Inducing Ethanol Tolerance in Free-Flying Honey Bees (Apis mellifera L.)

Abstract

Ethanol dependency affects the health of more than 15 million adults in the United States of America. Honey bees have been used as a model for ethanol studies because of similarities in neural structure to vertebrates and their complex social behaviors. This study compares honey bee free-flight visitation to a food source after exposure to ethanol in aqueous sucrose.  Individual bees were followed making 6 attachment visits to a test-station containing 1M sucrose. After attachment, honey bees were randomly assigned to one of five groups: 0%, 2.5%, 5%, 10% EtOH, or a staged increase in ethanol concentrations (2.5%, 5%, 10%). The results indicate that honey bees tolerate up to 2.5% EtOH without avoidance or altered behavior, and up to 5% EtOH without avoidance but with slower trips. At 10% ethanol, attrition was 75% by the 18th return trip.  In the staged increase in concentration, bees were more likely to return than bees that were offered 10% ethanol in sucrose solution after attachment. The results of this study imply that ethanol induced tolerance to the effects of ethanol can be achieved in honey bees through incremental increase in EtOH but only in terms of attrition.  Other measures of foraging efficiency did not show ethanol induced tolerance.   Understanding how ethanol tolerance develops in bees may provide insight into these processes in humans with minimized ethical considerations.