Characterization of honey bee sensitivity to ethanol vapor and its correlation with aggression

Several candidate genes identified from quantitative trait loci (QTL) for defensive behavior in honey bees (Apis mellifera L.) are homologous to genes known to influence ethanol sensitivity in other organisms. To investigate this possible link between aggression/defense and ethanol sensitivity, assays were developed to evaluate ethanol vapor responses in worker bees from a low-defensive (gentle) colony and a high-defensive colony. Defensive workers exhibited characteristic signs of ethanol-induced sedation significantly faster than gentle workers upon exposure to ethanol vapor. Backcross workers displayed ethanol sensitivity intermediate to the parental defensive and gentle lines, suggesting a genetic basis for the trait. Workers were screened with sequence-tagged site markers linked to three defensive-behavior QTL and their genotypes were tested for associations with ethanol sensitivity. There were no significant associations, indicating that the defensive QTL were not having a pleiotropic effect on ethanol sensitivity. It is possible that gentle-source alleles at these QTL are dominant with respect to sensitivity, one or more of these QTL were not segregating in the backcross family, or unidentified QTL are influencing alcohol sensitivity.