attack native 
plants are polyphagous, but highly damaging polyphagous species appear  to be  exceptional , 
and it h as been postulated that the impact of relatively specialised organisms is likely to be 
greater than highly polyphagous species . However, there are three introduced thrips species 
that can reach large populations on native plants in native ecosystems (pers.  comm. N. 
Martin , 12 Sept ember  2013). For instance, the introduced thrips Heliothrips haemorrhoidalis , 
which is found outdoors in central and southern Florida and southern California but in 
greenhouses elsewhere in the USA (Denmark and Fasulo 2010), is kno wn to cause damage 
to the seedlings of native trees in New Zealand (pers. comm. N. Martin , 12 Sept ember  2013). 
The northern areas of the North Island have a number of locally endemic plant species , which 
may be at risk from young -growth herbivory.  
12.3.4  Referen ces 
Affandi, A; Medina, C de la R; Velasco, L R I; Javier, P A; Depositario, D P T (2018) Development and 
survivorship of Scirtothrips dorsalis  Hood (Thysanoptera: Thripidae) in different growth stages of 
mango and selected weeds. AGRIVITA Journal of Agric ultural Science , 40(1): 101 –106. 
http://doi.org/10.17503/agrivita.v40i0.1650  
Amin , P W; Palmer , J M (1985) Identification of groundnut Thysanoptera. Tropical Pest Management , 
31(4): 286 –291. 
Ananthakrishnan, T N (1971) Thrips (Thysanoptera) in agriculture, horticulture and forestry: diagnosis, 
bionomics and control. Journal of Scientific and Industrial Research , 30: 113 –146. 
Beever, R E; Harman, H; Waipara, N; Paynter, Q; Barker, G; Burns, B ( 2007) Native Flora Biosecurity 
Impact Assessment. Landcare Research Contract Report: LC0607/196.  Manaaki Whenua Press 
(Landcare); NZ.  
Bhat, A S; Laxmidevi, V; Reddy, M K (2020) First report of groundnut bud necrosis virus natural 
occurrence in Solanum  nigrum L. in India. Journal of Plant Pathology , 102(4): 1285 . 
https://doi.org/10.1007/s42161 -020-00567 -6 
Chiu, H T; Shen, S M; Wu, M Y (1991) Occurrence and damage of thrips in citrus orchards in 
south ern Taiwan. Chinese Journal of Entomology , 11: 310 –316. 
Collins , D; Cannon , R; MacLeod , A (2006) Chilli thrips, Scirtothrips dorsalis . Plant Pest Notice #40. 
Central Science Laboratory, Department for Environment, Food and Rural Affairs. Sand Hutton, York,  
UK. 
Cronje, P J R; Crouch, E M; Huysamer, M (2005) Post -harvest calyx retention of citrus fruit. Acta 
Horticulturae , 682: 369 –376.  
415 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Denmark H A; Fasulo T R (2010) Featured Creatures: Heliothrips haemorrhoidalis . University of 
Florida. http://entnemdept.ufl.edu/creatures/orn/thrips/greenhouse_thrips.htm  Accessed September 
2013.  
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103–106.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 418 12.4 Thrips palmi  (melon thrips ) 
Thrips palmi  is a sap-feeding polyphagous insect pest of many horticultural and ornamental plants, 
especially in the Cucurbitaceae, Solanaceae and Orchidaceae families. This insect is a known vector 
of some plant viruses that are not known to be present in New Zealand. Adu lts and larvae feed mainly 
on the leaves, flowers and stems of host plants, and occasionally, on the surface of fruits, causing 
numerous feeding scars and deformities.  
 
Scientific name: Thrips palmi Karny, 1925  
Order/Family: Thysanoptera/Thripidae  
Other names:  Thrips leucadophilus, Thrips gossypicola, Chloethrips aureus, Thrips gracilis  
 
Notes on taxonomy : Despite being previously misidentified as Thrips flavus  in Taiwan, 
T. nigropilosus  in Hawaii and Frankliniella schu ltzei in India, T. palmi  is easily distinguish ed from other 
thrips (Palmer, 1992).  Sakimura et al. (1986) provided a list of major diagnostic characters to 
distinguish T. palmi  from the other known species of the same genus . The IPPC has produced a 
diagnostic protocol for Thrips palmi  (DP1 in ISPM 27) that includes morphological and molecular 
identification techniques (FAO 2016 a). 
 
Summary of c onclusion s 
 
Given the arguments and evidence presented : 
 
• Thrips palmi meets the criteria to be a quarantine pest for New Zealand . 
• Thrips palmi  has a weak association with citrus plants and no known association with citrus 
fruit (with low uncertainty).  
• Basic measures  reduce the likelihood of entry of T. palmi , if this pest were to be present  on 
citrus fruit , by a high degree  (with moderate uncert ainty); therefore, the likelihood of entry is 
considered low  to moderate.  
• The ability of T. palmi to transfer from imported fruit to suitable host plants is moderate, with 
high uncertainty.  
• The suitability of the New Zealand climate for establishment of Thrips palmi  outdoors is rated  
low to moderate, but it could be moderate  to high in some parts of the North Island, especially 
due to climate warming, and the pest can establish in glasshouses.  
• The e stablishment of Thrips palmi in glasshouses could result in transient high impacts , but 
impacts in outdoor areas are likely to be low (with moderate uncertainty).  
• It is recommended that  Thrips palmi  does  not require  consider ation  for additional measures, 
due to the lack of evidence of  association with citrus fruit and the degree by which minimum 
measures reduce the likelihood of entry on the commodity.  
 
Summary of risk assessment against criteria  
 
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Weak  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Low 
The ability to move from the imported commodity  onto a suitable host  Moderate  High 
Suitability of the N ew Zealand  environment  Low–moderate  Moderate  
Impacts on the New Zealand economy, environment, health and society  Low**  Moderate  
** Rating applies to impact outdoors; impacts may be high in individual glasshouses if the pest invades 
glasshouses . 
  
419 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  12.4.1  Hazard  identification: quarantine status  
Given the arguments and evidence below,  Thrips palmi meets the criteria to be a 
quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are: not present in PRA area (New 
Zealand), and of potential importance (able to establ ish and cause harm).  
 
There are no records of Thrips palmi from New Zealand .  
• The pest is not recorded in PPIN (2020), NZOR (2020) or NZ Inverts  (2020).  
 
Thrips palmi  is a regulated pest for New Zealand . 
• It is recorded as “regulated” in ONZPR  (2020) .  
 
Thrips palmi  has the potential to establish  outdoors in warmer parts of the upper North Island of New 
Zealand  and in glasshouses across the country . 
• Thrips palmi  is primarily a subtropical and tropical species , but survive s outdoors throughout 
the winter  on Kyushu Island in Japan, where the mean minimum winter (December –February) 
temperature is 5.3°C (Yoshihara 1982).  Mean minimum winter (June –August) temperatures in 
Gisborne and Kaitaia are 5.5 °C and 8.6 °C respectively (NIWA 2020).  
• Also, about 25% of the  location records for T. palmi available on the EPPO global database 
(EPPO 2020) (mostly in parts of China and India) have a climate match index (CMI)  value of  
≥0.7. This indicates enough similarity between the climate of these locations and the New 
Zealan d climate  to allow establishment of the pest (Phillips et al. 2018).  
• McDonald et al. (1999) calculated the lower development threshold of T. palmi  to be 10.1 °C 
and developed a degree -day model showing that the pest could , in principle,  complete 4 –5 
generat ions outdoors during summer in parts of the UK, which have a similar climate to New 
Zealand (CMI of 0.8 –0.9).  
 
Thrips palmi  has the potential to cause  impacts  in New Zealand . 
• Thrips palmi  is a highly polyphagous pest and has been recorded on over 200 host  species 
from over 20 plant families ( EFSA  2019; EPPO 2020).  
• Adults and larvae of T. palmi feed by bursting the cells of host plants and sucking the cell sap 
(Kirk 1997 , in Seal et al. 2013) , leading to stunting, distortion and scarring of plants and 
produce, with significant reductions in yield and marketability (Kawai 1990).  
• First recognised as a major threat to vegetable growers in Japan in 1978, by 1990 T. palmi  
had become the most serious  pest of Cucumis sativus  (cucumber ), Solanum melongena  
(eggplant)  and Capsicum annuum  (sweet peppers) in greenhouses and open fields in the 
western part of Japan (Kawai 1990).  
• Thrips palmi  is also a known vector of some plant tospoviruses (Ullman et al. 19 97; EFSA 
2019) that are either regulated or not known to be present in New Zealand ( ONZPR  2020; 
BRAD 2020; NZOR 2020; PPIN 2020).  
• T. palmi  host plants that are economically important to New Zealand include Capsicum  spp. 
(peppers), Solanum melongena  (egg pl ant), S. lycopersicum  (tomato), Cucurbita pepo  
(squash) and Cucumis sativus  (cucumber) ( Plant & Food Research 2019; Vegetables New 
Zealand 2020).  
12.4.2  Hazard identification: commodity association  
Thrips palmi  is associated with citrus plants, but is not reporte d from citrus fruit . 
• A single adult female T. palmi was detected in a sample of flowers of Citrus × latifolia  
(Tahitian lime) in Florida (Childers and Beshear 1992).   
• Adult  T. palmi  lay their eggs in incision s made with the ovipositor  in the green tissue  of host 
plants  (EPPO 2020), but no evidence was found to indicate that the pest lays eggs in/on 
citrus fruit.  
• There are no records of interceptions of T. palmi  on citrus fruit at EU and New Zealand 
borders (EPPO 2020; LIMS 2019 ). 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 420 12.4.3  Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below, Thrips palmi  has a weak association with 
citrus plants and no known association with citrus fruit  (with low uncertainty) . 
There are very few published record s of Thrips palmi  from citrus . 
• Citrus  is listed  in EPPO (2020) as an incidental host of T. palmi , likely based on the record of 
a single adult female collected from a ‘Tahiti ’'‘Tahiti '’ lime (Citrus  × latifolia ) flower sample in 
Dade County , Florida (Childers and Beshear 1992), although CABI (2020) includes citrus 
among the ‘main’ hosts of the pest without specific reference to primary sources.  
• Thrips palmi  was not among 36 species of thrips detected in surveys of seven unsprayed 
citrus orchards in south and central Florida conducted between 1 995 and 1996 (Childers and 
Nakahara 2006 ).  
 
There are no records of interception of T. palmi  on citrus fruit . 
• In the EU, the pest is frequently intercepted on plants for planting, fruits of eggplant ( Solanum 
melongena ), bitter melon ( Momordica  charantia ) and mango ( Mangifera indica ), and on cut 
flowers of species in the Orchidaceae, but there are no records of interceptions on any citrus 
commodity  (EPPO 2020).  
• Between 1999 and 2019, there were 103 interceptions of T. palmi  at the New Zealand border, 
none  of which was from citrus. Commodities on which the pest was intercepted were mainly 
cut flowers of Rosaceae, Orchidaceae and Asteraceae, cut foliage of Amaranthaceae and 
fresh produce of Cucurbitaceae, Malvaceae and Rosaceae (LIMS 2019).  
• The absence of in terception records for T. palmi  on citrus commodities at the EU and New 
Zealand borders indicates a weak association between the pest and citrus; however, it could 
be that additional phytosanitary measures  that eliminated T. palmi  were applied to the citru s 
commodities, but not to  the commodities  (cut flowers and foliage)  on which the pest has been 
intercepted.  
 
Therefore, given the very limited records of T. palmi  on citrus, combined with the fact that the pest has 
not been intercepted on citrus at the bor ders of both the EU and New Zealand, T. palmi is not likely to 
be present on the citrus fresh produce pathway.  
 
 
Given the arguments and evidence below,  basic measures  reduce the likelihood of 
entry of T. palmi on citrus fruit by a high degree (with moder ate uncertainty) , and  the 
likelihood of entry is considered low  to moderate.  
If T. palmi were to be present in citrus crops , it is likely to be detected  and eliminated in the field  and 
in packing houses, but some factors may make detection difficult:  
• Heavy infestations of T. palmi  are easily detected , because  the pest feeds externally and 
heavily infested plants are  characterised by a silvered or bronzed appearance of the leaves, 
stunted leaves and terminal shoots  and scarred and deformed fruits (Smith  et al. 1997 , in 
Seal and Sabines 2012).  
• However, at low levels of infestation, the pest may produc e little or no detectable symptoms . 
Also, given that citrus is an incidental host, detection of the pest may be more difficult in the 
field.  
• There is no evi dence to suggest that T. palmi  feeds on or lays eggs in citrus fruit, but o n fruit 
such as  eggplant , scarring damage caused by larval feeding  is often visible beyond the cover 
of the calyx , even though larvae of T. palmi  usually hid e under the calyx  (CABI 2020). Eggs 
laid in any fruit are unlikely to be detected  (FAO 2016 a). 
• If T. palmi  was present on citrus fruit, post -harvest processes such as washing, brushing, 
cleaning and waxing are likely to dislodge adults and larvae. However, there is moderat e 
uncertainty because a dults and larvae of T. palmi  are about 1 mm long and pale  in colour , 
which means they may not be easily detected and dislodged , especially if they were to hide 
under calyces or in the navel of navel oranges . 
  
421 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Note:  In a review on the pathways and possibilities of spread of T. palmi , Vierbergen (200 1) 
concluded that the re was no indication that products for consumption were an entry pathway for the 
pest and that plants for planting  was the  most likely entry pathway. These conclusions were based on 
analysis of interception data from the USA and Europe, and the pathways through which T. palmi had 
spread within Asia  out to the Pacific , and its incursions into glasshouses in the Netherlands.  
Furthermore, EPPO (2020) lists plants for planting as a commodity group for the likely spread of 
T. palmi  via trade but does not include fresh fruit for consumption.  
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of T. palmi to transfer from 
imported fruit onto a host plant to allow establishme nt is rated moderate (with 
moderate uncertainty) . 
Some aspects of the biology of the pest  limit its ability to transfer to suitable hosts . 
• Larvae , and, to a lesser extent, adults, are the stages of T. palmi  likely to be associated with 
citrus fruit; adults mostly feed on fresh leaves and flowers and occasionally  fruit, whereas 
larvae are found on older leaves and fruit of some hosts (capsicum and eggplant),  and 
pupation occurs in the soil (Capinera 2015; EPP O 2020; Kawai 1990).  
• There is no information on the ability of T. palmi  larvae to complete development on citrus 
fruit; for example, T. palmi  larvae reared on tomato and strawberry  were unable to pupate  
(Kawai 1986). Thus, if larvae are unable to complete development on discarded citrus fruit, 
they would need to disperse to  a suitable host  to complete development .  
• However, T. palmi  larvae are wingless and, therefore, less mobile (Capinera 2015; CABI 
2020; EPPO 2020), which will  limit their ability to disperse from discarded fruit to a suitable 
host plant /substrate to complete larval development . 
• Unmated adult female T. palmi  can lay viable eggs ( Yoshihara and Kawai  1982 ), with a 
preoviposition period of 1 –3 days  and 3–164 eggs ( 1.0–7.9 eggs per day) laid during their 
lifespan  (Wang et al.1989 ). However, all eggs produced by unmated females hatch into male 
offspring (Yoshihara and Kawai 1982) .  
• Hence, even if larvae were to complete development to adults and adult females disperse d to 
a suitable host, such females would not be able to  establish  a breeding population  without 
mating.  
• However, Yadav and Chang (2014)  found that unmated adult females lived for an average of 
56.7, 46.7 and 38.8 days at 16°C , 19°C and 22 °C respectively, and at these temperatures, 
the mean duration s of development (egg  to adult) of eggs laid by the females, were 35.7, 26.8 
and 19.3 days respectively.  These results raise the possibility that under  conditions similar to  
the experimental condit ions,  female T. palmi may live long enough to mate with their male 
offspring.  
• Considering that mean monthly temperatures during summer (December to January) in New 
Zealand’s upper North Island are between 17.8 °C and 24°C (NIWA 2020), newly emerged 
adult fe male T. palmi could potentially  live to mate with their male offspring.  This is, however, 
highly uncertain  because, while the studies by Yadav and Chang (2014) were conducted at 
constant temperatures under laboratory conditions , T. palmi  on fruit discarded  in outdoor 
areas in New Zealand will encounter temperatures that vary over the course of each day.  
 
Other traits and factors may increase the ability of T. palmi  to transfer to suitable hosts:  
• Although adult thrips are weak fliers, they can be blown long distances by wind (Lewis 1997), 
which may increase the chances of adults moving  from discarded fruit  landing on suitable 
hosts;  especially for a polyphagous species like T. palmi . 
• Also, some T. palmi populations in India were found to harbour the bacterial endosymbiont, 
Wolbachia  (Saurav et al. 2016) . Some strains of this symbiont are known to induce 
thelytokous parthenogenesis — the production of female offspring by unmated females in 
species th at are otherwise incapable of doing so (Stouthamer et al. 1999; Werren and 
Windsor 2000; Correa and Ballard 2016).  
• However, other plant -feeding thrips species such as Echinothrips americanus  (Thripidae) , 
Suocerathrips linguis  (Phlaeothripidae) and Gynaikothrips ficorum  (Phlaeothripidae), in which Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 422 Wolbachia  has been detected, are incapable of thelytoky (Kumm and Moritz 2008) and there 
is no data on whether the strain found in T. palmi  is capable of inducing thelytoky.  
• A thelytoky -inducing strain of Wolbachia  has been detected in  the predatory thrips 
Franklinothrips vespiformis  (family: Aeolothripidae ) (Arakaki et al. 2001).  
• Transfer of larvae and adults to a suitable host is also more likely if infested fruit waste is 
discarded near a glasshouse or i n a field with suitable host plants. A rrival of infested 
commodity and its disposal as waste during summer would  also increase the chances of 
T. palmi  completing development and transferring to suitable hosts . 
 
Uncertainty:  
The lack of information on whether T. palmi  can complete development on citrus fruit and how far 
adults can disperse to find to hosts raises some uncertainty around the likelihood of transfer , 
especially if fruit infested with larvae is discarded far from glasshouses and host plants .   
 
 
Given the arguments and evidence below,  the suitability of New Zealand’s climate 
for the establishment of T. palmi  outdoors is moderate (with high uncertainty ); the  
pest could establish outdoors in some northern locations and in glasshouses . 
Thrips palmi  is mainly a tropical  and subtropical specie s, with high temperature requirements for 
development . 
• The pest is native to south east Asia , and its current geographical  distribution includes Asia: 
Bangladesh, Brunei, China  (numerous provinces, including Hong Kong ), India (numerous 
states), Indonesia (Java, Sumatra), Japan , North Korea, South  Korea , Malaysia, Myanmar, 
Pakistan, Philippines, Singapore, Sri Lanka, Thailand,  Taiwan , Viet Nam ; Africa: Mauritius, 
Nigeria, R éunion, Sudan ; Caribbean : throughout; North America : United States (Florida and 
Hawaii ); South America : Brazil , Columbia, French Guiana, Venezuela; Oceania : American 
Samoa, Australia  (Queensland, Northern Territory, Western Australia), Federated States of 
Micronesia, French Polynesia, Guam, New Caledonia , Palau, Papua New Guinea and 
Samoa  (CABI 2020; EPPO 2020).  (Countries in bold  are included in the scope of this risk 
assessment. ) 
• The optimum temperature range for development of T. palmi  is 25 –30°C, and estimates of its 
lower development threshold range from 7.4 °C to 11.6°C (Kawai 1985; McDonald et al. 1999; 
Park et al. 2010; Yadav and Chang 2014). At 25°C, the life cycle lasts 17.5 d ays (Kawai 
1990), compared to 42 days when the insects were cultured at 15°C  (Capinera 2015).  
• When compared with the Auckland and Northland regions of New Zealand, 83% of 
georeferenced point locations (data from EPPO 2020) in countries where  T. palm i is currently 
established, have a climate match index (CMI) value <0.7. This indicates insufficient climate 
similarity and suggests that the pest would be unable to establish outdoors in most of New 
Zealand, including the northern regions (Phillips et al. 2018) . In Florida , for example , ﬁeld 
populations of T. palmi  have only been reported south of Orlando  (Capinera 2015 ; Seal and 
Stansly 2000 ), which, with a CMI range of 0.5 –0.6, has a climate that is insufficiently matched 
to that of New Zealand.  
• Tsumuki et al. (1987) analysed the cold hardiness of T. palmi  in Japan and concluded that it 
could not survive outdoor winter conditions in southern Honshu. In the southern Honshu cities 
of Hiroshima, Takamatsu and Osaka, the mean minimum winter (December –February) 
tempe ratures are 2.5 °C, 3.2°C and 3.3°C . 
 
However, some locations in the upper North Island of New Zealand may be marginally suitable for 
outdoor  establishment of T. palmi . 
• Climate models (Dentener et al 2002; Stephen and Dentener 2005) indicate that parts of t he 
upper North Island (including Kaitaia, Kerikeri, Gisborne and Auckland) may be suitable for 
the establishment of T. palmi  outdoors. Locations identified as potentially suitable, matched 
the known New Zealand distribution of Hercinothrips bicinctus  (bana na thrips), a species 
found worldwide in locations similar to that of melon thrips (Dentener et al. 2002).  
• Thrips palmi  surviv es outdoors throughout the winter  on Kyushu Island in Japan, where the 
mean minimum winter (December –February) temperature is 5.3°C (Yoshihara 1982) . Mean 
minimum winter temperatures are higher than 5.3°C (5.5°C and 8.6 °C respectively) in 
Gisborne and Kaitaia in New Zealand’s North Island (NIWA 2020).   
423 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • About 13% of the georeferenced locations (mostly in parts of China and India) where T. palm i 
occurs (data from EPPO 2020) have a climate match index (CMI)  value  of 0.7, when 
compared with Auckland and Northland regions of New Zealand . This indicates enough  
climate similarity to allow establishment of the pest (Phillips et al. 2018) in some sites in these 
regions of New Zealand.  
• McDonald et al. (1999) calculated the lower development threshold of T. palmi  to be 10.1 °C 
and developed a degree -day model from wh ich they estimated that the pest could potentially 
complete 3 –5 generations outdoors during summer in the Midlands area of the UK. The west 
Midlands have a CMI of 0.7 when compared with Auckland and Northland areas of New 
Zealand, whereas most of the east Midlands have a CMI of 0.6.  
• However, McDonald et al. (2000) measured cold tolerance of T. palmi and concluded that if  
introduced to the UK, overwintering of T. palmi  would be largely restricted to protected 
environments, as its cold tolerance is insufficie nt to permit outdoor survival for a complete 
winter , supported by data  that showed that on release, caged populations of T. palmi died out 
after as little as 25 days in outdoor winter conditions in Yorkshire, UK  (CMI: 0.6 –0.7).  
 
Thrips palmi  could establi sh transient populations in glasshouses in New Zealand:   
• Thrips palmi  has the  potential to infest hosts grown in glasshouse s (Capinera 2015) , and 
outbreaks have occurred  in and been eradicated from glasshouses  in the Netherlands , 
Germany and the UK (EFSA 2019; MacLeod et al. 2004 ; Cannon et al. 2007 ). 
• Nagai and Tsumuki  (1990) reported no reduction of adult populations of T. palmi  at 
temperatures as low as -3°C to -7°C on weeds in an unheated glasshouse between mid -
January  and mid -February in Japan , which suggests that glasshouses provide microclimates 
that mitigate some  of the negative effects of low temperature on the pest . 
• In New Zealand, s everal host plants  of T. palmi , e.g. eggplant, cucumber, sweet  pepper  and 
tomatoes, are cultivated in glasshouses , many of which are located around Auckland and 
other northern region s (Vegetables New Zealand 2020) . 
• The movement of infested material (plants for planting , packing material and soil)  could 
facilitate the spread of T. palmi  between nurseries and glasshouses.  
 
There is uncertainty around the likelihood and extent of establishment of T. palmi  in New Zealand, 
due to conflicting data in the literature about the cold tolerance  and lower development threshold of 
the species.  
 
Impacts  in New Zealand:  
 
Given the arguments and evidence below,  Thrips palmi is likely to cause low impacts 
in outdoor crops, but may cause high impacts in glasshouses . 
 
Thrips palmi can cause economic impacts in New Zealand, especially in host plants grown in 
glasshouses . 
• Adults and larvae of T. pa lmi feed mainly  on foliage , causing bronzing and premature  leaf and 
fruit drop, with h eavy infestations  result ing in scarred and/or deformed fruit with no marketable 
value  (Seal and Sabines  2012).  
• Since 1978, T. palmi  has become the most serious pest of cu cumber,  eggplant  and sweet 
pepper in glasshouses and open ﬁelds in south and western Japan, regularly  causing crop 
losses (Kawai 1990).  Continuous cultivation of its favoured hosts (cucumber, melon and 
eggplant) in glasshouses enables  the survival and quic k buildup of T. palmi populations, 
which results in very severe impacts (Murai 2002).  
• At the optimum temperature for population growth (25 –30°C), the number of generations was 
estimated at 25 –26/year (Huang and Chen 2004).   
• Several T. palmi host crops of e conomic importance, e.g. cucumbers, capsicums, melons. 
squash, eggplant and tomato, are mainly grown in glasshouses in New Zealand (Tomatoes 
NZ 2020; Vegetables New Zealand 2020 ).   
• The s ize of production area and domestic value in 2018 and the export value  in 2019 of some 
major hosts of T. palmi  grown in glasshouses in New Zealand were: Cucumber – 71 ha , 
NZ$20 million  domestic; eggplant  – $8.5 M domestic; tomato  – 120 ha , $176 M domestic, 
$11.2  M export; squash  – 6642 ha , $3 M domestic, $59.7 M export ; capsicum – 95 ha , $25 M Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 424 domestic, $20.6 M export; melons – 211 ha , $28 M domestic; lettuce  – 50 ha , $25 M domestic 
(Plant & Food Research  2018,  2019).  
• Cut flowers of orchids and chrysanthemums, which are important ornamental hosts of 
T. palmi  are grown in New Zealand glasshouses for domestic and export trade. Cut flower 
and foliage exports were worth NZ$27 million in 2016, with o rchids mak ing up the bulk of the 
sales at $14.6  million (Markham 2017 ).  
 
Thrips palmi  is a known vector of viruses in the genus Tospovirus  of the family Bunyaviridae . 
• The pest is reported to be able to transmit the following tospoviruses : Groundnut bud necrosis 
virus  (GBNV), Capsicum chlorosis virus  (CaCV)  and Watermelon bud necrosis virus  (WBNV) 
(Seepiban et al. 2011 ; EFSA 2019 ), which  are regulated pests for New Zealand  (ONZPR 
2020).  
• In transmission experiments in Thailand, T. palmi  transmitted Tomato necrotic ringspot virus  
(TNRV) isolated from tomato to leaf discs of Phys alis minima  (gooseberry), with an efficiency 
of 83 per cent (Seepiban et al. 2011). It is also a vector of Watermelon silver mottle virus  
(WSMoV) , Melon yellow spot virus  (MYSV)  (Okuda et al. 2002) and Calla lily chlorotic spot 
virus  (CCSV)  (Chen et al. 2005)  
• Although the four viruses above (TNRV, WS MoV, MYSV, CCSV) do not have a regulatory 
status in New Zealand, i.e. they are not currently regulated in ONZPR  (2020), they have not 
been reported from New Zealand (NZOR 2020; PPIN 2020).  
 
Thrips palmi  could lead to high costs for phytosanitary measures and eradication and  could  impact 
overseas trade . 
• Eradication or a long -term pest management strategy would be necessary to limit economic 
impacts of the pest in affected glasshouse crops. The estimated cost of eradicating T. palmi  
from an infested chrysant hemum glasshouse in Sussex (south of England) between April 
2000 and July 2001 exceeded £56,000 (MacLeod et al. 2004).  
• Impact on overseas trade is likely to be limited, as most host commodities of the pest 
produced in New Zealand are exported to countries  where the pest is already present 
(Vegetables New Zealand 2020). However, small volumes of T. palmi  host commodities (e.g. 
tomatoes and capsicums) are exported to Pacific countries where the pest is absent, and 
access to markets where the pest is absent could be affected.  
 
T. palmi may cause low  environmental impact, but is unlikely to cause social and health impacts . 
• The pest infests plant species in the Orchidaceae, Malvaceae and Rosaceae families (CABI 
2020; EPPO 2020). New Zealand has over 120 species of native wild orchids, which occur 
acros s the country (Carlos et al. 2016), including northern coastal areas, which may be 
suitable for establishment of T. palmi . There are also native Malvaceae, e.g. Hoheria  species, 
some of which also occur in parts of the North  Island where T. palmi  could pot entially 
establish.    
• There is no evidence that T. palmi  causes any negative human or animal health impacts .  
 
Uncertainty:  
There is uncertainty regarding the magnitude of impacts; impacts would be less, if T. palmi incursion  
into a glasshouse was quickly detected and transient, but higher, if the pest established year -round 
outdoor populations that then invade multiple glasshouses.  
 
12.4.4  References  
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BRAD (2020) Biosecurity Risk Analysis Database. MPI internal database. Ministry for Primary 
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CABI (2020) Thrips palmi  (melon thrips). Crop Protection Compendium . CAB International, 
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Slawson, D D; Gaunt, A (2007) Eradication of an invasive alien pest, Thrips palmi . Crop Protection , 
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Capinera , J (2015 ) Melon Thrips, Thrips palmi  Karny (Insecta: Thysanoptera: Thripidae). Publication 
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(Zantedeschia  spp.) is caused by a tospovirus serologically but distantly related to watermelon silver 
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Childers, C C ; Beshear, R  J (1992) Thrips (Thysanoptera) species associated with developing citrus 
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392–412. 
Childers, C C; Nakahara, S (2006) Thysanoptera (thrips) within citrus orcha rds in Florida: species 
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Correa, C C ; Ballard, J W O (2016) Wolbachia associations with insects: winning or losing against a 
master manipulator. Frontiers in Ecology and Evolution , 3: 153 –153.  
Dentener, P ; Whiting, D ; Connolly, P  (2002) Thrips palmi  Karny (Thysanoptera Thripidae) : could it 
survive in New Zealand ? New Zealand Plant Protectio n, 55: 18 –24. 
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Kawai A (1985) Studies on population ecology of Thrips palmi Karny. VII: effects of temper ature on 
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Kawai, A (1990). Life cycle and population dynamics of Thrips palmi  Karny. Japan Agricultural 
Research Quarterly , 23(4): 282 –288.  
Kumm, S ; Moritz, G (2008) First detection of Wolbachia in arrhenotokous populations of Thrips 
species (Thysanoptera: Thripidae and Phelaeothripidae) and its role in reproduction. Environmental 
Entomology , 37: 1422 –1428.  
Lewis, T (1997) Flight and dispersal. In Lew is, T (ed) Thrips as Crop Pests . CAB International; 
Wallingford, UK;  pp 175 –196. 
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2020.  
MacLeod, A ; Head, J ; Gaunt, A  (2004) An assessment of the potential economi c impact of Thrips 
palmi  on horticulture in England and the significance of a successful eradication campaign . Crop 
Protection , 23(7) : 601–610. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 426 Markham, B (2017) The problem with New Zealand’s floriculture industry. 
https://www.stuff.co.nz/business/farming/opinion/97268072/  Accessed 30 July 2020.  
McDonald J  R; Bale, J S; Walters , K F A (1999 ) Temperature, development and establishment 
potential of Thrips  palmi in the UK . European Journal of Entomology , 96: 169–173. 
McDonald, J  R; Head, J ; Bale, J  S; Walters, K  F (2000 ) Cold tolerance, overwintering and 
establishment potential of Thrips palm i. Physiological Entomology , 25(2) : 159–166. 
Murai, T (2002) The pest and vector from the Eas t: Thrips palmi . Proceedings of the 7th International 
Symposium on Thysanoptera . Australian National  Insect Collection ; Canberra , Australia; pp 19 –32. 
Nagai , H; Tsumuki , H (1990 ) Search for winter host plants of  T. palmi  in winter . [in Japanese]  
Japanese Journal of Applied Entomology and Zoology , 34: 105–108. 
NIWA (2020). The National Climate Database. https://cliflo.niwa.co.nz/  Accessed 27 July 2020.  
NZOR (2020) New Zealand Organisms Register. http://www.nzor.org.nz/  Accessed 20 July 2020.  
Okuda, M; Takeuchi, S; Taba, S; Kato, K; Hanada, K (2002) Melon yellow spot virus and Watermelon 
silver mottle virus: outbreak of cucurbit infecting tospovirus in Japan.  Acta Horticulturae , 588: 143 –
148. 
ONZPR (2020) Official New Zealand Pest Register. MPI public database. Ministry for Primary 
Industries; Wellington, NZ. https://pierpestregister.mpi.govt.nz/  
Park, C G ; Kim, H Y ; Lee, J H (2010) Parameter estimation for a temperature -dependent 
development model of Thrips palmi  Karny (Thysanoptera: Thripidae). Journal of Asia -Pacific 
Entomology , 13(2) : 145–149. 
Phillips, C  B; Kean, J M ; Vink, C J ; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’  
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand. Biological 
Invasions , 20(3) : 777–791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2018) Fresh Facts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ. https://www.freshfacts.co.nz/files/freshfacts -2018.pdf  
Accessed 18 December 2020.  
Plant & Food Research (2019) Fresh Facts: New Zealand Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ. https://www.freshfacts.co.nz/files/freshfacts -2019.pdf  
Accessed 10 June 2020.  
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Wellington, NZ.  Accessed 20  July 2020 . 
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Division of Plant Industry, Florida Department of Agriculture and Consumer Services  No. 280 . 
Saurav, G. K; Daimei, G; Rana, V S; Popli, S; Rajagopal, R (2016) Detection and localization of 
Wolbachia in Thrips palmi  Karny (Thysanoptera: Thripidae).  Indian Journal of Microbiology , 56(2): 
167–171. 
Seal, D R; Kumar , V; Kakkar , G; Mello , S C (2013 ) Abundance of adventive  Thrips palmi  
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96: 789–796.  
427 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Seal, D R ; Sabines, C M  (2012)  Combating melon thrips,  Thrips palmi  Karny (Thysanoptera: 
Thripidae) in South Florida . Proceedings of the Florida State Horticultural Society , 125: 196– 200. 
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Society, 113: 201–205. 
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tospovirus isolated in Thailand.  Archives of Virology , 156(2): 263 –274. 
Stephen, A E A; Dentener, P R (2005). Thrips palmi  – Potential su rvival and population growth in New 
Zealand. New Zealand Plant Protection , 58: 24–30. 
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171. 
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ovipositional behaviour. Chinese Journal of Entomology , 9(2): 251 –261 
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equilibrium?  Proceedings of the Royal Society of London B , 267(1450): 1277 –1285.  
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the Association for Plant Protection of Kyushu , 28: 130–a131.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 428 13. Mites  
 
13.1 Aculops pelekassi  (pink citrus rust mite ) 
Aculops pelekassi  is a monophagous mite species that feeds on citrus fruit. It is an economically 
significant pest in citrus orchards in Korea, Japan and Florida.   
 
Scientific name: Aculops pelekassi  (Keifer , 1944) 
Order/Family: Acarida/Eriophyidae  
Other names include: None  
 
Taxonomic notes : Aculops pelekassi is similar in appearance to Phyllocoptruta oleivora  (citrus rust 
mite)  but can be differentiated based on its concave back and dorsal tubercles that arise at the rear 
shield margins. The dorsal setae extend beyond the distal margin of the prodorsal shield ( Childers 
and Achor 1999 ). 
 
Summary of conclusions  
 
Given the arguments and evidence presented : 
 
• Aculops pelekassi  meets the criteria to be a quarantine pest for New Zealand.  
• Aculops pelekassi  has a  low to moderate  association with citrus fruit , with low uncertainty . 
• Basic measures  are likely to reduce the likelihood of entry of A. pelekassi  by a moderate 
degree . Consequently, the likelihood of entry is considered low.  The uncertainty associated 
with this conclusion is considered low.  
• Aculops pelekassi  is considered to have  a low to moderate ability (with moderate uncertainty) 
to move from imported fruit and into a suitable environment to allow establishment.  
• The suitability of the New Zealand environment for the establishment of A. pelekassi  is 
considered high, with low uncertaint y.  
• The level of impact caused by A. pelekassi  is likely to be low, with low uncertainty .  
• Aculops pelekassi may be considered for additional measures.  
 
Summary of risk assessment against criteria  
Criteria  Rate  Uncertainty  
Strength or frequency of association with the commodity  Low–moderate  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low Low 
The ability to move from the imported commodity  onto a suitable host  Low–moderate  Moderate  
Suitability of the N ew Zealand  environment  High Low 
Impacts on the New Zealand economy, environment, health and society  Low Low 
 
13.1.1  Hazard identification: quarantine status  
Given the arguments and evidence below,  Aculops pelekassi  meets the criteria to be 
a quarantine pest for New Zealand . 
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
is of potential importance (able to establish and cause harm).  
  
429 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Aculops pelekassi  is not known to be present in New Zealand .  
• Aculops pelekassi is a regulated pest ( ONZPR  2020) . 
• There is no record of A. pelekassi in NZOR (2020) or PPIN (2020).  
 
Aculops pelekassi  has the potential to establish and spread within New Zealand . 
• It is a subtropical species reported from subtropical host species in palearctic, oriental and 
neotropical regions (Vacante 2010).  
• The mite has been reported from countries with a similar climate to New Zealand, including 
Croatia (climate match index (CMI ) value  0.8), Italy (CMI 0.8 –0.9) and Greec e (CMI 0.8) 
(Phillips et al. 2018).  
 
The establishment of A. pelekassi  in New Zealand has the potential to cause unwanted impacts . 
• Aculops pelekassi feeds on leaves, shoots and fruits of citrus ( Tsuchida  and Masui 2018) . 
Damage is mainly caused to fruit a nd can be observed as either skin calluses or bronzing 
(Ashihara et al. 2004) , reducing the marketability of affected fruit. Damaged fruit is also 
smaller (Ashihara et al. 2004).  
• There are not likely to be any e nvironmental  or human health impacts caused by its 
establishment . 
13.1.2  Hazard identification: commodity association  
 
Aculops pelekassi  is associated with citrus fruit . 
• Adults of A. pelekassi  feed and lay eggs on the outside of the fruit of Citrus spp. ( Childers and 
Achor 1999 ; Ashihara et al. 2004).  
• The only hosts of the mite are Citrus spp. (Vacante 2016).  
• It has been reported associated with C. sinensis (sweet orange), C. reticulata (mandarin) 
(Childers 1994 , in Childers et al. 2017) and C. limon (lemon) (Mineo and Ragusa 1970 ). 
13.1.3  Risk assessment  
Likelihood of entry:  
 
Given the arguments and evidence below,  Aculops pelekassi  has a low to moderate 
association with citrus commodities , with low uncertainty.   
Citrus  species are the only  hosts of A. pelekassi . 
• Adults of A. pelekassi  feed and lay eggs o n the outside of citrus fruit ( Childers and Achor 
1999 ; Ashihara et al. 2004).   
• Mites overwinter ing in buds from late September to early October ha ve been reported in 
Florida (Childers and Achor 1999), Croatia ( Mijuskovic and Kosac 1972) and Japan (Seki 
1979). However, in Japan , if autumn temperatures are unusually warm , populations may be 
high through to early November (Ashihara et al. 2004) . Following overwintering , mites are not 
active on fruit again until mid -June, with populations on fruit reaching a peak in July and 
August in Korea and Japan (Seo and Kim 2014; Ashihara et al. 2004).  
• As citrus is a commodity that comes into season during winter (from October to June) (Florida 
Citrus Mutual 2017; Japan -Guide .com  2020) when the mite populations on fruits are lowest, 
the likelihood of the mites being associated with the harvested commodities is reduced to low  
to moderate.  
• In Florida , all citrus varieties are hosts of A. pelekassi (Qureshi et al.  2020).  
 
Aculops pelekassi  is present on Citrus spp. in countries that are included in the Citrus IHS project . 
• Aculops pelekassi  is present in Japan, USA (Florida) (Childers and Achor 1999 ), Korea (Seo 
and Kim 2014), Brazil and China (see Table 14.1.1 ).  
 
Given the argumen ts and evidence below, basic measures are likely to reduce the 
likelihood of entry of A. pelekassi  by a moderate degree . Consequently, the Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 430 likelihood of entry is considered low. The uncertainty associated with this conclusion 
is considered low.  
Chemical in -field controls are available for A. pelekassi and may  reduce populations to a low level:  
• Until the 1990s , the mite was successfully controlled in Japan using the fungicide 
dithiocarbamate, which was sprayed to prevent melacose disease caused by Diaporthe citri 
(Ashihara et al. 2004; Tsuchida and Masui 2020 ). However, since the development of 
dithiocarbamate -resistant A. pelekassi populations, the mite has sometimes reached outbreak 
levels that cause severe damage ( Ashihara et al. 2004).  
• In Florida, there is a recommended in -field control strategy, including sampling method and 
schedule, as well as chemical treatments for citrus growers to prevent damage by 
A. pelekassi  (Qureshi et al.  2020).  
• There are control methods available for the mite , and there is  ongoing research into its 
control. Surveying and chemical treatments are likely to reduce the prevalence of the mite in 
commercial citrus orchards to a low level but are unlikely to eliminate it.  
 
