Ontogeny of division of labor in a facultatively eusocial sweat bee Megalopta genalis

Abstract

In eusocial nests, colony task are divided among queens and workers, but how this division of labor develops is unknown for most species. We compared division of labor and aggressive behavior among queens and workers in the facultatively eusocial bee, Megalopta genalis, using nests with established queen-worker pairs and nests in which the incipient worker had recently emerged. We find that the majority of aggression is directed from queens toward workers in both incipient and established relationships. Established workers forage and perform trophallaxis as donors more frequently than queens, but both queens and workers perform trophallaxis as donors when workers are young. Queens spend significantly more time nest guarding than incipient and established workers, perhaps because older workers spend more time foraging and incipient workers spend significantly more time in cells than do queens. Our results show that the development of worker behavior involves dynamic temporal changes in task performance among queens and workers during the 10 days after worker emergence. During this establishment period, queens engage in maternal care by feeding their daughters, but are also aggressive toward them. This may be a mechanism by which queens coerce their daughters into becoming non-reproductive workers.