Effects of natural infections and environmental conditions on the thermoregulatory capacity of wild bumble bees (Bombus impatiens)

Thermoregulation is a vital trait for bumble bee colony survival, but it is an energetically costly trait. As response mechanisms to environmental stress are also energetically costly, it is likely that stressors will have a negative impact on thermoregulation, due to resource allocation trade-offs. Some stressors, such as pesticides and being immune challenged, have demonstrated negative impacts on thermoregulatory capacities. However, these studies involved commercially reared colonies and were in controlled conditions. Bumble bees in the field will experience more variable conditions such as resource scarcity, changing environments, and higher temperature extremes. The factors that impact wild bumble bee thermoregulation are poorly understood. We tested if body mass, location, and temperature when collected were important factors in determining thermoregulatory capacity in Bombus impatiens. We collected workers at four different locations in central Pennsylvania and utilized chill coma recovery as a proxy of thermoregulatory capacity. Body mass, ambient temperature, and location were not important predictors of how individuals recovered from chill coma. However, there were striking similarities to our previous work, where chill coma recovery is negatively impacted when immune challenged. In the future, we plan to screen these bees for infections and see if this help could explain the variation found within our results.