Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Karen Kester

Second Advisor

Salvatore Agosta


Native bees are only recently gaining attention for the extent to which they aid in pollination and ecosystem services. These services are threatened by predictions of warming temperatures if bees are not able to respond. Voltinism - the number of generations produced annually- can strongly influence thermal conditions experienced by both developing and adult bees based on emergence strategies for each voltinism type. Differences in experienced thermal conditions brought on by climate change could therefore affect upper thermal limits (UTL) in bees. This study observes UTLs across a foraging season within and among native bee species vi to elucidate the potential response by bees to a warming climate. Bees were collected across the field season in Central Virginia and subjected to dynamic ramping trials to determine the fatal knockdown point (FKP). Results show in both univoltine and multivoltine bees an increase in upper thermal tolerance as the foraging season progresses (in quadratic and linear fashions respectively). Within multivoltine bees, FKP was related to nest type; with stem-nesting bees having the highest FKP. All average FKPs were higher than historic air temperatures of the study region, but within several degrees of the highest recorded maximum temperature. The diversity of responses in native bees provides evidence for both genetic and plastic responses to extreme temperature. While bees still face a potential myriad of other issues brought on by climate change, the observed increases in FKP across warming temperatures offer tentatively hopeful predictions for limited physiological responses in native bees to a warming climate


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Available for download on Tuesday, May 07, 2024


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