Insect decline a major global crisis

Thursday 7th February 2019

A new paper – ‘Worldwide decline of the entomofauna: A review of its drivers’ by Francisco Sánchez-Bayo and Kris A.G. Wyckhuys – paints a grim picture of the decline of essential insects across the planet. it concludes that current declines could lead to the extinction of 40% of the world's insect species over the next few decades. Butterflies, moths, bees, wasps, and dung beetles are amongst the most at risk along with freshwater dependent dragonflies and damselflies, stoneflies, caddisflies and mayflies.

Matt Shardlow, Buglife’s Chief Executive commented. “It is gravely sobering to see this collation of evidence that demonstrates the pitiful state of the world’s insect populations. It’s not just about bees, or even about pollination and feeding ourselves, the declines also include dung beetles that recycle waste and insects like dragonflies that start life in rivers and ponds. It is becoming increasingly obvious our planet’s ecology is breaking and there is a need for an intense and global effort to halt and reverse these dreadful trends – allowing the slow eradication of insect life to continue is not a rational option”.

The paper shows that a small number of unfussy and pollutant-tolerant species are replacing the rich diversity of specialist species that make up the fabric of life on Earth, the analysis highlights four commonly reported drivers behind the declines:

  1. habitat loss due to urban growth and intensive agriculture;
  2. pollution including pesticides and fertilisers;
  3. biological factors, such as pathogens and non-native invasive species;
  4. climate change.

Buglife concurs that these are key drivers, but highlights that:

  1. Habitat fragmentation, agricultural intensification, pesticides, climate change and disease are not independent factors; they interact making it difficult to identify the ‘top’ issue.
  2. Some factors may be under reported because people are not aware of the issue, or they have not been adequately studied; this includes light pollution and electromagnetic radiation.
  3. It is easy to misattribute or fail to detect the pervasive impacts of climate change on species; Buglife considers there is ample evidence of insect declines in temperate regions being driven by climate change when combined with habitat fragmentation, for instance bumblebee declines in northern latitudes. 

Craig Macadam, Buglife’s Conservation Director, is undertaking research on the Upland summer mayfly (Ameletus inopinatus) which is retreating northwards, and to higher altitudes, and by 2080 will be restricted to the Alps, Scandinavia and the Cairngorms. Research by Buglife’s Chair, Prof. Steve Ormerod has found that a 3oC rise in temperature would lead to the local extinction of Gold-ringed dragonfly (Cordulegaster boltonii), biting midges and the Upland green caddisfly (Rhyacophila munda).

Matt Shardlow concluded. “Insects make up over half the species on Earth, the planet’s health depends on them, so it is very worrying that insect life is disappearing much faster that the more obvious birds and mammals – the local extinction rate for insects is eight times higher!  There is not a single cause, but the evidence is clear, to halt this crisis we must urgently reverse habitat fragmentation, prevent and mitigate climate change, clean-up polluted waters and replace pesticide dependency with more sustainable, ecologically-sensitive farming.”

Buglife and other wildlife NGOs are urging Michael Gove to take a stance in support of guidance on pesticide testing that would make sure that they do not cause long-term harm to honeybees, or to wild bees.  Protecting Europe’s bees and other pollinators from future directly harmful pesticides would be a comparatively easy step towards addressing one of the main causes of the massive insect declines being observed around the world.