Colony performance in honeybees (Apis mellifera capensis Esch.) depends on the proportion of subordinate and dominant workers

Abstract

Individual worker dominance correlated with trophallactic behavior, which affects several social behaviors related to colony fitness, shows a high genetic variance in worker bees. In a bioassay we tested trophallactic behavior of workers and selected dominant (receiving) and subordinate worker bees (offering) of Apis mellifera capensis to establish genetic lines of both kinds. Queenright test colonies were experimentally composed of 100% subordinate workers, 100% dominant workers, 50% dominant plus 50% subordinate workers, and 100% hybrid workers from the two genetic lines. The chosen test parameters were brood-rearing, comb building and hoarding behavior. In all cases, the colonies of pure subordinate bees showed the best colony performance, whereas the colonies composed of only dominant bees were nearly unproductive. The mixed colonies (50% dominant + 50% subordinate) ranked in the middle and did not differ significantly from the hybrid colonies. The results indicate that colony performance under queenright conditions depends on the proportion of subordinate workers. This result supports a selection model based on the combination of individual selection and on group selection at the colony level, which explains the high genetic variance of individual worker reproduction.