Poster: Body size nor sex influence critical thermal limits in a solitary spring bee

Colletes inaequalis is a common, ground-nesting solitary species that is among the first bees to emerge during North American springtime. The species is univoltine and, as in most solitary bees, males emerge first and are smaller than the females. Despite its value as a wild pollinator of early spring wild plants and potential crop pollinator, key aspects of the thermal ecology of C. inaequalis remain unexplored. We addressed this knowledge gap by assessing the lower (CT_Min) and upper (CT_Max) critical thermal limits and chill coma recovery. In addition, we examined the influence of body size (fresh weight and intertegular distance, ITD) and sex on these thermal traits. To provide context, we compared these thermal traits with those of the European honey bee, a similarly sized species frequently foraging during early spring at our locale. We found that critical thermal limits did not differ between sexes and that neither CT_Min nor CT_Max increased with increasing ITD. Fresh body weight did not impact chill coma recovery time. Colletes inaequalis tolerated lower temperatures and recovered much faster from chill coma compared to honey bees, which highlights its ability to withstand lower temperatures.