Disruption of Collective Behavior Correlates with Reduced Interaction Efficiency

Group-living organisms commonly engage in collective behavior to respond to an ever-changing environment. How individuals utilize local information to produce such large-scale, cohesive behaviors and the factors that impact these dynamics are of high research interest, especially since animals face increasingly challenging environmental conditions due to pollution and climate change. Western honeybees (Apis mellifera) are highly social insects that depend on the tight coordination of many individuals to ensure optimum colony function. We used fanning, a collective thermoregulatory behavior in honeybees that depends on both social and thermal contexts, as a case study for collective behavior. To elucidate the mechanisms behind the coordination of fanning, we used oxytetracycline, an antibiotic historically used in apiculture and known environmental pollutant that impairs bee physiology and behavior. Specifically, we hypothesized that oxytetracycline will interfere social interactions which will lead to a disruption in honeybee fanning behavior. We found that longer exposure to antibiotics decreases fanning in honeybees. Using an automated tracking software, we show that antibiotic treatment lowers the number of interactions bees have despite increasing average movement velocity, thereby impeding the social dynamics within these small bee groups. Our results contribute strong evidence that interactions between individuals may drive the collective thermoregulatory fanning response in honeybees. This work emphasizes the importance of understanding the social mechanisms that underlie critical collective animal coordination and how the effects of a common environmental pollutant on an individual can scale to affect populations.