Aculops pelekassi feeding  may be visually detectable in the field and/or packhouses, leading to the 
removal of infested  produce, but  individuals are likely to be undetected . 
• Feeding of the mites on citrus fruits causes obvious symptoms on the surface of the affected 
fruit (Childers and Achor 1999; Ashihara et al. 2 004). In Florida , early -season feeding of A. 
pelekassi caused extensive rind blemishing in many groves during 1999 (Childers and Achor 
1999). In Japan, early mite feeding has been associated with callus formation on the skin of 
Citrus unshiu (satsuma manda rin) (Ashihara et al. 2004). Feeding late in the season 
(September to October) causes skin bronzing, and both symptoms have been observed when 
mites feed mid -season (Ashihara et al. 2004). Such symptoms are likely to be detected during 
in field inspections  or during harvesting and packhouse activities , with  the infested fruit 
removed.  
• However, the mites are very small (females 140 –150 μm) and are golden yellow/pink in 
colour ( Childers and Achor 1999).  Therefore, mites on healthy -looking fruit would not be 
detected by visual inspection.  
• The mite feeds and lays eggs on the outside of fruit (Childers and Achor 1999) and is likely to 
be removed by post -harvest processes such as washing and brushing. However, it is possible 
that withi n a consignment of fruit a small proportion of mites could be sheltered under fruit 
calyces. Calyces are usually not removed from citrus as removal hastens decay (Cronje et al . 
2005).  
• The navel of some orange cultivars can be a complex structure with tight  spaces suitable for 
mites to hide in.  
• No detections of A. pelekassi at the New Zealand border have been recorded (LIMS  
database) . EPPO has not reported any detections of A. pelekassi at EU border s 1999 –2016  
(EPPO interceptions ).  
 
Aculops pelekassi is likely to  survive transit on citrus commodities . 
• Transit of citrus fruit usually includes cold storage, though temperatures may not be very low 
(for example, grapefruit and mandarin s exhibit chilling injury at 7 °C and 8°C respectively and 
unconditioned lem ons below 14.5°C; McGregor 1987).  Recommended storage and shipping 
temperature ranges for orange s (C. sinensis ) are within the range 0 °C to 8°C depending on 
the variety/cultivar/origin (BMT 2020).  
• Regions in Japan where citrus is produced can have average  daily winter temperatures  
similar to those that would be encountered during  cold storage , for example , Takamatsu has 
average low temperatures between December and March of 3.7 °C, 1.6 °C, 1.8 °C and 4.4 °C 
and Kyoto 3.2 °C, 1.2 °C, 1.4° C and 4 °C (Statistic s Bur eau, Japan 2020) . As the mite 
successfully overwinters in Japan, it is assumed that A. pelekassi would survive  cold transit to 
New Zealand. However, this may depend on whether the mites are physiologically prepared 
to overwinter.  
 
The overall likelihood of entry for A. pelekassi  on commercially produced citrus is considered  low, with 
low uncertainty. There are in-field control programs including sampling and chemical treatments 
available for the mite, which can prevent and reduce A. pelekassi  infestations. Furthermore, citrus 
varieties are in season when the mite populations on fruits are at their lowest. Inspection of fruit is  
431 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  likely to detect fruit damaged by mite feeding, but not the mites themselves. Therefore, the likelihood 
of entry of the mite is rate low, with low uncertainty.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of Aculops pelekassi  to transfer 
from imported citrus fruit into a suitable environment to allow establishment 
(exposu re) is considered to be low to moderate, with moderate uncertainty.  
 
Most organic  waste in New Zealand is disposed of by low -risk method s, meaning mites would be 
unable to reach suitable hosts . 
• The majority of waste in New Zealand is bagged and disposed of in landfills or run through  
kitchen disposal units.  These methods would mean that the mite is unlikely to survive or to 
find a suitable host. See section 2.4.1  for discussion on waste disposal.    
 
However,  some waste is likely to be disposed of using high -risk methods, including composting in 
gardens, discarding into the environment (e.g. roadsides, parks) and us ing as animal feed , potentially 
allowing mites to come into contact with suitable ho sts.  
• Citrus trees are not naturalised in the New Zealand environment ( Breitwieser et al.  2010). 
Therefore, any mites on fruit discarded into the environment are unlikely to find a suitable 
host.  
• However, citrus trees are commonly grown by home gardeners a cross the country. Therefore, 
any mites on fruits discarded into home compost bins or used to feed animals may be able to 
find a host for establishment.  
 
Adult A. pelekassi  can be spread between plants via wind .  
• Mite species in the Tetranychidae  and Eriophyidae have adaptive behaviours, such as 
moving to plant tips, raising their front legs and leaping into the air, which enable them to 
disperse better on wind currents . However, while aerial dispersal is considered the most 
important means of dispersa l for eriophyid mites, it has been regarded as the most risky 
mode of dispersal for specialised feeders, as the probability of landing on a suitable host is 
very low  (Michalska et al. 2010).  
• Individuals of A. pelekassi have been captured even up to 80  m from infested trees. This 
suggests that the mites can be moved on the wind between and among orchards. It is 
recommended that windbreaks are used to prevent spread between orchards ( Tsuchida and  
Masu i 2018).  
• Therefore, the mite may be spread by wind from an  open home compost bin to a suitable 
citrus host, particularly as citrus trees are commonly grown by home gardeners.   
 
There is moderate uncertainty associated with this conclusion (that the likelihood of exposure is low to 
moderate). There is no informat ion available on the movement of mites from discarded fruit , and 
furthermore, the assumptions regarding disposal methods may not be correct.   
 
Given the arguments and evidence below,  the suitability of New Zealand’s 
environment for the establishment of Aculops pelekassi  is considered high, with low 
uncertainty.  
Aculops pelekassi  is described as a subtropical species  and is reported from Mediterranean countries 
with high climate similarity to New Zealand : 
• It is a subtropical species recorded from palearctic, oriental and neotropical regions (Vacante 
2010).  
• The mite has been reported from countries with a similar climate to New Zealand, including 
Croatia (CMI 0.8), Italy (CMI 0.8 –0.9), mainland Japan (CMI 0.7 –0.8) and Greece (CMI 0.8) 
(Phillips et al. 2018). This species has also been reported from Florida (CMI 0.5 –0.7), Korea 
(CMI 0.6 –0.7) and Thailand (0.3 –0.5) (Phi llips et al. 2018).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 432 • It is highly likely that the New Zealand climate would be suitable to support establishment of 
the mite. However, the warmer, northern regions (where the majority of citrus crops are 
grown) are likely to be most suitable for the mite.  
 
However, the New Zealand climate may increase the developmental time and reduce the oviposition 
rate, compared to those countries wher e the mite is economically significant.  
• In Croatia , there are 18 –22 generations of the mite per year (Mijuskovic and Kosac 1972). No 
evidence was found of the mite being an economically significant pest in this country. The 
New Zealand climate is very simi lar to that of Croatia , and it is assumed the number of 
generations of the mite per year in New Zealand would be similar.  
• The development of the mites is influenced by temperature (Vacante and Bonsignore 2009). 
At 20 °C, the developmental time (from egg to adult) was 14.9 days compared to 6.3 days at 
30°C (Seki 1979).  
• Maximal oviposition occurs at 25°C with 21.8 eggs per female and stopped at 15°C (Seki 
1979). Increased relative humidity was also found to improve the life span and fecundity of 
the mites. Th e life span was 7.5, 14.5 and 14.6 days and the fecundity 5.4, 21.5 and 27.1 
eggs at 33 %, 75% and 84% relative humidity respectively (the temperature used is unknown) 
(Seo and Kim 2014).  
• In New Zealand , citrus i s mainly grown in areas with high humidity an d warm summers ; 
however , temperatures are rarely over 30 °C (Chappell 2013a, b; Chappell 2016) . Therefore, 
although the conditions are likely to be suitable for establishment, developmental times would 
be increased and oviposition may be reduced compared to countries where the mite is a 
serious pest.   
• Until Huang (1971) observed spermatophores on citrus leaves and the genital organs of some 
specimens indicated the presence of male mites, it was thought that A. pelekassi populations 
consisted o f only females (Ashihara et al. 2004). The sex ratios within populations in Japan 
are bias ed towards female s and vary between seasons . During overwintering , the population 
is 100% females (Ashihara et al. 2004). Therefore, the ability to reproduce and establish a 
population of A. pelekassi is unlikely to be limited by the ability to find a mate.  
 
Table 14.1.1  Geographic distribution of Aculops pelekassi on Citrus spp. Areas in bold  are included in the 
Citrus IHS project.  
Region  Country  Reference  
Europe  Croatia  Mijuskovic and Kosac (1972)  
Greece  Keifer (1959) , cited in Vacante (2016)  
Italy Costantino (1962) , cited in Vacante (2016)  
North America  USA  (Florida)  Denmark (1962)  
South America  Brazil  Keifer (1944) , cited in Ashihara et al. (2013)  
Paraguay  Flechtmann et al. (1970)  
Asia China  Kuang et al. (2005) , cited in Vacante (2016)  
Iran Hajizadeh  and Hosseini (2004) , cited in 
Vacante (2016)   
Japan  Ehara (1964) , cited in Vacante (2016)  
Korea  Seo and Kim (2014) ; Vacante (2010)  
Taiwan  Huang and Wang (1997)  
Thailand  Keifer and Korr (1978) , cited in Vacante 
(2016)  
 
Host availability  may be a limiting factor . 
• Citrus is the only host of A. pelekassi (Ellis 2019 ). Citrus species are commercially grown in 
New Zealand and by home gardeners around the country. However, commercial orchards are 
concentrated in specific regions in the north o f the country (see  section 2.4.2 ).  
• There are no Citrus species naturalised in the New Zealand environment ( Breitwieser et al.  
2010).  
433 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Therefore, the limited availability of suitable host plants my act as a barrier to establishment of 
A. pelekassi.  
• However, individuals of A. pelekassi  have been captured up to 80  m from infested trees 
(Tsuchida  and Masui 2018). Therefore, the mites are likely to be able to spread within and 
between citrus orchards.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by Aculops 
pelekassi  is likely to be low, with low uncertainty . 
Damage caused by A. pelekassi reduces  the quality and marketability of citrus fruits . 
• The mite is found, along with Phyllocop truta oleivora  (citrus rust mite), on all citrus varieties 
throughout Florida ( Childers and Achor 1999; Qureshi et al. 2020). No evidence was found of 
the mite affecting any host other than citrus.  
• Adult A. pelekassi feed on citrus fruit (Ashihara  et al. 2004). On Citrus sinensis , the feeding 
caused punctures in the skin , and on C. unshiu , calluses were formed if the mites fed as the 
fruit w as growing (Ashihara et al. 2004). In Florida , early feeding by A. pelekassi caused 
extensive rind damage dur ing the 1999 season (Childers and Achor 1999). Infestations in 
autumn cause skin bronzing. Sometime s both symptoms were seen on fruit (Ashihara et al. 
2004). Such symptoms would reduce the marketability and grade of the affected fruits 
(Qureshi et al.  2020 ).  
• The quality of fruit may also be reduced , as the size and weight of fruit following mite feeding 
were less than  the size and weight of  fruit not damaged by the mites (Ashihara et al. 200 4).  
• The mite is an economically significant pest on citrus in Kor ea (Seo and Kim 2014) , Japan 
(Ashihara et al. 200 4) and Florida ( Childers and Achor 1999) .   
• In Japan , outbreaks leading to severe damage occur when spring temperatures are above 
average and there is unusually low rainfall in early spring (Childers and Ach or 1999). 
Therefore, economically significant outbreaks may not occur every year, only when the 
climate is suitable.   
• Aculops pelekassi has a quarantine status in the EPPO database (EPPO 2020). Therefore, 
establishment of the mite in New Zealand has the potential to cause trade impacts.  
• No information on the mite causing yield losses of citrus crops was found.  
 
As the impacts associated with A. pelekassi are limited to reducing the marketability of citrus fruits 
and are only expected to be severe during years with unusually high spring temperatures, the impacts 
to the New Zealand economy are rated as low. However, during outbreak years , the mite has the 
potential to cause economically significant impacts for the citrus industry.   
 
Aculops pelekassi may cause low sociocultural impacts in home gardens.  
• Citrus trees are commonly grown in home gardens.  However, the symptoms caused by the 
mite (skin calluses and discolouration) do not affect the yield or taste of the fruit and are 
unlikely to cause severe affects for home gardeners.  
• However, during times of severe outbreaks , gardeners may have to invest in chemical control 
treatments.  
 
Environ mental impacts caused by the establishment of A. pelekassi are likely to be negligible . 
• Aculops pelekassi is a monophagous pest and only attacks citrus trees (Ellis 2019).  
• There are no native Citrus species in New Zealand , and the commercial species are not fully 
naturalised in the environment ( Breitwieser  et al. 2010). Therefore, establishment of A. 
pelekassi would not cause environmental impacts.  
 
Aculops pelekassi is unlikely to cause unwanted impacts on human health.   
• No evidence of such impacts has been found . 
 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 434 Risk assessment summary : 
Given the arguments and evidence below,  Aculops pelekassi  may be considered  for 
additional measures . 
• Mite feeding causes visible symptoms on citrus fruit skins, which are visibly detectable . 
• Adult mites feed and lay eggs  on the surface of  fruit and are likely to  be removed by general 
handling  and post -harvest processes. However, low levels of mites on healthy -looking fruit, or 
mites in areas such as navels, may not be detected . 
• Aculops pelekassi  may be capable  of moving , due to adaptive behaviours,  from imported fruit 
into a suitable environment to allow establishment . 
• The mite does not require a mate in order to reproduce and establish a population .  
• Although the New Zealand climat e is likely to be suitable for establishment, as the mite only 
affects citrus , availability of suitable hosts is likely to be limited.  
• The establishment of A. pelekassi is likely to cause low economic impacts to New Zealand.  
The mite is not known to cause environmental or human health impacts.  
 
 
13.1.4  References  
Ashihara, W; Kondo, A; Shibao, M; Tanaka, H; HiehataI, K; Izumi, K (2004) Ecology and control of 
eriophyid mites injurious to fruit trees in Japan.  Japan Agricultural Res earch Quarterly: JARQ , 38(1): 
31–41. 
BMT (2020) Oranges. Cargo Handbook . https://cargohandbook.com/Oranges  Accessed 22 
September 2020.  
Breitwieser , I; Brownsey P  J; Nelson W  A; Wilton , A D (eds) (2010) Flora of New Zealand Online . 
http://www.nzflora.info/  Accessed 30 September 2020.  
Chappell, P R (2013a) The climate and weather of Northland. NIWA Science and Technology Series 
59. 
Chappell, P R (2013b) The climate  and weather of Auckland. NIWA Science and Technology Series  
60. 
Chappell, P R (2016) The climate and weather of Gisborne. NIWA Science and Technology Series 
70. 
Childers, C C (1994) Biological control of phytophagous mites on Florida citrus utilizing pred atory 
arthropods. In Rosen, D; Bennett, F D; Capinera, J L (eds)  Pest Management in the Subtropics: 
Biological Control - A Florida Perspective . Intercept ; Andover, UK ; pp 255 –288.  
Childers, C C; Achor, D S (1999) The Eriophyoid  Mite Complex on Florida Citrus (Acari: Eriophyidae 
and Diptilomiopidae). Proceedings  of the Florida State Horticultural Society , 112: 79 –87. 
Childers, C C; Rogers, M E; Ebert, T A; Achor, D S (2017) Diptilomiopus floridanus  (Acari: 
Eriophyoidea: Diptilomi opidae): its distribution and relative abundance with other eriophyoid species 
on dooryard, varietal block, and commercial citrus in Florida.  Florida Entomologist , 100(2): 325 –333. 
Costantino, G (1962) Acari vechi e nuovi, parassiti degli agrumi in Italia.  Atti dell’Accademia 
Nazionale Italiana di Entomologia, Bologna , 10: 154–164.  
Cronje, P; Crouch, E M; Huysamer, M (2005) Postharvest calyx retention of citrus fruit. Acta 
Horticulturae , 682: 369 –376.  
435 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Denmark, H A (1962) Aculus pelekassi  Keifer , Another citrus mite in Florida. Proceedings of the 
Florida State Horticultural Society , 75: 25 –26. 
Ellis, W N (2019) Aculops pelekassi  (Keifer, 1959). Plant Parasites of Europe.  
https://bladmineerders.nl/parasites/animalia/arthropoda/ac ari/actinotrichida/prostigmata/eleutherengo
na/eriophyoidea/eriophyidae/phyllocoptinae/anthocoptini/aculops/aculops -pelekassi/  Last updated 21 
September 2019. Accessed 21 December 2020.  
EPPO Interceptions on Imported Commodities v10.0 (1999 –2016)  
Flechtmann , C H W; Aranda, B R (1970) New records and notes on eriophyid mites from Brazil and 
Paraguay, with a list of Eriophyidae from South America.  Proceedings of the Entomological Society of 
Washington , 72: 94–98. 
Florida Citrus Mutual (2017) Citrus seasons. http://flcitrusmutual.com/citrus -101/citrusseasons.aspx  
Accessed 21 December 2020.  
Hajizadeh, J; Hosseini, R (2004) Introducing of eight species of family Eriophyidae from forest plants 
in Guilan Province. Proceedings of the16th Plant Protection Congress , p 279.  
Huang, T (1971) Records of ten eriophyid mites associated with plants in Japan (with 64 text -
figures).  北海道大學理學部紀要 , 18(1): 256 –276. 
Huang, T; Wang, C (1997) A new -record species of  eriophyid mite on lemon from Taiwan (Acarina: 
Eriophyidae).  Chinese Journal of Entomology , 17(4): 269 –274. 
Japan -Guide.com (2020) Japanese fruits. https://www.japan -guide.com/e/e2347.html  Last updat ed 31 
October 2020. Accessed 21 December 2020.  
Keifer, H H (1959) Eriophyid studies XXVII, occasional paper 1.  California Department of Agriculture . 
Bureau of Entomology. Occasional Papers No. 1.  
Keifer, H H and Korr, L C (1978) Eriophyid mites of Thailan d. Plant Protection Service Technical 
Bulletin. No. 38. Depart. Agric. Ministry. Agric. and Co -ops. Bangkok, Thailand.  [cited in Childers and 
Achor 1999]  
Kuang, H Y; Luo, G H; Wang, A W (2005) Fauna of eriophyid mites from China (II)(Acari: 
Eriophyoidea).  China Forestry Publ. House, Beijing , 176. 
LIMS (20 16) Laboratory Information Management System (LIMS) -Plant Health and Environment. 
Accessed 30 September 2020.  
McGregor, B (1987) Tropical Products Transport Handbook . USDA; Washington DC , USA . 
(Agriculture Handbook No. 668 edition). https://naldc.nal.usda.gov/download/CAT89930509/PDF . 
Michalska, K; Skoracka, A; Navia, D; Amrine, J W (2010) Behavioural studies on eriophyoid mit es: an 
overview.  Experimental and Applied Acarology , 51(13): 31 –59. 
Mijuskovic, M; Kosac, D (1972) Control of Aculops pelekassi  Keifer (Acaria: Eriophyidae), an 
important mite injurious to citrus on the coast of Montenegro.  Jugoslovenskog Vocarstva , 21(22): 
835–842. [cited in Childers and Achor 1999]   
Mineo, G; Ragusa, S (1970) Severe infestations of Aculus pelekassi  Keifer and 
Polyphagotarsonemus latus  (Banks) in the lemon groves of the Palermo region. [Abstract only] 
Bollettino dell ’Istituto di Entomologia Agraria e dell ’Osservatorio di Fitopatologia di Palermo , 8: 53–56.  
NZOR (2020) New Zealand Organisms Register. http://www.nzor.org.nz/ . Accessed 18 September 
2020.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 436 ONZPR  (2020) Official New Zealand Pest Register . MPI public database. Ministry for Primary 
Industries; Wellington, NZ. https://pierpestregister.mpi.govt.nz/  
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: an evaluation with non -native ants in New Zealand.  Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io /CMI -maps -csv/ 
PPIN (2020) Plant Pest Information Network. MPI internal database. Ministry for Primary Industries; 
Wellington, NZ. Accessed 18 September 2020.  
Qureshi, J; Stelinski, L; Martini, Xavier; Diepenbrock, L M (2020) 2020 –2021 Florida Citrus Produ ction 
Guide: Rust Mites, Spider Mites, and Other Phytophagous Mites. UF/IFAS Extension.  University of 
Florida; Florida, USA. https://edis.ifas.ufl.edu/pdffiles/CG/CG00200.pdf  
Seki, M (1979) Ecological studies of the pink citrus rust mite, Aculops pelekassi  (Keifer), with special 
reference to the life cycle, forecasting of occurrence and chemical control of A. pelekassi . [cited in 
Childers and Achor 1999]  
Seo, Y D; Kim, D S (2014) Effects of humidity and citrus leaf age on the multiplication of Aculops 
pelekassi  (Acari: Eriophyoidea) and seasonal population abundances in citrus orchards.  [Abstract 
only] Korean Journal of Applied Entomology , 53(1):1–6.  
Statistics Bureau, Japan (2020) Climate. Statistical Handbook of Japan 2020 . Statistics Bureau, 
Ministry of Internal Affairs and Communication; Tokyo, Japan; pp 4 –5. 
https://www.stat.go.jp/english/data/handbook/pdf/2020all.pdf#page=17  Accessed 23 December 2020.  
Tsuchida, Y; Masui, S (2018) Aerial dispersal of pink citrus rust mite, Aculops pelekassi  (Acari: 
Eriophyidae).  [Abstract only]  Japanese Journal of Applied Entomology and Zoology , 62(3):189 –192.  
Tsuchida, Y; Masui, S (2020) Effects of providing pollen to Euseius sojaensis  or Amblyseius eharai  
(Acari: Phytoseiidae) on populations of the pink citrus rust mite, Aculops pelekassi  (Acari: 
Eriophyidae).  Applied En tomology and Zoology 55(2): 241 –248. 
Vacante, V (2010) Review of the phytophagous mites collected on citrus in the world. Acarologia , 
50(2): 221 –241. 
Vacante, V (2016) The Handbook of Mites of Economic Plants: Identification, Bio -Ecology and 
Control . CAB I nternational; Wallingford, UK.  
Vacante, V; Bonsignore, C (2009) L’acaro della ruggine degli agrumi (Aculops pelekassi (Keifer)). 
[The pink citrus rust mite ( Aculops pelekassi  (Keifer)) in Italy.] [Abstract only] Protezione delle Colture , 
2: 47 –50.   
437 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  13.2 Eotetranychus lewisi  (Lewis spider mite ) 
The female body is ovoid, about 360  µm long, a pale greenish -amber colour with blackish spots 
laterally. The male is smaller and of a mustard yellow colour (Vacante 2016).  
 
Scientific name: Eotetranychus lewisi  (McGregor, 1943 )  
Order/Family: Acari /Tetranychidae  
Other names include: Tetranychus lewisi  McGregor, 1943; Lewis mite  
 
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Eotetranychus lewisi meets the criteria to be a quarantine pest for New Zealand.  
• Eotetranychus lewisi has a moderate association with citrus fruit.  
• Basic measures  are likely to reduce the likelihood of introduction of E. lewisi  to a moderate 
degree; consequently , the likelihood of entry is low-moderate  (with low uncertainty) . 
• Eotetranychus lewisi has moderate ability to move from imported fruit and into a suitable 
environment to allow establishment, that is, onto a host plant  (with low uncertainty) . 
• The suitabilit y of the New Zealand environment for E. lewisi  to establish is considered 
moderate  (with low uncertainty) . 
• The level of impact caused by E. lewisi  is likely to be low to moderate (with moderate 
uncertainty ). 
• Eotetranychus lewisi may be considered for addit ional measures . 
 
Summary of risk assessment against criteria  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Moderate  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Low 
The ability to move from the imported commodity  onto a suitable host  Moderate  Low 
Suitability of the N ew Zealand  environment  Moderate  Low 
Impacts on the New Zealand economy, environment, health and society  Low–moderate  Moderate  
 
13.2.1  Hazard  identification: quarantine status  
 
Given the arguments and evidence below,  Eotetranychus lewisi  meets the criteria to 
be a quarantine pest for New Zealand  
Criteria for being a quarantine pest relevant to this assessment are: not present in New Zealand, and 
of potential i mportance (able to establish and cause harm).  
 
Eotetranychus lewisi  is not known to be present in New Zealand:   
• It is not recorded in NZInverts (2020); NZOR  (2020) or PPIN (2020).  
• It is listed as ‘ regulated’ in ONZPR  (2020) . 
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 438 Eotetranychus lewisi  has the potential to establish and spread in New Zealand . 
• The current geographical distribution of Eo. lewisi  includes countries with a  climate match 
index  (CMI) of 0.7 to 0.9  (Phillips et al. 2018), e.g. parts of Chile, USA, South Africa and 
Japan , indicating pot ential to establish in New Zealand.  
• Eo. lewisi  is polyphagous. It has been reported on  75 plant species ascribed to 28 families. 
The highest number of species are within the Euphorbiaceae (15) , and the second highest 
are in the Leguminosae (Fabaceae) (10) (Migeon et al. 2006 –2020).  
• A number of Eo. lewisi  hosts are widely grown  in New Zealand , such as citrus, roses,  
Euphorbia  spp. and Acacia  spp. 
 
Eotetranychus lewisi  has the potential to cause impacts on the economy and environment of New 
Zealand . 
• Host plants of Eo. lewisi  include crops that are economically important to New Zealand , such 
as citrus, strawberries, poinsettia and grapevine . 
 
Eotetranychus lewisi  has the potential to harm the New Zealand environment . 
• The Lewis mite has been reported on  plant species under genera that are present in New 
Zealand , e.g. Euphorbia , Rubus  and Solanum . 
 
13.2.2  Hazard identification: commodity association  
 
Eotetranychus lewisi  is associated with citrus fruit . 
 
Eotetranychus lewisi  is reported from citrus fruit . 
• Eotetranychus lewisi  occurs on the fruit of citrus and the underside of leaves of other hosts 
(Vacante 2016).  
 
Eotetranychus lewisi  has previously been intercepted at the New Zealand border on citrus fruit.  
• There are 6 historic records of live adults detec ted on oranges from California. These are 
likely to have been prior to the 1990s , given that the dates and consignment numbers were 
not recorded (MPI interception  database 1988 –2014).  
• However, there do not appear to be any recent interceptions of Eo. lewi si on citrus  recorded 
(LIMS database up to 2019 ). This could be for any of several reasons . Mite populations may 
be well managed and killed or removed prior to export, or  they may be  so few they are not 
detected , or they may be  too damaged for full identif ication. There have been detections of 
live tetranychid  eggs on citrus fruit ( e.g. consignments C2015/360546  and C2016/414962 , 
LIMS ). 
 
13.2.3  Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Eotetranychus lewisi  has a moderate  
association with citrus fruit  (with low uncertainty).  
 
Eotetranychus lewisi  is reported from citrus and specifically from the fruit.  
• Eotetranychus lewisi  lives and reproduces on the fruit of citrus, laying eggs in the depressions 
of the rind ( Jeppson et al . 1975 ). The egg has a short stalk , but no attachment  threads extend 
from the stalk to the host (Vacante 2016).  
• It attacks  lemon and sweet orange  in the southern citrus areas of California (Jeppson et al. 
1975).  
But:  
439 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Eotetranychus  lewisi  is considered a mi nor pest of citrus by Vacante (2010), occurring only 
occasionally on citrus in southern California, except for the desert areas (Jeppson et al. 
1975).  Although it is reported from other countries , it seems to be on other host plants , and 
specific association with citrus is not elaborated upon.  
 
 
 
Given the arguments and evidence below, basic measures are likely to reduce the 
likelihood of introduction of Eotetranychus lewisi  to a moderate  degree; 
consequently, the likelihood of entry is considered low  to moderate (with low 
uncertainty) : 
Visual inspection should usually detect Eo. lewisi  on citrus fruit.  
• Eotetranychus  lewisi  produces profuse webbing on leaves which collects dust and makes 
infestations highly visible. The presence of web bing is an indication that mites may be present 
(Jeppson et al. 1975).  
• Heavy infestations of the mite cause obvious feeding damage to the rind of citrus fruit 
(Jeppson et al. 1975).  
But: 
• The mites are very small (0.36  mm or less) and cryptically coloured ( Vacante 2016) so may 
not be readily detected on all lemons and oranges.  
 
A low level of infestation of mites in a consignment makes detection more difficult.  
• Webbing is less likely to be present , and mites  are less likely to be encountered during an 
inspe ction.  
 
Common post -harvest activities may not remove all mites.  
• It is expected  that most mites and eggs would leave or be removed from fruit during the usual 
post-harvest activities. However, it is possible that within a consignment of fruit , a small 
proportion of mites could be sheltered under fruit calyces. Calyces are usually not removed 
from citrus , as removal hastens decay (Cronje et al 2005).  
• The navel of some orange cultivars can be a complex structure with tight spaces suitable for 
mites to hide in.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Eotetranychus lewisi  has moderate  ability 
(with low uncertainty) to move from imported fruit and into a suitable environment to 
allow establishment, that is, onto a host plant  (exposure/transfer) . 
Most waste in New Zealand is disposed of using  low-risk method s. 
• Using l andfill s or kitchen disposal units are common waste disposal methods. In these 
situations, it is very unlikely mites on imported fruit would survive.  
 
Some citrus waste is likely to  be disposed of in proximity to host plants . 
• A proportion of the unavoidable waste generated by  citrus fruit will find its way into the 
environment, such as open composts in home gardens.  
• Hosts of Eo. lewisi  include lemons, roses, strawberry and cucurbit species, which are 
commonly grown in New Zealand home gardens.  
• A proportion of mites on discarded citrus waste may move to a nearby host plant.  
Tetranychid mites can disperse by both active and passive means.  
• “Dispersal of tetranychid mites occurs by locomotion [walking] between different parts of the 
same plant and/or between plants and by p assive dispersal. Air currents, rain, irrigation water, 
agricultural operators, harvesting tools and various animals may be involved in passive 
dispersal .” (Vacante 2016)  
 
Tetranychid nymphs (acti ve phase) and adults are mobile.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 440 • Eotetranychus  lewisi  nymphs  in their active phase and adults can walk between fruits/leaves 
and between plants, either on the webbing they produce or on the plant ’s surface. 
Deterioration of a host plant has been shown as a trigger for dispersal in some tetranychid 
species (Ghazy et  al. 2016). Eo. lewisi  produces silk and may be able to balloon on air 
currents like some  other  tetranychids ( e.g. T. kanzawai ). Passive movement is also possible 
on animals such as insects, birds, rodents or household pets, on garden equipment or on 
cloth ing (EFSA 2017 ). Some hosts of Eo. lewisi  are common in domestic gardens, residential 
areas and community spaces, such as lemons, roses, strawberry plants, oaks, acacia and 
species of Euphorbia .  
 
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for establishment of Eotetranychus  lewisi  is considered moderate  (with 
low uncertainty).  
 
The geographic distribution of Eotetranychus  lewisi  ranges across subtropical, tropical and temperate 
regions.  
• The current geographic distribution is presented in Table 14.2.1. The countries and areas that 
are underlined have a climate match  (see section  2.4.2) with New Zealand of at least 0.7 or 
greater ( Phillips et al. 2018) . 
• A climate match of 0.7 or greater indicates there are parts of New Zealand that are suitable 
for the establishment of E. lewisi .  
• In California it was found primarily along the coast (EFSA 2017). Northwards of Los Angeles , 
the Califo rnian  coastal regions mostly have a climate match of 0.7 to 0.8 with New Zealand, 
whereas southwards of Los Angeles has largely climate match index ( CMI) values  between 
0.6 and 0.7  with New Zealand (Phillips et al.  2018) . 
 
Table 1 4.2.1  Known geographic distribution of Eotetranychus lewisi  as at June 2020. Countries in bold  
are those considered as current or potential exporters of citrus fruit to New Zealand, and those underlined  have 
regions with a CMI of 0.7 or greater with New Zealand .  
 
Continent  /region  Country  /area  
Africa  South Africa ; Libya (Migeon et al. 2006 –2020 ) 
Asia Iran (Beyzavi et al. 2013); Japan ; Philippines ; Taiwan  
(Migeon et al.  2006 –2020 );  
North America  Mexico ; Canada ; (Migeon et al. 2006 -2020); USA - California , Florida , Hawaii , 
Maryland , Michigan , Arizona , Illinois , Massachusetts , Oregon , Washington  
(EFSA 2017)  
Central and South 
America  Bolivia ; Chile ; Colombia; Costa Rica; Ecuador ; El Salvador; Guadeloupe; 
Guatemala; Honduras; Nicaragua; Panama; Peru  (Migeon  et al. 2006 –2020 ) 
Europe  Portugal (Madeira) (Migeon et al. 2006 –2020); Poland  (greenhouses) (EFSA 
2017)  
 
Availability of host plants is unlikely to be a barrier to Eotetranychus  lewisi  establishment (with 
moderate uncertainty).  
• Eotetranychus  lewisi  is polyphagous, with a known host range of at least 75 species across 
28 families of which species in the Euphorbiaceae and Leguminosae are  favoured (Migeon 
and Dorkeld 2006 –2020 ). 
• Eotetranychus  lewisi  has been reported from  lemons ( Citrus limon ), oranges  (Citrus sinensis ), 
roses ( Rosa  sp.), Acacia  sp., oak ( Quercus  sp.), olive trees ( Olea europaea ), strawberry 
(Fragaria  x ananassa ), raspberry  (Rubus  sp.), peaches ( Prunus  persica ), pear ( Pyrus  
communis ), Ipomoea  sp., Cucurbita  sp., cottonwood, aspen ( Popul us deltoides  and P. 
tremuloides ), castor bean ( Ricinus communis ), ponderosa pine ( Pinus  ponderosa ), Solanum  
sp. and grapevine ( Vitis sp.) (Migeon and Dorkeld 2006 –2020) which are all grown in New  
441 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Zealand ( Breitwieser et al. 2010; NZCPN 2020). It is also a recognised major pest of the 
popular ornamental, poinsettia ( Euphorbia  pulcherima ) (Kaur and Zalom 2017).  
 
Greenhouses are likely to be suitable environments for E. lewisi  to live in.  
• Eotetranychus  lewisi  has been reported as a significant pest of greenhou se poinsettia (Zhang 
2003) , and is also known from greenhouses in Poland where it has occurred a few times 
(EFSA 2017). It is reported as a pest on poinsettia in Taiwan (Ho and Shih 2004).  
• Strawberry is a host for E. lewisi  and in New Zealand some of the c ommercial strawberry 
production is in greenhouses  (http://www.grower2grower.co.nz/news/post/year -round -
strawberry -production/ ). 
 
Eotetranychus  lewisi has biological characteristics that can assist its establishment in new 
environments  
• E. lewisi  can reproduce both sexually and parthenogenetically. The latter is arrhenotokous, 
producing only male offspring, and does not require the female to be mated. In this way, small  
founding populations may be initiated by an unmated female, as inbreeding between mothers 
and sons, sisters and brothers is common in tetranychid populations (in Vacante 2016).  
• Heavy infestations of E. lewisi produce loose webbing under which the colony w ill live and 
feed (Zhang 2003). The webbing gives protection against weather and predators.  
• Lai and Lin (2005) used a linear model and a Lactin model to calculate the lower threshold 
temperature [sic] for E. lewisi  (egg to adult) at 8.3 °C and 9.0 °C respect ively. Deutonymphs 
are the most cold -tolerant life stage with their lower threshold calculated at 2.5 °C (Lactin) and 
3.4°C (linear). The upper threshold temperature was calculated to be 28.2 °C. No eggs 
hatched at 30 °C. The highest net reproductive rate occ urred at 24 °C with 17.7 offspring per 
female; the egg -adult survival rate varied between 65 and 85% from 16 to 26 °C, but dropped 
considerably to about 30% at 28 °C. These estimates indicate E. lewisi  could establish in 
many parts of New Zealand where suitab le hosts can be found. Ho (2007) noted that E. lewisi  
was commonly found in Taiwan at higher altitudes where the temperatures were cooler.  
 
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by 
Eotetranychus lewisi  is likely to be low to moderate (with moderate uncertainty).  
Eotetranychus lewisi has been reported as a minor pest of citrus by Vacante (2010).  
• Citrus : 
o The reports of damage to citrus tend to be from California. On lemons, heavy 
infestations of the mite  cause silvering, and on oranges silvering or russeting. There 
is no notable damage to leaves other than the presence of webbing (Jeppson et al 
1975). On Madeira (Portugal) the mite is reported from ‘citrus’ (Vacante 2010). No 
information was found detaili ng economic impacts upon citrus in either California or 
Madeira. Eotetranychus  lewisi  is reported from other countries, but typically on other 
host plants or the hosts are not mentioned.  
However,  
• Other crops:  
o There have been reports of outbreaks of E. lewi si in vin eyards in some regions of 
Chile (EFSA 2017). However, no further information was provided regarding injury or 
economic losses. The mite is also noted from grapevine on the island of Madeira 
(EFSA 2014).  
o In north -central Mexico it is mostly found in peach and sometimes apple trees. It is of 
major economic importance in peaches as densities can be high on leaves and limit 
peach production. Yield was reduced by 62% and fruit weight was reduced by 54% 
with E. lewisi  infestations. It would take several years for heavily defoliated trees to 
recover from mite infestations (EFSA 2017). In New Zealand peaches (and a 
proportion of the apple crop) are grown in the Hawkes Bay. Fresh fruit peach sales 
earned $9m domest ically and processed peaches earned close to $13  m in 2019 
(Plant & Food Research 2019).  
o Eotetranychus  lewisi  is considered an emerging pest in California on organic 
strawberries and its presence on raspberry has been increasing. Feeding damage on Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 442 strawberry causes chlorosis and bronzing of the leaves and in high densities of the 
mite fruit production is reduced (Kaur and Zalom 2017a; Kaur and Zalom 2017b). The 
berryfruit industry in New Zealand earned $47.2m domestically for 2018 -2019 and in 
2019 e xported $47.7m worth of berryfruit to overseas markets.  
 
Resistance to miticides potentially reduces options for managing outbreaks of mites . 
• Some mites become resistant to certain chemical treatments. Generally, the same chemical 
shouldn’t be applied more  than once in a season 
(https://citrusindustry.net/2018/04/18/managing -mites -florida -citrus/ ). 
 
Eotetranychus lewis i may cause impacts to New Zealand sociocultural values  and potentially to the 
natural environment, but  it is unlikely to have impacts on  human health.  
• Ipomoea sp. is a reported host of E. lewisi . It is assumed that Ipomoea batatas  (kumara) 
could be affected by E. lewisi . Kumara is a taonga or  treasured plant t o Māori, and so 
damage to this plant would be considered significant.  
• A number of E. lewisi  hosts , such as roses, lemons, hydrangeas and oaks, are grown in 
domestic gardens and/or amenity plantings and would suffer the impacts of Eo. lewisi  
establishment.  
• Eotetranychus  lewisi  has hosts  in several families, in particular , Euphorbiaceae, Fabaceae 
and Rosaceae; there are genera in these families that are represented in the New Zealand 
native flora. In the Euphorbiaceae , there is  Euphorbia  glauca . The Fabaceae includes 
Carmichaelia spp. (native brooms), Clianthus puniceus (kakabeak) and, most commonly, 
Sophora spp. (kowhai) . The Rosaceae includes 4 species and 2 varieties of a species of 
Rubus  (e.g. R. australis, R. cissoides ) and several species of Acaena  (e.g. A. anserinifolia, 
bidibids ), as well as the less commonly encountered species of Geum . While both the latter 
two families have lots of  native representatives, Sophora , Rubu s and Acaena are the most 
likely to be regularl y encountered. Most exotic pests tha t attack native plants are 
polyphagous, but highly  damaging polyphagous species appear  to be  exceptional , and it has 
been postulated that the  impact of relatively specialised organisms is likely to be greater than 
highly polyphagous  species (Beever et al. 2007 ). Therefore, although E. lewisi  may cause 
some damage to native plants , it seems to be unlikely that it will have severe impacts.  
 
There is a moderate degree of uncertainty associated with this conclusion , as there is very limited 
quantitative information found on  the economic and environmental impacts of Eo. lewisi  overseas.  
 
