Neonicotinoid insecticides negatively affect ovary development in bumblebees

Photo credit: Randu Privantu

The majority of research on the effects of neonicotinoid pesticides on bees is conducted almost exclusively on one species—the European honeybee. To understand if these effects hold constant across other bee species, researchers conducted laboratory tests on four different bumblebees species to understand the effects of exposure to neonicotinoids at doses that bees would be exposed to in a field. The study, published in The Proceedings of the Royal Society Biology, exposed queen bumblebees to high or low doses of thiamethoxam for two weeks. As a control, those in another group were not fed insecticides. Overall, 506 queens were collected for study and after excluding individuals infected with parasites, 230 individuals were included in the analysis. Two of the four species consumed less food after exposure, and ovary development in the bees fed the high but still field relevant dose of the pesticide was impaired for all four species. “Bumblebee queens are not currently considered in pesticide risk assessments for pollinators, and yet these results indicate that queens are sensitive to neonicotinoids in realistic exposure scenarios,” the authors wrote, adding, “More information is urgently needed on residues and persistence of pesticides in crops, wild plants and in wild bee nests in order to accurately assess the exposure risks for the full range of species and castes of bees likely to encounter them. This is essential for understanding and managing the threat to wild bees from agrochemicals, and preventing further declines as a result of exposure to these pest control products.”