Effects of dietary imidacloprid exposure on honey bee (Apis mellifera) worker physiology

Honey bee colony losses have remained above sustainable rates for several years, which threatens the future production of many crops. Researchers generally agree that these losses are not due to any single factor, but rather a complex network of interacting factors that include parasites, diseases, and pesticides. Neonicotinoid insecticides in particular have come under intense scrutiny for their alleged role in colony declines, but have not been found to impact honey bee mortality at field realistic levels. It is therefore critical to investigate the sublethal impacts of neonicotinoid exposure and how they may interact with other stressors. Here, we present an experiment that details the effects of one neonicotinoid (imidacloprid) on nurse bee physiology (prophenoloxidase activity, glucose oxidase activity, hypopharyngeal gland protein content, midgut enzyme activity, and abdominal lipid stores). This information provides insight into the various mechanisms by which these insecticides may impact honey bee immunity, brood rearing, and protein digestion.