Moving without a purpose: an experimental study of swarm guidance in the Western honey bee (Apis mellifera Linnaeus)

Abstract

During reproductive swarming, honey bee scouts perform two very important functions. Firstly, they find new nesting locations and return to the swarm cluster to communicate their discoveries. Secondly, once the swarm is ready to depart, informed scout bees act as guides, leading the swarm to its final destination. We have previously hypothesised that the two processes, selecting a new nest site and swarm guidance, are tightly linked in honey bees. When swarms can be laissez faire about where they nest, reaching directional consensus prior to lift off seems unnecessary. If, in contrast, it is essential that the swarm reaches a precise location, either directional consensus must be near unanimous prior to swarm departure or only a select subgroup of the scouts guide the swarm. Here, we tested experimentally whether directional consensus is necessary for the successful guidance of swarms of the Western honey bee Apis mellifera by forcing swarms into the air prior to the completion of the decision-making process. Our results show that swarms were unable to guide themselves prior to the swarm reaching the pre-flight buzzing phase of the decision-making process, even when directional consensus was high. We therefore suggest that not all scouts involved in the decision-making process attempt to guide the swarm.

Sneeze to leave: African wild dogs (Lycaon pictus) use variable quorum thresholds facilitated by sneezes in collective decisions

“…This ensures that a minimum number of individuals (the actual quorum number) are ready to move off [4]. Past research in meerkats, Suricata suricatta, for example, has found that a quorum of at least two and usually three meerkats emitting 'moving calls' are necessary for the whole group to move to a new foraging patch, and 'piping signals' in honeybees, Apis mellifera [6], and 'trills' in white faced capuchin monkeys, Cebus capucinus, [7] are required for collective departures to occur.…”

Different bees, different needs: how nest-site requirements have shaped the decision-making processes in homeless honeybees (Apisspp.)

“…If, on the other hand, only bees that have experienced the quorum act as swarm guides, then none of the swarms in their experiments would have been able to fly. Makinson & Beekman [35] concluded that only bees that have directly experienced the quorum at the nest site guide the swarm, thereby ensuring that different groups of bees (those that have visited different potential nest sites) do not guide the flying swarm in different directions. We then need to assume that in the particular swarm Lindauer studied (see above) two nest sites reached a quorum simultaneously.…”

“…They also needed a means for precise guidance of the swarm in flight towards that site. Because a vectorial consensus is insufficient to achieve these goals [35], cavity-nesting bees need to reach a near-unanimous decision prior to the swarm taking to the air. And because consensus is so important to A. mellifera, this species has evolved a 'stop-signal', aimed at silencing bees dancing for the non-chosen site [33].…”

“…Because the preferred nest sites were in opposite directions and because each was supported by roughly the same number of bees, the swarm was unable to fly to either site and reclustered. Makinson & Beekman [35] investigated more precisely if A. mellifera swarms indeed require consensus in the sites danced for prior to lift-off, by forcing swarms to the air before the bees had been through the complete process described above. Swarms were forced to become airborne when the total number of bees dancing was similar to the number of bees dancing at the time of lift-off in non-manipulated swarms, but prior to the onset of the piping signal and while bees were dancing for multiple sites.…”

“…A swarm could either be guided by all bees actively involved in the decision-making process (all bees dancing prior to the swarm taking to the air), or only by those that have experienced the quorum. If all bees involved guide the swarm once airborne, Makinson & Beekman's [35] experimental swarms would have flown into the general direction of all dances present prior to liftoff. If, on the other hand, only bees that have experienced the quorum act as swarm guides, then none of the swarms in their experiments would have been able to fly.…”