SOCIAL SYNCHRONIZATION OF THE ACTIVITY RHYTHMS OF HONEYBEES WITHIN A COLONY

Colonies and isolated bees of the Cape honeybee, Apis mellifera capens is Esch., were observed for evidence of circadian rhythmicity under co nstant conditions. It was found that colonies develop free-running act ivity rhythms in self-selected light-dark cycles, which are slightly s horter than 24 h. The periods of the activity rhythms of individual is olated bees were longer than 24 h in self-selected light-dark and cons tant light, while they were shorter than 24 h in constant darkness. A greater variability in period was found in the isolated bees than in t he colonies. When the rhythms of colonies and individual bees from the se colonies were measured simultaneously, the activities of the isolat ed bees drifted with respect to that of the colonies, their period bei ng either longer or shorter than that of their own colony. After 12 da ys of isolation of individual bees from their colony, all coincidence between the phases of the two rhythms was lost. We conclude that the p eriods of common activity and common rest of the bees within a colony result from a mutual (social) synchronization of the rhythms of the in dividual bees.