Rice Insect Pest Invades the World from the USA

Rice Water Weevil Larva

Rice Water Weevil Larva

The home of the rice water weevil is the southeastern US where the species feeds on
grasses in swampy areas. When rice plants were introduced into America, the
insect quickly found this new grass plant to its liking and has been feeding on
rice ever since. The weevils move into rice fields every year from nearby woods
and clumps of grass. Farmers have used insecticides since 1950 to control the
weevil populations in rice fields. The rice water weevil has spread from the
southeastern US to Louisiana, Texas, California, Japan, China and Italy where
it would decrease rice production without insecticide sprays.

“The rice water weevil, Lissorhoptrus oryzophilus, is the most destructive insect pest of rice in the United States. The insect is native to the southeastern United States but has, over the past 60 years, invaded important rice-growing areas in California, Asia and Europe and thus poses a global threat to rice production.

Small-plot research and sampling of commercial fields indicate yield losses from the rice water weevil would likely exceed 10% in many areas if no insecticides are used.”

Authors: Stout, M. J., et al.
Affiliations: Department of Entomology, Louisiana State University.
Title: The influence of rice plant age on susceptibility to the rice water weevil, Lissorhoptrus oryzophilus.
Source: Journal of Applied Entomology. 2013. 137:241-248.


Chinese Rice Farmers Use Insecticides to Control Invasive US Pest

The rice water weevil is an insect native to the southern US, where its native food was grass. Following the introduction of rice into the US, the weevil shifted from grasses to feed on rice. This shift was first reported in the 1880s. In the late 1950s, the insect was found in northern California rice fields. From there, the weevil was carried across the Pacific into Asia in the mid-1970s. First detected in China in 1988, the rice water weevil has become a major rice pest and has spread all across the country.

“The rice water weevil was recognized as an important invasive pest immediately after its discovery in mainland China because of the severe rice yield losses. The adults feed on the upper leaf surfaces producing longitudinal scars. Larval feeding on roots causes stunted growth, yellowing of the leaves (chlorosis) and plants that are easily uprooted, resulting in few tillers and low grain yield. In mainland China yield losses typically exceeded 10% in the established paddies, but approached over 80% in newly infested areas.”

“Insecticides provide the most effective means of controlling the weevil in China as they do in the United States and Japan.”

Authors: Chen, H.¹, Z. Chen² and Y. Zhou²
Affiliation: ¹ Department of Biology, SUNY-Buffalo; ² Plant Quarantine Institute, Beijing, China
Title: Rice water weevil (Coleoptera: Curculionidae) in mainland China: Invasion, spread and control.
Publication: Crop Protection. 2005. 24:695-702.