Seasonal Variation in Abundance and Thermal Tolerance of Bumble Bees (Bombus) in Grand Teton National Park

Bumble bee (genus Bombus) emergence time is affected by temperature, elevation, and is correlated with flowering time of diverse plants. Critical thermal limits of bumble bees is effected by elevation, latitude, and genetics. However, little research has been done examining variation in thermal tolerance of Bombus at high elevation throughout their active season. I sampled for abundance of several species of Bombus in Grand Teton National Park throughout the summer and tested for critical thermal limits. I found that bumble bees begin emerging in late May but didn't appear in large numbers until late July. The most abundant species were B. mixtus, B. flavifrons, and B. bifarius with B. mixtus emerging the earliest. The critical minimum temperature did not vary between these three species while B. mixtus had a lower critical maximum temperature than B. flavifrons, and B. bifarius. This suggests a possible connection between emergence time and thermal tolerance that could be explored in further studies.