The risk posed by exposure to pesticides through beeswax to adult western honey bees (Apis mellifera).

Abstract

In western honey bee (Apis mellifera) colonies, beeswax can help manage bee exposure to lipophilic compounds via absorption, making the compounds bio-unavailable. However, trapped chemicals may be slowly released into the nest environment, posing risks to bees through chronic exposure. Due to their lipophilic properties (logP > 1), many insecticides used in agriculture or for Varroa destructor control in the honey bee nest can accumulate in beeswax. Via in vitro cage assays, we determined the LC50 values of six pesticides (coumaphos, amitraz, acrinathrin, chlorpyrifos, chlorfenvinphos, and bifenthrin) frequently detected in beeswax and determined if the concentrations found in beeswax pose a risk to honey bees. The LC50 values on adult bees exposed to these pesticides in beeswax did not follow the same ranking as their topical or oral LC50 values reported in the literature. The observed LC50 values (mg/g of beeswax) were: Amitraz (1.31), chlorfenvinphos (0.731), acrinathrin (0.504), bifenthrin (0.237), coumaphos (0.104), and chlorpyrifos (0.012). Based on mean beeswax residues of these compounds reported in the literature, the relative risk ranking to honey bees, from greatest to lowest risk, was: Coumaphos > acrinathrin > chlorpyrifos > amitraz > chlorfenvinphos > bifenthrin. Based on maximum beeswax residues reported in the literature, the relative risk ranking was: Coumaphos > chlorpyrifos > amitraz > acrinathrin > chlorfenvinphos > bifenthrin. Our data showed that the compounds tested do not appear to pose a significant risk to honey bee survival at concentrations in beeswax reported in the literature.