 
13.2.4  References  
Breitwieser , I; Brownsey P  J; Nelson W  A; Wilton , A D (eds) (2010) Flora of New Zealand Online . 
http://www.nzflora.info/index.html  Accessed July 2020 . 
Cronje, P; Crouch, E M; Huysamer, M (2005) Postharvest calyx retention of citrus fruit. Acta 
Horticulturae , 682: 369 –376. 
EFSA (2014 ). Scientific Opinion on the pest categorisation of Eotetranychus lewisi . European Food 
Safety Journal , 12(7):  3776, 35 p ages . DOI:  10.2903/j.efsa.2014.3776  
EFSA  (2017) Pest Risk Assessment: Eotetranychus lewisi . European Food Safety Journa l, 15(10): 
4878. DOI: 10.2903/j.efsa.2017.4878  
EPPO (2019) EPPO Global Database. https://gd.eppo.int/ . Accessed July 2020.  
Ghazy, N A; Otsuki, H; Sekido, T; Yano, S; Amano, H (2016) Dispersal of diapausing Tetranychus  
urticae  and T. kan zawai . Entomologia Experimentalis et Applicata . DOI: 10.1111/eea.12467  
Ho, C C; Shih, S P (2004) Eotetranychus lewisi , a new pest of poinsettia from Taiwan. Plant 
Protection Bulletin (Taipei) , 46(2): 173–176.   
443 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Ho, C -C (2007) Monitoring on two exotic spider mites in  Taiwan . Applied Zoology Division, 
Agricultural Research Institute, COA; Taichung, Taiwan, ROC; 9 pages.  
Jeppson L R; Keifer, H H ; Baker, W E (1975) Mites Injurious to Economic Plants . University of 
California Press; Berkley, California, USA.  
Kaur, P; Zalom, F G  (2017a) Effect of temperature on the development of Tetranychus  urticae  and 
Eotetranychus  lewisi  on strawberry. Journal o f Entomology and Zoology Studies , 5(4): 441 –444. 
Kaur, P; Zalom, F G  (2017b) Counteraction effect between Tetranychus urticae  Koch and 
Eotetranychus lewisi  (McGregor) on strawberry. Journal of Entomology and Zoology Studies , 5(5): 
653–656. 
Lai, H S; Lin, F C (2005) Development and population parameters of the Lewis spider mite, 
Eotetranychus  lewisi , on poinsettia. [in Chinese] Plant Protection Bulletin (Taichung),  47: 379 –390. 
http://scholars.tari.gov.tw/bitstream/123456789/5641/1/47 -4-2.pdf  
Migeon, A; Dorkeld, F (2006 –2020) Spider Mites Web: a comprehensive database for the 
Tetranychidae. http://www1.m ontpellier.inra.fr/CBGP/spmweb . Accessed August 2020.  
Nichols, M (2018) Year -round strawberry production. Grower 2 Grower . 
http://www.grower2grower.co.nz/news/post/y ear-round -strawberry -production/  Accessed 22 
December 2020.  
NZInverts (2020) New Zealand Land Invertebrates. https://nzinverts.landcareresearch.co.nz/ . 
Accessed 10 June  2020.  
NZOR (2020) New Zealand  Organisms Register. http://www.nzor.org.nz/ . Accessed July 2020.  
NZPCN (2020) Plant Conservation Network . http://www.nzpcn.org.nz/  Accessed July 2020.  
ONZPR  (2020) Official New Zealand Pest Register . MPI public database. Ministry for Primary 
Industries; Wellington, NZ. https://pierpestregister.mpi.govt.nz/  
Phillips , C B ; Kean , J M ; Vink , C J; Berry , J A (2018) Utility of t he CLIMEX ‘match climates regional ’ 
algorithm for pest risk analysis: An evaluation with non -native ants in New Zealand.  Biological 
Invasions , 20: 777–791. Climate match tool available at:  https://b3n z.shinyapps.io/CMI -maps -csv/ 
Plant and Food Research (2019) FreshFacts: New Zealand Horticulture . The New Zealand Institute 
for Plant and Food Research Ltd ; Auckland , NZ. https://www.fr eshfacts.co.nz/files/freshfacts -2019.pdf  
Accessed July 2020.  
PPIN (2020) Plant Pest Information Network. MPI internal database.  Ministry for Primary Industries; 
Wellington, NZ.  
Vacante , V (2010) Review of the phytophagous mites collected on citrus in the world. Acarologia , 
50(2): 221 –241. 
Vacante, V (2016) The Handbook of Mites of Economic Plants: Identification, Bio -Ecology and 
Control . CAB International; Wallingford, UK.  
Zhang, Z Q (2 003) Mites of Greenhouses: Identification, Biology and Control . CABI Publishing; 
Cambridge, UK.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 444 13.3 Tetranychus kanzawai  (kanzawa spider mite)  
Description:  Tetranychus  kanzawai  is a small  (about 0.4 –0.5 mm long) , carmine -coloured , 
polyphagous spider mite that can cause feeding and webbing damage to stems, leaves and fruits of 
economically important plants.  
 
Scientific name: Tetranychus kanzawai  Kishida,1927  
Order/Family: Prostigmata/Tetranychidae  
Other names include: Tetranychus hydrangeae Pritchard & Baker, synonymy by Navajas et al. 
2001; Kanzawa spider mite, tea red spider mite (Vacante 2016)  
 
Summary of conclusion s 
 
Given the arguments and evidence presented : 
 
• Tetranychus kanzawai  meets the criteria  to be a quarantine pest for New Zealand.  
• Tetranychus kanzawai  has a weak association with citrus fruit (with low uncertainty).  
• Basic measures  are likely to reduce the likelihood of introduction of T. kanzawai  to a 
moderate degree . Consequently , the likelihood of entry is low to moderate  (with low 
uncertainty) . 
• Tetranychus kanzawai  has a moderate ability to move from imported fruit and into a suitable 
environment to allow establishment, that is, onto a host plant (with low uncertainty) . 
• The suita bility of the New Zealand environment for establishment of T. kanzawai  is 
considered to be moderate (with low uncertainty) . 
• The level of impact caused by T. kanzawai  is considered  moderate (with low uncertainty) . 
• Tetranychus kanzawai  may be considered  for additional measures . 
 
Summary of risk assessment against criteria  
 
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Weak  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–moderate  Low 
The ability to move from the imported commodity  onto a suitable host  Moderate  Low 
Suitability of the N ew Zealand  environment  Moderate  Low 
Impacts on the New Zealand economy, environment, health and society  Moderate  Low 
 
13.3.1  Hazard  identification: quarantine status  
 
Given the arguments and evidence below,  Tetranychus kanzawai  meets the criteria 
to be a quarantine pest for New Zealand .  
Criteria for being a quarantine pest relevant to this assessment are:  not present in New Zealand, and 
of potential importance (able to establish and cause harm89). 
 
Tetranychus kanzawai is not known to be present in New Zealand .  
• T. kanzawai  is not listed in Zhang et al. (2002) , Gordon (2010) , PPIN (2020) or NZOR (2020).  
• T. kanzawai is listed as ‘ regulated ’ in ONZPR  (2020) . 
 
                                                      
89 Refer to ISPM 5  for the definition of a quarantine pest under the IPPC, and the Biosecurity Act 1993 , for factors to consider 
when defining “harm”.   
445 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Tetranychus kanzawai  has the potential to establish and spread in New Zealand . 
• The current geographical distribution of T. kanzawai  includes countries with a  climate match 
index  (CMI) of 0.7 to 0.9, e.g. parts of USA, South Africa, Japan and Eastern Australia 
(Phillips et al. 2018) , indicating potential to establish in New Zealand.  
• T. kanzawai  is highly polyphagous with a broad host range. It is reported from 193 wild and 
cultivated plants across 63 famili es, among which Fabaceae and Rosaceae have the highest 
number of species (24 and 19 respectively) (Migeon and Dorkeld 2006 –2020).  
• Many of these hosts are widespread and readily accessible in New Zealand, for instance , 
clover, citrus, and weed species such as Solanum nigrum . 
 
Tetranychus kanzawai has the potential to cause impacts to the economy and environment of New 
Zealand . 
• Host plants of T. kanzawai  include crops that are economically important to New Zealand, 
such as citrus, grapevine, strawberry, kumara, apple, pear, stonefruit, beans, eggplant, 
clover, maize; and ornamentals , such as hydrangea, roses, camellias and poinsettia (Migeon 
and Dorkeld 2006 –2020).  
• T. kanzawai  is reported to cause damage to some citrus in  California (Grafton -Cardwell et al. 
2017), strawberries, grapes, eggplant, hydrangeas, tea and other crops in parts of Asia 
(Vacante 2016) and has the potential to do so in New Zealand.  
 
13.3.2  Hazard identification: commodity association  
 
Tetranychus kanzawai  is associated with citrus fruit . 
 
Tetranychus kanzawai  is reported from citrus fruit . 
• Pest management guidelines for citrus in California note that T. kanzawai  produces more 
webbing than Tetranychus  urticae  on citrus, which is “more prominent on the fruit t han the 
leaves” (Grafton -Cardwell et al. 2017).  
• Kanzawa mite can be found on late -harvested Valencia oranges or red grapefruit , and 
extensive feeding causes rind blemishing and associated webbing (Grafton -Cardwell et al. 
2017).  
 
13.3.3  Risk assessment  
 
Likelihood  of entry:  
 
Given the arguments and evidence below,  Tetranychus kanzawai has a weak 
association with citrus fruit (with low uncertainty).  
 
Tetranychus  kanzawai  is considered a minor pest of citrus and seems uncommon on citrus fruit . 
• “Minor pests are those that are present and damage citrus only locally” (Gerson 2003). There 
do not appear to be global reports of serious damage to citrus fruit by T. kanzawai . Despite its 
large list of hosts, “the mite is a major pest of only a restricte d number of plants in Japan, 
southern China and Korea” (Vacante 2016)90. 
 
Tetranychus kanzawai  primarily feeds on leaves.  
• Generally, T. kanzawai  is more likely to be found on the underside of the host plant leaves 
and stems, where it will oviposit, feed and  build its webbing (Osakabe 1967; Zhang et al. 
2002, Vacante 2016). T. kanzawai  adults of both sexes and eggs have been intercepted at 
                                                      
90 Vacante (2016) goes on to say , ”The mite infests cherry in China (Wang 1981a), aubergine (Ho and Chen 1992b) and 
papaya in Taiwan (Chen g et al. 2009), and grapevines in Taiwan (Ho and Chen 1994) and Japan (Ehara 1964a; Ashihara 
1996). The mite was also recorded on strawberry in Taiwan (Chang and Huang 1995) and cassava in the Congo (Gutierrez and 
Bonato 1994) and the Philippines (Villacar los and Vasquez 1988) .” Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 446 the NZ border on cordyline leaves from Malaysia  (e.g. consignments C2014/80437  and 
C2014/115374 , MPI Interception databas e 1988 –2014 ). 
 
However , T. kanzawai  can also be found on fruit at times.  
• It is reported on the fruits of oranges and red grapefruit in California, usually in late summer to 
early autumn (Grafton -Cardwell et al. 2017). As citrus fruit and leaves are in clos e proximity, it 
is likely that in other states and countries, there will be occasions when the mite may be found 
on fruit.  
• Tetranych id91 mites are often intercepted at the New Zealand border on fruit, for example: 
oranges (Tetranychus  sp. from USA, C2014/54913 and C2014/101297  MPI Interception 
database 1988 -2014 ); strawberries ( Tetranychus  sp. from Australia, C2017/264467 LIMS ); 
grapes ( Tetranychus  sp. from Australia C2018/126264  LIMS ). Potentially, some of the 
unidentified intercepted Tetranychus  species may have been T. kanzawai . 
 
 
Given the arguments and evidence below, basic measures are likely to reduce 
likelihood of entry of T. kanzawai  to a moderate degree. Consequently, the likelihood 
of entry is considered to be low to moderate (with low uncertainty).  
Usually, visual inspection should detect adult females and males of T. kanzawai  on citrus fruit.  
• Presence of webbing is often an indication of mite presence.  
• Adults are up to 0.5 mm long and red or yellowish red (Zhang 2002; Vacant e 2016). They can 
be visible to the naked eye, though a ‘10x’ hand lens increases the likelihood of seeing them.  
• Generally, eggs and active life stages are aggregated on their hosts in the field, increasing 
the likelihood of detection.  
 
Life stage may inf luence detectability.  
• Eggs and nymphs are smaller and a lighter colour (Zhang 2002; Vacante 2016), so can be 
more difficult to see.  
• There is a quiescent period between each instar before moulting, from hatching through to 
adulthood (Vacante  2016). During this time, the mite is firmly anchored to its substrate 
(Crooker 1985, in Ikegami et al. 2000) and their colour usually begins to fade towards white 
prior to moult (Ikegami et al. 2000). Detectability may be reduced by their lack of movement  
and paleness.  
 
A low infestation of mites in a consignment makes detection more difficult.  
• Webbing is less likely to be apparent, and mites are less likely to be encountered during 
inspection.  
 
Common post -harvest activities may not remove all mites.  
• Tetranychus  species usually prefer the underside of leaves. In the absence of leaves, 
T. kanzawai  may shelter under the fruit calyx, where it would not be visible and would be well 
protected, for instance, from handling and surface washing. Calyces are not u sually removed 
from fruit as to do so hastens decay (Cronje et al. 2005).  
• The navel of some citrus, i.e. navel oranges, is also a potential shelter for mites.  
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  Tetranychus  kanzawai  has a moderate  
ability to move from imported fruit and into a suitable environment to allow 
establishment, that is, onto a host plant  (with low uncertainty)  (exposure) . 
Some citrus waste will be disposed of in proximity to host plants.  
• A proportion of the unav oidable waste generated from citrus fruit will find its way into the 
environment, e.g. open composts in home gardens (see section 2.4.1,  waste disposal).  
                                                      
91  A tetranychid is a mite of the family Tetranychidae , and Tetranychus  is a genus within the family Tetranychidae.   
447 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Many host plants of T. kanzawai  such as clover, citrus, beans, roses, impatiens, 
chrysanthemums, carna tions, hydrangeas, camellias and weed species are commonly found 
in home gardens and amenity plantings.  
• A proportion of mites on discarded citrus fruit or peel may move to a nearby host to ensure 
their survival.  
 
Tetranychid mites can disperse by both acti ve and passive means.  
• “Dispersal of tetranychid mites occurs by locomotion [walking] between different parts of the 
same plant and/or between plants and by passive dispersal. Air currents, rain, irrigation water, 
agricultural operators, harvesting tools an d various animals may be involved in passive 
dispersal.” (Vacante 2016)  
 
Tetranychus kanzawai  adults and nymphs (active phase) are mobile.  
• Host plant deterioration is one of several stimuli that can initiate dispersal in Tetranychus  
species (in Ghazy et al . 2016). Kondo and Takafuji (1985) showed in a laboratory experiment 
that T. kanzawai  responded more sensitively to food deterioration and dispersed more quickly 
than did T. urticae . Dispersal can occur via walking to a new plant or ‘ballooning’ on air 
currents by producing silken threads. The mite either moves up a plant to the apices for aerial 
dispersal or drops down in still air to the ground, from where it will crawl to another plant (in 
Ghazy et al. 2016).  
 
Given the arguments and evidence below, the suitability of the New Zealand 
environment for establishment of Tetranychus  kanzawai  is considered moderate 
(with low uncertainty).  
The geographic distribution of T. kanzawai  is largely tropical and subtropical, but also includes 
temperate areas.  
• Table 14. 3.1 provides the current geographical distribution. Countries or areas that are 
underlined have a climate match index (CMI) with New Zealand of at least 0.7 or greater 
(Phill ips et al. 2018).  
• Climate matches of 0.7 or greater indicate there are parts of New Zealand where the climate 
is similar enough to be suitable for T. kanzawai  establishment.  
• Climate niche modelling showed that similarity of some origin climates with New Z ealand 
climate regions (destination x season) could be above 70% and even 80% for most New 
Zealand sites, with the main exception (lower similarity due to high rainfall) being the western 
South Island (Halloy et al. 2019)  
• Additionally, T. kanzawai  shares a  very similar geographical distribution and biology with two 
congenerics , T. lambi  and T. ludeni , that have established in New Zealand (Zhang et al. 
2002).  
 
Table 14. 3.1  Known geographic distribution of Tetranychus kanzawai  as at June 2020. Countries in bold 
are current or potential exporters of citrus fruit to New Zealand, and those underlined  have regions with a CMI of 
0.7 or greater with New Zealand.  
 
Continent/region  Country/area  
Africa  Congo, South Africa  (EPPO 2019) , Ivory Coast (Migeon 2015)  
Asia China  (Anhui , Fujian , Guangxi, Jiangsu , Jilin, Liaoning , Shaanxi , Shandong , 
Xianggang  (Hong Kong) , Zhejiang  (EPPO 2019), Xinjiang (Zhang et al . 2009 ); 
Shanghai  (Takafuji and Hinemoto 2008 )), Iran (Beyzavi et al. 2013) , India, 
Indonesia, Japan  (Hokkaido , Honshu , Kyushu, Shikoku , Okinawa) South 
Korea , Malaysia, Philippines, Taiwan, Thailand, Viet Nam (EPPO 2019) , 
Singapore (Migeon and Dorkeld 2006 –2019)  
North America  Mexico  (EPPO 2019) , USA  (California , Wisconsin (greenhouse) ) (Navajas et 
al. 2001)  
Europe  Netherlands  (Migeon 2015), Greece  (Migeon and Dorkeld 2006 –2019)  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 448 Continent/region  Country/area  
Oceania  Australia  (New South Wales, Queensland)  (Gutierrez and Schicha 1983), 
Papua New Guinea  (EPPO 2019)  
 
Host plant availability is not a barrier to T. kanzawai  establishment.  
• T. kanzawai  is highly polyphagous, with a broad host range of at least 193 species in 63 
families, of which species in Fabaceae and Rosaceae seem to be more prominent (Migeon 
and Dorkeld 2006 –2020).  
• Host plants include commercially and domestically grown frui t/vegetable crops such as Citrus  
spp., sweet potato/kumara ( Ipomoea batatas ), cucumber ( Cucumis sativa ), melon ( Cucumis 
melo ), watermelon ( Citrullis lanatus ), tea92 (Camellia sinensis ), bean ( Phaseolus vulgaris ), 
pea ( Pisum sativum ), corn/maize ( Zea mays ), strawberry ( Fragaria × ananassa ), hop 
(Humulus lupulus ), stonefruit ( Prunus sp. ), apple ( Malus domesticus ), pear ( Pyrus 
communis ), persimmon ( Diospyros kaki ), sweet pepper ( Capsicum annuum ), eggplant 
(Solanum melongea ) and grapevine ( Vitis vinifera ); ornamental plants (commercial, amenity 
and domestic) such as roses, Cordyline  sp., Dianthus  caryophillus , Ageratum  sp., Gladiolus  
sp., Bidens  sp., Chrysanthemum  sp., Camellia japonica , Hydrangea  sp., Alcea rosea , 
Bambusa  sp. and Cyathea  sp.; and weed sp ecies such as Chenopodium  sp., Sonchus 
oleraceus  and Solanum nigrum .  
• The above -listed host plants grow in New Zealand, with many of them in places of likely first 
point of arrival, such as the Auckland and Bay of Plenty  regions. There are host plants for 
T. kanzawai  growing throughout New Zealand ( Breitwieser et al.  2010). 
 
Greenhouses are suitable environments for Tetranychus kanzawai , and some hosts are grown in 
them.  
• T. kanzawai  is reported from greenhouses in Japan on grapes (Kondo 2004) and in 
Wiscons in, USA (as T. hydrangeae , Navajas et al. 2001).  
• Greenhouse crops in New Zealand include beans, cucumber, capsicums, eggplant and some 
ornamentals like Euphorbia pulcherrima . 
 
Tetranychus kanzawai  has biological characteristics that facilitate establishmen t in new environments.  
• Tetranychus kanzawai  has two reproductive strategies: arrhenotoky, where an unmated adult 
female can lay eggs that will produce only male offspring, and sexual reproduction, which 
requires males to fertilise females resulting in offs pring of both sexes. The sex ratio is female -
biased, ranging from 2:1 to 3:1 (female:male) (Oku 2014). Inbreeding between mothers and 
sons and between sisters and brothers is common in tetranychid populations ( Vacante  2016), 
and so it seems likely that an unmated female could establish a small population. “There is 
mostly no expression of deleterious mutations and/or population death, as there is sufficient 
genetic variability to adapt to changes of conditions” (Vacante 2016 ). 
• Tetranychus kanzawai  females  attract males to them,  for mate guarding and initiating  
copulation, by emitting pheromones, which enhances the likelihood of meeting, mating and 
founding a population (Oku  and Shimoda  2013). 
• Tetranychus kanzawai  populations  from the four main islands  of Japan are known to have a 
strong capacity for diapause (Takafuji and Morishita 2001). Diapause enables survival of adult 
females in unfavourable conditions. The common stimulus for entry into diapause is a 
reduction in daylength and temperature. Also, Bou dreaux (1963) states that, “exhaustion of 
healthy food plants usually can induce diapause when otherwise the photoperiod would not.”  
• Hasanvand et al. (2019) demonstrated that T. kanzawai  can develop under a wide range of 
temperatures (from 15 °C to 37.5 °C) in Iran on soy bean. Osakabe (1967) estimated the lower 
developmental thresholds were 8.7°C for eggs, 14.6°C for larvae, 13.4°C for protonymphs 
and 13.2°C for deutonymphs on tea plants in Japan, which would allow development in parts 
of New Zealand.  
• Tetra nychus kanzawai  produces a complex and irregular webbing, usually on leaf surfaces 
(Saito 1985). The webbing is protection for all lifestages against some predators and adverse 
weather and, as the fecal pellets, cast skins and eggs collect upon it, the inh abited leaf 
surface remains relatively clean (Saito 1985; Oku 2003).  
                                                      
92 Tea production is a relatively recent boutique industry in New Zealand, e.g. Zealong Tea Estate in the Waikato produces 
organic premium tea.   
449 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   
Impacts in New Zealand:  
 
Given the arguments and evidence below, the level of impact caused by 
Tetranychus  kanzawai  is likely to be moderate  (with low uncertainty).  
Tetranychus kanzawai  feeding damage can reduce vigour, quality and yield of host plants.  
• Tetranychids mainly feed on leaves but can also feed on cotyledons, flowers, fruit and shoots, 
etc. They feed by piercing the cells of the palisade tissue, which is the primary area of 
photosynthesis. They remove chloroplasts and other cellular contents, creating necrotic areas 
(Vacante 2016). A reduction of photosynthetic ability can lead to reduced vigour in the host 
plant and a decrease of crop yields.  
• In a comparison of resource use b etween T. urticae93 and T. kanzawai , Kondo and Takafuji 
(1985) observed that damage by T. kanzawai  “more heavily hindered the growth of mottled 
kidney bean ( Phaseolus vulgaris ).” Injured leaves turned brown, withered and dropped. In 
summarising their work, Kondo and Takafuji (1985) stated that T. kanzawai  was more 
sensitive to food deterioration and dispersed more quickly than T. urticae , and it damaged its 
host plants more severely, causing earlier and more extensive defoliation.  
 
Tetranychus kanzawai  damag es crops of economic importance overseas.  
• Zhang et al. (1996) note that strawberries grown in Fuzhou (Fujian, China) may have 
infestation rates of T. kanzawai  as high as 90 –100%, with between 2,000 to 3,000 mites per 
leaf. 
• In Japan, it is a serious pest of  greenhouse grapevine (Kondo 2004) and damages vegetable 
and fruit crops (Vacante 2016).  
• In various Asian countries, it is damaging to tea, feeding on the new shoots, thus inducing 
direct crop loss (Vacante 2016). Hasanvand et al. (2019) report that damag e by T. kanzawai  
has significantly increased in recent years, with the increasing temperatures in parts of 
western Iran and is considered a disastrous mite on soybean.  
• In several countries, it is reported as a minor pest of citrus on which the symptoms an d 
damage are unclear (Vacante 2016). However, in California, Grafton -Cardwell et al. (2017) 
state that the numbers of T. kanzawai  can become problematic towards the end of the year 
(September to October) on late -harvested Valencia oranges or red grapefruit . Extensive 
feeding can lead to rind bleaching and associated webbing of fruit.  
But: 
• Most of the damage has been reported from the warmer areas of these countries, where 
T. kanzawai  is more likely to reach its full pest potential.  
 
New Zealand has horticul tural industries that could be economically impacted by T. kanzawai  
establishment.  
• The largest export earnings for 2019 in horticultur e came from the wine industry , which sold 
NZ$1.8 billion of wine to more than 100 overseas markets ( Plant & Food Research 2019).  
• Apple exports earned NZ$828.8 million , and berryfruits earned $47.7  million in exports and 
$47.1  million in domestic sales.  
• There are several other horticultural crops that might be affected, which include, but are not 
limited to, citrus, beans, peas, cucumbers, capsicum, kumara, eggplant, tea, sweet corn  and 
hop. 
• The ornamental industry and cut flowers/foliage industry grow several host plants of T. 
kanzawai , such as roses, camellias, chrysanthemums, orchids and hydrangea. In 2018, 
exports of chrys anthemums earned NZ$0.1 million, hydrangea $1.3 million and orchids $10.9 
million plus $11.6 million in domestic sales (Plant & Food Research 2019).  
• Clover  was estimated to contribute  over NZ$2 billion to the New Zealand economy (NZIER 
report 2012).  
 
Resistance to miticides potentially reduces options for managing outbreaks of mites.  
                                                      
93 Tetranychus urticae  is present in New Zealand (NZOR 2020)  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 450 • Chemical resistance is a well documented problem with mites under chemical control. 
Vacante (2016) reports several acaricides that have become ineffective in treating T. 
kanzawai . 
 
But: 
• Some horticultural industries are spread over New Zealand. For instance, grapes are grown 
around Auckland, Gisborne, Hawke’s Bay, Wairarapa, Nelson, Marlborough, Canterbury and 
Otago. It is likely that only a proportion of a national industr y would be affected and therefore 
only a proportion of the export/domestic value  of that industry.  
 
Tetranychus kanzawai  may cause impacts to sociocultural values of New Zealand and potentially to 
the natural environment, but is unlikely to have impacts up on human health.  
• Kumara ( Ipomoea  batatas ) is reported as a host of T. kanzawai . It is a treasured plant to 
Māori, and so damage to this plant would be considered significant.  
• Home gardens and amenity plantings use many of the hosts described and therefore would 
suffer damage from the establishment of T. kanzawai . 
• No evidence has been found that human health could be affected by T. kanzawai  
establishment.  
• “T. kanzawai has hosts in Rosaceae and Fabaceae (Migeon and  Dorkeld 2006); both these 
families have many  native representatives in New Zealand. For  Rosaceae, this includes 
Rubus (for example, bush lawyer, R. cissoides , which is in the  same genus as blackberry), 
and Acaena (for example A. anserinifolia, bidibids), as well as  Geum , which is less commonly 
encountered. For Fabaceae, this include s Carmichaelia spp. (native brooms), Clianthus 
puniceus (kakabeak), Monitigena novaezelandiae  and, most commonly, Sophora spp. 
(kowhai). While both families have lots of  native representatives, Sophora , Rubu s and 
Acaena are the most likely to be regularl y encountered. Most exotic pests that attack native 
plants are polyphagous, but highly  damaging polyphagous species appear exceptional , and it 
has been postulated that the  impact of relatively specialised  organisms is likely to be greater 
than highly polyphagous  species (Beever et al. 2007) .” (excerpt from BNZ -MAF 2009) 
Therefore, although T. kanzawai  may cause some damage to native plants, it seems to be 
considered unlikely that it will have severe impact s. 
 
 
13.3.4  References  
Beever, R E; Harman, H; Waipara, N; Paynter, Q; Barker, G; Burns, B (2007) Native Flora Biosecurity 
Impact Assessment. Landcare Research Contract Report: LC0607/196.  Manaaki Whenua Press 
(Landcare), NZ.  
Beyzavi, G; Ueckermann, E; Faraji, F;  Ostovan, H (2013) A catalog of Iranian prostigmatic mites of 
superfamilies Raphignathoidea and Tetranychoidea (Acari). Persian Journal of Acarology , 2(3): 389 –
474. 
Boudreaux, H B (1963) Biological aspects of some phytophagous mites. Annual Review of 
Entom ology , 8: 137 –154. 
Breitwieser , I; Brownsey , P J; Nelson , W A; Wilton , A D (eds) (2010)  Flora  of New Zealand  Online.  
www.nzflora.info  Accessed June 2020.  
Cronje, P; Crouch, E M; Huysamer , M (2005) Postharvest calyx retention of citrus fruit. Acta 
Horticulturae , 682: 369 –376. 
EPPO (2019 ) EPPO Global Database. https://gd.eppo.int/ . Accessed June  2020.  
Gerson, U (2003) Acarine pests of citrus: overview and non -chemical control. Systematic and Applied 
Acarology , 8(1): 3 –12.  
451 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Ghazy, N A; Otsuki, H; Sekido, T; Yano, S; Amano, H (2016) Dispersal of diapausing Tetranychus  
urticae  and T. kanzawai . Entomologia E xperimentalis et Applicata , 160(2): 126 –132. DOI: 
10.1111/eea.12467  
Gordon, D P (ed) (2010) New Zealand Inventory of Biodiversity. Volume 2. Kingdom of Animalia.  
Chaetognatha, Ecdysozoa, Ichnofossils . Canterbury University Press; Christchurch, NZ.  
Grafton -Cardwell, E E; Morse, J G; Haviland, D R; Faber, B A (2017) Kanzawa spider mite 
(Hydrangea mite), Tetranychus kanzawa i. UC IPM Pest Management Guidelines: Citrus  UC ANR 
Publication 3441.  https://www2.ipm.ucanr.edu/agriculture/citrus/Kanzawa -Spider -mite-Hydrangea -
Mite/  Updated Feb ruary  2017. Accessed June 2020 . 
Gutierrez, J; Schicha, E (1983) The  spider mite family Tetranychidae (Acari) in New South Wales. 
International Journal of Acarology , 9(3): 99 –116. 
Halloy, S; Anthony, D; Torres, U; Narouei -Khandan, H; Newfield, M (2019) Climate niches an d 
likelihood of  establishment of invasive organisms. In Christophersen,  A; Bailey, L; Cavana, R Y ( eds) 
Risk and Decision -Making Conference 2019: how different aspects of risk underpin  responsible and 
culturally -appropriate decision -making . GNS Science Miscellaneous Series ; Wellington, NZ ; p 46.  
Hasanvand , I; Jafari, S; Khanjani, M (2019) Life table parameters of Iranian population, Tetranychus  
kanzawai  (Acari:Tetranychidae) fed on soybean leaves. Systematic and Applied Acarology , 24(2): 
231–250. 
Ikegami, Y; Yano, S; Takabayashi, J; Takafuji, A (2000) Func tion of quiescence of Tetranychus  
kanzawai  (Acari: Tetranychidae), as a defense mechanism against rain. Applied Entomology and 
Zoology , 35(3): 339 –343. 
Kondo, A (2004) Colonising characteristics of two phytoseid mites, Phytoseiulus persimilis  Athis -
Henriot  and Neoseiulus womersleyi  (Schicha) (Acari: Phytoseiidae) on greenhouse grapevine and 
effects of their release on the kanzawa spider mite, Tetranychus  kanzawai  Kishida (Acari: 
Tetranychidae). Applied Entomology and Zoology , 39(4): 643 –649. 
Kondo, A; Takaf uji, A (1985) Resource utilization pattern of two species of tetranychid mites (Acarina: 
Tetranychidae). Research in Population Ecology , 27: 145 –157. 
Migeon, A (2015) The Jean Gutierrez spider mite collection. Zookeys , 489: 15 –24. 
Migeon, A; Dorkeld, F (20 06–2020) Spider Mites Web: a comprehensive database for the 
Tetranychidae. http://www1.montpellier.inra.fr/CBGP/spmweb . Accessed June 2020.  
Navajas, M; Gutierrez, J; Williams, M; Gotoh, T (2001) S ynonymy between two spider mite species, 
Tetranychus kanzawai  and T. hydrangeae  (Acari: Tetranychidae), shown by ribosomal ITS2 
sequences and cross -breeding experiments. Bulletin of Entomological Research , 91: 117 –123. 
NZIER (2015) How valuable is that pla nt species? Application of a method for enumerating the 
contribution of selected plant species to New Zealand’s GDP. NZ Institute of Economic Research 
report to the Ministry for Primary Industries , July 2015.  
NZOR (2020) New Zealand Organisms Register. http://www.nzor.org.nz/  Accessed 9 June 2020.  
Oku, K (2014) Sexual selection and mating behaviour in spider mites of the genus Tetranychus  
(Acari: Tetranychidae). Applied Entomology and Zoology , 49: 1 –9. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 452 Oku, K; Shimoda , T (2013) Indirect evidence that guarded quiescent deutonymph females invest 
energy to attract conspecific males in the Kanzawa spider mite (Acari: Tetranychidae). Experimental 
and Applied Acarology , 60: 445 –449. 
Oku, K; Yano, S; Osakabe, M; Takafuji , A (2003) Spider mites assess predation risk by using the 
odour of injured conspecifics. Journal of Chemical Ecology , 29(11): 2609 –2613.  
Osakabe, M (1967) Biological studies on the tea red spider mite, Tetranychus  kanzawai  Kishida, in 
tea plantation.  [In Japanese; English summary] Bulletin of the Tea Research Station (Chagyo 
Shikenjo Kenhyu Hokoku) , 4: 35 –156. 
Phillips, C B; Kean, J M; Vink, C J; Berry, J A (2018) Utility of the CLIMEX ‘match climates regional’ 
algorithm for pest risk analysis: An evaluati on with non -native ants in New Zealand. Biological 
Invasions , 20(3): 777 –791. Climate match tool available at:  https://b3nz.shinyapps.io/CMI -maps -csv/ 
Plant & Food Research (2019) Fresh Facts: New Zeal and Horticulture . The New Zealand Institute for 
Plant and Food Research Ltd ; Auckland , NZ. https://www.freshfacts.co.nz/files/freshfacts -2019.pdf  
Accessed June 2020.  
PPIN (2020 ) Plant Pest Information Network . MPI database. Ministry for Primary Industries, NZ.  
Saito, Y (1985) Life types of spider mites. In Helle, W; Sabelis, M W (eds)  Spider Mites . Their Biology , 
Natural Enemies and Control,  Vol. 1A. Elsevier; Amsterdam, Netherlands; pp  253–264.  
Takafuji, A; Hinemoto, N (2008) The distribution and geographic variation in diapause capacity among 
populations of two Tetranychus  species (Acari: Tetranychidae) in East and Southeast Asia. Journal of 
the Acarology Society of Japan , 17(1): 1 –15. 
Takafuji, A; Morishita, M (2001) Overwintering ecology of two different species of spider mites (Acari: 
Tetranychidae) on different host plants. Applied Entomology and Zoology , 36(1): 169 –175. 
Vacante, V (2010) Review of the phytophagous mites collected on citrus in the world. Acarologia  
50(2): 221 –241. 
Vacante, V (2016) The Handbook of Mites of Economic Plants: Identification, Bio -Ecology and 
Control . CAB International; Wallingford, UK.  
Zhang, Z -Q; Henderson, R; Flynn, A; Martin, N A (2002) Key to Tetranychidae of New Zealand. 
Landcare Research Contract Report: LC0102/144. Prepared for MAF Science Policy, project FMA 
180.   
453 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14. Vector  analysis  
14.1 Insect vector  analysis : aphids, mealybugs, thrips  
 
[See 15.2 for an analysis of mite vectors]  
 
An insect v ector analys is was carried out for 17 insect species ( Table 15.1. 1) that are present in one 
or more citrus -exporting countries and are associated with citrus  fruit. All 17 species are recorded 
from New Zealand , but they are considered in th is analysis because th ey are known to vector various 
pathogens , some of which are not reported from New Zealand . 
 
    Table 15.1. 1  The 17 vector species considered in this analysis  
Scientific name  Common name  Pest group  Order: Family  
Aphis gossypii  cotton aphid  / melon aphid  aphid Hemiptera: Aphididae  
Aphis spiraecola  green citrus aphid  aphid Hemiptera: Aphididae  
Aphis craccivora  cowpea aphid  aphid Hemiptera: Aphididae  
Brachycaudus persicae  black peach aphid  aphid  Hemiptera: Aphididae  
Macrosiphum  euphorbiae  potato aphid / tomato aphid  aphid  Hemiptera: Aphididae  
Macrosiphum rosae  green rose aphid  aphid  Hemiptera: Aphididae  
Myzaphis rosarum   aphid  Hemiptera: Aphididae  
Myzus persicae  green peach aphid  aphid  Hemiptera: Aphididae  
Toxoptera aurantii  black citrus aphid  aphid  Hemiptera: Aphididae  
Toxoptera citricida  oriental black citrus aphid  aphid  Hemiptera: Aphididae  
Pseudococcus calceolariae  citrophilus mealybug  mealybug  Hemiptera: Pseudococcidae  
Pseudococcus longispinus  long-tailed mealybug  mealybug  Hemiptera: Pseudococcidae  
Planococcus citri  citrus mealybug  mealybug  Hemiptera: Pseudococcidae  
Pseudococcus viburni  obscure mealybug  mealybug  Hemiptera: Pseudococcidae  
Frankliniella intonsa  eastern flower thrips  thrips Thysanoptera: Thripidae  
Frankliniella occidentalis  western flower thrips  / alfalfa thrips  thrips Thysanoptera: Thripidae  
Thrips tabaci  common cotton thrips  thrips Thysanoptera: Thripidae  
 
Generally, the risk posed by vectors is considered to be low. This is because successful introduction 
of the pathogen requires the vector to: i) acquire the pathogen from its host (either citrus or another 
plant host); ii) remain infectious during transit and after arrival in New Zealand and then iii) 
successfully find and transmit the pathogen to another suitable plant host in which the pathogen is 
able to establish (and cause unwanted impacts).  
 
Pathogens that are associated with citrus are considered to  be higher risk than those that are not 
associated with citrus. It is assumed that entry  of citrus -associated pathogens transmitted by insect 
vectors is possible, no matter if the pathogen is transmitted in a non -persistent, semi -persistent or 
persistent m anner. Non -citrus pathogens that are transmitted in a non -persistent manner are unlikely 
to be retained by the vector long enough to be exposed to suitable hosts in New Zealand. Non -citrus 
pathogens that are transmitted in a semi -persistent or persistent m anner by the insect vector may be 
able to enter  New Zealand. This is because non -persistent transmission has a retention time94 of 
several minutes to hours, but semi -persistent and persistent transmission have a retention time of 
                                                      
94 Retention time: the length of time after virus acquisition that the vector carries the virus .  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 454 several hours to a few days  and a few days to a lifetime  of the insect respectively (Ng and Falk 2006). 
If the commodities are transported by air, it is possible that they can arrive in New Zealand from the 
exporting country within a few days. However, this risk is much lower than t hat associated with citrus -
associated pathogens. This is because successful entry  requires an extra step, i.e . the vector must 
successfully acquire the pathogen from a non -citrus host, move to citrus and remain associated with 
the citrus commodity before s uccessfully locating a suitable host in New Zealand. In most cases , the 
host range of the pathogen is more restricted than that of the insect vector.  
 
When assessing the risk of vectors associated with fresh produce , it is usually assumed that 
commercial citrus orchards are grown as monocultures and that vectors are unlikely to be in contact 
with plant species other than the commodity being assessed. Therefore, vector analysis is usually 
limited to considering vector ed pathogens that are associated with the commodity. However, a large 
number of citrus -exporting countries are involved  in the citrus IHS , and agricultural practices may be 
different  among  these countries  (e.g. companion planting , close distanc ing between citrus and other 
plant crops  and multi -cropping ), although monoculture is likely to be the most common practice. 
Different agricultural practices like companion planting and  close distanc ing between citrus and other 
plant crops  increase the risk of vectors  being in contact with other plants that are potentially infected 
with pathogens not associated with citrus. To allow for this possibility, high -priority viruses and viroids 
(Table 15.1. 2) are also considered in this analysis to determine whether any of th e insect vectors 
have the potential to transmit these pathogens. This list of pathogens95 is compiled from the MPI high-
priority organism  (HPO) list and the list of sector risk organisms  (SRO) as listed/described by each 
government industry agreement  (GIA).   
 
Table 15.1. 2  Pathogens initially considered in this section . This list is compiled from the MPI high -priority 
organism  (HPO) list and the list of sector risk organisms  (SRO) as listed/described by each government industry 
agreement (GIA ) partner in e ither their draft operational agreement, biosecurity plan  or website . 
Scientific name  Family:  Genus  
Avocado sunblotch viroid  Avsunviroidae : Avsunviroid  
Blueberry scorch virus  Quinvirinae : Carlavirus  
Broad bean wilt virus  Comovirinae : Fabavirus  
Clover yellow mosaic virus  Alphaflexiviridae : Potexvirus  
Cucumber green mottle mosaic virus  Virgoviridae : Tobamovirus  
Cucurbit yellow stunting disorder virus  Closteroviridae : Crinivirus  
High Plains wheat mosaic emaravirus = High Plains virus  Fimoviridae : Emaravirus  
Hop stunt viroid  Pospiviroidae : Hostuviroid  
Pea early -browning virus  Virgaviridae : Tobravirus  
Plum pox virus  Potyviridae : Potyvirus  
Potato mop -top virus  Virgaviridae : Pomovirus  
Potato spindle tuber viroid  Pospiviroidae : Pospiviroid  
Pepino mosaic virus  Alphaflexiviridae : Potexvirus  
Squash leaf curl virus  Geminiviridae : Begomovirus  
Tomato apical stunt viroid  Pospiviroidae : Pospiviroid  
Tomato torrado virus  Secoviridae : Torradovirus  
Maize dwarf mosaic virus  Potyviridae : Potyvirus  
Capsicum chlorosis orthotospovirus  Tospoviridae : Orthotospovirus  
Potato virus Y  Potyviridae : Potyvirus  
Grapevine pinot gris virus  Betaflexiviridae : Trichovirus  
Grapevine red blotch virus  = Grapevine red blotch -associated virus  Geminiviridae : Grablovirus  
Little cherry virus  2 Closteroviridae : Ampelovirus  
                                                      
95 Only viruses and viroids from th e MPI priority pest and disease list and the list of sector risk organisms are considered.   
455 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Scientific name  Family:  Genus  
Pea enation mosaic virus * See information  below table  * 
Peach rosette mosaic virus  Comovirinae : Nepovirus  
Tomato ringspot virus  = Peach yellow bud mosaic disease, yellow bud mosaic  Comovirinae : Nepovirus  
Pelargonium zonate spot virus  Bromoviridae : Anulavirus  
Potato virus H Quinvirinae : Carlavirus  
Tomato brown rugose fruit virus  Virgoviridae : Tobamovirus  
Tomato chlorosis virus  Closteroviridae : Crinivirus  
Tomato infectious chlorosis virus  Closteroviridae : Crinivirus  
Tomato leaf curl New Delhi virus  Geminiviridae : Begomovirus  
Tomato leaf curl purple vein virus  Geminiviridae : Begomovirus   
Tomato mottle virus  Geminiviridae : Begomovirus   
Tomato yellow leaf  curl virus  Geminiviridae : Begomovirus   
* Pea enation mosaic virus is regulated in ONZPR  (2020). Neither Pea enation mosaic virus 1  (Luteoviridae : Enamovirus ) nor 
Pea enation mosaic virus 2  (Calvusvirinae : Umbravirus ) is known to be present in New Zealand (PPIN; Veerakone  et al. 2015).  
 
Therefore, the criteria for an insect vector to be considered a hazard  on any country pathway  in the 
analysis are:  
• The insect transmits at least one citrus pathogen or one pathogen in the HP O or SRO list  that 
is regulated96 or not present in  New Zealand;  
• For pathogens not associated with citrus, the insect transmits the risk pathogen  in a persistent 
or semi -persistent manner ; and 
• Both the insect vector and the pathogen are present in the same citrus -exporting country.   
 
