Physical Interactions Drive Collective Thermoregulatory Behavior in Honey Bees

Social animals can coordinate complex behaviors, which can affect massive change on the environment. Within groups, individuals can sense the environment and communicate that information with others. Direct contact, like physical touch, is a key method of communication among social animals, and may be a mechanism to facilitate the coordination of collective behaviors that buffer environmental change. Here, we use a collective thermoregulatory fanning behavior in honey bees (Apis mellifera) to test the hypothesis that direct physical contact is necessary to perform this behavior. By modulating their ability to engage in physical contact, we establish that honey bee workers must touch each other to coordinate the fanning response. We then manipulated social density by changing the physical space the bees occupied to modulate likelihood of contact and found that in high social densities, honey bees are more likely to fan. Using video tracking, we then verified that bees in higher social density indeed have more direct physical interactions. This work identifies a mechanism of communication and potentially information synthesis in an ecologically relevant collective behavior. By understanding the ways in which animals communicate, we may be able to pinpoint the mechanisms of resilience that social insects evolved to manage a changing world.