It’s getting hot out here: Thermal traits of bumble bee species in the face of climate change

Bumble bees provide vital services to natural and agricultural landscapes, making them integral to terrestrial ecosystems. Populations of bumble bees are declining for a myriad of reasons, threatening the stability of the planet’s ecology and our human food supply. Anthropogenic climate change has been identified as one possible cause of their decline. Despite this concern, we lack basic information on the thermal physiology of different species. This knowledge is important because bumble bee species vary in their susceptibility to decline, with some species being vulnerable while others resistant. Our study aims to explore evidence of thermal trait differences in two bumble bee species that may help explain variability in their population dynamics. We hypothesize that less stable species of bumble bees lack the ability to acclimate to temperature, making them more susceptible to climate change. Two species, Bombus impatiens and Bombus auricomus, were collected from the field and subjected to current and future warming climate conditions. We used infrared thermal imaging to measure rewarming ability after chill coma pre-acclimation, post-acclimation, and post-treatment. Preliminary results suggest species differences in rewarming physiology and a lack of acclimation ability in both species possibly make them susceptible to future climate change. The results will aid in identifying bumble bee species resistant to climate change while identifying species of concern that may require translocations to other climatic regions. This work has multiple implications for bumble bees including modeling of future population declines and providing important baseline information on species’ traits, furthering their conservation.