Meeting Abstract
Global declines in honey bees (Apis mellifera) have been linked to Colony Collapse Disorder (CCD), a phenomenon that occurs when worker bees disappear from the colony, leaving the brood unattended. While there is no single cause of CCD, sublethal doses of pesticides cause physiological and behavioral changes that adversely affect hive health. This research examined the effects of sublethal doses of the neonicotinoid imidacloprid on biomarkers for cellular stress, Heat Shock Protein 70 (HSP 70) and the oxidative enzyme superoxide dismutase (SOD). Honey bee foragers collected from central PA apiaries were harnessed, fed to satiation, and randomly assigned to control or imidacloprid treatments. Control bees were fed 1.5 M sucrose. Bees in treatment groups were fed 1.5 M sucrose with imidacloprid (Macho® 4.0, AgriStar) at doses of 1/5th, 1/10th, 1/20th, 1/50th, 1/100th and 1/500th of the LD50 (18 ng/bee). After four hours, bee heads were removed, frozen and homogenized. Bees exposed to high doses (1/5 and 1/10 of the LD50) of imidacloprid had higher SOD activity than low doses (≤0.18 ng/bee). HSP70 levels displayed a hormetic stress response. Positive controls had higher levels of HSP70 than negative controls. The 1/100 and 1/5 treatments were lower than the positive control. Doses of 1/10 and 1/50 showed intermediate stress levels, overlapping both positive and negative controls, with 1/20th of the LD50 being the median high dose. Future work will examine the effects of imidacloprid on gene expression in honey bee brains following the administration of a conservative dose of 1/20th of the LD50 of imidacloprod. This research seeks to further our understanding of how neonicotinoids affect the honey bee brain and the role they may play in CCD.
