Bees remain heat tolerant after acute exposure to desiccation and starvation

Authors: GONZALEZ, VICTOR - University Of Kansas; RANCHER, WESLEY - University Of Oregon; VIGIL, RYLEE - Samford University, School Of Public Health, Department Of Nutrition And Dietetics; GARINO-HEISEY, ISABELLA - Hanover College; Oyen, Kennan; TSCHEULIN, THOMAS - University Of Aegean; PETANIDOU, THEODORA - University Of Aegean; HRANITZ, JOHN - Bloomsburg University; BARTHELL, JOHN - University Of Oklahoma

Submitted to: Indian Journal of Experimental Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2024
Publication Date: 12/19/2024
Citation: Gonzalez, V.H., Rancher, W., Vigil, R., Garino-Heisey, I., Oyen, K.J., Tscheulin, T., Petanidou, T., Hranitz, J.M., Barthell, J.F. 2024. Bees remain heat tolerant after acute exposure to desiccation and starvation. Indian Journal of Experimental Biology. 227(24). Article 249216. https://doi.org/10.1242/jeb.249216.
DOI: https://doi.org/10.1242/jeb.249216

Interpretive Summary: Insects face numerous challenges including pesticide exposure, extreme temperatures, drought, and starvation. Most studies consider the impact of these stressors individually, but in the environment insects are likely to experience multiple stressors such as heat and drought simultaneously. Here we measured the impact of both dehydration and extreme temperature on two pollinators. We found that exposure to dehydration had little impact on a bee's ability to survive stressful temperatures. These findings suggest that multiple stressors does not necessarily lead to reduced performance in some bees.

Technical Abstract: Organisms may face simultaneously thermal, desiccation, and nutritional stresses under climate change. Understanding the potential effects arising from the interactions among these stressors is relevant for predicting organisms’ responses to climate change and for developing effective conservation strategies. Using both dynamic and static protocols, we assessed for the first time how sublethal desiccation exposure (at 16.7, 50.0, and 83.3% of LD50) impacts the heat tolerance of foragers from two social bee species found on the Greek island of Lesvos: the managed European honey bee Apis mellifera and the wild, ground-nesting sweat bee, Lasioglossum malachurum. In addition, we explored how a short-term starvation period (24 h) followed by a moderate sublethal desiccation exposure (50% of LD50) influences honey bees’ heat tolerance. We found that neither the critical thermal maximum (CTMax) nor the time to heat stupor was significantly impacted by sublethal desiccation exposures in both bee species. A short starvation period followed by a moderate sublethal desiccation exposure also did not affect the average CTMax estimate, but it did increase its variance. Our results suggest that sublethal exposures of these environmental stressors may not always lead to significant changes in bees’ heat tolerance and, thus, they are unlikely to significantly increase their vulnerability to rapid temperature changes during extreme weather events, such as heat waves. However, the increase in CTMax variance suggests greater variability in individual responses to temperature stress under climate change, which may impact colony-level performance. The effect of these stressors on solitary species remained to be assessed.