Neonicotinoid pesticides and nutritional stress synergistically reduce survival in honey bees

The honey bee (Apis mellifera L.) is a major pollinator whose health is of global concern. Declines in honey bee health are related to multiple factors, including resource quality and pesticide contamination. Intensive agricultural areas with crop monocultures potentially reduce the quality and quantity of available nutrients and expose bee foragers to pesticides. However, there is, to date, no evidence for synergistic effects between pesticides and nutritional stress in animals. The neonicotinoids clothianidin (CLO) and thiamethoxam (TMX) are common systemic pesticides that are used worldwide and found in nectar and pollen. We therefore tested if nutritional stress (limited access to nectar, and access to nectar with low sugar concentrations) and sublethal, field-realistic acute exposures to two neonicotinoids (CLO and TMX at 1/5 and 1/25 of LD50) could alter bee survival, food consumption, and hemolymph sugar levels. Bee survival was synergistically reduced by the combination of poor ...