Nutrient levels in individual honey bees (Apis mellifera) following treatment with pesticides

The use of pesticides, including fungicides and miticides, may increase the stress on individual honey bees which could possibly be a cause of weaker hives resulting in colony losses. Twenty colonies were studied from the fall of 2012 through the summer of 2013 in Blacksburg, VA to examine the effects of pesticides on nutrient levels. Each of five colonies received a treatment of either fumagillin, tau-fluvalinate or chlorothalonil, while 5 colonies received sugar syrup as a control. Treatments were applied during the fall of 2012, the spring of 2013 and the summer of 2013. Samples were taken at pre-treatment, 2 weeks post-treatment, and 4 weeks post-treatment intervals. Additionally, colonies were sampled in the winter, but not treated at that time. Fifteen individual bees from each colony were analyzed for wet weight, total protein and carbohydrate levels. During the Fall sampling, average bee weight was significantly affected by treatment (p<0.01) and the treatment period (p<0.05). Bees from control, untreated colonies and those treated with fumagillin did not vary significantly, but weighed significantly less than samples treated with chlorothalonil and tau-fluvalinate (p<0.01). Overall, colonies treated with tau-fluvalinate had significantly higher mean protein levels compared with control, chlorothalonil and fumagillin-treated colonies (p<0.01). Protein levels in bees from all colonies showed significant increases during the Fall sampling period(p<0.01). In all of the pesticide treated colonies, protein levels decreased in the winter but continued to increase in the untreated, control colonies. Carbohydrate levels were not significantly different between the control colonies and the tau­-fluvalinate treated colonies, however bee samples from the chlorothalonil and fumagillin treated colonies had significantly lower carbohydrate levels compared to the controls (p<0.05). Macromolecule levels followed similar trends in the fall and winter, regardless of pesticide treatment, leading to the conclusion that tau-fluvalinate, chlorothalonil and fumagillin do not cause significant difference in macromolecule levels, and that the difference in bee weight, protein and carbohydrate levels were most likely due to other environmental factors.