How does a swarm of the giant Asian honeybee Apis dorsata reach consensus? A study of the individual behaviour of scout bees
The last few years have seen a renewed interest in the mechanisms behind nest-site selection in honeybees. Most studies have focused on the cavity-nesting honeybee Apis mellifera, but more recently studies have included the open-nesting A. florea. Amongst species comparisons are important if we want to understand how the process has been adapted over evolutionary time to suit the particular species’ nest-site requirement. Here, we describe the behaviour of scout bees of the giant Asian honeybee A. dorsata on three artificially created swarms to determine the mechanisms used to collectively decide on a location to move to, either in the same environment (nest-site selection) or somewhere further afield (migration). In all swarms, scouts’ dances converged on a general direction prior to lift-off and this direction corresponded to the direction that swarms flew. Scouts from one swarm danced for sites that were far away. These dances did not converge onto a specific distance, implying they were migration dances. Dances for different sites differed in the number of circuits per dance suggesting that A. dorsata scouts make an assessment of site quality. Similarly to A. florea, but in contrast to A. mellifera, A. dorsata scouts did not reduce dance duration after repeated returns from scouting flights. We found that many scouts that dance for a non-preferred location changed dance location during the decision-making process after following dances for the consensus direction. We conclude that the consensus-building process of A. dorsata swarms relies on the interaction of scout bees on the swarm.