Impacts of neonicotinoid use on long-term population changes in wild bees in England

Wild bee declines have been ascribed in part to neonicotinoid insecticides. While short-term laboratory studies on commercially-bred species (principally honeybees and bumblebees) have identified sub-lethal effects, there is no strong evidence linking these insecticides to losses of the majority of wild bee species. We relate 18 years of UK national wild bee distribution data for 62 species to amounts of neonicotinoid use in oilseed rape. Using a multi-species dynamic Bayesian occupancy analysis, we find evidence of increased population extinction rates in response to neonicotinoid seed treatment use on oilseed rape. Species foraging on oilseed rape benefit from the cover of this crop, but were on average three times more negatively affected by exposure to neonicotinoids than non-crop foragers. Our results suggest that sub-lethal effects of neonicotinoids could scale-up to cause losses of bee biodiversity. Restrictions on neonicotinoid use may reduce population declines.