Genotypic constraints on plasticity for corpse removal in honey bee colonies

The hypothesis that plasticity in honey bee, Apis mellifera, division of labour can be influenced by genotypic differences in worker behaviour was tested in colonies with electrophoretically distinct subfamilies. Undertaking behaviour (removal of dead bees from the nest) was studied because it is possible to vary the level of corpse-removal stimuli in a precise way. Subfamilies of workers with low thresholds of response to corpses were predicted to be overrepresented as undertakers relative to subfamilies with higher thresholds, and this difference was predicted to be reduced under higher stimulus conditions (more corpses). Allozyme analyses revealed that the genotypic composition of the undertaker group that responded to a low stimulus was significantly different from the composition of the whole colony. Contrary to predictions, the genotypic composition of the undertaker group that responded to a high stimulus was just as different from the composition of the whole colony. A second experiment examined the effects of undertaker depletion (about 2-3% of each colony’s population): there were significant decreases in rates of corpse removal for several days following the removal of undertakers. These results suggest that strong genetic influences on the likelihood that an individual worker will perform a particular task, such as undertaking, may constrain a colony’s ability to respond to changing conditions.