Seasonal Effects and the Impact of In-Hive Pesticide Treatments on Parasite, Pathogens, and Health of Honey Bees.

Honey bee, Apis mellifera (L.; Hymenoptera: Apidae), populations are in decline and their losses pose a serious threat for crop pollination and food production. The specific causes of these losses are believed to be multifactorial. Pesticides, parasites and pathogens, and nutritional deficiencies have been implicated in the losses due to their ability to exert energetic stress on bees. While our understanding of the role of these factors in honey bee colony losses has improved, there is still a lack of knowledge of how they impact the immune system of the honey bee. In this study, honey bee colonies were exposed to Fumagilin-B, Apistan (tau-fluvalinate), and chlorothalonil at field realistic levels. No significant effects of the antibiotic and two pesticides were observed on the levels of varroa mite, Nosema ceranae (Fries; Microsporidia: Nosematidae), black queen cell virus, deformed wing virus, or immunity as measured by phenoloxidase and glucose oxidase activity. Any effects on the parasites, pathogens, and immunity we observed appear to be due mainly to seasonal changes within the honey bee colonies. The results suggest that Fumagilin-B, Apistan, and chlorothalonil do not significantly impact the health of honey bee colonies, based on the factors analyzed and the concentration of chemicals tested.

Effects of Pesticide Treatments on Nutrient Levels in Worker Honey Bees (Apis mellifera).

Honey bee colony loss continues to be an issue and no factor has been singled out as to the cause. In this study, we sought to determine whether two beekeeper-applied pesticide products, tau-fluvalinate and Fumagilin-B(®), and one agrochemical, chlorothalonil, impact the nutrient levels in honey bee workers in a natural colony environment. Treatments were performed in-hive and at three different periods (fall, spring, and summer) over the course of one year. Bees were sampled both at pre-treatment and two and four weeks post-treatment, weighed, and their protein and carbohydrate levels were determined using BCA and anthrone based biochemical assays, respectively. We report that, based on the pesticide concentrations tested, no significant negative impact of the pesticide products was observed on wet weight, protein levels, or carbohydrate levels of bees from treated colonies compared with bees from untreated control colonies.