 
Summary of the analysis  
 
Six vector species are considered to be hazards in this analysis. These vectors are considered to be 
risks on at least one of the following citrus fresh produce pathways:  Australia, Brazil, China, Egypt, 
Spain and the USA . Table 15.1. 3 summarises  the vector species considered to be hazards, the 
pathways on which the vectors are considered to be risks and the risk pathogens that are transmitted 
by these vectors.  
 
Table 15.1. 3  The six vector species considered to be hazards in this analysis and their associated risk 
pathogen/pathway combinations.  
Hazard spp.  Suggested 
regulated 
pathway  Virus infecting (or affecting) citrus  Viruses in the priority pest and 
disease list that are transmitted in a 
persistent manner (all hosts)  
Aphis gossypii  Australia   Pea enation mosaic virus  
China   Pea enation mosaic virus  
Egypt   Pea enation mosaic virus  
Spain   Pea enation mosaic virus  
USA  Pea enation mosaic virus  
Aphis spiraecola  China  Citrus yellow vein clearing virus   
Aphis craccivora  China  Citrus yellow vein clearing virus   
Macrosiphum 
euphorbiae  Australia   Pea enation mosaic virus  
China   Pea enation mosaic virus  
Egypt   Pea enation mosaic virus  
                                                      
96 Strains of pathogens that are not recorded in New Zealand and have  no defined entity (a named subspecies, pathovar, 
haplotype , etc.) are not considered hazards in this analysis. The criteria for regulating taxa below species level require that:  
• There is a defined entity (a named subspecies, pathovar, haplotype , etc.) that is not known to be present in New Zealand.  
• The entity is biologically distinct (for example host range, pathogenicity or vector relationships). Genetic differences alone 
are not sufficient.  
• There is an increased risk to New Zealand posed  by the entity.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 456 Hazard spp.  Suggested 
regulated 
pathway  Virus infecting (or affecting) citrus  Viruses in the priority pest and 
disease list that are transmitted in a 
persistent manner (all hosts)  
Spain   Pea enation mosaic virus  
USA  Pea enation mosaic virus  
Myzus persicae  Australia   Pea enation mosaic virus  
China   Pea enation mosaic virus  
Egypt   Pea enation mosaic virus  
Spain   Pea enation mosaic virus  
USA  Pea enation mosaic virus  
Toxoptera citricida  Brazil  Citrus sudden death -associated virus   
 
Aphis craccivora , My. persicae , A. spiraecola  and are considered to have a weak  to moderate 
association with citrus fruit , while A. gossypii , Ma. euphorbiae  and T. citricida  are considered to have 
a weak association with citrus fruit.  Basic measure s are likely to reduce the likelihood of entry of Aphis 
gossypii, A. spiraecola, A. craccivora, Macrosiphum euphorbiae, Myzus persicae and Toxoptera 
citricida  by a high degree . Consequently , the likelihood of entry is considered to be very low. In 
addition, generally, the risk posed by vectors that are present in New Zealand is considered to be low. 
Therefore,  it is recommended that  Aphis gossypii, A.  spiraecola, A. craccivora, Ma. e uphorbiae, My. 
persicae and T . citricida  do not require  consider ation  for additional measures . 
 
   
457 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Insect vector analyses – vector species considered to be hazards  
14.1.1  Aphis gossypii  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:  
Aphis gossypii  is present in all of the potential citrus -exporting countries considered in this analysis, 
i.e. Australia, Brazil, China, Cook Islands, Egypt, Fiji, Japan, Korea, Mexico, New Caledonia, Peru, 
Samoa, Solomon Islands, Spain, the USA, Vanuatu  and Viet Nam (C PC 2020).  
 
New Zealand status:  
• Aphis gossypii  is present in New Zealand (NZOR 2020).  
• Aphis gossypii  is listed as a  ‘potential vector’ in ONZPR  (2020).  
 
Plant hosts:  
Aphis gossypii  is polyphagous and has been recorded on over 92 plant families (CPC 2020 ). It has 
been recorded on crop, fib re and ornamental species , including but not limit ed to: soursop ( Annona 
muricat a), avocado ( Persea americana ), betel  (Piper betle ), kava ( Piper methysticum ), carnation 
(Dianthus caryophyllus ), cocoa (Theobroma cacao ), kenaf ( Hibiscus cannabinus ), okra ( H. 
esculentus ), Chinese hibiscus ( H. rosa -sinensis ), cotton ( Gossypium hirsutum ; G. arboretum ), 
passionfruit ( Passiflora  edulis ), papaya/pawpaw ( Carica papaya ), cucumber ( Cucumis sativus ), melo n 
(Cucumis  melo ), pumpkin  (Cucurbita spp.), zucchini ( Cucurbita  pepo), tomato ( Solanum 
lycopersicum ), turnip ( Brassica campestris ), persimmon ( Diospyros virginiana ), apple ( Malus pumila ), 
strawberry ( Fragaria  spp.), pear ( Pyrus communis ), loquat ( Eriobotrya japonica ), cowpea ( Vigna 
unguiculat a), green gram / mung bean  (Vigna radiata ), black  gram ( Vigna mungo ), bean ( Phaseolus 
vulgaris ), soybean ( Glycine max ), Egyptian clover ( Trifolium alexandrinum) , macadamia ( Macadamia  
sp.), guava ( Psidium guava ), pomegranate ( Punica granatum ), grape ( Vitis vinifera ), lychee  (Litchi 
chinensis ), cashew nut ( Anacardium occidentale ), orange ( Citrus sinensis ), lime ( C. auranti ifolia), sour 
orange ( C. aurantium ), lemon ( C. limon ), mandarin ( C. reticulata ), grapefruit ( Citrus × paradis i), celery 
(Apium  graveolens ), carrot ( Daucus carota ), eggplant ( Solanum melongena ), chilli (Capsicum 
annum ), potato ( Solanum  tuberosum ), tobacco ( Nicotiana tabacum ), sweet potato ( Ipomoea batatas ), 
blond psyllium / isabgol ( Plantago  ovata ), breadfruit ( Artocarpus altilis;  A. communis ), sesame 
(Sesamum indicum ), gardenia ( Gardenia  augusta ), chrysanthemum ( Dendrathema grandiflorum ), 
sunflower ( Helianthus ann uus), zinnia ( Zinnia elegans ), lettuce ( Lactuca sativa ), coconut ( Cocos 
nucifera ), taro ( Colocasia esculenta ), sugarcan e (Saccharum officinarum ), corn ( Zea mays ), wheat 
(Triticum aestivum ), banana ( Musa  acuminat a), abaca ( Musa textilis ), Easter  lily (Lilium longiflorum ), 
garlic ( Allium sativum ), Japanese plum ( Prunus salicina ), peanut/ groundnut ( Arachis hypogaea ), 
sugarbeet ( Beta vulgaris ) and Chinese yam ( Dioscorea batatas ) (CPC 2020 ; Ebert and Cartwright 
1997). Pawpaw, melo n, cucumber, pumpkin, cotton, Japanese plum and tomato are categorised as 
‘main’ host s by CPC ( 2020 ). 
 
Plant parts affected:  
Aphis gossypii  attacks most plant parts if the population density is high enough, with the exception of 
direct feeding on mature fruits, berries, nuts and roots (CPC 2020 ). However, CPC ( 2020 ) also states 
that fruits can carry adults and nymphs externally in plant trade , but it did not specify the host plants 
for which the pest may be found  on fruit . In addition, Aphis gossypii  has been identified on orange fruit 
once at the New Zealand border (LIMS 2019).  
 
Vectored organism s: 
Aphis gossypii  is known to transmit a number of non -persistent and persistent viruses, which includes , 
but is not limited to: Alfalfa mosaic virus , Bean common mosaic necrosis virus , Bean common mosaic 
virus , Bean leafroll virus , Bean yellow mosaic virus , Beet yellows v irus, Commelina  mosaic virus,  
Carnation mottle virus , Cauliflower mosaic virus , Citrus tristeza virus , Citrus woody gall virus (= Citrus 
vein enation virus ), cotton  blue disease , Cowpea aphid -borne mosaic virus , Cucumber mosaic virus , 
Lettuce mosaic virus , Lily symptomless virus , Maize dwarf mosaic virus , Onion yellow dwarf virus , 
Papaya ringspot virus , pea enation mosaic virus , Peanut mottle virus , Peanut stripe virus , Pepper 
veinal mottle virus , Plum pox virus , Potato leafroll virus , Potato virus Y , Sugar cane mosaic virus , 
Sweet potato feathery mottle virus , Tobacco etch virus , Tulip breaking virus , Turnip mosaic virus , Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 458 Watermelon mosaic virus , Watermelon mosaic virus 1 , Yam mosaic virus and Zucchini yellow mosaic 
virus (CPC 2020 ). 
 
Of the reported viruses , only two pathogens are known to affect citrus  – Citrus tristeza virus  (CTV) 
and Citrus vein enation virus  (CVEV). Both CTC and CVEV are present in New Zealand (Veerakone 
et al. 2015).  
 
Of the reported viruses, Plum pox virus  (PPV) , Maize dwarf mosaic virus  (MDMV) and pea enation 
mosaic virus (PEMV) are in the HP O or SRO list in New Zealand and are known to be transmitted by 
A. gossypii . PPV and MDMV are transmitted by A. gossypii  in a non -persistent manner (CPC 2020). 
PEMV is regulated in ONZPR  (2020) and is transmitted by A. gossypii  in a persistent manner (CPC 
2020). Both PEMV and A. gossypii  are present in Australia (Department of Agriculture, New South  
Wales  1943), the USA (CPC 2020),  China (Larsen and Porter 2010), Egypt ( Makkouk  et al. 1988) and 
Spain (Tornos et al. 2008).  
 
Hazard identification conclusion:  
Aphis gossypii  is considered to be a hazard in this analysis . Aphis gossypii  is considered to be a risk 
on the citrus fresh produce pathway from Australia, China, Egypt, Spai n and the USA , given that:  
• Aphis gossypii  is known to transmit PEMV, which is in the priority pest and disease list, in a 
persistent manner;  and 
• Both P EMV and A. gossypii  are present in Australia, China, Egypt, Spain and the USA . 
 
 
 
   
459 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14.1.2  Aphis spiraecola  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:  
Aphis spiraecola  is present in Egypt, Japan, Mexico, Spain, the USA, Vanuatu, Australia, Korea, 
Brazil, China, Peru, Viet  Nam and Fiji (CPC 2020 ). 
 
New Zealand status:  
• Aphis spiraecola  is present in  New Zealand (NZOR 2020) . 
• Aphis spiraecola  is listed as a  ‘potential vector’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Aphis spiraecola  is moderately polyphagous, with hosts from over 20 families. The p rimary hosts are 
citrus and meadowsweet ( Spiraea  spp.). Other crop plant hosts include , but are not limited to , celery, 
capsicum, pawpaw, cucumber, carrot, soybean, walnut, lettuce, apple, avocado, common bean, stone 
fruits ( Prunus  spp.), pear, potato, grapevine and maize ( Zea mays ).  
 
Plant parts affec ted: 
Feeding damage can be found on leaves, flowers and fruits. Eggs or colonies can be spread in trade 
on planting material or fruit (especially citrus and apple) (CPC 2020 ). 
 
Vectored organism s: 
Aphis spiraecola  transmits the viburnum strain of Alfalfa mosaic virus, Citrus psorosis virus B, Citrus 
tristeza virus, Cowpea aphid -borne mosaic virus, Cucumber mosaic virus, Maize dwarf mosaic virus, 
Papaya ringspot virus (= Watermelon mosaic virus 1 ), Peanut stunt virus, Plum pox virus, Potato virus 
Y, Watermelon mosaic virus 2  and Zucchini yellow mosaic virus  (CPC 2020 ). It has also been 
reported to  transmit Asystasia  mottle virus  (Thouvenel  et al. 1988),  Araujia mosaic virus (Charudattan 
et al. 1980) , Chilli veinal mottle virus (Ong et al. 1978 ), cowp ea severe mottle virus (Santos et al. 
1984), Groundnut chlorotic spot virus (Dollet et al. 1987) , Moroccan watermelon mosaic virus  
(Chatzivassiliou et al. 2016) , Papaya mosaic virus  (Adsuar 1946), Sri Lankan passionfruit mottle virus  
(Dassanayake  et al. 2003) , Tobacco etch virus (Laird and Dickson 1963), Tobacco vein banding 
mosaic virus (Chin 1983),  Citrus yellow vein clearing virus  (Zhang et al. 2018), Groundnut rosette 
virus  (Dollet  et al. 1987), Soybean mosaic virus  (Quimio  and Calilung  1993), Blueberry scorch virus, 
Bean common mosaic virus, Beet mosaic virus, Bidens mottle virus, Carrot virus Y, Passiflora 
ringspot virus, Pepper veinal mottle virus  and Telfairia mosaic virus  (Smith and Eyre 2014).  
 
Of the reported viruses, only three p athogens are known to affect citrus  – Citrus tristeza virus  (CTV), 
Citrus psorosis virus B97 (CPsV B) and Citrus yellow vein clearing virus (CYVCV ). CTV and CPsV are 
present in New Zealand (Veerakone et al. 2015) , so they are not considered to be  risk pathogens  in 
this analysis . CYVCV is regulated in ONZPR  (2020)  (as “yellow vein clearing of lemon”)  and is 
present in China (CPC 2020 ). 
 
Of the reported viruses, Maize dwarf mosaic virus (MDMV) , Plum pox virus  (PPV)  and Blueberry 
scorch virus  (BIScV) are  in the high -priority pest and disease list and are known to be vectored by 
A. spiraecola . MDMV , PPV  and BIScV  are transmitted by aphids in a non -persistent manner  (CPC 
2020; Lowery et al. 2008), and therefore, they are not considered to be  risk pathogens  in this 
analysis.  
  
Hazard identification conclusion:  
Aphis spiraecola is considered a hazard in this analysis. Aphis spiraecola is considered to be a risk on 
the citrus fresh produce pathway from China , given that:  
• CYVCV is regulated in ONZPR  (2020) (as “yellow vein clearing of lemon”) ; 
• CYVCV is present in China (CPC 2020 ); 
• Aphis spiraecola  is a vector of CYVCV ; and  
• Both Aphis spiraecola  and CYVCV are present in China.  
   
                                                      
97 CPsV B is regulated in BORIC (2020). However, according to BRAD, there are records of CPsV in  New Zealand, but these 
records do not state whether the virus present in New Zealand is CPsV A or CPsV B. As CPsV is present in New Zealand, it 
does not meet the criteria to be considered a hazard in this analysis.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 460 14.1.3  Aphis cracc ivora  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:  
Aphis craccivora  is present in Egypt, Japan, Mexico, Samoa, Spain, the USA, Australia, Korea, Brazil, 
China, Solomon Islands, Viet  Nam and Fiji (CPC 2020 ). 
 
New Zealand status:  
• Aphis craccivora  is present in New Zealand (NZOR 2020).  
• Aphis craccivora  is listed a s a ‘potential vector’ in ONZPR  (2020).  
 
Plant hosts:  
Aphis craccivora  is polyphagous. It has a marked preference for Leguminosae, such as Caragana, 
Lupinus, Medicago, Melilotus, Robinia, Trifoli um and Vicia . Groundnut  (peanut) , pigeon pea ( Cajanus 
cajan ), honey locust ( Gleditsia  triacanthos ), lentil ( Lens culinaris  subsp. culinaris ), lucerne ( Medicago 
sativa ), mung bean ( Vigna radiata ) and cowpea ( V. unguiculata ) are listed as  “main” host s of A. 
craccivora  in CPC ( 2020 ). 
 
Plant parts affected:  
Direct fee ding damage of A. craccivora  can be found on young leaves, shoots, flowers and immature 
seedpods. The aphid  has been identified (alive) on citrus fruit three  times (orange and mandarin from 
Australia) at the New Zealand border from 1929 to 2019 (LIMS 2019 ). 
 
Vectored organism s: 
Alfalfa mosaic virus , Bean common mosaic virus, Bean leafroll virus, Bean yellow mosaic virus, 
Blackeye cowpea mosaic virus , Broad bean wilt virus (1 & 2), Chickpea chlorotic stunt virus, Chilli 
veinal mottle virus, Cowpea aphid -borne mosaic virus, Cucumber mosaic virus, Faba bean necrotic 
stunt virus, Faba bean necrotic yellows virus, Groundnut rosette assistor virus, Groundnut rosette 
virus, Maize dwarf mosaic virus, Onion yellow dwarf virus, Papaya ringspot virus, Pea seed -borne 
mosaic virus, Bean leafroll virus (= Pea leafroll virus ), Peanut mottle virus, Peanut stripe virus, Peanut 
stunt virus, Pepper venial mottle virus , Plum pox virus, Senna mosaic virus , Soybean mosaic virus, 
Subterranean clover stunt virus, Sudanese broad bean mosaic virus , Sunflower mosaic virus, 
Watermelon mosaic virus, Zucchini yellow mosaic virus (CPC 2020 ). Alfalfa leaf curl virus 
(Ryckebusch et al. 2020 ), Asparagus virus 1 (Nothnagel et al. 2013) , Beet western yellows virus 
(Schwinghame r et al. 2009) , bitter gourd mosaic virus ( Tomar  and Jitendra 2001), Canavalia maritima 
mosaic virus (Edwardson and Christie 1991) , celery mosaic virus  (Karl and Wolf 1974),  Chickpea 
distortion mosaic virus (Mali et al. 1988 ), Chickpea stunt disease  associated virus (Reddy and Kumar 
2004), Citrus tristeza virus  (Chavan and Singh 2005),  Citrus yellow vein clearing virus  (Onelge  et al. 
2011),  Clover yellows virus (Ohki et al. 1976) , Cowpea stunt virus (Tsuchizaki et al. 1986 ), 
Desmodium mosaic virus  (Sreenivasulu et al. 1992) , Garlic mosaic virus (Marrou et al. 1972), Peanut 
chlorotic ring mottle (Fukumoto et al. 1987), Groundnut eyespot virus (Dubern and Dollet 1980) , 
Groundnut mosaic virus ( Badak et al. 2009 ), Johnsongrass mosaic virus (Karina et al.  2016 ), Lucerne 
enation virus (Leclant et al. 1973) , Milk vetch dwarf virus (Inouye et al. 1968 ), Pepper severe mosaic 
virus (Roy et al. 2003) , periwinkle chlorotic stunt virus (Zaidi et al. 1984), Pigweed mosaic virus (Singh 
et al. 1972), pole sitao mosaic virus  (Dolores and Valdez 1988),  pumpkin mosaic virus (Singh 1982), 
Ranunculus mottle virus  (Laird and Dickson 1967), Sweet potato feathery mottle virus  (Moyer and 
Kennedy 1978), Tobacco vein banding mosaic virus (Fang et al. 1985), Solanum torvum m osaic virus 
(Singh et al. 1975), Tobacco etch virus  (Herold 1970), Tomato aspermy virus (Haack et al. 1986 ), 
Turnip mosaic virus (Sako et al. 1984), Wisteria vein mosaic virus (Conti and Lovisolo 1969) and Yam 
mosaic virus (Thouvenel and Fauquet 1979).  
 
Of these viruses, only Citrus yellow vein clearing virus  (CYVCV) and Citrus tristeza virus  (CTV) are 
known to affect citrus.  CTV is present in New Zealand (Veerakone et al. 2015).  CYVCV is regulated in 
ONZPR  (2020) (as “yellow vein clearing of lemon”)  and is present in China (CPC 2020 ). 
 
Of the reported viruses, Maize dwarf mosaic virus (MDMV) , Plum pox virus  (PPV) and Broad bean wilt 
virus  (BBWV) are in the high -priority pest and disease list and are known to be vectored by A. 
craccivora . MDMV, PPV an d BBWV are transmitted by aphids in a non -persistent manner (CPC 
2020).  
  
461 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Hazard identification conclusion:  
Aphis craccivora is considered to be a hazard in this analysis. Aphis craccivora  is considered to be a 
risk on the citrus fresh produce pathway from  China , given that:  
• Aphis craccivora  is known to vector CYVCV, which affects citrus; and  
• Both A. craccivora  and CYVCV are present in China . 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 462 14.1.4  Macrosiphum euphorbiae  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:  
Macrosiphum euphorbiae  is present in Egypt, China, Japan, Korea, Spain, Mexico, the USA, 
Australia, New Caledonia, Brazil  and Peru (CPC 2020 ). 
 
New Zealand status:  
• Macrosiphum euphorbiae  is present in New Zealand (NZOR 2020).  
• Macrosiphum euphorbiae  is listed as a  ‘potential ve ctor’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Macrosiphum euphorbiae  is polyphagous, with hosts in more than 20 plant families. The primary host 
is roses.  Sugarbeet, sweet potato lettuce, tomato, eggplant, potato and maize are “main” hosts in 
CPC ( 2020 ). Citrus  spp. are also hosts of M. euphorbiae  (e.g. Sellami et al. 2013; Abo Kaf 2005).  
 
Plant parts affected:  
It is recorded that nymphs and adults of M. euphorbiae  can be found on flowers, fruits, leaves and 
stems in plant trade (CPC 2020 ). 
 
Vectored or ganism s: 
Macrosiphum euphorbiae  can transmit more than 40 plant viruses, such as Bean common mosaic 
necrosis virus, Bean common mosaic virus, Bean leafroll virus, Bean yellow mosaic virus, Beet 
chlorosis virus, Beet yellows virus, Beet yellow net virus , Cowpea aphid -borne mosaic virus, 
Cucumber mosaic virus, Cucurbit aphid -borne yellows virus, Hop mosaic virus, Lettuce mosaic virus, 
Maize dwarf mosaic virus, Papaya ringspot virus, Pea enation mosaic virus , Potato leafroll virus, 
Potato virus Y, Sugarcane mo saic virus, Sweet potato leaf speckling virus, Tobacco etch virus, Tulip 
breaking virus, Watermelon mosaic virus and Zucchini yellow mosaic virus (CPC 2020 ). 
 
There is no pathogen vectored by M. euphorbiae  that is known to affect citrus.  
 
Among  the reported viruses, Maize dwarf mosaic virus (MDMV)  and pea enation mosaic virus  (PEMV) 
are in the HPO or SRO list. MDMV is transmitted by M. euphorbiae  in a non -persistent manner (CPC 
2020). PEMV is regulated in ONZPR  (2020), and it is transmitted by M. euphorbiae  in a persistent 
manner (Hinz 1966). Both PEMV and M. euphorbiae  are present in  Australia ( Guy et al. 2020; 
Department of Agriculture, New South Wales  1943), the USA (CPC 2020),  China (Larsen and Porter 
2010), Egypt ( Makkouk  et al. 1988) and Spain (Tornos et al. 2008).  
 
Hazard identification conclusion:  
Macrosiphum  euphorbiae  is considered to be a hazard in this analysis . Macrosiphum  euphorbiae  is 
considered to be a risk on the citrus fresh produce pathway from Australia, Ch ina, Egypt, Spain and 
the USA , given that:  
• Macrosiphum  euphorbiae  is known to transmit PEMV , which is in the priority pest and disease 
list, in a persistent manner;  and 
• Both P EMV and M. euphorbiae  are present in Australia, China, Egypt, Spain and the USA . 
   
463 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14.1.5  Myzus persicae  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:  
Myzus persicae  is present in Egypt, China, Japan, Korea, Viet  Nam, Spain, Mexico, the USA, 
Australia, Fiji, New Caledonia, Brazil  and Peru (CPC 2020 ).  
 
New Zealand status:  
• Myzus persicae  is present in New Zealand (NZOR 2020).  
• Myzus persicae  is listed as a  ‘potential vector’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Myzus persicae  is highly polyphagous on summer hosts with host species in over 40 plant families, 
while primary win ter hosts are Prunus  spp. Many plant crops are recorded as “main” hosts of M. 
persicae in CPC ( 2020 ), such as celery, citrus, groundnut  (peanut) , horseradish ( Armoracia 
rusticana ), asparagus ( Asparagus officinalis ), sugarbeet, Chinese cabbage ( Brassica rapa subsp. 
chinensis ), pigeon pea, capsicum and pawpaw.  
 
Plant parts affected:  
Myzus persicae can be found on leaves, stems, inflorescence and growing points of the host (CPC 
2020 ). It has been identified five times (one alive) on citrus fruits (from the USA and Australia) at the 
New Zealand border between 1929 to 2019 (LIMS 2019 ).  
 
Vectored organism s: 
Myzus persicae  has been shown to transmit over 100 plant viruses  (CPC 2020 ), such as Alfalfa 
mosaic virus, Bean common mosaic ne crosis virus, Bean common mosaic virus, Bean leafroll virus, 
Bean yellow mosaic virus, Beet mild yellowing virus, Beet mosaic virus, Beet western yellows virus, 
Beet yellows virus, Carnation latent virus, Cauliflower mosaic virus, Clover yellow vein virus,  Cowpea 
aphid -borne mosaic virus, Cucumber mosaic virus, Hop mosaic virus, Lettuce mosaic virus, Maize 
dwarf mosaic virus, Onion yellow dwarf virus, Papaya ringspot virus, Pea enation mosaic virus  1, 
Peanut mottle virus, Peanut stripe virus, Peanut stunt v irus, Pepper ve nial mottle virus, Plum pox 
virus, Potato leafroll virus, Potato virus S, Potato virus Y, Red clover vein mosaic virus, Soybean 
mosaic virus, Sugarcane mosaic virus, Tobacco etch virus, Tobacco vein distorting virus, Tobacco 
vein mottling virus, Tobacco yell ow net virus , Tuberose mild mottle virus, Tulip breaking virus, Turnip 
mosaic virus, Watermelon mosaic virus , Zucchini yellow mosaic virus  (CPC 2020 ), Citrus vein enation 
virus  (Hermoso de Mendoza et al. 1994),  Citrus tristeza virus  (El-Sharkawy  2002), Cowpea mosaic 
virus (Nagaraju et al. 1997), Subterranean clover stunt virus  (Grylls and Butler 1959) and Tobacco 
necrotic dwarf virus .  
 
Of these viruses, only Citrus vein enation virus  (CVEV) and Citrus tristeza virus  (CTV) are known to 
affect citrus.  Both CVEV and CTV is present in New Zealand (Veerakone et al. 2015).  
 
Among  the reported viruses, Maize dwarf mosaic virus (MDMV) , Plum pox virus  (PPV)  and Pea 
enation mosaic virus  (PEMV) are in the HPO or SRO list. MDMV and PPV are transmitted by M. 
persi cae in a non -persistent manner (CPC 2020). PEMV is regulated in ONZPR  (2020), and it is 
transmitted by M. persicae  in a persistent manner (CPC 2020). Both PEMV and M. persicae are 
present in  Australia ( Department of Agriculture, New South Wales  1943), the USA (CPC 2020), China 
(Larsen and Porter 2010), Egypt ( Makkouk  et al. 1988) and Spain (Tornos et al. 2008).  
 
Hazard identification conclusion:  
Myzus persicae is considered to be a hazard in this analysis . Myzus persicae  is considered to be a 
risk on the citrus fresh produce pathway from Australia, China, Egypt, Spain and the USA , given that:  
• Myzus persicae is known to transmit PEMV , which is in the priority pest and disease list, in a 
persistent manner;  and 
• Both P EMV and M. persicae are present in Australia, China, Egypt, Spain and the USA . 
 
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 464 14.1.6  Toxoptera citricida  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:   
Toxoptera citricida is present in China, Japan, Korea, Viet  Nam, Spain, Mexico, the USA, Australia, 
Fiji, Cook Islands, Samoa, Solomon Islands, Vanuatu, Brazil and Peru (CPC 2020 ).  
 
New Zealand status:  
• Toxoptera citricida is present in New Zealand (NZOR 2020).  
• Toxoptera citricida is listed as a  ‘potential vector’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Primary hosts of T. citricida  are citrus, and they occasionally feed on other Rutaceae (CPC 2020 ). 
 
Plant parts affected:  
Direct feeding damage of T. citricida can be found on shoots, flower buds and sometimes young fruits 
(OEEP/EPPO 2006). However, CPC ( 2020 ) states that flowers are not a preferred host tissue, and 
mature leaves, stems and fruit cannot sustain T. citricida  populations.  
 
Vectored organism s: 
Toxoptera citricida can transmit Citrus tristeza virus , Papaya ringspot virus , Watermelon mosaic virus  
(CPC 2020 ), Citrus psorosis virus  (Portillo and Benatena 1986), Citrus vein enation virus (Maharaj 
and Graca 1989), Chilli veinal mottle virus  (Ong et al. 1978), Cucurbita mosaic virus (Owolabi et al. 
2011), Cowpea aphid -borne mosaic virus (Pio -Ribeiro et al. 2000), Soybean mosaic virus  (Halbert et 
al. 1986), Pepper veinal mottle virus  (Wijs 1973), Plum pox virus (Gildow et al 2004) and Yam mosaic 
virus  (Thouvenel and Fauquet 1979) . Toxoptera citricida is a putative aphid vector for Citrus sudden 
death -associated virus  (Loeza -Kuk et al. 2008).  
 
Vectored organism s: 
Of the reported viruses, Citrus tristeza virus (CTV) , Citrus psorosis virus  (CPsV),  Citrus vein enation 
virus (CEVE) and Citrus sudden death -associated virus  (CSDaV) are known to affect citrus.  CTV, 
CPsV and CEVE are present in New Zealand ( Veerakone et al. 2015 ). CSDaV is not recorded in 
ONZPR  (2020) and BRAD and is not known to be present in New Zealand (PPIN; Veerakone et al. 
2015).  It has been detected in adult T. citricida  in Brazil (Loeza -Kuk et al. 2008).  Both CSDaV and T. 
citricida  are present in Brazil ( CPC 2020; Loeza -Kuk et al. 2008 ). CSDaV was suggested to be 
associated with citrus sudden death disease in Brazil (Fadel et al. 2 018; Matsumura et al. 2016). This 
disease is highly destructive and has caused the eradication of millions of citrus trees in southern 
Brazil (Fadel et al. 2018).  
 
Of the reported viruses, Plum pox virus  (PPV) is in the priority pest and disease list in New Zealand 
and is known to transmitted by T. citricida . PPV is transmitted by T. citricida  in a non -persistent 
manner (CPC 2020).  
 
Hazard identification conclusion:  
Toxoptera citricida is considered to b e a hazard in this analysis. Toxoptera  citricida  is considered to 
be a risk on the citrus fresh produce pathway from Brazil, given that:  
• CSDaV affects citrus and is not present in New Zealand ; 
• CSDaV was suggested to be associated with the highly destructiv e citrus sudden death 
disease in Brazil;  
• CSDaV was detected in adult T. citricida ; and 
• Both CSDaV and T. citricida are present in Brazil.  
 
   
465 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14.1.7  Entry  assessment for Aphis gossypii , A. spiraecola, A . craccivora, Macrosiphum 
euphorbiae, Myzus persicae and Toxoptera citricida  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Aphis gossypii, A. spiraecola, 
A. craccivora, Macrosiphum euphorbiae, Myzus persicae and Toxoptera citricida 
have a weak  to moderate association with citrus fruit depending on individual 
species.  
Aphis spiraecola, A. craccivora, Ma. euphorbiae, My. persicae and Toxoptera citricida  are likely to be 
associated with citrus, but the strength of association with the fruit of citrus varies.  
• Citrus  spp. has been reported as hosts o f these aphid species in CPC (2020).  
• Interception of these aphid species is not common at the New Zealand border. Adults of 
A. gossypii , A. craccivora  and My. persicae  have been identified at the New Zealand border 
on citrus fruits for one, three and five times respectively between 1929 to 2019 (LIMS 2019).  
• For A. spiraecola , CPC (2020) reported that citrus is one of the primary hosts. Feeding 
damage can be found on leaves, flowers and fruits, and eggs or colonies can be spread in 
trade on planting materia l or fruits (especially citrus and apple) (CPC 2020). There  were no 
identification s of A. spiraecola  at the New Zealand border from 1929 to 2019 (LIMS 2019).  
• The p rimary hosts of T. citricida  are Citrus spp., and  they occasionally feed on other 
Rutaceae  (CPC 2020). Direct feeding damage caused by  T. citricida can be found on shoots, 
flower buds and sometimes young fruits (OEEP/EPPO 2006). However, CPC (2020) states 
that flowers are not a preferred host tissue, and mature leaves, stems and fruit cannot su stain 
T. citricida  populations.  
• For A. gossypii  and Ma. euphorbiae , CPC (2020) reported that fruit can carry adults and 
nymphs externally in plant trade, but it did not specify which plant species  the fruit is from . No 
record was found mentioning Ma. euphorbiae  on citrus  fruit specifically.  
• Aphis gossypii  has been identified once (alive) on orange fresh produce at the New Zealand 
border from 1929  to 2019 (LIMS 2019). However, CPC (2020) reported that A. gossypii 
attack s most parts of the plant, apart from direct ly feeding on mature reproductive structures 
and roots.  
 
Aphis gossypii, A.  spiraecola, A. craccivora, Ma. euphorbiae, My. persicae and Toxoptera citricida are 
present in at least one of the citrus -exporting countries in the citrus fresh produce IHS.  
 
Therefore, the strength of association  of A. gossypii , A. spiraecola, A. craccivora, Macrosiphum 
euphorbiae, Myzus persicae and Toxoptera citricida with citrus fruit varies : 
• Aphis craccivora , My. persicae , A. spiraecola  and are considered to have a weak  to moderate 
association with citrus fruit .  
• Aphis gossypii , Ma. euphorbiae  and T. citricida  are considered to have a weak  association 
with citrus fruit.  
 
Given the arguments and evidence below,  basic measure s are likely to reduce the 
likelihood of entry of Aphis gossypii, A. spiraecola, A. craccivora, Macrosiphum 
euphorbiae, Myzus persicae and Toxoptera citricida  by a high degree . Consequently , 
the likelihood of entry is considered to be very low. 
 
Aphis gossypii , A. craccivora  and My. persicae  may survive transit on some citrus commodties.  
• Living A. gossypii , A. craccivora  and My. persicae  have been identified on citrus fruit at the 
New Zealand border, suggesting some of them were able to survive transit on so me citru s 
commodities.  
• However, interception is not common. There are only five, three and one identification records 
for My. persicae , A. craccivora  and A. gossypii  respectively from 1929  to 2019 (LIMS 2019).  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 466 Visual inspection can usually detect infestations of aphids.   
• Aphid species excrete honeydew, which leads to the growth of sooty moulds that will be 
visible  during inspection (Richards and Davies 1977).  
• Except for the  egg stage, life stages of aphids are mobile, so they are likely to be visible when 
moving.  
• However, a phids are small insects. The s ize of adults of A. gossypii , A. spiraecola , A. 
craccivora , Macrosiphum euphorbiae , Myzus persicae and Toxoptera citricida range s from 1 –
3.6 mm (CPC 2020).  If aphids hide in sheltered places on citrus commodities , such as in the 
navel of navel  oranges , visual inspection can be difficult. Navel orange has been reported as 
a host of Ma. euphorbiae , but no reports found mention  that the aphid is associat ed with fruits 
of navel  orange. Myzus persicae, A. craccivora  and A. goss ypii have been intercepted on 
fresh oranges  at the New Zealand border , but interception event s are not common ( five, three 
and one time s for My. persicae , A. craccivora  and A. gossypii  respectively from 1929  to 2019 
(LIMS 2019 )).  
 
General handling after harvesting is likely to remove most aphids on the commodity.  
• All life stages (except eggs)  of aphids have legs and are mobile (Richards and Davies 1977) . 
• Aphids are likely to move away from  commodities or be killed during general handling  (e.g. 
washing, brushing and grading) . 
• If eggs are laid in protected places (e.g.  the navel of navel orange s), they can be difficult to 
detect. However, the association of the eggs of these aphids is likely to be weak, as no report 
was found mentioning tha t eggs from these aphids were laid on citrus fruit.  
 
   
467 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Insect vector analyses – vector species not considered to be hazards  
14.1.8  Brachycaudus persicae  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:  
Brachycaudus persicae is present in Australia (CPC 2019).  
 
New Zealand status:  
• Brachycaudus persicae is present in New Zealand (NZOR 2020).  
• Brachycaudus persicae is listed as  ‘non-regulated’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Brachycaudus persicae feeds on Prunus  spp. (CPC 2019). Citrus is not re corded as a host in CPC 
(2019), but B. persicae  was identified once on citrus fresh produce (mandarin) from Australia at the 
New Zealand border in 2015 (LIMS interception data).  
 
Plant parts affected:  
Injury caused by B. persicae  consists of leaf curling, yellowing, and premature leaf drop (UC IPM 
2017).  Apart from the border interception on mandarin , other evidence of B. persicae  on citrus cannot 
be found.  
 
Vectored organism s: 
Brachycaudus persicae can transmit Plum pox virus  (PPV). PPV is not known to affect citrus and is 
not vectored by B. persicae  in a persistent manner.  
 
Hazard identification conclusion:  
Brachycaudus persicae is not considered to be a hazard in this analysis , given that:  
• Brachycaudus persicae is not known to transmit any pathogen that is known to affect citrus;  
and 
• Brachycaudus persicae is not known to transmit any pathogen in the priority pest and disease 
list in a persistent or semi -persistent manner.  
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 468 14.1.9  Macrosiphum rosae  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:  
Macrosiphum rosae is present in Egypt, China, Korea, Spain, the USA, Australia  and Brazil (CPC 
2019).  
 
New Zealand status:  
• Macrosiphum rosae is present in New Zealand (NZOR 2020).  
• Macrosiphum rosae is listed as a  ‘potential vector’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Macrosiphum rosae is commonly found on Rosaceae, especially on species in the genus Rosa . It is 
also commonly found on Fragaria , Geum , Pyrus , Malus  and Rubus (CPC 2019). Host record s for 
citrus cannot be found in CPC (2019) or CAB Abstract s, but M. rosae has been identified once on 
orange from Australia (in 2005) at the New Zealand border (LIMS 2019 ).  
 
Plant parts affected:  
Nymphs and adults of M. rosae  can be found on flowers, leaves and stems  of plant h osts. It has been 
identified on  orange fruit at the New Zealand border (LIMS 2019 ). 
 
Vectored organism s: 
Macrosiphum rosae  can transmit Bean yellow mosaic virus  (CPC 2019), Strawberry vein banding 
caulimovirus , Teasel mosaic potyvirus , Strawberry mild yellow edge luteovirus  (BRAD).  
 
There is no pathogen vectored by M. rosae  that is known to affect citrus.  
 
There is no virus that is in the HPO or SRO list which  is known to be transmitted by M. rosae in a 
persistent manner.  
 
Hazard identif ication conclusion:  
Macrosiphum rosae is not considered to be a hazard in this analysis , given that:  
• Macrosiphum rosae is not known to transmit pathogens that are known to affect citrus;  and 
• Macrosiphum rosae is not known to transmit any pathogen in the priority pest and disease list 
in a persistent or semi -persistent manner.  
 
   
469 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14.1.10  Myzaphis rosarum  (Hemiptera: Aphididae)  
 
Citrus -exporting countr y status:  
Myzaphis rosarum is present in the USA (Frazier 1951).  
 
New Zealand status:  
• Myzaphis rosarum is present in New Zealand (NZOR 2020).  
• Myzaphis rosarum is listed as a  ‘potential vector’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Hosts of Myzaphis rosarum are Rosa  spp. Myzaphis rosarum  has been trapped downwind of a plot of 
Potato virus Y  (PVY) -infected potatoes and  is reported as  able to transmit PVY ( Lewis  1985). It is not 
recorded as a pest on citrus in literature in search results from  CPC (2019), CAB Abstract s and 
Google Scholar, b ut there is an identification record (in 2008) of M. rosarum  on orange fresh produce 
from Australia (LIMS interception database). However, according to CPC (2019), CAB Abstract and 
Google Scholar, M. rosarum  is not known to be present in Australia.  
 
Plant  parts affected:  
Myzaphis spp. live on the undersides of leaves (Kanturski et al. 2018).  
 
Vectored organism s: 
Myzaphis rosarum can transmit PYV (Lewis  1985). It was recorded to be capable of transmitting  the 
strawberry virus complex experimentally in California (Frazier 1951). These viruses are not known to 
affect citrus and are not vectored by M. rosarum  in a persistent manner.  
 
Hazard identification conclusion:  
Myzaphis rosarum is not considered to be a ha zard in this analysis , given that:  
• Myzaphis rosarum is not known to transmit pathogens that are known to affect citrus;  and 
• Myzaphis rosarum is not known to transmit any pathogen in the priority pest and disease list 
in a persistent or semi -persistent manner.  
 
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 470 14.1.11  Toxoptera aurantia  (Hemiptera: Aphididae)  
 
Citrus exporting countr y status:  
Toxoptera aurantia is found in Egypt, China, Japan, Viet  Nam, Spain, Mexico, the USA, Australia, Fiji, 
New Caledonia, Samoa, Solomon Islands, Vanuatu, Brazil  and Peru (CPC 2019).  
 
New Zealand status:  
• Toxoptera aurantia is present in New Zealand (NZOR 2020).  
• Toxoptera aurantia is listed as  ‘non-regulated’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Toxoptera aurantia has a relatively limited range of plant hosts. Citrus , Camellia , Coffea , Mangifera , 
Theobroma  are listed as  “main” hosts of T. aurantia  in CPC (2019).  
 
Plant parts affected:  
Toxoptera aurantia  is often found on the undersides of young leaves and young shoots of many 
economically important plants (CPC 2019). It has been identified once on citrus fresh produce 
(orange) from Australia at the New Zealand border (LIMS 2019 ).  
 
Vectored organism s: 
Toxoptera aurantia  is reported to be capable of transmitting Citrus tristeza virus , Zucchini yellow 
mosaic virus  (CPC 2019), Papaya ringspot potyvirus  (type W) (Chao and Chen 1991), Citrus psorosis 
virus  (Portillo and Benatena 1986), Citrus vein enation viru s (Manjunath 1987), Cucumber mosaic 
virus (Chin 1983) and Tea rose yellow mosaic virus  (Ahlawat and Sardar 1973).  
 
