Field evaluation of sub-lethal residues in brood comb on honey bee (Apis mellifera) colony health

Since the 1980’s, beekeepers have gone to great lengths to prevent honey bee colony losses to the parasitic mite, Varroa destructor, using synthetic in-hive miticides. As a consequence of the wide diversity of pesticides that have been used through the years to counteract the problem of mite resistance, exposure to non-hive agricultural chemicals and the slow replacement rate of honey bee brood combs, there has been a significant accumulation of miticides and other pesticides in the wax combs used to rear brood. Previous work has shown that miticide residues in brood comb can adversely affect individual bee behavior and development. This study evaluates how miticide-induced changes in individual behavior and development affect the health of a colony as a whole.

Beginning in 2010, we will measure the colony-wide response for a number of apiculturally important variables in 20 colonies reared on brood comb with accumulated miticide residues and in 20 colonies where the comb has had no history of synthetic miticide use. These variables include queen acceptance, honey yield, adult and brood population size, parasite load and overwintering capability. Results obtained from the study will help clarify the effects of sub-lethal pesticide load on colony health. Based on preliminary results, we expect that high miticide residues in brood combs will negatively affect colony health, and that comb replacement, combined with an integrated mite management program is critical to maintain the integrity of honey bee operations.