Meeting Abstract
When honeybee colonies reproduce, about half of the workers (~10,000 bees) and a queen fly from the nest and form a cluster on a nearby tree branch. The swarm remains here for a period of hours to days while scouts search for suitable nest sites. The cluster of bees is exposed to fluctuating ambient temperatures and changes its collective morphology to maintain stable core temperature. Previous work has shown that the cluster reduces its surface area and porosity when exposed to cool temperatures to conserve heat. At high temperatures, the cluster expands to dump heat to the environment. However, little is known about the control and dynamics of this morphing process or how the cluster balances mechanical stability and thermal stability. We placed honeybee swarms in a temperature controlled room and exposed them to various rates of heating and cooling. We used a custom 3D scanner to reconstruct the shape of the swarm every few minutes during these temperature cycling trials. This allows us to accurately quantify how the swarm changes its volume, surface area, density and other morphological characteristics in response to finely controlled temperature fluctuations. Preliminary results suggest that the cluster uses different strategies when responding to rapid temperature fluctuations than it does in response to slow fluctuations. In addition, the cluster is able to contract more rapidly than it can expand. This rate-dependence and hysteresis is likely attributed to packing and unpacking dynamics and mechanical constraints associated with breaking and reforming linkages while supporting a load.
