Honey bees are resilient to the long-term presence of alcohol in their diet

Abstract

Previous studies on various organisms have suggested that low doses of ethanol can have stimulatory effects, while higher doses may lead to toxicity, a response known as hormesis. Low ethanol concentrations occur naturally in the environment, particularly in fermenting fruits and flower nectar, where pollinators such as honey bees may encounter it. This study aimed to investigate the potential hormetic effects of low-level ethanol consumption on honey bees. Bees were divided into three groups: one provided with only sucrose solution, one both with sucrose and 0.5% ethanol in sucrose, and one with only 1% ethanol in sucrose. The bees were exposed to these diets for 14 days, and their performance was assessed through survivorship, flight endurance, body mass, lipid content, and trehalose and ethanol levels in the haemolymph. The results showed no significant differences in most parameters between the groups. However, bees constantly exposed to 1% ethanol had slightly higher trehalose levels compared to the control group, suggesting a possible adaptive response to ethanol exposure. Ethanol levels in the haemolymph differed significantly between groups, with bees exposed to ethanol showing its detectable levels in their system. While no clear hormetic effects were observed in terms of improved performance, the elevated trehalose levels in bees constantly exposed to 1% ethanol may indicate adaptations protecting from ethanol-induced damage. The study provides insights into how honey bees tolerate low-level ethanol exposure and highlights the need for further research on the ecological implications of ethanol consumption in pollinators.