Lack of worker reproduction in the giant honey bee Apis dorsata Fabricius

Abstract

Worker policing (any behavior performed by workers that reduces reproduction by other workers) via egg eating has been observed in three species of honey bee (Apis mellifera, A. cerana, and A. florea). The maternity of drones of the giant honey bee A. dorsata (n = 660) was determined using DNA microsatellite analysis. None carried markers from the queen's mates indicating that none was a worker's son. In addition, dissection of 1,902 workers from 8 colonies showed that none had activated ovaries indicating that worker sterility is usual. Worker policing behavior involves costs when police workers make errors: removing eggs laid by a queen or failing to remove worker-laid eggs. We develop a model that examines the effect of these costs on the acceptance threshold of eggs. The model shows that costs may be reduced by any cues that help police workers distinguish worker-laid and queen-laid eggs. Once such cue may be the use of unique cells for rearing drones and workers. Unlike other Apis, A. dorsata rear both workers and drones in the same-size cells with the drone brood scattered among worker brood. Thus, the ability of A. dorsata workers to detect and eliminate (police) worker-laid eggs may be associated with higher costs than in other species. Our model suggests that these higher costs may select for a more permissive egg-acceptance threshold, because of the costs of erroneously removing queen-laid eggs, leading to greater worker reproduction. However our empirical results suggest that worker reproduction is very low in the species, suggesting that worker policing is efficient and that police workers have no difficulty in distinguishing queen-laid and worker-laid eggs.