A survey of multiple pesticide residues in pollen and beebread collected in China.

Honeybees, as major pollinators, make vital contributions to humans and ecosystems. Worryingly, a phenomenon known as honeybee colony losses has been reported in recent years. One of the factors underlying the occurrence of honeybee colony losses is exposure of honey bees to pesticide residues in their food, which cause detrimental sublethal effects and may lead to the collapse of their colonies. In this paper, 189 pollen samples and 226 beebread samples collected from five major beekeeping areas in China were analyzed from spring 2016 to autumn 2017. The most common active ingredient residues found include the insecticides (imidacloprid, thiamethoxam, fenpropathrin, bifenthrin and chlorpyrifos), the acaricides (coumaphos and fluvalinate) and the fungicides (carbendazim and triadimefon). Our data shows that the residual level of three chemicals (i.e. imidacloprid, thiamethoxam and chlorpyrifos) was higher in pollen than in beebread. Moreover, contamination of pollen and beebread was most serious in spring and in the middle and lower reaches of the Yellow River Area of China. Our data lay the foundation for the risk assessment of pesticides on honeybees in China.