Epigenetics of neonicotinoids in an important insect pollinator

This project will contribute to assessing an important threat to food crop pollination by quantifying, for the first time, the epigenetic effects of neonicotinoids on bumblebees. Epigenetics is defined as heritable and stable changes in how a gene is expressed with no underlying changes in the sequence of the gene. Bumblebees are among the most important wild pollinators in the temperate Northern Hemisphere and at least 25 major crops grown within the EU are visited by bumblebees. Collectively, insect pollination services are worth 14.2 billion euros to Europe’s economy. In the UK, 52% of the surveyed areas have experienced a decline in bee-species richness since 1980. Eleven percent of bumblebee species are listed as ’near threatened’ or above using the IUCN Red List criteria.

Neonicotinoid insecticides have been strongly implicated in the decline of bees. Neonicotinoids are effective insecticides used on many important crops. Neonicotinoids disrupt the function of insect brains and cause paralysis and death. In addition to direct mortality, laboratory and field studies have documented numerous effects of low doses of neonicotinoids on both honeybees and wild bees such as bumblebees, including reduced fertility in queens and males, impaired immune response, impaired navigation and learning, reduced pollen collection and reduced food consumption.

The breadth of the effects of neonicotinoids on bees suggests that neonicotinoids have multiple modes of action beyond their designed direct impact on insect brains. We have preliminary data showing neonicotinoids affect methylation. Methylation is the addition of a chemical to DNA, which causes the gene affected to be expressed differently. Methylation is involved in many important biological functions in bees. An exciting possibility is that these widespread neonicotinoid effects are due to neonicotinoids affecting the bees’ methylation.

The proposed project will examine the whole genome of the bee to measure methylation and expression changes of neonicotinoid treated bumblebees in order to quantify the epigenetic effects of neonicotinoids on these important pollinators.

The finding of epigenetic effects of neonicotinoids will inform future discussion on legislation controlling these important pesticides. In 2013 the European Union imposed a partial restriction on neonicotinoid use which is currently being reviewed. Outside of Europe, few countries have introduced restrictions on neonicotinoid use and they remain the most widely used insecticides in the world. The finding of epigenetic effects of neonicotinoids will inform future discussion on legislation controlling these important pesticides.