Of the reported viruses, Citrus tristeza virus  (CTV) , Citrus psorosis virus  (CPsV)  and Citrus vein 
enation virus (CEVE) are known to affect citrus.  CTV, CPsV and CEVE are present in New Zealand 
(Veerakone et al. 2015) . 
 
There is no virus that is in the HPO or SRO list that is known to transmitted by T. aurantia  in a 
persistent manner.  
 
Hazard identification conclusion:  
Toxoptera aurantia  is not considered to be a hazard in this analysis , given that:  
• Toxoptera aurantia  is not known to transmit any pathogen that is known to affect citrus and is 
not known to be present in New Zealand;  and 
• Toxoptera aurantia  is not known to transmit any pathogen in the priority pest and disease list 
in a persistent or semi -persistent manner.  
 
 
   
471 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14.1.12  Pseudococcus calceolariae  (Hemiptera: Pseudococcidae)  
 
Citrus -exporting countr y status:   
Pseudococcus calceolariae  is present in China, Spain, Mexico, the USA, Australia and Brazil (CPC 
2019).  
 
New Zealand status:  
• Pseudococcus calceolariae  is present in New Zealand (NZOR 2020).  
• Pseudococcus calceolariae  is listed as  ‘non-regulated’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Pseudococcus calceolariae is highly polyphagous and has hosts from over 40 plant families. Citrus is 
one of the main hosts of P. calceolariae  (CPC 2019).  
 
Plant parts affected:  
Pseudococcus calceolariae feeds on fruits, growing points, inflor escence, roots and stems (CPC 
2019). It has been identified on citrus fruit at the New Zealand border over 1 ,800 times (LIMS 2019 ).  
 
Vectored organism s: 
Pseudococcus calceolariae can transmit Grapevine leafroll -associated virus -3 (CPC 2019) , which is 
present in New Zealand ( Veerakone et al. 2015 ). 
 
Hazard identification conclusion:  
Pseudococcus calceolariae is not considered a hazard in this analysis , given that  
• Pseudococcus calceolariae is not known to transmit pathogens that are known to a ffect citrus;  
and 
• Pseudococcus calceolariae is not known to transmit any pathogen in the priority pest and 
disease list in a persistent or semi -persistent manner.  
 
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 472 14.1.13  Pseudococcus longispinus  (Hemiptera: Pseudococcidae)  
 
Citrus exporting countr y status:  
Pseudococcus longispinus is present in Egypt, China, Japan, Viet  Nam, Spain, Mexico, the USA, 
Australia, Cook Islands, Fiji, New Caledonia, Solomon Islands, Vanuatu, Brazil and Peru (CPC 2019).  
 
New Zealand status:  
• Pseudococcus longispinus is present in New Zealand (NZOR 2020).  
• Pseudococcus longispinus is listed as a  ‘potential vector’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Pseudococcus longispinus is highly polyphagous and has been recorded on over 100 host plants 
belonging to 78 plant families. Hos t plants include many plants of economic importance, such as 
citrus, pear and grapevine (CPC 2019).  
 
Plant parts affected:  
Signs of e xternal feeding of P. longispinus  can be found on fruit, growing points, inflorescence s, 
leaves and stems (CPC 2019). It has been identified over 800 times on citrus fruit at the New Zealand 
border (LIMS interception database).  
 
Vectored organism s: 
Pseudococcus longispinus is known to vector Grapevine leafroll -associated virus 1  (GLRaV) (Bertin et 
al. 2010), Grapevine leafro ll-associated virus 3  (CPC 2019), Grapevine leafroll -associated virus 5  
(=GLRaV 4) (Golino et al. 2002), Grapevine leafroll -associated virus 9  (=GLRaV 4) (Tsai et al. 2010), 
Grapevine virus A  (GVA) (Notte et al. 1997), Grapevine virus B  (GVB) (Kuniyuki et al. 2006) and 
Cacao swollen shoot virus  (CSSV) (CPC 2019). In  Solomon Islands and other islands in the 
southwest Pacific region, it is a vector of the smaller of two bacilliform viruses associated with 
‘bobone’ disease in taro and Xanthosoma  sp. It is also  associated with viruses with stem -pitting in 
grapevines (CPC 2019).  
 
None of the reported viruses are known to affect citrus. GLRav 1, 3 and 4 and GVA and GVB are 
‘Non-regulated’ in New Zealand ( ONZPR  2020). There is no virus in the HPO or SRO list that is 
known to be transmitted by P. longispinus  in a persistent manner.  
 
Hazard identification conclusion:  
Pseudococcus longispinus is not considered to be a hazard in this analysis , given that:  
• Pseudococcus longispinus is not known to transmit pathogens tha t are known to affect citrus;  
and 
• Pseudococcus longispinus is not known to transmit any pathogen in the priority pest and 
disease list in a persistent or semi -persistent manner.  
 
 
   
473 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14.1.14  Planococcus citri  (Hemiptera: Pseudococcidae)  
 
Citrus -exporting countr y status:  
Planococcus citri is present in Egypt, China, Japan, Viet  Nam, Spain, Mexico, the USA, Australia, 
Cook Island s, Fiji, New Caledonia, Samoa, Brazil  and Peru (CPC 2020).  
 
New Zealand status:  
• Planococcus citri is present in New Zealand (NZOR 2020).  
• Planococcus citri is listed as a  ‘potential vector’ in ONZPR  (2020).  
 
Plant hosts:  
Planococcus citri is highly polyphagous, with hosts of over 200 plant species belonging to 82 families. 
Many plants of economic importance are hosts of the pest, such as citrus, banana and taro (CPC 
2020).  
 
Plant parts affected:  
Nymphs and adults of P. citri  can be found on fruits, growing points, leaves, inflorescence, roots and 
stems (CPC 2020). It has been identified on citrus fruits at the New Zealand border over 90 tim es 
(LIMS 2019 ). 
 
Vectored organism s: 
Planococcus citri is known to vector Banana streak disease  (BSD) , Cacao swollen shoot virus  
(CSSV) , Cucumber mosaic virus , Dioscorea bacilliform virus  (DBV) , Schefflera ringspot virus  (SRV) 
(CPC 2020), Grapevine virus A , Grapevine leafroll -associated virus 1 , Grapevine leafroll -associated 
virus 3  (Bertin et al. 2016), Citrus mosaic disease  (a synonym for Citrus yellow mosaic virus ) (Reddy 
et al. 2010; Ahlawat and Pant 2003) and Piper yellow mottle virus  (PYMV) (Silva et al. 2002).  
 
Of the reported viruses, Citrus yellow mosaic virus  (CiYMV) is known to affect citrus.  CiYMV is 
regulated in New Zealand ( ONZPR  2020)  and transmitted by P. citri  in a persistent manner (CPC 
2020; Reddy et al. 2020).  According to CPC (2020) and result s from literature search es in CAB 
Abstract s, CiYMV is only known from India (CPC 2020).  India is not one of the citrus -exporting 
countries in the citrus fresh produce IHS .  
 
There is no virus in the HPO or SRO list that is known to be transmitted by P. citri  in a persistent 
manner.  
 
Hazard identification conclusion:  
Planococcus citri is not considered to be a hazard in this analysis , given that:  
• Planococcus citri  transmits CiYMV , which can affect citrus, but the virus is not present in any 
citrus -exporting country in the IHS;  and 
• Pseudococcus longispinus is not known to transmit any pathogen in the priority pest and 
disease list in a persistent or semi -persistent manner.  
 
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 474 14.1.15  Pseudococcus viburni  (Hemiptera: Pseudococcidae)  
 
Citrus -exporting countr y status:  
Pseudococcus viburni  is present in China, Korea, Spain, Mexico, the USA, Australia, Brazil  and Peru 
(CPC 2019).  
 
New Zealand status:  
• Pseudococcus viburni  is present in New Zealand (NZOR 2020).  
• Pseudococcus viburni  is listed as  ‘non-regulated’ in  New Zealand ( ONZPR  2020).  
 
Plant hosts:  
The “main” hosts of P. viburni  in CPC (2019) are tea ( Camellia sinensis ), citrus, apple, orchids 
(Orchidaceae), Pelargonium , pear, potato and grapevine.  
 
Plant parts affected:  
Nymphs and adult s of P. viburni  can be found on whole plants, including leaves, inflorescences, fruit, 
growing points, roots and stems (CPC 2019). It has been identified on citrus fresh produce at the New 
Zealand border 19 times ( 15 alive) from 1929 to 2019 (LIMS 2019 ). 
 
Vectored organi sms: 
Pseudococcus viburni  can transmit Cacao swollen shoot virus (CSSV) (Obok et al. 2018), Grapevine 
leafroll -associated virus 3 (CPC 2019) , Grapevine virus A, Grap evine virus B (Garau et al. 1995). 
Apart from CSSV, these viruses are all ‘ non-regulated’ in New Zealand ( ONZPR  2020).  CSSV is listed 
as ‘regulated’ ( ONZPR  2020). CSSV is vectored by mealybug species in a semi -persistent manner 
(Obok 2016) , and it is not in the HP O or SRO list.  
 
Hazard identification conclusion:  
Pseudococcus viburni  is not considered to be a hazard in this analysis , given that:  
• Pseudococcus viburni  is not known to transmit pathogens that are known to affect citrus;  and 
• Pseudococcus viburni  is not known to transmit any pathogen in the priority pest and disease 
list in a persistent or semi -persistent manner.  
 
 
   
475 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14.1.16  Frankliniella intonsa  (Thysanoptera: Thripidae)  
 
Citrus -exporting countr y status:  
Frankliniella intonsa  is present in Japan, Spain, the USA (Washington), Korea  and China (CPC 2020 ).  
 
New Zealand status:  
• Frankliniella intonsa  is present in New Zealand (NZOR 2020).  
• Frankliniella intonsa  is listed as a  ‘potential vector’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
In CPC ( 2020 ), the “main” hosts of F. intonsa  are okra, groundnut  (peanut) , asparagus, capsicum, 
chrysanthemum, strawberry, soybean, cotton, lucerne ( Medicago sativa ), rice ( Oryza sativa ), common 
bean, pea, peach, tomato and adzuki bean ( Vigna angularis ). Citrus is not liste d as a host of F. 
intonsa  in CPC (2020). However, it is one of the common thrips found in citrus orchards in mainland 
China and Taiwan (Xu et al. 2012; Qin et al. 2010; Chiu et al. 1991).  
 
Plant parts affected:  
Eggs of F. intonsa  may be laid in leaves, flowers or fruit. Larvae tend to reside in concealed places on 
hosts, such as within flowers or developing leaves or under the calyx of fruit. It has been found on 
young citrus fruit in Taiwan (Chiu et al. 1991).  
 
Vectored organism s: 
Frankliniella intonsa can transmit  Chrysanthemum stem necrosis  orthotospovirus  (Okuda et al. 2013),  
Groundnut  ringspot  orthotospovirus  (Wijkamp 1995) , Impatiens necrotic spot virus  (Sakurai et a. 
2004), Tomato spotted wilt virus  (CPC 2020 ) and Tomato chlorotic spot orthotospovirus  (Wijkamp 
1995).  
 
There is no pathogen vectored by F. intonsa  that is known to affect citrus.  
 
There is no virus in the HPO or SRO list that is known to be transmitted by F. intonsa  in a persistent 
manner. Capsicum chlo rosis orthotospovirus (CaCV) is a species in the orthotospovirus and in the 
SRO list. In general, viruses in this genus are transmitted by thrips in a persistent and propagative 
manner. However, Chiaki et al. (2020) shows that CaCV can be transmitted by T. palmi  but not by T. 
tabaci , Frankliniella occidentalis  or F. intonsa .  
 
 
Hazard identification conclusion:  
Frankliniella intonsa  is not considered to be a hazard in this analysi s, given that:  
• Frankliniella intonsa  is not known to transmit any pathogen that is known to affect citrus;  and 
• Frankliniella intonsa  is not known to transmit any pathogen in the priority pest and disease list 
in a persistent or semi -persistent manner.  
 
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 476 14.1.17  Frankliniella occidentalis  (Thysanoptera: Thripidae)  
 
Citrus exporting coun try status:  
Frankliniella occidentalis  is present in Egypt, China, Japan, Mexico, Spain, the USA, Australia, Korea, 
Brazil  and Peru (CPC 2020 ).  
 
New Zealand status:  
• Frankliniella occidentalis  is present in New Zealand (NZOR 2020).  
• Frankliniella  occidentalis  is listed as a ‘potential vector’ in ONZPR  (2020).  
 
Plant hosts:  
Frankliniella occidentalis  is highly polyphagous. It has been recorded on plant species belonging to 
over 65 families. It attacks many plants of economic importan ce growing bot h outdoor s and in 
glasshouses, such as onion, beetroot, capsicum, orange, grapefruit, cucumber, carrot, strawberry, 
peach, potato and grapevine (CPC 2020 ). 
 
Plant parts affected:  
Eggs of F. occidentalis  may be laid in leaves, flowers or fruit. Larvae tend to reside in concealed 
places on hosts, such as within flowers or developing leaves or under the calyx of fruit (CPC 2020 ). 
 
Vectored organism s: 
Frankliniella occidentalis  has been reported  to transmit Alstroemeria necrotic streak orthotospovirus 
(Hassani -Mehraban et al. 2010), Chrysanthemum stem necrosis  orthotospovirus , Impatiens necrotic 
spot orthotospovirus , Tobacco streak virus , Tomato spotted wilt virus , Tomato yellow ring 
orthotospovirus  (Mortazavi and Aleosfoor 2015), Tomato zonate spot orth otospovirus (CPC 2020 ), 
Tomato chlorotic spot orthotospovirus  (Webster et al. 2015), Groundnut ringspot orthotospovirus  
(Webster et al. 2015) and Parietaria mottle virus  (Aramburu et al. 2010). It  has also transmit ted Maize 
chlorotic mottle virus  (Zhao et al. 2014) experimentally.  
 
None of the reported viruses are known to affect citrus.  
 
There is no virus in the HPO or SRO list that is known to be transmitted by F. occidentalis  in a 
persistent manner. Capsicum chlorosis orthotospovirus (CaCV ) is a species in the orthotospovirus  
and in the SRO list . In general, viruses in this genus are transmitted by thrips in a persistent and 
propagative manner. However, Chiaki et al. (2020) shows that CaCV can be transmitted by T. palmi  
but not by T. tabaci , Frankliniella occidentalis  or F. intonsa .  
 
 
Hazard identification conclusion:  
Frankliniella occidentalis  is not considered to be a hazard in this analysis, given that:  
• Frankliniella occidentalis  is not known to transmit any pathogen that is known to affect citrus;  
and 
• Frankliniella occidentalis  is not known to transmit any pathogen in the priority pest and 
disease list in a persistent or semi -persistent manner.  
 
   
477 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  14.1.18  Thrips tabaci  (Thysanoptera: Thripidae)  
 
Citrus -exporting countr y status:  
Thrips tabaci  is present in Egypt, New Caledonia, Japan, Mexico, Spain, USA, Australia, Korea, 
Brazil, Peru, Solomon Islands, Viet  Nam, Fiji (CPC 2019)  
 
New Zealand status:  
• Thrips tabaci  is present in New Zealand (NZOR 2020).  
• Thrips tabaci  is listed as a  ‘potential v ector’ in New Zealand ( ONZPR  2020).  
 
Plant hosts:  
Thrips tabaci  is polyphagous.  Onion is its preferred host plant. Other “main” hosts include , but are not 
limited to , garlic, leek, cauliflower, daisy, cucumber and tobacco (CPC 2019).  
 
Plant parts affected:  
Nymphs and adults of T. tabaci  can be found on flowers, fruit, leaves and stems in plant trade (CPC 
2019) . Thrips tabaci  has been identified on citrus fruit (orange, mandarin and tangor) at the New 
Zealand border. These specimens were from the USA and Australia (LIMS interception database).  
 
Vectored organism s: 
Thrips tabaci  has been reported to be able to transmit Iris yel low spot virus, Maize chlorotic mottle 
virus, Prunus necrotic ringspot virus, Sowbane mosaic virus, Tobacco ringspot virus, Tobacco streak 
virus  (TSV) , Tomato spotted wilt virus, Tomato yellow fruit ring virus (syn. of Tomato yellow ring virus ) 
and Alstroe meria yellow spot virus (CPC 2019; Hassani -Mehraban et al. 2019; Mwando et al. 2018; 
Mortazavi and Aleosfoor 2015; Golnaraghi et al. 2007; Messieha 1969).  
 
None of the above viruses are known to affect citrus.  
 
There is no virus in the HPO or SRO list that is known to be transmitted by T. tabaci  in a persistent 
manner. Capsicum chlorosis orthotospovirus (CaCV) is a species in the orthotospovirus  and in the 
SRO list . In general, viruses in this genus are transmitted by thrips in a persistent and propagat ive 
manner. However, Chiaki et al. (2020) shows that CaCV can be transmitted by T. palmi  but not by T. 
tabaci , Frankliniella occidentalis  or F. intonsa .  
 
Hazard identification conclusion:  
Thrips tabaci is not considered to be a hazard in this analysis , given that:  
• Thrips tabaci is not known to transmit pathogens that are known to affect citrus;  
• Thrips tabaci  is not known to transmit any pathogen in the priority pest and disease list in a 
persistent or semi -persistent manner . 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 478 14.1.19  References  
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  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 486 14.2 Mite vector analysis : Brevipalpus  spp. (flat mites or false spider 
mites) , vectors of citrus leprosis viruses  
[See 15. 1 for an analysis of insect  vectors]  
 
Subclass/Family: Acari/ Tenuipalpidae  
 
Scientific name : Brevipalpus californicus  (Banks 1904)  
Other names : Brevipalpus australis , Tenuipalpus australis , T. californicus , citrus flat mite (CABI 
2020), sweet  potato false spider mite  (EPPO 2020).  
 
Scientific name : Brevipalpus obovatus  Donnadieu , 1875  
Other names : Brevipalpus inornatus , Tenuipalpus obovatus, T. inornatus , scarlet tea mit e privet  mite, 
ornamental flat mite  (CABI 2020; EPPO 2020)  
 
Scientific name : Brevipalpus phoenicis  (Geijskes  1939)  sensu lato  (s. l.) 
Other names : Tenuipalpis phoenicis  Geijskes, 1939, Brevipalpus yothersi  Baker 1949, passion vine 
mite (CABI 2020), red and black flat mite, leprosis mite (EPPO 2020).  
 
Brevipalpus  species are very small (< 1  mm long),  plant -feeding mites with wide host ranges that 
include many cultivated (ornamentals, fruit trees,  forest tree s, vegetables) and wild plants.  Citrus 
hosts of Brevipalpus spp. include C. aurantium , C. aurantiifolia, C. latifolia , C. limon , C. reticulata  and 
C. sinensis ) (Vacante 2016). Among the over 300 Brevipalpus species worldwide, B. californicus , 
B. obovatus  and B. phoenicis  s. l. are considered to be of particular economic importance , mainly 
because they are implicated in the transmission of plant viruses, especially those that cause citrus 
leprosis. Citrus leprosis  leads to defoliation, premature fruit drop , dry branches and, in advanced 
stages, death of citrus trees. The disease has resulted in enormous losses in Brazilian citriculture  
(Roy et al. 2015; Bastianel et al. 2010; Kitajima et al. 2010; Childers and Rodrigues 2011).  At high 
densities, these mites  may also cause direct  feeding  damage to economic plants such as citrus.  
Although the Brevipalpus  spp. of concern are present in New Zealand (NZOR 2020; PPIN 2020), they 
are regulated as potential vectors in ONZPR  (2020) because of their association with citrus leprosis 
viruses, which are not present in the country.  
 
Brief n otes on taxonomy : As with many other mite groups, poor descriptions of Brevipalpus mites 
have caused substantial taxonomic challenges for several decades (Beard et al. 2013). Thus, the 
actual host ranges and role of these three Brevipalpus species  in virus transmission is complicated by 
historical misidentifications. The recent taxonomic revision by Beard et al. (2015), which established 
that B. phoenicis sensu lato  (s. l.) is a complex (a group) with eight distinct species, has provided 
some clarity. However, it also creates uncertainty regarding the actual geographic distribution 
(including the New Zealand status), host range and vector competence of these species.  
 
 
Summary of conclusi ons 
 
Given the arguments and evidence presented : 
 
• The Brevipalpus species assessed (those implicated as vectors of citrus leprosis and other 
viruses) have a strong association with citrus fruit, with low uncertainty.  
• Basic measures  will reduce the likeliho od of entry of Brevipalpus spp. on citrus fruit by a 
moderate  to high degree (with moderate uncertainty); therefore, the likelihood of entry is 
considered  low to moderate, with low uncertainty.  
• The ability of Brevipalpus spp. to transfer from imported fruit to citrus hosts, leading to the 
potential transmission of citrus viruses, is low (with moderate uncertainty).  
• Entry and transfer of Brevipalpus spp. infected with citrus leprosis viruses, to a citrus host, 
leading to introduction of the viruses,  is likely to cause a hig h level of impact to New Zealand’s 
citrus industry , but the impact to the overall New Zealand economy is likely to be low (with 
moderate uncertainty).   
487 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • Entry and transfer of Brevipalpus mites that are not infected with citrus leprosis vi ruses, is 
likely to have negligible impact, with low uncertainty; but entry of Brevipalpus species not 
currently present in New Zealand, may have phytosanitary implications . 
• Some Brevipalpus spp. (including  species in the B. phoenicis  complex) m ay be consi dered for 
additional measures on citrus fruit from countries where citrus leprosis virus is confirmed to be 
present.  
 
Summary of risk assessment against criteria  
Criteria  Rating  Uncertainty  
Strength or frequency of association with the commodity  Strong  Low 
Likelihood of entry on the commodity, given the application of basic measures  Low–Moderate  Low 
The ability to move from the imported commodity  onto a suitable host  Low Moderate  
Suitability of the N ew Zealand  environment  Not assessed98  
Impacts on the New Zealand economy, environment, health and society  Moderate99 High 
 
14.2.1  Hazard identification: quarantine status  
 
Given the arguments and evidence below,  the Brevipalpus  species assessed ( B. 
californicus , B. obovatus  and B. phoenicis s. l.) meet some, bu t not all, of the criteria 
to be quarantine pests for New Zealand .  
• Brevipalpus obovatus , B. californicus  and B. phoenicis s. l. are present in New Zealand; they 
are recorded in NZ Inverts (2020), NZOR (2020) and PPIN (2020) . 
• However, because of their association with regulated viruses, these mites are ‘regulated ’ as 
potential vectors in ONZPR  (2020).  
• Of relevance to this assessment is c itrus leprosis  (CL), an important and well -characterised 
disease of citrus, especially sweet orange  (Citrus sinensis ), which is transmitted by 
Brevipalpus  spp. (EFSA 2017; Bastianel et al. 2010).   
• Six viruses  belonging to three different genera have been identified as causing CL symptoms 
in various citrus varieties. They are: Citrus leprosis virus C  (CiLV‐C, genus Cilevi rus), Citrus 
leprosis virus  C2 (CiLV‐C2, genus Cilevirus ), Hibiscus green spot virus 2  (HGSV‐2, genus 
Higrevirus ), Citrus leprosis virus N  dichoravirus  (CiLV‐N, genus Dichorhavirus ) and Citrus 
chlorotic spot dichoravirus  (CiCSV, genus Dichoravirus ) and the citrus strain of Orchid fleck 
dichoravirus  (OFV, genus Dichoravirus ) (EFSA 2017; Roy et al. 2015; Bastianel et al. 2010; 
Childers et al. 2003).  
• The viruses that cause CL are not known to be present in New Zealand ; they are not 
recorded in NZOR (2020), NZFungi (2020 ) and  PPIN (2020).  
• Also, species in the Brevipalpus phoenicis  s. l. complex whose distributions, host ranges and 
roles as vectors are yet to be determined pose an undetermined level of risk to New Zealand.  
• Dispersal of Brevipalpus spp. (especially B. phoenicis sensu lato ) represent s the most 
important means of the spread of the viruses causing citrus leprosis (EFSA 201 7).  
• Entry of Brevipalpus spp. from an area with citrus leprosis viruses,  and exposure (transfer) of 
virus -infected mites to citrus hosts in New Zealand is sufficient to introduce these viruses; 
once infected, all motile stages of the mites (larvae, nymphs and adults)  remain  infective 
throughout their lifespan and only need to feed o n a host plant for 2 –3 hours to transmit the 
virus ( Childers et al. 2003 ; Bastianel et al. 2006 ; Tassi et al. 2017; Ferreira et al. 2020).   
• The viruses responsible for citrus leprosis and their Brevipalpus  vectors  (including B. yothersi 
a species within th e B. phoenicis complex, which is the main vector of CiLVC) are present in  
                                                      
98 Suitability of the New Zealand environment for establishment was not considered in this assessment because the Brevipalpus  
species assessed are known to be present in New Zealand. Additionally, an infected mite entering on fruit need only transfer to, 
and feed on, a suitable host (establishment is not necessary) to introduce citrus leprosis  
99 Level of economic impact is likely to be high for the citrus industry, if entry of the mites and transfer to host plants lead s to the 
introduction of citrus leprosis v iruses. Otherwise, impact is likely to be negligible  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 488 two of the citrus exporting countries in this IHS , i.e. Brazil and Mexico (Roy et al. 2015; 
SENASICA 2018; CPC 2020; EPPO 2020).  
 
This assessment, therefore, determines the likelihoo d of entry into New Zealand, of Brevipalpus  spp. 
on imported citrus fruits and their ability to transfer from imported commodities to citrus host plants, 
which could lead to the introduction of citrus leprosis viruses that are not recorded from New Zealand  
(NZFungi 2020; NZOR 2020; PPIN 2020).  
 
Given that the Brevipalpus spp. in this PRA are already established in New Zealand, the suitability of 
the New Zealand environment for  establishment of the mites is not assessed. The level of impact is 
assessed mainly  as it relates to the introduction of leprosis disease. Other viruses transmitted by 
Brevipalpus mites , but for which citrus is not a known host, are not considered100. 
 
14.2.2  Hazard identification: commodity association  
 
Given the arguments and evidence bel ow, Brevipalpus spp. implicated in the 
transmission of citrus leprosis disease  have a strong association with citrus:  
There are reliable records of Brevipalpus spp. on citrus:  
• Brevipalpus spp. attack the stems, leaves and fruit of many citrus species (Chil ders et al. 
2003)  
• In Brazil, B. phoenicis  s. l. has been reported causing damage on citrus, mainly due to the 
transmission of citrus leprosis virus (Bastianel et al 2010; Rodrigues et al. 2003).  
• Brevipalpus yothersi (syn. B. phoenicis s. l.) was associated  with the first report of Citrus 
leprosis virus C (CiLV -C) in groves of sweet orange ( C. sinensis) in the south Mexican states 
of Tabasco and Chiapas  (Castillo et al. (2011), and B. californicus  s. l. was detected in CiLV -
N -infected citrus groves located at high elevation ( between 1,500 and 2,200m above sea 
level) on the central Mexican plateau and was the only Brevipalpus  species present at these 
altitudes  (Roy et al. 2016).  
• In the Mexican states of Yucatan, Quintana Roo and Campeche101, B. phoenicis s. l. and B. 
californicus were collected and identified from citrus orchards containing sweet orange ( C. 
sinensis ), grapefruit ( C. paradisi ), bitter orange ( C. aurantium ), mandarin ( C. recticulata ) and 
Persian/Tahiti lime ( C. latifolia ).    
• Between 1994 and 2017, live Brevipalpus spp. (B. phoenicis  s. l., B. obovatus , B. californicus ) 
were  intercepted 107 times at the New Zealand border on citrus fresh produce : limes ( C. 
aurantiifolia  and C. latifolia ), oranges  (C. sinensis ), pomelo  (C. maxima ), grapefruit  (C. x 
paradisi ) and mandarins ( C. reticulata ). These interceptions were mostly from the USA , with 
the remaining records being from Australia, Vanuatu, Samoa and Tonga (LIMS 2020).  
• The confirmed citrus hosts of the three vector species u nder consideration, based on the 
most recent taxonomic revision of Brevipalpus  spp. (Beard et al. 2015), are shown in Table 
15.2.1 below.  
 
Table 15.2.1  Brevipalpus  spp. that are suspected or confirmed vectors of citrus leprosis virus, with their 
confirmed  citrus hosts  
Species  Citrus hosts  
B. californicus  C. sinensis  (sweet orange) C. aurant iifolia (key lime) C. limon (lemon)  C. reticulata  (tangor)  
B. phoenicis  s. l. C. sinensis (sweet orange) C. aurant iifolia (Mexican/key lime) C. latifolia  (Persian/Tahitian lime) 
C. medica  (citron) , C. reticulata  (mandarins)  
                                                      
100 Brevipalpus mites entering New Zealand on fresh citrus fruit, are likely to have fed, mainly (if not solely), on citrus hosts , 
given that they are poor dispersers. Thus, the likelihood that a mite fed on a non -citrus host, acquired a non -citrus virus and 
then, transferred to a citrus fruit in an exporting country, is considered to be negligible. And while it is theoretically po ssible for 
the same mite to enter NZ on imported citrus fruit and transfer to  a non -citrus host of the said virus in New Zealand, the 
likelihood of this sequence of events is also considered to be negligible.  
101 In Campeche, only B. phoenicis was present in orchards containing sweet orange, mandarin and lime.   
489 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Species  Citrus hosts  
B. obovatus  C. limon  (lemon), C. sinensis  
Due to previous taxonomic confusions, only hosts based on Brevipalpus  spp. specimens identified by Beard et al . 
(2013 ), are listed .  
 
14.2.3  Risk assessment  
 
Likelihood of entry:  
 
Given the arguments and evidence below,  Brevipalpus spp. have a strong 
association with c itrus plants and fruit , with low uncertainty  
 
There are  reliable records of Brevipalpus spp. on citrus  hosts and commodities : 
• In Bra zil, B. phoenicis  s. l. has been reported causing damage on citrus, mainly due to the 
transmission of CiLV -C (Bastianel et al 2010; Rodrigues et al. 2003, 2011).  
• Brevipalpus  yothersi , one of the species within the B. phoenicis  sensu lato  complex (Beard et 
al. 2015) is reported as the most common species in Mexican and Brazilian citrus orchards 
(Sánchez Velázquez et al. 2015; Salinas -Vargas et al. 2016).  
• In Mexico, B. californicus  s. l. was detected in CiLV -N -infected citrus groves locate d at high 
elevation ( between 1,500 and 2,200m above sea level ) in the central Mexican plateau and 
was the only Brevipalpus  species present at these altitudes  (Roy et al. 2016).  
• Brevipalpus phoenicis is recorded as a pest of sweet oranges ( Citrus sinensis ) in Mexico 
(Chiapas , Oaxaca, San Luis Potosi, Sinaloa, Tabasco and Veracruz) and citrus leprosis is 
reported as a disease of oranges in the Mexican states of Chiapas , Queretaro, Tabasco  and 
Veracruz  (SENASICA 2018).  
• Live adults  and nymphs  of B. phoenicis, B. californicus and B. obovatus  have been 
intercepted many times at the New Zealand border, on citrus fresh produce; limes ( C. 
aurantiifolia  and C. latifolia ), oranges  (C. sinensis ), pomelo  (C. maxima ), grapefruit  (C. x 
paradisi ) and mandarins ( C. reticulata ) from the USA , Australia and the Pacific Island 
countries of Samoa, Tonga and Vanuatu (LIMS 2020).  
 
Given the arguments and evidence below,  basic measures  will reduce the likelihood 
of entry of viruliferous Brevipalpus spp. on citrus fruit by a moderate -high degree  
(with moderate uncertainty); consequently, the likelihood of entry is low -moderate  
 
Brevipalpus  mites, especially at high infestations on citrus fruits, are likely to be detected:  
• On citrus hosts, the population of Brevipalpus mites is  usually low, but high  densities occur  in 
natural cracks and crevices on the surface of fruit, as well as cracks caused by wind or hail 
(Vacante 2016).  
• High mite densities in cracks/crevices on fruit occur because females tend to oviposit in such 
sites and  juvenile and adult stages feed around the edges of these sites, which emphasizes 
the cracks (Vacante 2016) and makes the mites more likely to be detected, leading to the 
removal of infested fruit during field, packhouse and pre -export inspections.  
• Though eggs are laid singly, they are also likely to be detected because of their bright red 
colour and occurrence in clusters formed by several females laying eggs close together in the 
same cracks  on citrus fruit (Denmark and Fasulo 2018).  
 
High infestations of  Brevipalpus  spp. cause detectable feeding injuries:  
• High population densities of Brevipalpus spp. cause feeding injuries on citrus, such as silvery 
patches on lemon fruit (Jeppson et al. 1975 in Childers and Rodrigues 2011).  
• In grapefruit and orange, hig h density populations of B. californicus and B. phoenicis s. l. have 
been associated with rind spotting that begins as slight yellowish circular discoloured lesions 
in depressions on the surface of grapefruit and orange, which later develop central brown Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 490 necrotic areas or spots that darken and become corky (Dean & Maxwell 1967; Rakha 1994 
cited in Vacante 2016). The brown spots are irregular in shape and vary from 3 -12 mm in 
diameter.  
• Commercially produced fruits with some, or all, of the above signs of da mage, are likely to be 
culled during packing house processes.  
• In a risk management document for the importation of lemons from Argentina, the United 
States Department for Agriculture (USDA) determined that visual inspection was an adequate 
phytosanitary me asure against B. californicus , B. obovatus  and B. phoenicis , “as mite 
infestations cause bronzing of fruits that can be detected upon inspection” (USDA 2016).  
 
Fruits infected with citrus leprosis (and infested with mite vectors) can be detected and are li kely to be 
excluded from consignments:  
• Mature orange fruit that have been infected with citrus leprosis virus (and which may harbour 
virus -infected mites) often have lesions (10 –20mm in diameter) that appear as slightly 
depressed necrotic spots with a cha racteristic dark brown halo (Rodrigues et al. 2003; León 
et al. 2006) . 
• On green fruits, the lesions are initially yellowish, later becoming brown or blackish, 
sometimes depressed, and reduce the market value of the fruits (Rodrigues et al. 2003).  
• Fruits in fested with viruliferous mites are usually lighter (in weight) than uninfested fruits, with 
weight decreasing as the number of mites increases. Also, affected fruits drop 50% more 
frequently than fruits without mites or lesions (Rodrigues et al. 2003), mak ing them less likely 
to be packed.  
 
However, fruit  with few mites may not show symptoms of infestation or disease:  
• Brevipalpus spp. are very small mites, with the largest life stage (adult females) measuring 
between 200 – 300 µm lon g, which makes them diff icult to detect without magnification, 
especially at low densities (Vacante 2016; Childers et al. 2003).  
• Leprosis s ymptoms appear from 17 to 60 days after mite transmission, with most symptoms 
appearing between 21 and 30 days  after (Chiavegato and Salibe  1984 cited in EFSA 2017 ).  
• If leprosis lesions are not yet evident, and feeding injuries are not obvious due to low mite 
density, the mites may not be detected. Therefore, it is possible for asymptomatic fruit with 
low mite infestations to be unknowingly in cluded in consignments.  
 
In-field pest control and common packing house postharvest processes will greatly reduce the density 
of mites on harvested fruit, but are unlikely to completely eliminate the mites:  
• In countries where citrus leprosis disease is present, Brevipalpus spp. are regularly controlled 
in citrus crops using a combination of cultural, biological, but mainly chemical methods (EFSA 
2017; Rodrigues et al. 2011), which is likely to lead to low den sity of mites on fruit.  
• Rodrigues et al. (2003) considered that packing house processes, which included a double 
wash, drying and waxing, were sufficient to eliminate the mites from citrus fruit for export.  
• However, Peña  et al. (2015) tested the efficacy o f commonly used fruit cleaners, soaps, 
waxes, and mechanical brushing techniques to remov e and kill all life stage s of Brevipalpus  
mites on lemons ( Citrus limon ), using virus -free B. yothersi  (one of the species in the B. 
phoenicis s. l. complex) as a model  and found that:  
o no treatment provided 100% reduction of all mite stages, and reduction following 
single treatments (soap rinse, brushing or waxing alone) was not significantly different 
from reduction obtained with a water drench control.  
o several com bination treatments, particularly those that included application of a food -
grade wax coating, achieved ~90% reduction of mites.  
• Peña  et al. (2015) concluded that a combination of treatments, including a soap wash and 
mechanical brushing followed by a wax  coating, may be the most effective method to achieve 
significant reduction (although not complete elimination ) of all stages of Brevipalpus  mites 
from infested citrus.  
 
The Brevipalpus  spp. considered in this assessment are likely to survive transit on ci trus fruit:  
• Frequent interception of live adults, nymphs and eggs of B. phoenicis , B. obovatus and B. 
californicus  at the New Zealand border, especially on citrus fruits imported from the USA 
(LIMS 2020), suggests that Brevipalpus  spp. can survive transit conditions for citrus shipped 
to New Zealand.   
491 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  • There are currently no data on interceptions of Brevipalpus spp. on commodities from Mexico 
and Brazil (where citrus leprosis is present) at the New Zealand border (LIMS 2020); probably 
because there has been n o trade in host commodities of Brevipalpus  spp. between these 
countries and New Zealand (QuanCargo 2020).  
 
Uncertainty:  
• The main source of uncertainty is the fact that the mites may not be detected at low levels of 
infestation and post -harvest processes may not eliminate all undetected mites from fruit, 
which increases the likelihood of entry.  
 
 
Likelihood of establishment:  
 
Given the arguments and evidence below,  the ability of Brevipalpus spp. to transfer 
from imported fruit onto a citrus host plant, le ading to establishme nt of citrus leprosis, 
is rated as low (with moderate uncertainty)  
 
Brevipalpus  spp. have poor natural dispersal ability, and are likely to remain on or near discarded 
fruit, unless passively dispersed by wind and other agents:  
• Under experimental greenhouse conditions , only about 3% of 6000 B. phoenicis  s. l. crawled 
40-50cm  from the point of release in 24 hours, with the remaining 97% crawling only about 
1cm/day (Alves et al. 2005).  
• Alves et al. (2005) further demonstrated ( under labor atory conditions ) that fan -generated wind 
speeds below 30 km/h were unable to dislodge B. phoenicis  from the surface of citrus fruit, 
while higher wind speeds (30 – 40 km/h ) dispers ed only about 1% of the mite population . 
• In a field study using sticky traps, only three adults of B. phoenicis  were captured on traps 
placed 1.5m from the hedge around two separate plots of citrus groves (Alves et al. 2005).  On 
sticky traps placed within the two plots, 99% and 83% of the mites  collected belonged to the 
family Tetranychidae, 0.8% and 4.8% to the family Phytoseiidae and 0.4% and 11.8% to 
Tenuipalpidae – the family to which Brevipalpus  spp. belong.  
• Based on their results, (Alves et al. 2005) suggested that, relative to other mite species, 
Brevipalpus  mites have limited aerial dispersal ability , which was  attributed to  their flat 
anatomy , behaviour of hiding in cracks or protrusions and lesions on fruits and branches , as 
well as their low response to wind currents – as demonstrated in the laboratory studies. In 
contrast, mite species in the Tetranychidae  and Eriophyidae have adaptive behaviours, which 
enable them to disperse better on wind currents (Al ves et al. 2005).  
• In another field experiment (Peña et al. 2010 ), B. phoenicis -infested lemons were placed on 
the ground 2m away from the lemon tree, and one mite was detected on the tree after 14 
days, with wind speeds averaging about 33 km/h. Also, when the lemons were placed 
touching the base of the tree, two mites were able to transfer to the tree after 14 days (Peña 
et al. 2010).  
• The mites failed to transfer , from lemon fruit placed in a trash can, to a lemon tree 2m away. 
And even when infested fruits  were suspended 1m above ground, no mites were detected on 
fruit placed at different heights on the tree after 28 days (Peña et al. 2010).  
• When lemons infested with B. phoenicis  were placed in contact with fruit flies, 3/60 fruit flies 
had mites attached t o their seta or body (Peña et al. 2010 ). Transfer to citrus hosts via 
attachment to other insects or birds is highly uncertain, as this would depend on the 
sites/hosts visited by the transporting agent, and there is no data indicating that mites have 
the a bility to choose which “transport agents” they become attached to.  
• Given that there are likely to be few mites on export grade fruit, and that Brevipalpus spp. are 
not known to have the ability to control where they land when carried by wind (Bassanezi and  
Laranjeira 2007) , dispersal by wind does not guarantee that a mite will land on a citrus host.  
• Mites dispersed by wind or other agents, would have a higher chance of landing on a citrus 
host in the main citrus producing areas of New Zealand and , possibly,  in home gardens 
across the country, where citrus plants, especially lemons, are commonly grown.  
• Taken together, the evidence presented above indicates that transfer  of Brevipalpus spp. 
from imported citrus fruit to citrus host plants in New Zealand is only likely, if infested fruits are Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 492 discarded in citrus orchards, or on open compost heaps very close to citrus hosts in home 
gardens.  
 
Uncertainty:  
• High wind speeds are common in New Zealand and may increase the likelihood of dispersal 
of mites from fruit discarded in open areas close to citrus hosts.  
• There are no current data on the proportion of imported citrus waste that is discarded in and 
around citrus orchards or composted in hom e gardens. Although Hogg et al. (2010) report ed 
that New Zealanders discard around 400,000 tonnes of kitchen waste each year  and about 
12.5% is composted, there are no data on the proportion of composted waste that is imported 
citrus. Also, the distances o f compost heaps to citrus hosts in home gardens is unknown.  
 
