Meeting Abstract
Social insects are capable of collectively responding to environmental perturbations in the absence of central control. A key challenge for studying the health of social insects such as bees and the ecosystem services they provide is understanding how proximate effects of environmental stressors on individual workers impact these collective behaviors. Here, we study the temporal dynamics of worker behavior and their disruption by a common neonicotinoid pesticide in bumblebee (Bombus impatiens) colonies. Using an automated system to continuously monitor behavior of individual workers from multiple colonies in parallel, we show that (a) worker behavior shows strong and stable circadian dynamics within bumblebee colonies, and that (b) exposure to field-realistic concentrations of imidacloprid (~6 ng/g) disrupts key aspects of worker behavior (including nursing), but that the impacts are variable over the circadian cycle, with the strongest effects occurring at night. We find a similar pattern for collective thermoregulation performance in colonies exposed to imidacloprid in the field. Finally, using a combination of modeling approaches and automatic thermal tracking of individual workers, we examine the role of socially-modulated arousal in driving these colony-level behavioral dynamics. Overall, our results show that neonicotinoid pesticides impact worker behavior and colony performance through complex interactions with the environment, and highlight the need for a more complete understanding of the physiological and neurobiological underpinnings of collective behavior in bumblebees.
