Insecticide exposure alters feeding and impairs ovary development in a solitary bee

Insecticide exposure is a growing concern due to its implication in population declines and disruption of key ecosystem services such as pollination. Bees and other beneficial insects can be exposed to insecticides multiple times throughout their lives and across generations, with impacts on behavior and reproduction. To investigate mechanisms underlying reduced reproduction in bees exposed to insecticide over time, I quantified the direct and carryover effects of insecticide exposure on the feeding and ovary development of the solitary bee, Osmia lignaria. Bees were exposed to the insecticide, imidacloprid, as larvae and/or as adults in a fully crossed design over two years. Insecticide exposure to bees as adults, but not as larvae, reduced pollen and nectar feeding and impaired ovary maturation. These findings reveal mechanisms underlying insecticide effects on bees, indicating that negative impacts on reproduction may be attributed to reduced ovary development driven by the anti-feeding effects of imidacloprid, even at low levels of exposure.