 
Impacts in New Zealand:  
 
Given the arguments and evidence below,  introduction of citrus leprosis disease by 
Brevipalpus spp. is likely to cause low-moderate impacts in New Zealand (with high 
uncertainty)  
Citrus leprosis is likely to cause high economic impacts for growers, especially, of sweet oranges:  
• Citrus leprosis virus (CiLV) causes one of the most serious virus diseases of citrus, 
associated with premature fruit drop, defoliation, and deat h of the twigs or branches, with crop 
damage sometimes leading to 100% yield loss (Childers and Rodrigues 2011; Rodrigues et 
al. 2003).  
• The most sensitive hosts for CiLV ‐C and CiLV ‐C2 are sweet orange ( C. sinensis ), but 
mandarin ( C. reticulata ) and its hybrids  are also widely affected, although varieties express 
various degree s of resistance or tolerance to CiLV ‐C (EFSA 2017; Roy et al. 2015) . 
• In Brazil, citrus leprosis has been reported to cause losses of 35 –75% in sweet oranges, due 
to premature fruit  drop (Rodrigues et al. 2003), while le mons ( C. limon ), Mexican lime ( C. 
aurant iifolia), grapefruit ( Citrus paradisi ), sweet lemon (C. limetta ) and Persian lime ( C. 
latifolia ) are not found naturally infected with CiLV ‐C and are considered resistant , while  C. 
limetta  is considered to be immune to CiLV ‐C (Bastianel et al. 2010 ). 
• Introduction of any of the citrus leprosis  viruses  into New Zealand  is likely to affect exports of 
citrus because the disease is not known to occur in any of the countries that are e xport 
destinations for New Zealand citrus.  
• The cost of r esponse activities,  including eradication efforts that involve elimination of all 
infected hosts and mites from an area, may be considerable.  
 
Costs for long -term mite and disease control may be high:  
• Bastianel et al. (2010) reported that Brazilian citrus growers spent around US$800 million 
(21% of production costs) every year to control the Brevipalpus  mites that vector citrus 
leprosis.  
• Observations made in the State of São Paulo, Brazil, indicate that when virus inoculum is 
present in an area and acaricides are not applied, 2 –3 years are sufficient to allow for the 
complete spread of leprosis throughout an orchard; the large size of citrus orchards 
contributes to the occurrence and widespread distr ibution of citrus leprosis in the São Paulo 
industry, making control more difficult (Rodrigues et al. 2003).  
• No evidence was found (Google; HortResearch and New Zealand Citrus Growers 
Incorporated 2001 ) to indicate that Brevipalpus spp. require control in New Zealand citrus, but 
introduction of citrus leprosis would necessitate mite control (likely using chemicals) and 
increase production costs.  
• Increased use of chemicals to control Brevipalpus spp. may lead to increased outbreaks of 
citrus red mite ( Panony chus citri ), which is typically considered a ‘pesticide induced’ pest in 
New Zealand citrus  (Pyle & Stevens 2004 cited in Jamieson & Stevens 2009).  
• Populations of citrus red mite (CRM) have been observed to increase dramatically in orchards 
following appli cation of broad -spectrum insecticides to control other major pests, particularly 
Kelly’s citrus thrips ( Pezothrips kellyanus ) and citrus flower moth ( Prays nephelomima ). It is 
thought that these chemicals disrupt the activity of CRM natural enemies, especi ally the  
493 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  coccinellid ladybird, Stethorus  sp. and the predatory mite, Agistemus longisetus  (Jamieson et 
al. 2005, 2008).  
  
Economic impacts may be moderated by the non -systemic nature of citrus leprosis viruses and the 
inability of mites to transmit them to  their offspring:  
• In contra st to the vast majority of plant ‐infecting viruses, citrus leprosis viruses are unable to 
systemically invade their citrus host plants (Bastianel et al. 2010; Roy et al. 2015).  
• Thes e viruses are only able to move locally from an  infected cell to immediately neighbouring 
cells, which results in the development , around inoculation points , of the localised, centimetric 
infection lesions on leaves, young stems or fruits  that is  typical of the disease (Bastianel et al. 
2010; Roy et al . 2015).  
• There are no known systemic hosts for these viruses (Bastianel et al. 2010; Roy et al. 2015) , 
therefore, virus lesions are only associated with the feeding sites of Brevipalpus  spp. vectors , 
and vegetative multiplication practices used to produce  planting materials are highly  unlikely 
to represent a major mechanism for virus spread  (EFSA 2017).  
• Bassanezi and Laranjeira (2007)  reported that in citrus orchards in Brazil, leprosis -infected 
plants clustered together, partly because the vector Brevipalpus mites move slowly and 
depend on passive  mechanisms (such  as being carried on  tools, machinery or clothing of 
farm workers) for dispersal within  orchard s.  
• Adult Brevipalpus  mites  are not known to transmit the viruses to their eggs, so unless ad ults 
and their offspring feed on an infected site and disperse to other plants, the disease cycle can 
be broken (Tassi et al. 2017; Bastianel et al. 2010).  
 
Introduction of citrus leprosis viruses by Brevipalpus spp. is likely to cause very low environment al 
impacts, with high uncertainty:  
• The recorded natural hosts of the citrus leprosis viruses are mainly citrus species, and there 
are no Citrus  species native to New Zealand.  
• There are two genera within the Rutaceae that are endemic to New Zealand: Leione ma and 
Melicope , but none of the species in either genera are considered threatened (NZPCN 2020).  
• Outside the Rutaceae, there are very few recorded natural infections of plants by leprosis 
viruses: CiLV -C has been recorded from Commelina benghalensis  (Comm elinaceae); CiLV -
C2 and OFV citrus strains from Dieffenbachia  sp. (Araceae); HGSV -2 from Hibiscus 
arnottiana  and CiCSV from Hibiscus tiliaceus  (Rosaceae) ( Freitas -Astúa  2018; Roy et al. 
2015). There are two native ( non-endemic) Hibiscus  species in New Zeal and, which are both 
considered “threatened, nationally critical” ( H. richardsonii  and H. diversifolius  subsp. 
diversifolius ) (NZPCN 2020).  
• Uncertainty centres on the host range of the citrus leprosis viruses, which appears to not be 
fully elucidated; this is in part related to the uncertain host ranges of their known vectors and 
the possibility of unidentified vectors . Both  of these uncertainties  are, in turn,  linked to the 
taxonomic difficulties within the genus Brevipalpus . 
 
Introduction of citrus leprosis by Brevipalpus spp. is unlikely to cause health impacts, but may cause 
low social impacts (with high uncertainty):  
• No evidence was found of any citrus leprosis viruses causing human health issues.  
• The high economic impact of  citrus leprosis may cause social impacts in citrus growing 
communities.  
• A biosecurity response is likely to be mounted following an incursion, and will involve activities 
that disrupt cultural practices in citrus producing areas, including the trade and movement of 
host commodities.   
 
Uncertainty:  
• There is uncertainty around the conclusion on impacts, since the natural host ranges of the 
Brevipalpus  transmitted viruses are not fully known/described; CiLV -C has a wide  range of 
several hundreds of experimental hosts, ranging from Arabidopsis  to Phaseolu s (Arena et al. 
2017; Garita et al. 2014).  
• Although the host ranges of the viruses may be expected to fall within those of the vector 
mites’, the host ranges of the vector s are also uncertain; given historical taxonomic difficulties 
and recent revisions of the genus Brevipalpus . For example, it is suspected, but yet to be Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 494 confirmed  that HGSV -2 is transmitted by Brevipalpus  mites, and a tentative vector species  
has not been identi fied (Freitas -Astúa  2018; Roy et al.  2015) . 
• There is also uncertainty around which Brevipalpus  spp. are present in New Zealand, part ly 
due to  a recent taxonom ic revision of  the genus by Beard et al. (2015).   
 
 
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2020.  
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FAO (2019) The use of integrated measures in a systems approach for pest risk management . ). 
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Garita, L C; Tassi, A D; Calegario, R F; Freitas -Astúa, J; Salaroli, R B; Romão, G O; Kitajima, E W 
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43–55. 
Haramoto , F H (1969 ) Biology and control of Brevipalpus phoenicis  (Geijskes) (Acarina: 
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Hogg, D; Wilson, D; Gibbs, A; Holmes, A; Eve, L (2010) Household Organic Waste Cost Benefit 
Analysis Report to Greenfingers Garden Bags/Earthcare Environmental Limited & Envirofert Limited. 
Eunomia Research and Consulting Ltd, Auckland, New Zealand.  
HortResearch and New Zealand Citrus Growers Incorporated (2001 ) Growing Citrus in New Zealand: 
a practical guide https://www.zeafruit.co.nz/wp -content/uploads/2019/01/NZCGI -Growing -Citrus -in-
NZ-A-Practical -Guide.pdf  Accessed 29 October 2020.  
Jamieson, L E; Charles, J G; Stevens, P S; McKenna, C; Bawden, R (2005) Natural enemies of citrus 
red mite ( Panonychus citri ) in citrus orchards. New Zealand Plant Protection , 58: 299 –305. 
Jamieson, L E; Chhagan, A; Charles, J G ( 2008) Predation of citrus red mite ( Panonychus  citri) by 
Stethorus  sp. and Agistemus longisetus . New Zealand Plant Protection , 61: 317 –321. 
Jamieson, L E; Stevenson, P S (2009) Miticides against citrus red mites ( Panonychus citri ). New 
Zealand Plant Protec tion, 62: 302 –309.  
Kitajima, E W; Chagas, C M; Rodrigues, J C V (2003) Brevipalpus -transmitted plant virus and virus -
like diseases: cytopathology and some recent cases. Experimental and Applied Acarology , 30:135 –
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León M, G A ; Kitajima, E W;  Freitas -Astúa, J (2006) Diagnóstico y recomendaciones de manejo para 
la leprosis de los cítricos. Boletín Técnico  47. Corporación Colombiana de Investigación 
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Miami (Coconut Grove), Florida USA. 
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quarantine treatments against Brevipalpus yothersi  (Acarina: Tenuipalpidae). Florida Entomologist , 
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Salinas -Vargas D, Santillán -Galicia MT, Guzmán -Franco AW, Hernández -López A, Ortega -Arenas 
LD, Mora -Aguilera G. (2016) Analysis of genetic variation in Brevipalpus yothersi  (Acari: 
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D; Hernández -López, A ; Sánchez -Soto, S (2019) Development and reproduction of Brevipalpus 
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Salinas -Vargas, D ; Santillán -Galicia, M  T; Valdez -Carrasco, J ; Mora, -Aguilera, G; Atanacio -Serrano, 
Y; Romero -Pescador, P (2013) Species composition and abundance of Brevipalpus  spp. on different 
citrus species in Mexican orchards. Neotropical Entomology , 42(4): 419–425. 
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497 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Appendi x 1: Summary of taxa excluded at hazard identification  
 
Appendix 1, Table 1  Groups and species identified at the hazard iden tificat ion stage as not requiring further assessment and not requiring measures over and 
above basic measures, and the rationale for exclusion  
 
Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Fungi  
Family 
Aspergillaceae  Aspergillus flavus, A. niger, Penicillium digitatum and P. italicum  reported from citrus fruit but are present in New Zealand (NZ Fungi2 
2020; PPIN 2020). Penicillium ulaiense  was considered in more depth , because it is recorded as absent from New Zealand 
(NZFungi2 2020) ; however, it is not recorded as a citrus pathogen, although it can cause rot of citrus fruit in storage. Penicillium 
ulaiense  was commonly associated with packing  houses in the USA but coul d not be detected at production sites (Holmes et al. 
1994). In Egypt , it has been reported in packing houses (Youseff et al . 2010) , and in Japan , it has been reported only as a storage 
rot of stored fruit (Tashiro et al. 2012).  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 498 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Family 
Botryosphaeriaceae  Phyllosticta citricarpa (Guignardia citricarpa ) required a full pest risk assessment . Several other Phyllosticta spp. were excluded at 
the hazard identification stage , because they are not associated with fruit or do not meet the criteria for additional mea sures. For 
example:  
• Phyllosticta citribraziliensis  and P. paracapitalensis have only been reported as endophytes from healthy citrus leaves and have 
not been reported from fruit (Glienke et al. 2011; EFSA 2014a; Guarnaccia et al. 2017a ).  
• Phyllosticta citr imaxima was isolated from tan spots on the fruit surface of  pomelo fruit in Thailand (Wikee et al. 2013) .  
• Phyllosticta paracitricarpa  was isolated from leaf litter of C. limon  in Greece and fruit spots on  C. limon  and C. sinensis  in China 
(Guarnaccia  et al. 2017a, 2019). Since this species was only recently described, there is only limited evidence for its 
pathogenicity to citrus fruit (Guarnaccia  et al.  2017a carried out preliminary pathogenicity testing on detached mature orange 
fruit) and insufficient information for a pest risk assessment .  
• Phyllosticta citriasiana  causes citrus tan spot on C. maxima  fruit and leaves. It is only reported from tropical areas such as 
Thailand and Viet Nam and several tropical provinces of China (Wulandari et al. 2009; Wa ng et al. 2012) , which have very 
different climate conditions to the whole of New Zealand, indicated by a climate match index (CMI) of ≤ 0.6 (Phillips et al. 2018). 
Pomelo ( C. grandis/C. maxima ) is the only recorded host of P. citriasiana  (Wulandari  et al. 2009; Wang et al. 2012) and is not 
widely grown in New Zealand. Therefore, both likelihood of establishment and potential for this fungus to have impacts in New  
Zealand were considered  extremely low.  
• Phyllosticta citrichinaensis was isolated from mandarins ( C. reticulata ), pomelos ( C. maxima ), oranges ( C. sinensis ) and lemons 
(C. limon ) (Wang et al. 2012) . Infected fruit and leaves show some irregular spots or freckles. However, pycnidia (reproductive 
structures) were not found on lesions , so there is no evidence that P. citrichinaensis could move from imported fruit to a new host 
in New Zealand. No significant losses resulted from this pathogen (Wang et al. 2012).   
 
Several Lasiodiplodia  spp. were also excluded at the hazard identification stage , because they are not associated with citrus fruit, 
they do not meet the criteria for additional measures , or searches102 found insufficient information to assess further on citrus fruit. For 
example:  
• There is only a single report of L. pseudotheobromae  from citrus fruit as a post -harvest rot of lemons in Turkey (Awan et al. 
2016).  
Lasidiplodia pseudotheobromae and L. brasiliensis  were also reported from Persian lime plants in Mexico with gummosis, stem 
cankers and dieback symptoms (Bautista -Cruz et al . 2019). However, searches (Google Scholar; CAB Abstracts, July 2020) on the 
search terms ‘Lasidiplodia brasiliensis’ and citrus found no evidence of citrus fruit rots caused by this fungus.  
                                                      
102 Searches of CAB abstr acts, CPC and Google Scholar using the species name and “citrus” as search terms.   
499 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Family 
Ceratobasidiaceae  Rhizoctonia noxia  (synonyms Corticium koleroga ; Ceratobasidium noxium; Koleroga noxia Pellicularia koleroga ) has previously been 
assessed on fresh citrus fruit from Samoa, as C. koleroga  (MAF 2008) and does not currently have additional measures on citrus 
fruit from Samoa. Rhizoctonia noxia  attacks twigs, fruit and leaves of Citrus  trees (Timmer 2000). Rhizomorphs form and cover the 
tissue , which may die if heavily invaded. Small black sclerotia often form on the rhizomorphs and basidiospores may form on the 
wefts of mycelium on host tissue (Ti mmer 2000). Timmer (2000) states that C. koleroga  infection on citrus  fruit is seldom severe 
enough to require treatment. MAF (2008) concluded that recent infections (less than one week old) of C. koleroga  are unlikely to be 
detected by visual inspection o n arrival in New Zealand, but that fruit with sclerotia will be detected during harvesting and handling 
and be rejected prior to export. Infestations of thread blight are highly unlikely to go undetected on citrus plants grown in  commercial 
production.  
Family 
Ceratocystidaceae  Ceratocystis fimbriata  was considered in the hazard identification , because it is a major pathogen and has been reported as 
associated with citrus . However, fruit is not infected by C. fimbriata  and is not considered to be a pathway  for entry (EFSA 2008a). 
The CPC datasheet (CABI 2020) makes a general statement that the surface of host fruit may be contaminated with fruiting bodi es; 
hyphae; spores. However, searches of CAB Abstracts  and Google Scholar  found no evidence for a routine association between 
Ceratocystis fimbriata  and citrus  fruit. Farr and Rossman (2020) list substrates as woody branches and stems, roots, leaves, tubers, 
but do not include fruit. Search results for ‘Ceratocystis fimbriata’ and ‘ citrus ’ and ‘fruit’ often re lated to a fruity odour or to biocontrol 
of fungi with citrus oils.  
Ceratocystis radicicola causes post -harvest and opportunistic rots of citrus fruit but is extremely unlikely to be associated with 
unblemished fruit. In pathogenicity tests, intact citrus fruit were not susceptible to infection by fungal spores of C. radicola ; the fungus 
could only enter damaged fruit through wounds or cracks (Mirzaee and Mohammadi 2005).  
Family 
Dermateaceae  Cryptosporiopsis citricarpa  (synonym Pseudofabraea citricarpa ) does not meet the criteria for further assessment , because there is 
no evidence for an association with citrus  fruit. Cryptosporiopsis citricarpa  is a destructive leaf spot , which was first reported China in 
2010 (Zhu et al, 2012). The same species or a species with the same name was recorded on older leaves of several citrus  species in 
the Cook Islands, Fiji, Niue, Tonga, Vanuatu and Western Samoa (Johnston and Fullerton 198 8). Cryptosporiopsis citricarpa  was not 
reported from fruit in either case. Searches103 found only these reports and taxonomic studies referring to Zhu et al. (2012).  
Paracercosporidium microsorum  (synonyms Cercospora microsora, Mycosphaerella microsora, Myc osphaerella millegrana, 
Passalora microsora ) was added to the initial hazard list for further checking because it was historically listed in the citrus nursery 
stock pest list. However, it did not meet the criteria for further assessment , because searches (CAB  Abstracts ; Farr and Rossman ; 
Google Scholar, June 2020) using ‘Paracercosporidium microsorum’ or the synonyms above and ‘citrus’ as search terms found no 
references suggesting that this fungus is associated with citrus.  
                                                      
103 Searches of CAB Abstracts, CPC and Google Scholar in June and October 2020 using the species name and “citrus” as search term s. Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 500 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Family Diaporthaceae  A number of recently described Diaporthe species are associated with citrus, either as symptomless endophytes or associated with 
leaf scab and cankers on twigs, branches and trunks (Huang et al. 2013 , 2015) . Generally, these have no association with fruit.  
Although Huang et al. (2015) isolated D. subclavata  from pomelo fruit ( C. grandis ) and D. unshiuensis from C. unshiu fruit with 
melanose symptoms in China (Huang et al. 2015), this study appears to be the only primary record of these species associated wi th 
citrus fruit, although several later taxonomic studies refer back to this study.  
Family 
Didymellaceae  Plenodomus tracheiphilus  (synonym Phoma tracheiphila ) was considered in more depth , because it causes economically important 
damage to citrus, particu larly lemon trees, in Greece, Italy and Turkey (EFSA 2014b; Karapapa et al. 2015; Nigro 2011). Fruit of 
diseased citrus plants can be invaded by  P. tracheiphilus, causing discolouration of the peel, withering and mummification or fruit 
drop (Nigro et al. 2011). Although  Plenodomus tracheiphilus  can be detected in citrus fruit and as mycelium on the coats of seeds, 
there is no evidence that the pathogen is spread by the movement of fruit (EFSA 2014). Infected fruit is of low quality and usually 
falls to the  ground before harvest ( Migheli  et al. 2009) . 
Family Elsinoeaceae  Elsinoe australis  required a pest risk assessment , and the regulatory status of several pathotypes of E. fawcettii has also been 
assessed, because these strains have not been reported in Ne w Zealand. No evidence was found for other fungi in this family that 
would qualify as quarantine pests associated with citrus fruit.  
Family Erysiphaceae  The powdery mildew fungi Erysiphe quercicola  and Fibroidium tingitaninum  (synonym Oidium tingitaninum ) are unlikely to be 
associated with mature fruit at the time of harvest. They infect leaves and immature fruit in the first flush of growth and c an cause 
premature fruit drop (Biosecurity Queensland 2011).   
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Family 
Glomerellaceae  A number of Colletotrichum  species were considered in more depth at the hazard identification stage , but either there is no evidence 
that they would be associated with mature fruit at harvest , or they do not meet the criteria for additional measures because 
symptoms would be highly  visible and infected fruit would not meet the commodity symptom. For example:  
• The lime anthracnose strain of C. acutatum (synonyms: C. limetticola; Gloeosporium limetticola ; Gloeosporium fructigenum f. 
limetticola ) is highly likely to be detected during production or phytosanitary inspection, or to damage infected fruit to the extent 
that is not fit for export.  
o Young tissues, including young fruit of key lime ( C. aurantiifolia ) are susceptible to C. acutatum (Peres et al. 2005, 
2008).   
o Spores germinate rapidly when they land on young susceptible fruit , almost immediately causing necrotic lesions.  
• No evidence was found for an association of C. abscissum with mature fruit at harvest.  
o Colletotrichum abscissum  is associated with blossoms and immature fruit (Crous et al. 2015; Rodrigues Marques et al. 
2020). It causes post -bloom drop of immature fruit at a very early stage of development.  
o The fruitlets detach between the caly ces and young fruit, and the caly ces (or buttons) remain on the plant and do not 
abscise as they normally would if no fruit is set (Dewdney 2015; Rodrigues Marques et al. 2020).  
• Colletotrichum queenslandicum  has been reported only once on citrus (from Persian lime leaves in USA) (Kunta et al . 2018) , and 
there is no evidence of an association with citrus fruit.  
A number of recently described Colletotrichum species (e.g. C. catinaense, C. helleniense, C. hystricis and C. limonicola ) cause 
lesions on citrus  fruit (Guarnaccia et al. 2017b) but a re not reported from any of the IHS countries. There is very little information 
about these pathogens beyond the initial report. These species may need to be assessed in future if their distribution change s.   
Family Meliolaceae 
(sooty blotches)  Meliola citricola has previously been assessed on citrus fruit from Samoa (MAF 2008) and is likely to be managed by basic 
measures. Although infections develop slowly, M. citricola  requires young leaves to infect, and it could be assumed the same applies 
to fruit (MAF 2008). Therefore, it is likely M. citricola  will have developed visible symptoms (unsightly black fungal growth) by time of 
harvest , and infected fruit are likely to be removed prior to export. Meliola camelliae is also reported from citrus (Farr and Rossman 
2020).  
Meliola citricola  is not a strong parasite , and economic loss is usually related to the unsightly appearance of the black fungal growth 
on the fruit (MAF 2008). Like sooty moulds, severe infections may affect the photosynthesis ability of p lants and reduce fruit yields. 
(MAF 2008). Searches  using  the species name and ‘citrus’ as search terms in CAB Abstract s and Google Scholar (November 2020) 
and literature records in Farr and Rossman (2020) found some records of M. citricola  and M. camellia e in historic country indexes 
and lists of fungal species but no evidence of recent or severe economic impacts.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 502 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Family 
Mycosphaerelleaceae  A number of leaf and fruit spot species in the Mycosphaerelleaceae were considered during the hazard identification process, 
including:  
• Mycosphaerella citri  (synonym Zasmidium citri ) does not meet the criteria for further assessment , because there is no pathway 
for establishment from citrus  fruit (based on MAF 2008). Mycosphaerella citri  is extremely unlikely to establish from  citrus fruit 
that meets the commodity description (in particular without leaves) , because it overwinters in the soil and sporulates on fallen 
leaves (MAF 2008).  
• Mycosphaerella horii is also reported to sporulate on  decomposing leaves (Ieki 1986).  
• There is no evidence that either M. citri  or M. horii can complete their life cycle s on discarded citrus peel or fruit.  
• Searches104 found very little life  cycle information about M. loefgreni, C ercospora  penzigii, Z. fructicola or Z. fructigenum ;they  are 
either recently described, or there is very little information about them and no record of economic impacts. They are  assumed to 
have a similar life cycle to the  closely related species M. citri and M. horii.  
• Mycospha erella citrigena and Z. indonesianum are reported from leaves but not fruit of citrus species.  
• Pseudocercospora angolensis is only found in sub -Saharan Africa and Yemen (EFSA 2017). It is not currently found in any of 
the countries being assessed for the c itrus fresh fruit IHS. This species would require urgent assessment if it spreads to an IHS 
country.  
Family Nectriaceae  Two species in the Nectriaceae were considered in more detail because they have been reported from citrus fruit:  
• Cylindrocarpon licheni cola (synonyms include Fusarium lichenicola; Neocosmospora lichenicola ) was reported as a cause of 
severe post -harvest fruit rot of pomelo in Viet  Nam (Amby et al . 2015). However, although other citrus species developed rot 
symptoms in pathogenicity tests (Amby et al. 2015) searches using the search term ‘ Cylindrocarpon lichenicola’ or its synonyms 
and ‘citrus’ found no other reports of C. lichenicola from citrus. Cylindrocarpon lichenicola  is also reported as a cause of 
opportunistic infections in humans i n tropical areas (e.g. Summerbell and Schroers 2002), and it is likely that it is a common 
environmental fungus in tropical areas that can cause opportunistic fruit rots.   
Fusarium solani  has been reported from citrus fruit (Abd -Elsalam et al. 2015). Fusa rium solani is now considered to be a species 
complex ; however , F. solani sensu stricto (as its synonym Nectria haematococca ) has been recorded from citrus plants in New 
Zealand (NZFungi2).   
                                                      
104 Searches of CAB Abstracts, CPC and Google Scholar in June –August 2020 , using the species name and “citrus” as search terms   
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Family 
Pleosporaceae  A number of Alternaria species were considered in more depth at the hazard identification stage but do not meet the criteria for 
additional measures:  
• Alternaria limicola,  the cause of the citrus leaf spot disease mancha foliar de los citros, may produce small lesions on young 
fruitlets, but symptoms disappear as the fruit develops (Timmer et al. 2000; Timmer et al. 2003). Therefore, it is highly unlikely to 
be associated with mature fruit at harvest.  
A number of other Alternaria  species are described from Citrus  but are now considered synony ms of species that are present in 
New Zealand  and have been recorded from citrus  here (e.g.  A. pellucida  is a synonym of A. alternata ; A. scorzonerae  is a synonym 
of A. linicola ).   
Root, butt or wood rot 
fungi (e.g. Agaricales, 
Hymenochaetales, 
Polyporales, many 
Xylariales)  Fungi that are primarily reported as root or wood rots were not assessed further unless there was evidence for an association  with 
fruit. For example, Armillaria  spp., Rosellinia  spp. are root rots , and Pyrrhoderma noxium  (Phellinus noxius ) and Ganoderma spp. are 
wood rots.  
Sooty moulds 
(Families 
Capnodiaceae and 
Chaetothyriaceae)  Capnodium citri  is a sooty mould fungus associated with honeydew -excreting insects such as mealybugs, aphids or soft scales (MAF 
2008). It is not p athogenic to plants, although it can cause production losses by impairing photosynthesis (MAF 2008).  
The following sooty moulds have been reported from citrus but fungal symptoms (and the underlying insect infestations) are vi sually 
detectable in a phytos anitary inspection, and the biosecurity risks associated with these species are managed by basic measure s: 
Antennella citrina, Capnodium citri, Capnodium tanakae, Capnophaeum fuliginoides, Chaetothyrium citri, Chaetothyrium javanicu m, 
Chaetothyrium spinige rum, Hypocapnodium japonicum.  
Yeasts  No yeast species were found that met the criteria for additional measures. Galactomyces citri -aurantii  (synonyms Geotrichum 
candidum, Galactomyces geotrichum, Geotrichum candidum var. citri-aurantii ) is very commonly r eported from citrus (e.g . CABI 
2020a and b; NPPO country pest lists) but is present in New Zealand (NZFungi2 2020) and non -regulated in ONZPR  (2020) . 
Eremothecium coryli  (synonym Nematospora coryli ) does not meet the criteria for additional measures. It is an insect -transmitted 
yeast associated with dry rot in native and cultivated citrus fruits (Shivas et al. 2005). However, there is no evidence that  there is a 
pathway for E. coryli to establish fr om infected citrus fruit . 
Bacteria  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 504 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Bacteria  Xanthomonas citri  (citrus canker) required assessment. No evidence was found during hazard ID for other bacteria that may meet 
the criteria for further assessment; most are not a risk on fruit. Some serious vector -transmitted pathogens can be associated with 
citrus fruit , e.g. Xylella fastidiosa  (Pierce’s disease of grapevine), huanglongbing  (citrus greening) causative agents (‘ Candidatus  
Liberibacter africanum’, ‘ Ca. L. asiaticum’, ‘ Ca. L. americanum’, ‘ Ca. L. carribeanus’), Spiroplasma citri  (citrus stubborn disease) ; 
however , there is no plausible means for them to be transferred to host plants in New Zealand (see vector -transmitted pathogens 
section of this table).  
Oomycetes  
Oomycetes  One oomycete species was identified during scoping as requiring further assessment ( Phytophthora palmivora ). Other species did 
not meet requirements because they were not clearly associated with disease on citrus fruit.  
Seed -transmitted pathogens  
Seed -transmitted 
pathogens  Seed -transmitted pathogens were n ot considered in scoping, as they have n o plausible means of establishing from citrus fruit. Wild 
records of citrus in New Zealand are rare (see section 2.1), indicating that propagation from discarded seeds is highly unlikely.  
Vector -transmitted pathogens  
Vector -transmitted 
pathogens  Vector -transmitted pathogens have n o plausible means of establishment from citrus fruit. For this reason, such significant pathogens 
as Xylella fastidiosa  (Pierce’s disease of gra pevine), citrus greening (huanglongbing) causative agents (‘ Candidatus  Liberibacter 
africanum’, ‘ Ca. L. asiaticum’, ‘ Ca. L. americanum’, ‘ Ca. L. carribeanus’), Spiroplasma citri (citrus stubborn disease) were not 
considered for further assessment. For exam ple, DEFRA (2014) and EFSA (2015) consider  infected fruit  unlikely to represent an 
efficient entry pathway for X. fastidiosa . 
Note that vectors of pathogens have been considered in separate vector analysis PRAs.  
Insects  
Order Coleoptera 
(beetles)  Scoping has not found any evidence that there are Coleoptera that can occur internally in fruit or have other traits that would mean 
they would remain with fruit and be undetected.   
505 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Order Diptera:  
Family Tephritidae 
(fruit flies)  Bactrocera occipitalis  and B. pedestris  have been ruled out as hazards in this import risk analysis , because there is insufficient 
evidence for them being found in the countries in the scope for this IHS. Both of these flies have been identified as being reported on 
citrus in China by the USDA in the pest risk analysis for “Importation of Citrus  spp. (Rutaceae) fruit from China into the continental 
United States” (United States Department of Agriculture 2020). The USDA cites Li et al. (1997) as evidence for the presence o f these 
two species in China ; however, this paper is based on expert opinion and therefore only provides anecdotal evidence, not data. 
Because both B. occipitalis  and B. pedestris  are part of the B. dorsalis  species complex , they are often confused with other  taxa in 
the complex such as B. carambolae , B. papayae , B. melastomatos , B. philippinensis  and B. dorsalis  sensu stricto (Drew and 
Hancock 1994) – the last of which has a confirmed distribution in China (EPPO 2020). It is likely that any reports of B. occi pitalis  and 
B. pedestris  in China are actually reports of B. dorsalis  sensu stricto.  Literature searches in both the English language and Chinese 
language literature support this contention. Hardy (1974) considers the distribution of B. pedestris  to be in the Philippines, Indonesia 
and Malaysia , whereas White and Elson -Harris (1994) consider B. pedestris  to be a very rare fruit fly known from only one locality in 
the Philippines. Although Huang et al. (1984) has been cited as evidence for the presence of B. pedestris  on citrus in China (Liquido 
et al. 2016), the paper refers to Chaetodacus ferrugineus  (a synonym for B. dorsalis ) (EPPO 2020) and makes no reference to 
C. ferrugineus  var. pedestris  (a synonym of B. pedestris ) (EPPO 2020).  Similarly, both EPPO (2020) and Plant Health Australia 
(2018) consider the distribution of B. occipitalis  to be restricted to Borneo and the Philippines. There is a single report of Dacus 
(Bactrocera) occipitalis  in a mango orchard in Hainan province in Ch ina; however, based on the taxonomic issues raised above , this 
is likely to be a misidentification (Liang 1985). A subsequent paper states that Dacus occipitalis  has not been reported in China (Xie 
et al. 1987).  
 
Bactrocera umbrosa  has been ruled out as a hazard in this import risk analysis , because there is insufficient evidence for Citrus  
being a host for the species. White and Elson -Harris (1994) consider B. umbrosa  to be a pest of breadfruit ( Artocarpus altilis ) and 
jackfruit ( A. heterophyllus ) and cite  old host records requiring confirmation for pummelo ( Citrus maximus ) (Perkins 1938) and sour 
orange ( C. aurantium ) (Froggatt 1909). Perkins (1938) gives a secondhand account of Strumeta umbrosa  (a synonym of 
B. umbrosa ) being found on “falling and rotting ” pomelos in Kuala Lumpur in 1921, whereas Froggatt (1909) gives a secondhand 
account of Dacus frenchi  (a synonym of B. umbrosa ) being bred from oranges coming into Victoria from New Caledonia. There are 
no further references in the literature to citrus  being a host for B. umbrosa , and subsequent field surveys have only recorded the 
species from a small number of Artocarpus  species (Tan and Soo -Lam 1982; Allwood et al. 1999; Leblanc et al. 2012).  
 
Bactrocera halfordiae  (Tryon) has been ruled out as a hazard  in this import risk analysis , because the information supporting citrus 
as a host is weak for this species. This species, however, is currently regulated on grapefruit, lemon, lime, mandarin, orang e, 
tangelo, tangerine from Australia. White and Elson -Harris (1994) state that records from grapefruit ( Citrus  paradisi ), mandarin 
(C. reticulata ), and sweet orange ( C. sinensis ) were probably based on misidentifications of B. tryoni . They considered citrus to be a 
doubtful host and only included the records to indicate previously published records that should be dismissed as being in err or. 
Vargas et al. (2015) list B. halfordiae  as a Category C pest [relatively minor oligophagous or  specialist fruit or cucurbit pests] noting 
that it is oligophagous. Hancock et al. (2000) listed C. paradisi  (grapefruit) and C. reticulata  (mandarin) as host species, citing May 
(1953). Royer (2015) states that B. halfordiae  was recently considered a pos sible market access pest due to old host records from 
citrus (May 1953, in Hancock et al. 2000). The author goes on to say that since then, the only host records have been in rain forest 
fruit, citing Hancock et al. (2000). Royer (2015) states that the pref erred host is Planchonella australis  (Sapotaceae) , which is Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 506 common in rainforest s in southeast Queensland. Bactrocera halfordiae  is considered a fruit fly of economic concern in Australia , and 
Sultana (2020) lists citrus as a host for the species  (citing H ancock et al. 2000) and indicates that citrus is a major commercial 
species. Distribution: Australia (Hancock et al. 2000, White and Elson -Harris 1994).  
 
Bactrocera musae  (Tryon) has been ruled out as a hazard in this import risk analysis , because there is  insufficient evidence citrus is 
a host for this species. Hancock et al. (2000) note that Musa banksii  (native banana) is a major host for B. musae . These authors list 
Citrus paradisi  (grapefruit) and C. reticulata  (mandarin) as host species, citing the QDPI ESEQld Papaya fruit fly database . However, 
Hancock et al. (2000) state that there is only one record for C. paradisi  as a host, and one record from ripe fruit for C. reticulata  as a 
host. They also state that care should be taken for records from large databases, such as that for the QDPI ESEQld Papaya fruit fly 
database, because these contain a variety of suspected errors. They further note that many of those in unusual hosts, based o n a 
single or few specimens (which they note in comments in the host l ists), are particularly doubtful and at least some may represent 
contamination of samples. This implies some doubt by these authors for the records of B. musae  from C. paradisi  and C. reticulata . 
Citrus  spp. are not listed as hosts for B. musae  in White an d Elson -Harris (1994). There were no records of B. musae  from Citrus  in 
the survey carried out in the Pacific by Leblanc et al. (2012). Plant Health Australia (2018) describe the host range as: “Po lyphagous. 
Recorded on 16 hosts from nine families, althoug h these are mostly single records or specimens that may be dubious. Confirmed 
families are Musaceae, Caricaceae and Myrtaceae. Primary economic host is banana, but papaya and guava are occasional hosts.”  
 
Dirioxa pornia  (Walker) (Island fruit fly) has been  ruled out as a hazard in th is import risk analysis , because it is attracted to overripe 
or damaged fruit of Citrus , and Citrus  can be considered a conditional host. Such fruit would not meet the commodity description for 
this import risk analysis. White and Elson -Harris (1994) state that D. pornia  is frequently reared from cultivated fruits, but it is not a 
pest, as it usually only attacks damaged fruit, preferring fruit that has been thorn -pricked, fallen or damaged by another fruit fly or 
codling moth. The authors note that it has been recorded from lemon ( Citrus limon ), mandarin orange ( C. reticulata ), orange ( Citrus  
sp.), citing Gurney (1912).  Hancock et al. (2000) list many Citrus  spp. as hosts for D. pornia  and comment for each Citrus  species 
that D. pornia  is associated with ripe or damaged fruit.  Plant Heath Australia (2011) states that D. pornia  attacks ripe, damaged and 
fallen fruit. It has been recorded on hosts from a wide range of families, including Rutaceae.  Hancock (2015) states: “Larv ae of 
Dirioxa pornia  (Walker) attack a wide range of overripe or damaged fruit and even fallen Araucaria cones (Permkam and Hancock 
1995 ; Hancock et al. 2000).”  Plant Health Australia (2018) states that D. pornia  is polyphagous but on overripe, damaged or fallen 
fruit. They describe the host range as: “Recorded on 83 hosts in 27 families including Anacardiaceae, Annonaceae, Caricaceae,  
Curcurbitaceae, Lauraceae, Lecythidaceae, Moraceae, Musaceae, Myrtaceae, Oxalidaceae, Passifloraceae, Rosaceae, Rubiaceae, 
Rutaceae, Sapotaceae and Solanaceae. Commercial hosts include mango, papaya, carambola, peach, pear, citrus, capsicum and 
eggplant.”  
 
Zeugodacus cucumis  (French) (cucumber fruit fly)  (syn Bactrocera cucumis ) has been ruled out as a hazard in this import ri sk 
assessment , because there is insufficient evidence that Citrus  is a host,  though  it is possible that Citrus  fruit that is damaged could 
be a conditional host. Such fruit would not meet the commodity description for this import risk analysis.  White and Elson -Harris 
(1994) note that this species is a serious pest of cucurbits, tomato and papaya and do not list any Citrus  (or other Rutaceae) as 
hosts. These authors also state that under laboratory conditions, B. cucumis  will not readily accept fr uit outside its normal host range 
when deprived of preferred hosts, citing Fitt (1986).  Hancock et al. (2000) list Citrus limon  (lemon), C. paradisi  (grapefruit),  
507 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
C. reticulata  (mandarin) and C. sinensis  (orange) as host species, citing the QDPI ESEQld Pap aya fruit fly database. However, 
Hancock et al. (2000) comment that there is only one record for each of these Citrus  species as hosts for B. cucumis  [Z. cucumis ]. 
They also state that care should be taken for records from large databases, such as that for  the QDPI ESEQld Papaya fruit fly 
database, because these contain a variety of suspected errors. They further note that many of those in unusual hosts, based o n a 
single or few specimens (which they note in comments in the host lists), are particularly dou btful, and at least some may represent 
contamination of samples. This implies some doubt by these authors for the records of Z. cucumis  from C. limon , C. paradisi , 
C. reticulata  and C. sinensis . Plant Health Australia (2018) describe the host range as: “Po lyphagous. Recorded from 40 hosts in 15 
families including the families Caricaceae, Curcurbitaceae, Myrtaceae, Passifloraceae, and Solanaceae, although many recorded  
hosts are single records and may require confirmation. Major commercial hosts include papa ya, cucumber, pumpkin, squash, 
zucchini, guada bean, passionfruit and tomato.”  CABI (2020 c) states that most major hosts of B. cucumis  [Z. cucumis ] are cucurbits; 
however, tomato can suffer heavy attack, and pawpaw moderate attack, and there are isolated records from several other fruit crops. 
CABI (2020 c) goes on to say: “Hancock et al. (2000) presented a comprehensive list and only those marked as moderate or major 
hosts in that list are included here. The rare or incidental hosts (usually a single reari ng) include mango, avocado, guava, carambola, 
apricot, some species of Citrus , and capsicum. It is likely that most of these records could be attributed to fruit damage prior to 
oviposition.”  
Order Diptera:  
Drosophila suzukii   
(SWD)  There are host records  for Drosophila suzukii  (SWD ) from some Citrus  species in the scientific literature and in extension reports. 
Where clearly specified, these records are in association with overripe or damaged fruit, e.g.  
• Wang et al. (2016) state SWD can complete development on ‘suboptimal’ hosts such as orange when these hosts are damaged, 
rotted, or overripe;  
• Haviland et al. (2016) found that SWD was not able to reproduce on intact or rotting  citrus fruit , but was able to reproduce on 
sound, split fruit. These au thors concluded that commercially harvested citrus fruit should not be considered a host of SWD, 
although it is clear that damaged fruit in an orchard can serve as reproductive host s for SWD throughout the winter.  
• In California, Wang et al. (2019) reported  that SWD adults emerged in very low numbers from field collected mandarins and 
oranges, but only from damaged fruit, not from intact fruit. They showed in laboratory tests that SWD was only able to ovipos it 
into rotting or cut navel oranges.  
 
