Wild bees that forage from neonicotinoid-treated oilseed rape crops are more likely to undergo long-term population declines than bees that forage from other sources, shows an 18-year study in Nature Communications this week. The paper surveys 62 bee species from the United Kingdom and links population declines over this 18-year period to the escalating use of neonicotinoid pesticides.
Neonicotinoid insecticides are used in a variety of crops worldwide and have been shown to be harmful to commercial honeybees and bumblebees, but most studies have only tested short-term effects in experimental settings. Neonicotinoids were initially licensed for use as a pesticide in the UK in 2002; by 2011, the percentage of UK oilseed rape seeds treated with this class of chemicals has risen to 83%.
Ben Woodcock and colleagues examine how large-scale applications of neonicotinoids to oilseed rape crops influenced population changes among 62 wild bee species in the UK between 1994 and 2011. They find that bees foraging from treated oilseed rape are three times more likely to experience population declines than bees that forage from other crops or wild plants.
These results demonstrate persistent, long-term effects of neonicotinoids on a community of wild bees, an effect that has previously been largely unexplored.