No evidence has been found to show that the fly can infest sound, undamaged citrus fruit.  Therefore , fruit complying with the 
commodity description in this IRA (fruit must have an intact skin, free from defects such as splits and cuts) is not considered to be a 
host f or SWD . 
Order Hemiptera: 
Family Aleyrodidae 
(whiteflies)  The whitefly group, including Aleurocanthus woglumi  (citrus blackfly) , Aleurodicus dispersus  (spiralling whitefly) , Aleurocanthus 
spiniferus  (citrus spiny whitefly) and Dialeurodes citri  (citrus whitefly), does not m eet the criteria for further assessment , because no 
evidence was found that the pests are directly associated with the fruit of citrus.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 508 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
Order Hemiptera: 
Family Aphididae 
(aphids)  Aphids that are present in New Zealand but have the potential to vector viruses and are associated with citrus fruit are assessed in a 
separate vector analysis PRA.  
Other species were excluded from further assessment due to at least one of the following reasons: 1) no evidence suggests the  pest 
is associated with citrus fruits; 2) the pest is not known to be present in any citrus -exporting countries in the citrus fresh produce IHS; 
3) impact is limited to hosts that are not important to New Zealand; 4) establishment in New Zealand is unlikely.  
Orde r Hemiptera: 
Family Cicadellidae 
(leafhoppers)  No evidence was found of a strong association between leafhoppers and fruit of citrus. Adults and nymphs feed externally, mai nly on 
sap from either leaves, stem or twigs; they  are not expected to feed on mature fruit. A dult females lay eggs in/on leaves, not fruit.  
Leafhoppers, as their name implies, are very mobile; quickly hopping off leaves when disturbed. This means that even if they were 
present on fruit, they are highly l ikely to jump off or be dislodged during harvesting and post -harvest processing prior to packing of 
the fruit.  
This group includes known vectors for Spiroplasma citri  and Xylella fastidiosa .  
Order Hemiptera: 
Family 
Pseudococcidae 
(mealybugs)  Three mealyb ug species were identified during scoping as requiring further assessment ( Nipaecoccus viridis, Planococcus 
kraunhiae, Pl. minor ). Other species were excluded from further assessment due to at least one of the following reasons: 1) no 
evidence suggests the  pest is associated with citrus fruits; 2) the pest is not known to be present in any citrus -exporting countries in 
the citrus fresh produce IHS; 3) there is little information on the pest; 4) there is  little information on  the impact of the pest.  
Note tha t mealybugs that are potential vectors, e.g. Pseudococcus calceolariae, Ps. viburni , Ps. longispinus , will be assessed in a 
separate vector analysis PRA.  
Order Hemiptera: 
Family Psyllidae 
(psyllids)  Psyllids, in general, do not met the criteria for further assessment , because the pests have a weak association with citrus fruit as 
hitchhikers. Two psyllid species were identified during scoping as requiring further assessment ( Diaphorina citri , Trioza erytreae ), 
because of their attraction to citrus an d close relatives in the Rutaceae and their status as vectors  of the  liberibacters that cause the 
significant citrus disease huanglongbing.   
509 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Order Lepidoptera 
(moths, butterflies)  Four species that can attack healthy fruit and occur internally in the fruit were identified during scoping as requiring further 
assessment based on their biology  (Marmara gulosa, Spodoptera littoralis, Thaumatotibia leucotreta and Gymnandrosoma 
aurantianum ). Thaumatotibia leucotreta  was excluded , as it is not present in any of the countries under consideration for this IRA.  
 
Amyelois  transitella  (navel orangeworm)  was excluded , as it is reported as usually infesting already damaged citrus fruit, which 
would not meet the com modity description that is part of basic measures.  
 
Ostrina furnacalis  (Asian corn borer) is unlikely to be associated with commercially produced citrus fruit:  
• Larvae mainly infest maize and sweetcorn (CABI 2019a); infestation of citrus only occurs if maize grows near citrus groves . 
• Larvae bore into citrus fruit; infestations on young citrus fruit can lead to early drop (Cai and Peng 2008) . 
 
Cryptoblabes gnidiella  (lemon borer moth) is unlikely to be present on citrus fruit that meets the commodity desc ription and to which 
minimum measures are applied:  
• In its early stages, it feeds on honeydew excreted on the fruit surface by aphids or mealybugs, and in later stages burrows 
into the fruit using holes previously made by birds or other borers.  
• Fruit that become infested are typically smaller in size (Moore, 2003), and damage by larvae feeding internally causes the 
fruit to yellow prematurely and may cause them to drop (Silva and Mexia 1999).  
• It is a secondary pest of citrus fruit (Silva and Mexia 1999).  
 
Carposina sasakii  / C. niponensis  are unlikely to be associated with citrus fruit meeting basic measures (following information from 
CABI 2019b; EFSA 2018):  
• The pest is not reported from citrus and is mainly a pest of Rosaceae (pears, apples, peaches).  
• The USA PRA decided to associate it with citrus , because C. niponensis , whose identity has been confused with C. sasakii , 
has been associated with citrus in China.  
• On the pest’s identity, EFSA 2018 notes that C. niponensis , a valid species of no economic sign ificance, was previously 
mistakenly synonymised with C. sasakii  and was regulated in Annex IIAI of 2000/29 EC.  
• A taxonomic review by Diakonoff in 1989 concluded that C. niponensis  and C. sasakii  were distinct and valid species; 
C. niponensis  is of no econo mic importance , whereas C. sasakii  is known as a major pest of rosaceous fruits in eastern 
Asia.  
• International trade of rosaceous fruits is a possible cause of spread of C. sasakii , but it is difficult for it to enter non -native 
countries under quarantine inspection.  
o Several eggs may be laid on each fruit, usually near the calyx, and many larvae may tunnel a single fruit (up to 13 
have been recorded), which would make penetration holes visible on fresh fruit.  
o Even if C. sasakii  enters non -native countries by international trade, it is not easy to establish a population, probably 
because the larvae in fruits cannot find a cocooning site near rosaceous plants after escaping from the fruits .  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 510 Pest taxon  Rationale for excluded taxa, examples of excluded taxa  
• The distribution of C. sasakii  is limit ed to the temperate Far East, centred on northeastern China and Japan. It is not known 
to have spread to other areas.  
Prays citri  (citrus flower moth). External feeder on flowers, leaves, buds. Eggs are laid individually on the flowers, and sometimes on 
young fruit. On hatching the larvae bore flowers and small fruits, however, larvae are likely to have emerged from infested young fruit 
by the time fruit is mature . Cocoons may be found on fruits, flowers and leaves (CABI 2019c). From EFSA (2008b): eggs are 
occasionally also laid on larger fruits, but it is reported that in lemon, larval development from such eggs is not successfu l. Larvae 
very rarely infest more developed fruits. Pupal cocoons may be found externally on fruits but can easily be dete cted by the naked 
eye. Eggs or late developmental stages (like fully grown larvae or pupae) of P. citri  that could be present on the outside of the fruit 
are unlikely to survive routine packinghouse procedures (washing, waxing, grading).  
 
Other Lepidoptera  identified as potentially feeding on citrus typically feed on plant parts other than fruit and are unlikely to be 
associated with fruit in trade, e.g. Eudocima fullonia  (fruit-piercing moth – adult only feeds on fruit), Gymnoscelis rufifasciata  (double -
striped pug), Platynota stultana  (omnivorous leafroller), Spodoptera eridania  (southern armyworm), Stathmopoda auriferella , 
Trichoplusia ni  (cabbage looper), Xestia c -nigrum  (spotted cutworm).   
Order Thysanoptera 
(thrips)  Four thrips were identified as requ iring further assessment ( Caliothrips fasciatus, Chaetanaphothrips orchidii, Scirtothrips dorsalis, 
Thrips palmi ). Of the few other thrips that were reported to be associated with fruit, such as Thrips hawaiiensis  and Scirtothrips citri , 
the association wa s with very young fruit or the flower ovary and therefore did not meet the criteria for further assessment.  
 
Note that thrips that are potential vectors, e.g. Thrips tabaci , Frankliniella intonsa  and F. occidentalis , were assessed in a separate 
vector anal ysis PRA.  
Mites  
Subclass Acari 
(mites):  
(Families 
Eriophyidae, 
Tenuipalpidae, 
Tetranychidae)  Three  mites were identified as requiring further assessment ( Auculops pelekassi, Eotetranychus lewisi, Tetranychus kanzawai ). Of 
the few other mites that were reported to be associated with citrus fruit, such as Eotetranychus kankitus , the association was either 
with very young fruit or caused premature fruit drop and therefore did not meet the criteria for further assessment.  
Note that mites that are potential vectors, e.g. Brevipalpus phoenicus  and other Brevipalpus  spp., w ere assessed in a separate 
vector analysis PRA.  
  
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517 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Appendix 2: Glossary  and Ab breviations  
 
Term or a bbreviation  Definiton  
BRAD  Biosecurity Risk Analysis Database . MPI internal  database  that records 
the historic  regulatory status and other information about plant pests.  
CASE  Contention Argument Source Evidence. Under the CASE schema, the 
contention or conclusion is presented first, followed by the arguments 
supporting this contention and the evidence and sources supporting 
each argument.  
CMI Climate (or composite) match index , a value that indicates the 
similarities between a location overseas and New Zealand (Phillips et al. 
2018).  
Commercial  
production  Definition for the purposes of risk assessment: a  process/system where 
activities, such as in -field monitoring, in -field pest control activities, 
harvesting, cleaning, sorting and grading have been undertaken to 
produce a commodity that is free of defects such as broken skin, rot and 
damage. Depending on  the systems in place, these activities can be 
undertaken at any stage from the point of planting to the point of export.  
commodity 
description  A description of a commodity that includes all relevant aspects of its 
production or manufacture, storage, tran sport and processing or 
treatment that is not mandated through measures (and as such does 
not require a risk assessment).  
conditional non -host  A commodity  at a specified physical condition that cannot support the 
complete development of a particular pest or disease . 
CPC  Crop Protection Compendium . A CABI database  that provides 
information about crop pests.  
disease  A finite abnormality of structure or function with an identifiable 
pathological or clinicopathological basis, and with a recognizable 
syndrome  of clinical signs. Its cause may not be known or may be from 
infection with a known organism (Blood & Studdert 1990).  
endemic  An animal, plant, pest, or disease that is native to and is not naturally 
found outside a defined geographical area.  
establishment  Perpetuation, for the foreseeable future, of an organism or disease 
within an area after entry  (ISPM 5 20 21). 
ERS Emerging Risk System , an MPI workflow  system that  allows MPI to  
receive,  process and store information about new biosecurity risks and 
to manage those risks  in a timely fashion.  
exposure  The transfer of a pest or disease from an imported commodity or 
inanimate object, to a host or environment suitable for the completion of 
development or production of offspring.  
exotic  This word has different meanings in different fields, but in this 
document , it is defined as an animal, plant, pest or disease that is not 
indigenous to New  Zealand.  
hazard  Any pest or disease that is associat ed with a commodity or import 
pathway and has the potential to produce adverse consequences within 
a risk analysis area.  
indigenous  Native; organism originating or occurring naturally in a specified area.  
inspection  Official visual examination of plants,  plant products or other regulated 
articles to determine if pests are present and/or to determine 
compliance with phytosanitary regulations ( ISPM 5 20 21). 
introduced  Not indigenous, not native to the area in which it now occurs, having 
been brought into this area directly or indirectly by human activity.  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 518 Term or a bbreviation  Definiton  
IPPC  International Plant Protection Convention, a 1951 multilateral treaty 
overseen by the Food and Agriculture Organization that aims to secure 
coordinated, effective action to prevent and to control th e introduction 
and spread of pests of plants and plant products.  
ISPM  International Standards for Phytosanitary Measures , international 
standard s adopted by the Conference of the Food and Agriculture 
Organization, the Interim Commission on phytosanitary m easures or the 
Commission on phytosanitary measures, established under the IP PC. 
IHS Import Health Standard  (See “Import Health Standard” for a definition .) 
Import Health 
Standard  An import health standard (IHS) is a document issued under section 
24A of the Biosecurity Act 1993. It states the requirements that must be 
met before risk goods can be imported into New Zealand.  
IRA Import Risk Analysis, an administrative process through which 
quarantine policy is developed or reviewed, incorporating risk 
asse ssment, risk management and risk communication.  
MPI Ministry for Primary Industries, New  Zealand  
non-host  A commodity that will not support the complete development of a 
particular pest or disease . 
NPPO  National Plant Protection Organisation, official service established by a 
government to discharge the functions specified by the IPPC  (ISPM 5 
2021) . 
NZOR  New Zealand  Organisms Register , an actively maintained compilation of 
all organism names relevant to New Zealand: indigenous, endemic or 
exotic species or species not present in New Zealand but of national 
interest . 
ONZPR  Official New Zealand Pest Register. MPI database  that records 
organisms that  may be associated with plants or plant products that are 
imported into New Zealand.  Plant and plant product importers can use 
ONZPR  to find out the regulatory  status of a pest or disease  – regulated 
or non -regulated.  
pest Any species, strain or biotype of plant, animal, or pathogenic agent 
injurious to plants or plant products  (ISPM 5 20 21) 
pest-free a rea An area in which a specific pest is absent as demonstrated by scientific 
evidence and in which, where appropriate, this condition is being 
officially maintained  (ISPM 5 20 21). 
pest-free place of 
production  Place of production in which a specific pest is absent as demonstrated 
by scientific evidence and in which, where appropriate, this condition is 
being officially maintained for a defined period (ISPM 5 2021).  
PFA Pest-free area (See “Pest -free area” for a  definition .) 
PFPP  Pest-free place of production  (See “Pest -free place of production ” for a 
definition .) 
PPIN  Plant Pest Information Network database (MPI) , a record of organisms 
collected in New Zealand and identified by MPI’s Plant Health and 
Environment Laboratory.  
PRA  Pest Risk Assessment or Pest Risk Analysis  
QuanCargo  New Zealand border transaction database, detailing commercial 
consignments and interceptions of pests made by quarantine inspection 
(MPI).  
quarantine pest  A pest of potenti al economic importance to the area endangered 
thereby and not yet present there, or present but not widely distributed 
and being officially controlled  (ISPM 5 20 21).  
519 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Term or a bbreviation  Definiton  
risk management  
question/s  Specific question/s which the risk manager needs answered in o rder to 
make a decision . 
systems approach  A pest risk management option that integrates different measures, at 
least two of which act independently, with cumulative effect (ISPM 5 
2021) . 
vector  An organism or object that transfers a pest, parasite, pathogen or 
disease from one area or host to another.  
 
  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 520 Appendix 3: Risk Status of Armoured Scale Insects  
To facilitate the management of pests and diseases associated with an imported commodity, an IHS 
can include a list of pests or diseases that are a risk on the pathway e.g., if they were associated with 
the pathway they have a likelihood of entry and a level of impact that when combined equate to an 
unacceptable level of risk.  
ISPM 19 (2003) provides guidelines on creating lists of regulated pests and  diseases. The standard 
covers generic lists of regulated pests and specific lists of regulated pests and diseases by commodity 
which equates to the pest list include in an IHS. The standard notes that the IPPC requires technical 
justification for all regu lated pests through pest risk analysis.  
The standard states that “ A specific list of regulated pests, which should be a subset of those lists, 
may be provided by the importing contracting party to the exporting contracting party as the means 
to make known to the exporting contracting party those pests for which inspection, testing or other 
specific procedures are required for particular imported commodities, including phytosanitary 
certification. ” 
MPI (2014) assessed the risk of diaspidids on the fresh prod uce pathway and concluded that exotic 
diaspidid species are unlikely to be successfully introduced into New Zealand. The highest overall risk 
identified was “moderate” (for Pseudaulacaspis pentagona ) on favoured hosts, e.g. , kiwifruit. 
Measures may be just ified if the risk estimate  (as determined by the risk assessment ) is very low or 
greater (MPI Risk Analysis Guidelines 2021).  
Some factors are recognised as increasing the risk associated with this pathway (see below). 
Polyphagous species and species that  reproduce parthenogenetically (asexually) are considered to 
present a higher risk, as are host commodities that are architecturally complex and/or particularly 
robust or have high amounts of unavoidable waste associated with them (MPI 2014).  
Although Cit rus fruit is relatively robust, it is also structurally simple. In general, aggregations of 
diaspidids or infestations by adult females, which present the highest risk, are considered likely to be 
visible during harvesting, processing and on inspection105. In addition, while there is unavoidable 
waste (peel) associated with Citrus commodities, this waste is unlikely to remain suitable for the 
development of the scale insect once discarded (MPI 2014).  
Summary of Advice  
The d iaspidid scale insects associated wi th Citrus  species treated by Garcia Morales et al. (2016)  are 
listed in Tables 2 –7. This list is reasonably comprehensive but not exhaustive. It is expected to cover 
the spectrum of risk that species in this family pose to New Zealand on this pathway.  
Records of scale species present in all e xporting countries are tabulated for each Citrus  species.  
The following risk factors are assessed106: 
• Commodity association: presence on the fresh produce pathway, in particular the Citrus  
fresh produce pathway. MPI databases, DAWE (2021), EPPO interception records and 
selected publications were searched.  
• Mode of reproduction: diaspidids that are capable of unisexual or parthenogenetic 
reproduction are likely to represent a higher risk than sexually reproducing specie s. 
                                                      
105 However low levels of infestation, particularly by cryptically coloured species, may not be detected (Table 8).  
106 Information from limited sources (see reference list) in order to meet the required timeframe.   
521 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Information on mode of reproduction was sourced from Garcia Morales et al. (2016), 
Watson (2002) and selected publications.  
• Host range: polyphagous species are considered to represent a higher risk than oligophages 
or monophages (MPI 2014). Information on host range was sourced from Garcia Morales et 
al. (2016), Watson (2002) and selected publications.  
• Economic impacts: a very brief precis of information on impacts on plant species of 
importance to New Zealand is summarised from Garcia Morales et al. (20 16) and/or Watson 
(2002). No other sources have been consulted due to time constraints. This information 
should be interpreted in the context of the discussion of economic impacts of diaspidids in 
MPI (2014). Where no impacts are reported in either of thes e databases it could suggest that 
the species in question is not likely to be an important pest species, though this is an 
unsupported assumption.  
• Environmental impacts: while some exotic diaspidids have been reported on native plants in 
New Zealand, there  have been no reports of impacts in native systems here. Unlike 
pseudococcids, diaspidids do not secrete honeydew nor are they know to vector plant 
diseases (MPI 2014 and references within).  
• As a group, diaspidids are likely to present a similar but sligh tly lower likelihood of 
establishing via the fresh produce pathway than pseudococcids (mealybugs). Diaspidids are 
unable to move once the crawler stage is settled, whereas all pseudococcid lifestages have 
some ability to move. Their greater mobility is lik ely to result in a slightly increased 
likelihood of exposure for pseudococcids, especially when they are associated with host 
material (discarded harvested fruit or fruit waste) that is no longer in optimal condition. In 
addition, many mealybugs feed on ro ots of plants as well as above ground plant parts, 
whereas this is not common in diaspidids. Plant roots could be easily accessible near 
disposed waste.  
Supporting Information  
The scope of this assessment is limited to searches of the database “ScaleNet” ( Garcia Morales et al. 
2016) for the Citrus  commodities assessed in MPI (2021) (Table 1).  Note that there are no results for 
Citrus reticulata × Citrus paradisi (“Tangelo”) or Citrus reticulata × Citrus sinensis  (“Tangor”). It is expected 
that range of dias pidids assessed for other Citrus  species  will be representative for these hosts.  
Commodity associations were obtained from Watson (2002), ScaleNet (2016), Garcia Morales et al. 
2016, CPC (2021), MPI interceptions databases, EPPO GPD (2021) and DAWE (2021).  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 522 Commodity/Country Table  
Table 1: Citrus aurantiifolia  
Citrus 
aurantiifolia  ONZPR 
status  Exporting countries in 
which scale is reported  
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Aonidiella 
comperei  Regulated  Brazil, China, Japan, Vietnam  infests leaves, twigs, and 
larger branches (Garcia 
Morales et al. 2016), but 
detected on non -citrus FP 
(LIMS)  polyphagous; 12 host 
genera known (Garcia 
Morales et al. 2016)  male  has not been identified 
(Garcia Morales et al. 
2016); may reproduce 
parthenogenetically  reported as a pest of 
papaya in Brazil and 
the Pacific (Martins et 
al. 2004)  Very low  
Aspidiotus 
excisus  Regulated  China, Fiji, Japan, Mexico, 
USA, Vietnam  detected on citrus FP (LIMS)  30 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 a pest of ornamental 
plants (García Morales 
et al. 2016)  Very low  
Chrysomphalus 
aonidum  Regulated  Australia,  Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, Spain, 
USA, Vietnam, South Korea, 
Western Samoa  detected on citrus FP (LIMS); 
infests leaves and fruit 
(Garcia Morales et al. 2016)  very polyphagous; 181 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually (Garcia 
Morales et al. 2016)  a serious citrus pest in 
a number of countries; 
a minor avocado pest 
(Watson 2002)  Very low  
Chrysomphalus 
dictyospermi  Regulated  Australia , Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico,  New Caledonia, 
Peru, Solomon Islands, 
Spain, United States, Viet 
Nam, South Korea, Western 
Samoa  detected on citrus FP (LIMS)  very polyphagous; 196 
host genera known 
(Garcia Morales et al. 
2016)  unisexual and bisexual 
populations have been 
reported (Garci a Morales et 
al. 2016)  a serious pest of 
avocado and citrus; 
capable of infesting a 
range of commercial 
crops (MPI 2014)  Low 
Howardia 
biclavis  Regulated  Australia , Brazil, China, Cook 
Islands, Fiji, Japan, Mexico, 
New Caledonia, Peru, Spain, 
United States, Vanuatu, 
Western Samoa  detected on non -citrus FP 
(LIMS)  195 host genera known 
(Garcia Morales et al. 
2016)  reproduces 
parthenogenetically (Garcia 
Morales et al. 2016)  a pest of citrus, 
ornamentals, tea and 
coffee (García Morales 
et al. 2016)  Low 
Lepidosaphes 
conchiformis  Regulated  China, Egypt, Japan, Spain, 
USA, North Korea, South 
Korea  infests fruit (Garcia Morales et 
al. 2016)  38 host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually (Garcia 
Morales et al. 2016)  a fig pest (García 
Morales et al. 2016)  Very low   
523 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Citrus 
aurantiifolia  ONZPR 
status  Exporting countries in 
which scale is reported  
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Lepidosaphes 
gloverii  Regulated  Australia , Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Solomon Islands, Spain, 
United States, Viet Nam, 
South Korea, Western Samoa  detected on citrus FP (LIMS)  polyphagous (Watson 
2002); 40 host genera 
known (Garcia Morales 
et al. 2016)  reproduces sexually 
(Watson 2002)  serious pest of Florida 
citrus (García Morales 
et al. 2016); often 
under effective 
biological control 
(Watson 2002)  Very low  
Lopholeucaspis 
cockerelli  Regulated  Australia, Brazil, Cook 
Islands, Fiji, Japan, Mexico, 
Peru, USA, Vanuatu, Western 
Samoa  infests leaves (Watson 2002) ; 
not associated with citrus fruit 
(GG)  polyphagous (Watson 
2002); 68 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 minor pest in the 
Pacific (Watson 2002)  Negligible  
Opuntiaspis 
carinata  Regulated  Mexico, Peru, USA  no information  Two host genera known 
(Garcia Morales et al. 
2016)  males known (Hamon  1978) 
so reproduction is probably 
sexual1 no information  Very low  
Parlatoria 
cinerea  Regulated  Brazil, China, Cook Islands, 
Japan, Mexico, New 
Caledonia, Spain, United 
States, Vanuatu, Viet Nam, 
Western Samoa  detected on citrus FP (LIMS); 
mainly on stems and 
branches, but sometimes on 
leaves and fruit (Watson 
2002)  polyphagous (Watson 
2002); 14 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 citrus pest in the 
Pacific (Watson  2002)  Very low  
Parlatoria ziziphi  Regulated  Australia, Brazil, China, 
Egypt, Japan, Peru, Spain, 
USA, Vietnam  detected on citrus FP (LIMS)  16 host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  important citrus pest in 
some regions (Watson 
2002)  Very low  
Pinnaspis 
strachani  Regulated  Australia, Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Peru, Solomon Islands, USA, 
Vanuatu, Viet Nam, South 
Korea, Western Samoa  detected on non-citrus  FP 
(LIMS)  highly polyphagous 
(Watson 2002); 247 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  important occasional 
pest of several 
economic crops 
including citrus, 
avocado, olive and 
asparagus (Watson 
2002)  Very low  
Pseudaonidia 
trilobitiformis  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, New 
Caledonia, Peru, USA, 
Vanuatu, Vietnam  detected on citrus FP (LIMS)  highly polyphagous 
(Watson 2002); 111 
host genera known 
(Garcia Morales et al. 
2016)  males unknown (Garcia 
Moral es et al. 2016) so may 
reproduce 
parthenogenetically  important pest of 
cashew, citrus and 
cacao (Watson 2002)  Very low  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 524 Citrus 
aurantiifolia  ONZPR 
status  Exporting countries in 
which scale is reported  
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Pseudischnaspis 
acephala  Regulated  Mexico, Peru  undersides of  leaves (Garcia 
Morales et al. 2016) ; “not 
associated with citrus fruit” 
(Grousset et al. 2016)  11 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 potential pest of 
avocado in Colombia 
(Kondo et al. 2016)  Negligible  
Selenaspidus 
articulatus  Regulated  Australia, Brazil, China, Fiji, 
Japan, Mexico, Peru, 
Solomon Islands, USA, 
Vietnam  detected on citrus FP (LIMS); 
on leaves, sometimes on fruit 
(Watson 2002)  highly polyphagous 
(Watson 2002); 105 
host genera known  males known (Garcia 
Morales et al. 2016) so  
reproduction is probably 
sexual1 important pest of 
citrus  and coffee 
(Watson 2002)  Very low  
Unaspis citri  Regulated  Australia, Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Peru, Solomon Islands, 
Spain, USA, Vanuatu, Viet 
Nam, American Samoa, 
Western Samoa  detected on citrus FP (LIMS); 
usually on the trunk and main 
limbs, but occasionally on 
leaves and fruits (Watson 
2002)  fairly polyphagous 
(Watson 2002); 18 host 
genera known  reproduces sexually 
(Watson 2002)  one of the princip al 
pests of citrus spp. in 
many regions of the 
world (Watson 2002)  Very low  
1Does not exclude the possibility of uniparental populations  
 
Table 2: Citrus latifolia  
Citrus latifolia 
(1) ONZPR  
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Pseudaonidia 
trilobitiformis  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, New 
Caledonia, Peru, USA, 
Vanuatu, Vietnam  detected on citrus  FP (LIMS)  highly polyphagous 
(Watson 2002); 111 
host genera known 
(Garcia Morales et al. 
2016)  males unknown (Garcia 
Morales et al. 2016) so may 
reproduce 
parthenogenetically  important pest of 
cashew, citrus and 
cacao (Watson 2002)  Low 
  
525 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   Table 3: Citrus limon  
Citrus limon 
(25) ONZPR  
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Acutaspis 
scutiformis  Regulated  Brazil, Mexico, USA  no evidence found of 
association with fruit; infests 
leaves (Garcia Morales et al. 
2016) ; “not associated with 
citrus fruit” (Grousset et al. 
2016)  10 host genera known 
(Garcia Morales et al. 
2016)  no males have been 
observed (Garcia Morales 
et al. 2016), so may 
reproduce 
parthenogenetically  a citrus and banana 
pest in Central and 
South America 
(García Morales et al. 
2016)  Negligible  
Aonidiella citrina  Regulated  Australia, China, Egypt, Fiji, 
Japan, Mexico, USA, 
Vietnam, South Korea, 
Western Samoa  detecte d on citrus FP (LIMS); 
infests mainly leaves and fruit 
(Garcia Morales et al. 2016)  polyphagous (Garcia 
Morales et al. 2016); 43 
host genera known  reproduces sexually (Garcia 
Morales et al. 2016)  a pest of citrus in 
some regions 
(Watson 2002)  Very low  
Aonidiella 
orientalis  Regulated  Australia, Brazil, China, 
Mexico, Peru, USA, Vietnam  detected on non -citrus FP 
(LIMS)  highly polyphagous; 
163 host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually (Garcia 
Morales et al. 2016)  a serious pest on 
some tropical crops, 
also reported as a 
pest of citrus and 
ornamentals (Watson 
2002)  Very low  
Aulacaspis citri  No entry  China  detected on citrus at Korean 
border, pathway not specified 
(Suh 2016)  5 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 important citrus pest 
in Sichuan (Lin et al. 
1997)  Low  
Chrysomphalus 
aonidum  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, Spain, 
USA, Vietnam, South Korea, 
Western Samoa  detected on citrus FP (LIMS); 
infests leaves and fruit 
(Garcia Morales et al. 2016)  very polyphagous; 181 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually (Garcia 
Morales et al. 2016)  a serious citrus pest 
in a number of 
countries; a minor 
avocado pest 
(Watson 2002)  Very low  
Chrysomphalus 
dictyospermi  Regulated  Australia , Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Peru, Solomon Islands, 
Spain, USA, Vietnam, South 
Korea, Western Samoa  detected on citrus FP (LIMS)  very polyphagous; 196 
host genera known 
(Garcia Morales et al. 
2016)  unisexual and bisexual 
populations have been 
reported (Garcia Morales et 
al. 2016)  a serious pest of 
avocado and citrus; 
capable of infesting a 
range of comm ercial 
crops (MPI 2014)  Low Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 526 Citrus limon 
(25) ONZPR  
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Clavaspidiotus 
apicalis  No entry  Egypt  forms dense colonies on 
citrus fruit (Garcia Morales et 
al. 2016)  3 host genera known 
(Garcia Morales et al. 
2016)  no information  a potential citrus pest 
(García Morales et al. 
2016)  Very low 
Diaspidiotus 
degeneratus  No entry  China, Japan, USA, North 
Korea, South Korea  infests leaves (Garcia 
Morales et al. 2016 , DAWE 
2020 ) 11 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably  
sexual1 once a common 
nursery pest, now 
rare (García Morales 
et al. 2016)  Negligible  
Duplaspidiotus 
claviger  Regulated  China, Cook Islands, Fiji, 
Japan, USA, Western Samoa  on twigs and branches, under 
the epidermis (Watson 2002) ; 
“not associated with citrus 
fruit” (Grousset et al. 2016)   13 host genera known 
(Garcia Morales et al. 
2016)  male is not known (Watson 
2005), so may reproduce 
parthenogenetically   a pest of ornamentals 
(Watson 2002)  Negligible  
Fiorinia 
proboscidaria  Regulated  China, Fiji, Japan, USA  detected on citrus FP (LIMS)  13 host genera known 
(Garcia Morales et al. 
2016)  male known (FDACS 2015) 
so reproduction is probably 
sexual1 a potential citrus pest 
(García Morales et al. 
2016)  Very low  
Hemiberlesia 
palmae  No entry  Australia, Brazil, China, Fiji, 
Mexico, Peru, Solomon 
Islands, USA, Vietnam, 
Western Samoa  detected on non-citrus  FP 
(LIMS)  97 host genera known 
(Garcia Morales et al. 
2016)  unisexual and bisexual 
populations have been 
reported (Garcia Morales et 
al. 2016)  a pest of various 
crops and palms in 
the tropics (García 
Morales et al. 2016)  Low 
Howardia 
biclavis  Regulated  Australia , Brazil, China, Cook 
Islands, Fiji, Japan, Mexico, 
New Caledonia, Peru, Spain, 
USA, Vanuatu, Western 
Samoa  detected on non-citrus  FP 
(LIMS)  195 host genera known 
(Garcia Morales et al. 
2016)  reproduces 
parthenogenetically (Garcia 
Morales et al. 2016)  a pest of citrus, 
ornamentals, tea and 
coffee (García 
Morales et al. 2016)  Low 
Lepidosaphes 
gloverii  Regulated  Australia , Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Solomon Islands, Spain, 
United States, Vietnam, 
South Korea, Western Samoa  detected on citrus FP (LIMS)  polyphagous (Watson 
2002); 40 host genera 
known (Garcia Morales 
et al. 2016)  reproduces sexually 
(Watson 2002)  serious pest of Florida 
citrus (García Morales 
et al. 2016); often 
under effective 
biological control 
(Watson 2002)  Very low  
Lopholeucaspis 
cockerelli  Regulated  Australia, Brazil, Cook 
Islands, Fiji, Japan, Mexico, 
Peru, USA, Vanuatu, Western 
Samoa  infests leaves (Watson 2002) ; 
“not associated with citrus 
fruit” (Grousset et al. 2016)  polyphagous (Watson 
2002); 68 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 minor pe st in the 
Pacific (Watson 2002)  Negligible   
527 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Citrus limon 
(25) ONZPR  
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Morganella 
longispina  Regulated  Australia, Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
USA, Western Samoa  detected on citrus FP (LIMS); 
on branches and occasionally 
on fruit (Watson 2002)  polyphagous (Watson 
2002); 39 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 minor citrus pest 
(García Morales et al. 
2016); also  a pest of 
other tropical fruit but 
more often 
ornamentals (Watson 
2002)  Very low  
Odonaspis 
morrisoni  Regulated  Fiji no information due to limited 
distribution  6 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 no information  due to 
limited distribution  Very low  
Parlatoria 
cinerea  Regulated  Brazil, China, Cook Islands, 
Japan, Mexico, New 
Caledonia, Spain, United 
States, Vanuatu, Vietnam, 
Western Samoa  detected on citrus FP (LIMS);  
mainly on stems and 
branches, but sometimes on 
leaves and fruit (Watson 
2002)  polyphagous (Watson 
2002); 14 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 citrus pest in the 
Pacific (Watson 2002)  Very low  
Parlatoria crypta  Regulated  N/A (does not occur in any of 
the exporting countries)  intercepted on non-citrus  FP 
(DAWE 2021)  39 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 pest of olive (Najafinia 
et al. 2002)  Very low  
Parlatoria oleae  Regulated  Australia, Brazil, China, 
Egypt, Mexico, Spain, USA  infests fruit (Garcia Morales et 
al. 2016)  highly polyphagous 
(Watson 2002); 120 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  pest of olives; also 
stonefruit, pipfruit 
(particularly on fruits) 
and ornamentals 
(Watson 2002)  Very low  
Parlatoria 
pergandii  Regulated  Australia, Brazil, China, Cook 
Islands, Egypt, Japan, 
Mexico, Spain, USA, 
Vietnam, South Korea, 
Western Samoa  detected on citrus FP (LIMS)  polyphagous (Watson 
2002); 57 host genera 
known (Garcia Morales 
et al. 2016)  reproduces sexually 
(Watson 2002)  important citrus pest, 
occasional pest of 
ornamentals  (Watson 
2002)  Very low  
Parlatoria 
ziziphi  Regulated  Australia, Brazil, China, 
Egypt, Japan, Peru, Spain, 
USA, Vietnam  detected on citrus FP (LIMS)  16 host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  important citrus pest 
in some regions 
(Watson 2002)  Very low  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 528 Citrus limon 
(25) ONZPR  
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Pinnaspis 
strachani  Regulated  Australia, Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Peru, Solomon Islands, USA, 
Vanuatu, Vietnam, South 
Korea, Western Samoa  detected on non-citrus  FP 
(LIMS) highly polyphagous 
(Watson 2002); 247 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  important occasional 
pest of several 
economic crops 
including citrus, 
avocado, olive and 
asparagus (Watson 
2002)  Very low  
Pseudaonidia 
trilobitiformis  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, New 
Caledonia, Peru, USA, 
Vanuatu, Vietnam  detected on citrus FP (LIMS)  highly polyphagous 
(Watson 2002); 111 
host genera known 
(Garcia Morales et al. 
2016)  males unknown (Garcia 
Morales et al. 2016) so may 
reproduce 
parthenogenetically  important pest of 
cashew, citrus and 
cacao (Watson 2002)  Low 
Selenaspidus 
articulatus  Regulated  Australia, Brazil, China, Fiji, 
Japan, Mexico, Peru, 
Solomon Islands, USA, 
Vietnam  detected on citrus FP (LIMS); 
on leaves, sometimes on fruit 
(Watson 2002)  highly polyphagous 
(Watson 2002); 105 
host genera known  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 important pest of 
citrus  and coffee 
(Watson 2002)  Very low  
Unaspis citri  Regulated  Australia , Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Peru, Solomon Islands, 
Spain, USA, Vanuatu, 
Vietnam, American Samoa, 
Western Samoa  detected on citrus FP (LIMS); 
usually on the trunk and main 
limbs, but occasionally on 
leaves and fruits (Watson 
2002)  fairly polyphagous 
(Watson 2002); 18 host 
genera known  reproduces sexually 
(Watson 2002)  one of the principal 
pests of citrus spp. in 
many regions of the 
world (Watson 2002)  Very low  
1Does not exc lude the possibility of uniparental populations  
  
529 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   Table 4: Citrus maxima  
Citrus maxima 
(24) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Aonidiella 
comperei  Regulated  Brazil, China, Japan, 
Vietnam  infests leaves, twigs, and 
larger branches (Garcia 
Morales et al. 2016), but 
detected on non -citrus FP 
(LIMS)  polyphagous; 12 host 
genera known (Garcia 
Morales et al. 2016)  male has not been identified 
(Garcia Morales et al. 
2016); may reproduce 
parthenogenetically  reported as a pest of 
papaya in Brazil and 
the Pacific (Martins et 
al. 2004)  Very low  
Aonidiella 
orientalis  Regulated  Australia, Brazil, China, 
Mexico, Peru, USA, 
Vietnam  detected on non-citrus  FP 
(LIMS)  highly polyphagous; 
163 host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually (Garcia 
Morales et al. 2016)  a serious pest on 
some tropical crops, 
also reported as a 
pest of citrus and 
ornamentals (Watson 
2002)  Very low  
Aspidiotus 
destructor  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, 
Solomon Islands, USA, 
Vanuatu, Vietnam, South 
Korea, American  Samoa, 
Western Samoa  detected on citrus FP (LIMS)  highly polyphagous 
(Watson  2002); 134 
host genera known 
(Garcia Morales et al. 
2016)  Reproduces sexually 
(Watson 2002).  
Taylor (1935) reported that 
A. destructor reproduces 
parthenogenetically, but 
Beardsley (1970) refutes 
this. See footnote 2.  mainly a pest of 
coconut , banana 
(García Morales et al. 
2016) , also mangoes 
and ornamentals 
(Grousset et al. 2016)  Very low  
Aulacaspis citri  No entry  China  detected on citrus at Korean 
border, pathway not specified 
(Suh 2016)  5 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 important citrus pest 
in Sichuan (Lin et al. 
1997)  Low  
Chrysomphalus 
aonidum  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, 
Spain, USA, Vietnam, 
South Korea, Western 
Samoa  detected on citrus FP (LIMS); 
infests leaves and fruit 
(Garcia Morales et al. 2016)  very polyphagous; 181 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually (Garcia 
Morales et al. 2016)  a serious citrus pest 
in a number  of 
countries; a minor 
avocado pest 
(Watson 2002)  Very low  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 530 Citrus maxima 
(24) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Chrysomphalus 
dictyospermi  Regulated  Australia, Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, Peru, Solomon 
Islands, Spain, USA, 
Vietnam, South Korea, 
Western Samoa  detec ted on citrus FP (LIMS)  very polyphagous; 196 
host genera known 
(Garcia Morales et al. 
2016)  unisexual and bisexual 
populations have been 
reported (Garcia Morales et 
al. 2016)  a serious pest of 
avocado and citrus; 
capable of infesting a 
range of commercial  
crops (MPI 2014)  Low 
Clavaspidiotus 
apicalis  No entry  Egypt  forms dense colonies on 
citrus fruit (Garcia Morales et 
al. 2016)   no information  a potential citrus pest 
(García Morales et al. 
2016)  Very low  
Fiorinia 
proboscidaria  Regulated  China, Fiji, Japan, USA  detected on citrus FP (LIMS)  13 host genera known 
(Garcia Morales et al. 
2016)  male known (FDACS 2015) 
so reproduction is probably 
sexual1 a potential citrus pest 
(García Morales et al. 
2016)  Very low  
Lepidosaphes 
citricola  No entry  China  no information  due to limited 
distribution  1 host genus known 
(Garcia Morales et al. 
2016)  no information  due to 
limited distribution  no information due to 
limited distribution  Very low  
Lepidosaphes 
gloverii  Regulated  Australia, Brazil, China, 
Cook Islands , Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, Solomon 
Islands, Spain, United 
States , Vietnam, South 
Korea, Western Samoa  detected on citrus FP (LIMS)  polyphagous (Watson 
2002); 40 host genera 
known (Garcia Morales 
et al. 2016)  reproduces sexually 
(Watson 2002)  serious pest of Florida 
citrus (García Morales 
et al. 2016); often 
under effective 
biological control 
(Watson 2002)  Very low  
Lepidosaphes 
tokionis  Regulated  Australia, Fiji, Japan, 
Mexico, USA, Western 
Samoa  detected on NS/CFF but not 
FP (LIMS); on leaves 
(Watson 2002)  9 host genera known 
(Garcia Morales et al. 
2016)  male known (Watson 2002) 
so reproduction is probably 
sexual1 minor pest (Watson 
2002)   Negligible  
Lopholeucaspis 
cockerelli  Regulated  Australia, Brazil, Cook 
Islands, Fiji, Japan, Mexico, 
Peru, USA, Vanuatu, 
Western Samoa  infests leaves (Watson 2002) ; 
“not associated with citrus 
fruit” (Grousset et al. 2016)  polyphagous (Watson 
2002); 68 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
repro duction is probably 
sexual1 minor pest in the 
Pacific (Watson 2002)  Negligible   
531 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Citrus maxima 
(24) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Lopholeucaspis 
japonica  Regulated  Australia, Brazil, China, 
Japan, USA, North Korea, 
South Korea  rarely on fruit; on bark of 
branches and trunk, rarely on 
leaves and fruits (Watson 
2002)  polyphagous (Watson 
2002); 60 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 major pest of citrus, 
other fruits, tea  and 
ornamental plants 
(García Morales et al. 
2016)  Very low  
Morganella 
longispina  Regulated  Australia, Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, USA, Western 
Samoa  detected on citrus FP (LIMS); 
on branches and occasionally 
on fruit (Watson 2002)  polyphagous (Watson 
2002); 39 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 minor citrus pest 
(García Morales et al. 
2016); also a pest of 
other tropical f ruit but 
more often 
ornamentals (Watson 
2002)  Very low  
Parlatoria cinerea  Regulated  Brazil, China, Cook Islands, 
Japan, Mexico, New 
Caledonia, Spain, United 
States, Vanuatu, Vietnam, 
Western Samoa  detected on citrus FP (LIMS); 
mainly on stems and 
branches, but sometimes on 
leaves and fruit (Watson 
2002)  polyphagous (Watson 
2002); 14 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 citrus pest in the 
Pacific (Watson 2002)  Very low  
Parlatoria 
pergandii  Regulated  Australia, Brazil, China, 
Cook Islands, Egypt, Japan, 
Mexico, Spain, USA, 
Vietnam, South Korea, 
Western Samoa  detected on citrus FP (LIMS)  polyphagous (Watson 
2002); 57 host genera 
known (Garcia Morales 
et al. 2016)  reproduces sexually 
(Watson 2002)  important citrus pest, 
occasional pest of 
ornamentals (Watson 
2002)  Very low  
Parlatoria ziziphi  Regulated  Australia, Brazil, China, 
Egypt, Japan, Peru, Spain, 
USA, Vietnam  detected on citrus FP (LIMS)  16 host genera know n 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  important citrus pest 
in some regions 
(Watson 2002)  Very low  
Pinnaspis 
strachani  Regulated  Australia , Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, Peru, Solomon 
Islands, USA, Vanuatu, 
Vietnam, South Korea, 
Western Samoa  detected on non-citrus  FP 
(LIMS)  highly polyphagous 
(Watson 2002); 247 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  important occasional 
pest of several 
economic  crops 
including citrus, 
avocado, olive and 
asparagus (Watson 
2002)  Very low  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 532 Citrus maxima 
(24) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Pseudaonidia 
trilobitiformis  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, New 
Caledonia, Peru, USA, 
Vanuatu, Vietnam  detected on citrus FP (LIMS)  highly polyphagous 
(Watson 2002); 111 
host genera known 
(Garcia Morales et al. 
2016)  males unknown (Garcia 
Morales et al. 2016) so may 
reproduce 
parthenogenetically  important pest of 
cashew, citrus and 
cacao (Watson 2002)  Low 
Pseudaulacaspis 
pentagona  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, 
Solomon Islands, Spain, 
USA, Vanuatu, Vietnam, 
South Korea, Western 
Samoa  detected on non-citrus  FP, 
especially kiwifruit (LIMS)  251 host genera known 
(Garcia Morales et al. 
2016)  reproduces s exually 
(Watson 2002)  pest of a wide range 
of crops grown in New 
Zealand, including 
kiwifruit and 
stonefruit. Unusually 
for a scale insect, it is 
known to be able to 
kill some of its hosts 
(MPI 2014 and 
references within ) Very low  
Selenaspidus 
articulatus  Regulated  Australia, Brazil, China, Fiji, 
Japan, Mexico, Peru, 
Solomon Islands, USA, 
Vietnam  detected on citrus FP (LIMS); 
on leaves, sometimes on fruit 
(Watson 2002)  highly polyphagous 
(Watson 2002); 105 
host genera known  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 important pest of 
citrus  and coffee 
(Watson 2002)  Very low  
Unaspis citri  Regulated  Australia , Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, Peru, Solomon 
Islands, Spain, USA, 
Vanuatu,  Vietnam, 
American Samoa, Western 
Samoa  detected on citrus FP (LIMS); 
usually on the trunk and main 
limbs, but occasionally on 
leaves and fruits (Watson 
2002)  fairly polyphagous 
(Watson 2002); 18 host 
genera known  reproduces sexually 
(Watson 2002)  
 one of the principal 
pests of citrus spp. in 
many regions of the 
world (Watson 2002)  Very low  
Unaspis euonymi  Regulated  China, Egypt, Japan, 
Mexico, Spain, USA, South 
Korea  all plant parts (Garcia Morales 
et al. 2016)  33 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 serious pest of some 
ornamentals, 
particularly Euonymus 
(García Morales et al. 
2016)  Very low   
533 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Citrus maxima 
(24) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Unaspis 
yanonensis  Regulated  Australia, China, Fiji, Japan, 
Vietnam, South Korea  detected on citrus FP (LIMS)  18 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 important pest 
of citrus in some 
growing regions 
(Watson 2002)  Very low  
1Does not exclude the  possibility of uniparental populations  
2 Taylor (1935) reported that A. destructor  reproduced primarily by parthenogenesis in Fiji. This report has been repeated by other publications and in other databases e .g. Crop Knowledge Master 
(Aspidiotus destructor (hawaii.edu) ); CPHST data sheet ( 2821 (purdue.edu) ). However Beardsley (1970) refutes this assertion  and states (of Aspidiotus destructor ): “Taylor states that males are 
superfluous in this species and that crawlers of both sexes are produced by parthenogenesis. However cytological studies of A. destructor  based on material from several localities in the  West Indies, 
have revealed no evidence of parthenogenesis”, citing Brown (1965). More recent primary sources do not mention parthenogenesi s as a mode of reproduction for this species, e.g. Watson (2002), 
Garcia Morales et al. (2016) only mention sexual re production.  
 
 Table 5: Citrus reticulata  
Citrus reticulata 
(21) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity Association  Host range  Reproduction  Impact  Risk 
Assessment 
(pre- 
inspection)  
Aonidiella citrina  Regulated  Australia, China, Egypt, Fiji, 
Japan, Mexico, USA, 
Vietnam, South Korea, 
Western Samoa  detected on citrus FP (LIMS); 
infests mainly leaves and fruit 
(Garcia Morales et al. 2016)  polyphagous (Garcia 
Morales et al. 2016); 43 
host genera known  reproduces sexually 
(Garcia Morales et al. 
2016)  a pest of citrus in some 
regions (Watson 2002)  Very low  
Aonidiella 
inornata  Regulated  Australia, China, Fiji, Japan, 
USA, Vanuatu, Vietnam, 
Western Samoa  detected on citrus FP (LIMS)  34 host genera known 
(Garcia Morales et al. 
2016)   a pest of papaya and 
mango (García Morales 
et al. 2016)  Very low  
Aspidiotus 
excisus  Regulated  China, Fiji, Japan, Mexico, 
USA, Vietnam  detected on citrus FP (LIMS)  30 host genera known 
(Garcia Morales et al. 
2016)   a pest of ornamental 
plants (García Morales 
et al. 2016)  Very low  
Aulacaspis citri  No entry  China  detected on citrus at Korean 
border, pathway not specified 
(Suh 2016)  5 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016)  so 
reproduction is probably 
sexual1 important citrus pest in 
Sichuan (Lin et al. 
1997)  Low  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 534 Citrus reticulata 
(21) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity Association  Host range  Reproduction  Impact  Risk 
Assessment 
(pre- 
inspection)  
Chrysomphalus 
aonidum  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, 
Spain, USA, Vietnam, 
South Korea, Western 
Samoa  detecte d on citrus FP (LIMS); 
infests leaves and fruit 
(Garcia Morales et al. 2016)  very polyphagous; 181 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Garcia Morales et al. 
2016)  a serious citrus pest in a 
number of  countries; a 
minor avocado pest 
(Watson 2002)  Very low  
Chrysomphalus 
dictyospermi  Regulated  Australia , Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, Peru, Solomon 
Islands, Spain, USA, 
Vietnam, South Korea, 
Western Samoa  detected  on citrus FP (LIMS)  very polyphagous; 196 
host genera known 
(Garcia Morales et al. 
2016)  unisexual and bisexual 
populations have been 
reported (Garcia Morales 
et al. 2016)  a serious pest of 
avocado and citrus; 
capable of infesting a 
range of commercial 
crops (MPI 2014)  Low 
Fiorinia fioriniae  Regulated  Australia , Brazil, China, 
Cook Islands, Egypt, Japan, 
Mexico, New Caledonia, 
Peru, Spain, USA, Vanuatu, 
Western Samoa  detected on citrus at Taiwan 
border, pathway not specified 
(DAWE 2021)  highly polyphagous  
(Watson 2002); 93 host 
genera known (Garcia 
Morales et al. 2016)  male known (Watson 
2002) so reproduction is 
probably sexual1 a pest of palms and 
ornamentals, avocado 
and olive (Watson 
2002)  Very low  
Fiorinia 
proboscidaria  Regulated  China, Fiji, Japan, USA detected on citrus FP (LIMS)  13 host genera known 
(Garcia Morales et al. 
2016)  male known (FDACS 
2015) so reproduction is 
probably sexual1 a potential citrus pest 
(García Morales et al. 
2016)  Very low  
Hemiberlesia 
palmae  No entry  Australia , Brazil, Ch ina, Fiji, 
Mexico, Peru, Solomon 
Islands, USA, Vietnam, 
Western Samoa  detected on non-citrus  FP 
(LIMS)  97 host genera known 
(Garcia Morales et al. 
2016)  unisexual and bisexual 
populations have been 
reported (Garcia Morales 
et al. 2016)  a pest of various crops 
and palms in the tropics 
(García Morales et al. 
2016)  Low 
Lepidosaphes 
gloverii  Regulated  Australia , Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, Solomon 
Islands, Spain, United 
States, Vietnam, South 
Korea, Western Samoa  detected on citrus FP (LIMS)  polyphagous (Watson 
2002); 40 host genera 
known (Garcia Morales 
et al. 2016)  reproduces sexually 
(Watson 2002)  serious pest of Florida 
citrus (García Morales 
et al. 2016); often under 
effective biological 
control (Watson 2002)  Very low   
535 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Citrus reticulata 
(21) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity Association  Host range  Reproduction  Impact  Risk 
Assessment 
(pre- 
inspection)  
Morganella 
longispina  Regulated  Australia , Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, USA, Western 
Samoa  detected on citrus FP (LIMS); 
on branches and occasionally 
on fruit (Watson 2002)  polyphagous (Watson 
2002); 39 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 minor citrus pest 
(García Morales et al. 
2016); also a pest of 
other tropical fruit but 
more often ornamentals 
(Watson 2002)  Very lo w 
Octaspidiotus 
stauntoniae  Regulated  China, Japan, Vietnam, 
South Korea  reported on citrus leaves, fruit 
and twigs (Dao et al. 2017)  23 host genera known 
(Garcia Morales et al. 
2016)  no information  no information  Very low  
Parlatoria cinerea  Regulated  Brazil, China, Cook Islands, 
Japan, Mexico, New 
Caledonia, Spain, United 
States, Vanuatu, Vietnam, 
Western Samoa  detected on citrus FP (LIMS); 
mainly on stems and 
branches, but sometimes on 
leaves and fruit (Watson 
2002)  polyphagous (Watson 
2002); 14 host genera 
known (Garcia Morales 
et al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 citrus pest in the Pacific 
(Watson 2002)  Very low  
Parlatoria oleae  Regulated  Australia, Brazil, China, 
Egypt, Mexico, Spain, USA  infests  fruit (Garcia Morales et 
al. 2016)  highly polyphagous 
(Watson 2002); 120 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  pest of olives; also 
stonefruit, pipfruit 
(particularly on fruits) 
and ornamentals 
(Watson 2002)  Very low 
Parlatoria 
pergandii  Regulated  Australia, Brazil, China, 
Cook Islands, Egypt, Japan, 
Mexico, Spain, USA, 
Vietnam, South Korea, 
Western Samoa  detected on citrus FP (LIMS)  polyphagous (Watson 
2002); 57 host genera 
known (Garcia Morales 
et al. 2016)  reproduces sexually 
(Watson 2002)  important citrus pest, 
occasional pest of 
ornamentals (Watson 
2002)  Very low  
Parlatoria ziziphi  Regulated  Australia, Brazil, China, 
Egypt, Japan, Peru, Spain, 
USA, Vietnam  detected on citrus FP (LIMS)  16 host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  important citrus pest in 
some regions (Watson 
2002)  Very low  
Pinnaspis 
strachani  Regulated  Australia, Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, Peru, Solomo n 
Islands, USA, Vanuatu, 
Vietnam, South Korea, 
Western Samoa  detected on non-citrus  FP 
(LIMS)  highly polyphagous 
(Watson 2002); 247 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  important occasional 
pest of several 
economic crops 
including citrus, 
avocado, olive and 
asparagus (Watson 
2002)  Very low  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 536 Citrus reticulata 
(21) ONZPR 
status  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 
2016)  Commodity Association  Host range  Reproduction  Impact  Risk 
Assessment 
(pre- 
inspection)  
Pseudaulacaspis 
pentagona  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, 
Solomon Islands, Spain , 
USA, Vanuatu, Vietnam, 
South Korea, Western 
Samoa  detected on non-citrus  FP, 
especially kiwifruit (LIMS)  251 host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Watson 2002)  pest of a wide range of 
crops grown in New 
Zealand, including 
kiwifruit and stonefruit. 
Unusually for a scale 
insect, it is known to be 
able to kill some of its 
hosts ( MPI 2014 and 
references within ) Very low  
Selenaspidus 
articulatus  Regulated  Australia, Brazil, China, Fiji, 
Japan, Mexico, Peru, 
Solomon Islands, USA, 
Vietnam  detected on citrus FP (LIMS); 
on leaves, sometimes on fruit 
(Watson 2002)  highly polyphagous 
(Watson 2002); 105 
host genera known  males known (Garcia 
Morales et al. 2016) so 
reproducti on is probably 
sexual1 important pest of 
citrus  and coffee 
(Watson 2002)  Very low  
Unaspis citri  Regulated  Australia, Brazil, China, 
Cook Islands, Egypt, Fiji, 
Japan, Mexico, New 
Caledonia, Peru, Solomon 
Islands, Spain, USA, 
Vanuatu, Vietnam, 
American Samoa, Western 
Samoa  detected on citrus FP (LIMS); 
usually on the trunk and main 
limbs, but occasionally on 
leaves and fruits (Watson 
2002)  fairly polyphagous 
(Watson 2002); 18 host 
genera known  reproduces sexually 
(Watson 2002)  one of the principal 
pests of citrus spp. in 
many regions of the 
world (Watson 2002)  Very low  
Unaspis 
yanonensis  Regulated  Australia, China, Fiji, Japan, 
Vietnam, South Korea  detected on citrus FP (LIMS)  18 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 important pest of  citrus 
in some growing 
regions (Watson 2002)  Very low  
1Does not exclude the possibility of uniparental populations  
  
537 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand   Table 6: Citrus paradisi  
Citrus paradisi 
(5) NZ 
(ONZPR)  Exporting countries in 
which scale is reported 
(Garcia Morales et al. 2016)  Commodity association  Host range  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Aonidiella citrina  Regulated  Australia, China, Egypt, Fiji, 
Japan, Mexico, USA, 
Vietnam, South Korea,  
Western Samoa  detected on citrus FP 
(LIMS); infests mainly 
leaves and fruit (Garcia 
Morales et al. 2016)  polyphagous (Garcia 
Morales et al. 2016); 43 
host genera known  reproduces sexually 
(Garcia Morales et al. 
2016)  a pest of citrus in some 
regions (Wats on 2002)  Very low  
Chrysomphalus 
aonidum  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, Spain, 
USA, Vietnam, South Korea, 
Western Samoa  detected on citrus FP 
(LIMS); infests leaves and 
fruit (Garcia Morales et al. 
2016)  very polyphagous; 181 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Garcia Morales et al. 
2016)  a serious citrus pest in a 
number of countries; a 
minor avocado pest 
(Watson 2002)  Very low  
Chrysomphalus 
dictyospermi  Regulated  Australia , Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Peru, Solomon Islands, 
Spain, USA, Vietnam, South 
Korea, Western Samoa  detected on citrus FP 
(LIMS)  very polyphagous; 196 
host genera known 
(Garcia Morales et al. 
2016)  unisexual and bisexual 
populations have been 
reported (Garcia Morales 
et al. 2016)  a serious pest of 
avocado and citrus; 
capable of infesting a 
range of commercial 
crops (MPI 2014)  Low 
Lepidosaphes 
gloverii  Regulated  Australia , Brazil, China, Cook 
Islands, Eg ypt, Fiji, Japan, 
Mexico, New Caledonia, 
Solomon Islands, Spain, 
United States, Vietnam, 
South Korea, Western Samoa  detected on citrus FP 
(LIMS)  polyphagous (Watson 
2002); 40 host genera 
known (Garcia Morales et 
al. 2016)  reproduces sexually 
(Watson 2002)  serious pest of Florida 
citrus (García Morales 
et al. 2016); often under 
effective biological 
control (Watson 2002)  Very low  
Lopholeucaspis 
cockerelli  Regulated  Australia, Brazil, Cook 
Islands, Fiji, Japan, Mexico, 
Peru, USA, Vanuatu, Western 
Samoa  infest s leaves (Watson 
2002) ; “not associated with 
citrus fruit” (Grousset et al. 
2016)  polyphagous (Watson 
2002); 68 host genera 
known (Garcia Morales et 
al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 minor pest in the Pa cific 
(Watson 2002)  Negligible  
1Does not exclude the possibility of uniparental populations  
 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 538  Table 7: Citrus sinensis  
Citrus sinensis 
(16) NZ 
(ONZPR)  Exporting countries in which 
scale is reported (Garcia 
Morales et al. 2016)  Commodity association  Polyphagy  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Aonidiella citrina  Regulated  Australia, China, Egypt, Fiji, 
Japan, Mexico, USA, 
Vietnam, South Korea, 
Western Samoa  detected on citrus FP 
(LIMS); infests mainly 
leaves and fruit (Garcia 
Morales et al. 2016)  polyphagous (Garcia 
Morales et al. 2016); 43 
host genera known  reproduces sexually 
(Garcia Morales et al. 
2016)  a pest of citrus in some 
regions (Watson 2002)  Very low  
Aonidiella 
comperei  Regulated  Brazil, China, Japan, Vietnam  infest s leaves, twigs, and 
larger branches (Garcia 
Morales et al. 2016), but 
detected on non -citrus FP 
(LIMS)  polyphagous; 12 host 
genera known (Garcia 
Morales et al. 2016)  male has not been 
identified (Garcia Morales 
et al. 2016); may 
reproduce 
parthenogenetically  reported as a pest of 
papaya in Brazil and the 
Pacific (Martins et al. 
2004)  Very low  
Aonidiella 
orientalis  Regulated  Australia, Brazil, China, 
Mexico, Peru, USA, Vietnam  detected on non-citrus  FP 
(LIMS)  highly polyphagous; 163 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Garcia Morales et al. 
2016)  a serious pest on some 
tropical crops, also 
reported as a pest of 
citrus and ornamentals 
(Watson 2002)  Very low  
Aspidiotus 
destructor  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, 
Solomon Islands, USA, 
Vanuatu, Vietnam, South 
Korea, American Samoa, 
Western Samoa  detected on citrus FP 
(LIMS)  highly polyphagous 
(Watson 2002); 134 host 
genera known (Garcia 
Morales et al. 2016)  Reproduces sexually 
(Watson 2002).  
Taylor (1935) reported 
that A. destructor 
reproduces 
parthenogenetically, but 
Beardsley (1970) refutes 
this. See footnote 2.  mainly a pest of 
coconut , banana 
(García Morales et al. 
2016) , also mangoes 
and ornamentals 
(Grous set et al. 2016)  Very low  
Chrysomphalus 
aonidum  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, Mexico, 
New Caledonia, Peru, Spain, 
USA, Vietnam, South Korea, 
Western Samoa  detected on citrus FP 
(LIMS); infests leaves and 
fruit (Garcia Morales et  al. 
2016)  very polyphagous; 181 
host genera known 
(Garcia Morales et al. 
2016)  reproduces sexually 
(Garcia Morales et al. 
2016)  a serious citrus pest in a 
number of countries; a 
minor avocado pest 
(Watson 2002)  Very low  
Chrysomphalus 
dictyospermi  Regulat ed Australia, Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Peru, Solomon Islands, 
Spain, USA, Vietnam, South 
Korea, Western Samoa  detected on citrus FP 
(LIMS)  very polyphagous; 196 
host genera known 
(Garcia Morales et al. 
2016)  unisexual and bisexual 
populations have been 
reported (Garcia Morales 
et al. 2016)  a serious pest of 
avocado and citrus; 
capable of infesting a 
range of commercial 
crops (MPI 2014)  Low  
539 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Citrus sinensis 
(16) NZ 
(ONZPR)  Exporting countries in which 
scale is reported (Garcia 
Morales et al. 2016)  Commodity association  Polyphagy  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Fiorinia 
proboscidaria  Regulated  China, Fiji, Japan, USA  detected on c itrus FP 
(LIMS)  13 host genera known 
(Garcia Morales et al. 
2016)  male known (FDACS 
2015) so reproduction is 
probably sexual1 a potential citrus pest 
(García Morales et al. 
2016)  Very low  
Lepidosaphes 
gloverii  Regulated  Australia, Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Solomon Islands, Spain, 
United States, Vietnam, 
South Korea, Western Samoa  detected on citrus FP 
(LIMS)  polyphagous (Watson 
2002); 40 host genera 
known (Garcia Morales et 
al. 2016)  reproduces sexually 
(Watson 2002)  serious pest of Florida 
citrus (García Morales 
et al. 2016); often under 
effective biological 
control (Watson 2002)  Very low  
Lopholeucaspis 
cockerelli  Regulated  Australia , Brazil, Cook 
Islands, Fiji, Japan, Mexico, 
Peru, USA, Vanuatu, Western 
Samoa  infests leaves (Watson 
2002) ; “not associated with 
citrus fruit” (Grousset et al. 
2016)  polyphagous (Watson 
2002); 68 host genera 
known (Garcia Morales et 
al. 2016 ) males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 minor pest in the Pacific 
(Watson 2002)  Negligible  
Parlatoria 
cinerea  Regulated  Brazil, China, Cook Islands, 
Japan, Mexico, New 
Caledonia, Spain, United 
States, Vanuatu, Vietnam, 
Western Samoa  detected on citrus FP 
(LIMS); mainly on stems 
and branches, but 
sometimes on leaves and 
fruit (Watson 2002)  polyphagous (Watson 
2002); 14 host genera 
known (Garcia Morales et 
al. 2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 citrus pest in the Pacific 
(Watson 2002)  Very low  
Parlatoria 
crotonis  Regulated  Brazil, China, Cook Islands, 
Egypt, Fiji, Mexico, New 
Caledonia, Solomon Islands, 
USA no evidence of association 
with fruit; detected on 
NS/CFF (LIMS)  15 host genera known 
(Garcia Morales et al. 
2016)  males known (Garcia 
Morales et al. 2016) so 
reproduction is probably 
sexual1 Listed as a “potential or 
actual” pest of citrus in 
Egypt (FAO 1996)  Negligible  
Parlatoria oleae  Regulated  Australia, Brazil, China, 
Egypt, Mexico, Spain, USA  infests fruit (Garcia Morales 
et al. 2016)  highly polyphagous 
(Watson 2002); 120 host 
genera known (Garcia 
Morales et al. 2016)  reproduces sexually 
(Watson 2002)  pest of olives; also 
stonefruit, pipfruit 
(particularly on fruits) 
and ornamentals 
(Watson 2002)  Very low  
Parlatoria 
pergandii  Regulated  Australia, Brazil, China, Cook 
Islands, Egypt, Japan, 
Mexico, Spain, USA, 
Vietnam, South Korea, 
Western Samoa  detected on citrus FP 
(LIMS)  polyphagous (Watson 
2002); 57 host genera 
known (Garcia Morales et 
al. 2016)  reproduces sexually 
(Watson 2002)  important citrus pest, 
occasional pest of 
ornamentals (Watson 
2002)  Very low  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 540 Citrus sinensis 
(16) NZ 
(ONZPR)  Exporting countries in which 
scale is reported (Garcia 
Morales et al. 2016)  Commodity association  Polyphagy  Reproduction  Impacts  Risk 
Assessment 
(pre- 
inspection)  
Parlatoria 
ziziphi  Regulated  Australia, Brazil, China, 
Egypt, Japan, Peru, Spain, 
USA, Vietnam  detected on citrus FP 
(LIMS)  16 host genera known 
(Garcia Morales et al. 
2016) reproduces sexually 
(Watson 2002)  important citrus pest in 
some regions (Watson 
2002)  Very low  
Pseudaonidia 
trilobitiformis  Regulated  Australia, Brazil, China, 
Egypt, Fiji, Japan, New 
Caledonia, Peru, USA, 
Vanuatu, Vietnam  detected on citrus FP 
(LIMS)  highly polyphagous 
(Watson 2002); 111 host 
genera known (Garcia 
Morales et al. 2016)  males unknown (Garcia 
Morales et al. 2016) so 
may reproduce 
parthenogenetically  important pest of 
cashew, citrus and 
cacao (Watson 2002)  Low 
Unaspis citri  Regulated  Australia, Brazil, China, Cook 
Islands, Egypt, Fiji, Japan, 
Mexico, New Caledonia, 
Peru, Solomon Islands, 
Spain, USA, Vanuatu, 
Vietnam, American Samoa, 
Western Samoa  detected on citrus FP 
(LIMS); usually on the trunk 
and main limbs, but 
occasionally on lea ves and 
fruits (Watson 2002)  fairly polyphagous 
(Watson 2002); 18 host 
genera known  reproduces sexually 
(Watson 2002)  one of the principal 
pests of citrus spp. in 
many regions of the 
world (Watson 2002)  Very low  
1 Does not exclude the possibility of uniparental populations  
2 Taylor (1935) reported that A. destructor  reproduced primarily by parthenogenesis in Fiji. This report has been repeated by other publications and in other databases e .g. Crop Knowledge Master 
(Aspidiotus destructor (hawaii.edu) ); CPHST data sheet ( 2821 (purdue.edu) ). However Beardsley (1970) refutes this assertion and states (of Aspidiotus  destructor ): “Taylor states that males are 
superfluous in this species and that crawlers of both sexes are produced by parthenogenesis. However cytological studies of A. destructor  based on material from several localities in the West Indies, 
have reveale d no evidence of parthenogenesis”, citing Brown (1965). More recent primary sources do not mention parthenogenesis as a mode of reproduction for this species, e.g. Watson (2002), 
Garcia Morales et al. (2016) only mention sexual reproduction.  
 
  
541 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Table 8: Pre liminary assessment of detectability of adult female diaspidids associated with Citrus  species  
Species  Detectability  Colour 
Contrast*  Tolerance from 
600 sample  Sample to achieve 
0.5% tolerance  
Acutaspis scutiformis  scale is dark brown, with the exuviae yellowish (García Morales et al. 2016); likely to be detectable  100%  0.5%  600 
Aonidiella citrina  scale is lemon yellow to yellow -brown (Watson 2002); may be harder to detect on citrus fruit  80% 0.5%  600 
Aonidiella comperei  scale is yellow, turning orange  at maturity (García Morales et al. 2016); may be harder to detect on 
citrus fruit  40% 0.63%  
(1 in 159)  759 
Aonidiella inornata  scale is yellow -brown, translucent (García Morales et al. 2016); may be harder to detect on citrus fruit  60% 0.5%  600 
Aonidiella orientalis  scale is off -white to pale brown or yellow, with yellow to dark brown exuviae (Watson 2002) and is likely 
to be detectable on citrus fruit  100%  0.5%  600 
Aspidiotus destructor  scale is pale and translucent, with yellow exuviae (Watson  2002) and may be harder to detect on citrus 
fruit 70% 0.5%  600 
Aspidiotus excisus  scale is semi -transparent, whitish or very pale ochreous with yellow exuviae (García Morales et al. 2016) 
and may be harder to detect on citrus fruit  70% 0.5%  600 
Aulacasp is citri  scale is white or dirty white (García Morales et al. 2016) and is likely to be detectable on citrus fruit  100%  0.5%  600 
Chrysomphalus aonidum  scale is dark brown or bluish -black  with reddish brown central exuviae (Watson 2002) and is likely to be 
detectable on citrus fruit  100%  0.5%  600 
Chrysomphalus dictyospermi  scale is greyish or reddish -brown, often with a coppery tinge and with yellow or white exuviae (Watson 
2002) and may be harder to detect on citrus fruit  70% 0.5%  600 
Clavaspidiotus apicalis  No information found  100%  0.5%  600 
Diaspidiotus degeneratus  scale is very light brown, becoming white sub -centrally (García Morales et al. 2016) and may be harder 
to detect on citrus fruit  70% 0.5%  600 
Duplaspidiotus claviger  scale is often concealed under host's epidermis, grey with subcentral yellow -orange or bronze exuviae 
(Watson 2002) (unlikely to be on fruit)  20% 1.25%  
(1 in 80)  1,497  
Fiorinia fioriniae  scale is transparent light or yellowish brown with a yellowish exuviae (Watson 2002) and may be harder 
to detect on citrus fruit  50% 0.55%  
(1 in 182)  655 
Fiorinia proboscidaria  scale is light brown, glossy with white cast skin (FDACS) and may be harder to detect on citrus fruit  60% 0.5%  600 
Hemiberlesia palmae  scale is off -white or straw -coloured to dark brown with darker exuviae (Watson 2002); some variations 
may be harder to detect on citrus fruit  70% 0.5%  600 
Howardia biclavis  scale is white or yellow with light brown submarginal exuviae (Watson 2002) and is likely to be 
detectable on citrus fruit  100%  0.5%  600 
Lepidosaphes conchiformis  scale is brown (García Morales et al. 2016) and may be harder to detect on citrus fruit  80% 0.5%  600 
Lepidosaphes gloverii  scale changes from brownish -yellow to dark brown with age, with yellowish -brown exuviae (Watson 
2002); some variations may be harder to detect on citrus fruit  70% 0.5%  600 
Lepidosaphes tokionis  scale is more or less pale brown, sometimes with a p aler margin, with brown terminal exuviae (Watson 
2002) and may be harder to detect on citrus fruit  70% 0.5%  600 Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 542 Species  Detectability  Colour 
Contrast*  Tolerance from 
600 sample  Sample to achieve 
0.5% tolerance  
Lopholeucaspis cockerelli  scale is brown but covered in a thin secretion of white wax that sometimes gets rubbed off (Watson 
2002); some variations may be harder to detect on citrus fruit  80% 0.5%  600 
Lopholeucaspis japonica  scale is red -brown with grey -white wax cover (sometimes gets rubbed off) and a brown exuviae (Watson 
2002); likely to be detectable  100%  0.5%  600 
Morganella longispina  scale is almost black, with a dark central exuviae (Watson 2002) and is likely to be easily detectable  100%  0.5%  600 
Octaspidiotus stauntoniae  scale is grey, semi -transparent (García Morales et al. 2016) and may be harder to detect on citrus fr uit 80% 0.5%  600 
Odonaspis morrisoni  No information found  Unknown  Unknown  Unknown  
Opuntiaspis carinata  No information found  Unknown  Unknown  Unknown  
Parlatoria cinerea  scale is white or grey, with yellow -brown  exuviae (Watson 2002) and is likely to be detectable  100%  0.5%  600 
Parlatoria crotonis  No information found  Unknown  Unknown  Unknown  
Parlatoria crypta  No information found  Unknown  Unknown  Unknown  
Parlatoria oleae  scale is white to very light grey with darker exuviae (Watson 2002) and is likely to be detectable  100%  0.5%  600 
Parlatoria pergandii  scale is translucent light tan or grey -brown, with slightly darker yellow -brown exuviae (Watson 2002) and 
may be harder to detect on citrus fruit  70% 0.5%  600 
Parlatoria ziziphi  scale is black with a lip of white wax on the posterior margin (Watson 2002) and is likely to be easily 
detectable  100%  0.5%  600 
Pinnaspis strachani  scale is white to grey, with yellowish -brown exuviae (Watson 2002) and is likely to be detectable  100%  0.5%  600 
Pseudaonidia trilobitiformis  scale is pale or yellow -brown, with dark red -brown exuviae (Watson 2002) and may be harder to detect 
on citrus fruit  60% 0.5%  600 
Pseudaulacaspis pentagona  scale is white or yellow -white  with yellow or reddish brown exuviae (Watson 2002) and is likely to be 
detectable  100%  0.5%  600 
Pseudischnaspis acephala  No information found  Unknown  Unknown  Unknown  
Selenaspidus articulatus  scale is semitransparent, grey to light brown, with margin white or yellow; exuviae yellow or brown 
(Watson 2002); may be harder to detect on citrus fruit  60% 0.5%  600 
Unaspis citri  scale is brown or brown -black  with a paler margin with brown -yellow terminal exuviae (Watson 2002) 
and is likely to be easily detectable  100%  0.5%  600 
Unaspis euonymi  No information found  Unknown  Unknown  Unknown  
Unaspis yanonensis  scale is blackish -brown  with a paler margin and brownish -yellow exuviae (Watson 2002) and is likely to 
be easily detectable  100%  0.5%  600 
*note: estimates only based on description.  
  
543 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  Additional information was requested about weedy and poaceous hosts of the following species: 
Aonidiella comperei, Chrysomphalus dictyospermi, Hemiberlesia palmae, Howardia biclavis and Pseudaonidia 
trilobitiformis.  
1. Aonidiella comperei  
• This species is not highly polyphagous  
• no grasses ( Poaceae ) are reported as hosts by García Morales  et al. (2016)  
2. Chrysomphalus dictyospermi  
• a wide variety of common garden plants present in New Zealand* are reported as hosts by García 
Morales  et al. (2016), e.g. roses, camel lias, box hedging, peonies  
• some common New Zealand weedy species are reported as hosts by García Morales  et al. (2016), e.g 
wild broom ( Cytisus scoparius ), barberry ( Berberis ) and cotoneaster  
• the only Poaceae (grass family) García Morales  et al. (2016) rec ord C. dictyospermi  from is bamboo  
3. Hemiberlesia palmae  
• some common New Zealand weedy species belong to genera that are reported as hosts by García 
Morales  et al. (2016), e.g. milkweed ( Euphorbia peplus ) and the weedy grass species Miscanthus 
nepalensis  
• Cordyline  has been reported as a host ( García Morales  et al. 2016), indicating that native cabbage 
trees may host this species  
4. Howardia biclavis  
• no grasses ( Poaceae ) are reported as hosts by García Morales  et al. (2016)  
• “Howardia biclavis  is a tropical specie s, probably of African origin, but now occurs almost world -wide 
(under glass in cooler regions)” (Watson 2006)  
• Though it has been detected at the NZ border on non -citrus FP (LIMS), it does not have a strong 
association with fruit. “On bark of trunk and bra nches, often under the epidermis” (Watson 2006)  
5. Pseudaonidia trilobitiformis  
• no grasses ( Poaceae ) are reported as hosts by García Morales  et al. (2016)  
• some New Zealand weedy species are reported as hosts by García Morales  et al. (2016), e.g loquat 
(Eriobotrya japonica ) and Passiflora  edulis  
• Cordyline has been reported as a host ( García Morales  et al. 2016), indicating that native cabbage 
trees may host this species  
References: references for plant presence in NZ are from New Zealand Plant Conservatio n Network New 
Zealand Plant Conservation Network (nzpcn.org.nz) . Weed species are listed here: Consolidated list of 
environmental weeds in New Zealand (doc.govt.nz) . 
 
Additional information on impacts was requested for: Hemiberlesia palmae and Pseudaonidia 
trilobitiformis  Biosecurity New Zealand   Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1 • 544 1. Hemiberlesia palmae  
Some plant species of economic importance to New Zealand have been reported as hosts of Hemiberlesia 
palmae, including apple, avocado, citrus species, Eucalyptus  and Pinus , however it does not appear to have 
been reported to be economically important on th ese species. It has been reported as a pest (economically 
important) on some tropical crops, e.g. bananas, tea and oil palm in Malaysia and bananas in Fiji (DAWE 2021, 
Watson 2006).  
Watson (2002) describes Hemiberlesia palmae as a tropical species and García Morales  et al. (2016) report it 
as a “pest of crops in the tropics”. It is present in temperate countries “under glass”, i.e. in glasshouses and 
other sheltered environments. As such, its impact on outdoor crops in New Zealand and also its distribution  is 
likely to be limited by climate, However it may cause damage and control costs to host crops grown under 
cover, such as orchids and palms in greenhouses ( García Morales et al. 2016) . 
2. Pseudaonidia trilobitiformis  
Some plant species of economic importanc e to New Zealand have been reported as hosts of Pseudaonidia 
trilobitiformis , including avocado, capsicum, citrus species, pears and grapevine. Impacts have been reported 
on citrus (Watson 2006) but otherwise this species is not reported to be an important  pest. Leathers (2016) 
states: “despite its polyphagous nature and widespread distribution, Pseudaonidia trilobitiformis  is not well -
documented to be a plant pest and is therefore not expected to lower crop yields. It may increase crop 
production costs as growers may treat to control scale populations for quarantine purposes”.  
Cordyline has been reported as a host ( García Morales  et al. 2016), indicating that native cabbage trees may 
host this species.  
 
References for Appendix 3  
 
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Islands . Proceedings of the Hawaiian Entomological Society  20 (3): 505 –508. 5100231.pdf (core.ac.uk)  . 
Dao, H -T; Beattie, G A C; Watson, G W; Van Lam, P ; Van Liem, N; Khanh, L D; Hoa, N T; Viet, N D; 
Holford,  (2017) Citrus diaspidids in Viet Nam: New, and confirmation of previous, records based on 
morphological and molecular verification of taxa. Journal of Asia -Pacific Ento mology  
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DAWE (2021) Final group pest risk analysis for soft and hard scale insects on fresh fruit, vegetable, 
cut-flower and foliage imports. Department of Agriculture, Water and the Environment, Canberra , 
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Din, S; Arthurs, S P (2018) Featured Creatures: Coconut scale, Aspidiotus destructor  Signoret (Insecta: 
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Publication number EENY -622. 
https://entnemdept.ufl.edu/creatures/FRUIT/TROPICAL/coconut_scale.htm  . 
EPPO (2021) EPPO Global Database. https://gd.eppo.int/. Accessed October 2021.  
FAO (1996) Citrus Pest Problems and Their Control in the Near East . Food & Agriculture Org anisation, 
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FDACS (2015) Pest Alert : Fiorinia proboscidaria  Green (Hemiptera: Diaspididae), a new armored  scale 
pest of Citrus in Florida. Florida Department of Agriculture and Consumer Services, Division of Plant 
Industry. FDACS -P-02033. PEST_ALERT_fiorini a_proboscidaria.pdf (fdacs.gov)  .  
545 • Citrus  fresh fruit for consumption IRA, October 2021, Version 1.1  Biosecurity New Zealand  García Morales, M; Denno, B D; Miller, D R; Miller, G L; Ben -Dov, Y; Hardy, N B (2016) ScaleNet: A 
literature -based model of scale insect biology and systematics. Database. doi: 
10.1093/database/bav118. http://scalenet.info . 
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1.3 Report for Oranges and Mandarins – Fruit pathway and Alert List . 4_orange_mandarin_report.pdf 
(eppo.int)  
Hamon, A (1978) Opuntiaspis carinata (Cockerell) (Homoptera: Coccoidea: Diaspididae). Entomology 
circular No. 196. Florida Department of Ag riculture and Consumer Services, Division of Plant 
Industry. ent196.pdf (fdacs.gov)  .  
Kondo, T ; Muñoz, J  A (2016) Scale insects (Hemiptera: Coccoidea) associated with avocado crop, 
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Insecta Mundi  0465: 1 –24. 
https://digitalcommons.unl.e du/cgi/viewcontent.cgi?article=1973&context=insectamundi  . 
Leathers, J (2016) California pest rating for Pseudaonidia trilobitiformis  (Green): Trilobate scale. 
Pseudaonidia trilobitiformis (Gree n): Trilobe Scale | Pest Rating Proposals and Final Ratings . 
Lin, Y; Peng, Y  K; Chen, S  Z (1997 ) Studies on the bionomics of Aulacaspis citri  Chen and its control. 
Journal of Southwest Agricultural University  19 (5): 442–444.  
Martins, D; Culik , M P; Wolff, V R (2004)  New Record of Scale Insects (Hemiptera: Coccoidea) as 
Pests of Papaya in Brazil. Neotropical Entomology  33 (5): 655 –657. 
MPI (2014) Generic Pest Risk Assessment: Armoured scale insects (Hemiptera: Coccoidea: 
Diaspididae) on the fr esh produce pathway.  Ministry for Primary Industries, Wellington, New 
Zealand.  
MPI (2021) Import Risk Analysis: Citrus (Citrus) fresh fruit for human consumption. Version 1.0. April 
2021. Ministry for Primary Industries, Wellington, New Zealand.  
MPI Risk Analysis Guidelines (2021). Internal MPI guidance.  
Najafinia, M ; Azadvar, M; Namvar,  P; Moghadam , M (2002)   Introduction of Parlatoria crypta  (M. 
Kenzie) as a new pest on olive trees in Iran.  Applied Entomology and Phytopathology Pe93 –Pe94.  
Suh, S -J (2016) Armoured scale insects (Hemiptera: Diaspididae) intercepted at the ports of entry in 
the Republic of Korea over the last 20 years. EPPO Bulletin  46 (2): 313 –331.  
Taylor, T H C (1935) The Campaign Against  Aspidiotus destructor, Sign., in Fi ji. Bulletin of 
Entomological Research 26: 1 –102.  
Watson, G W (2005 and updates) Arthropods of economic importance: Diaspididae of the world. 
Webpage: http://nlbif.eti.uva.nl/bis/diaspididae.php. Accessed 2021.  
 