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Gonzalez VH, Herbison N, Robles Perez G, Panganiban T, Haefner L, Tscheulin T, Petanidou T, Hranitz J. Bees display limited acclimation capacity for heat tolerance. Biol Open 2024; 13:bio060179. [PMID: 38427330 PMCID: PMC10979511 DOI: 10.1242/bio.060179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 02/28/2024] [Indexed: 03/02/2024] Open
Abstract
Bees are essential pollinators and understanding their ability to cope with extreme temperature changes is crucial for predicting their resilience to climate change, but studies are limited. We measured the response of the critical thermal maximum (CTMax) to short-term acclimation in foragers of six bee species from the Greek island of Lesvos, which differ in body size, nesting habit, and level of sociality. We calculated the acclimation response ratio as a metric to assess acclimation capacity and tested whether bees' acclimation capacity was influenced by body size and/or CTMax. We also assessed whether CTMax increases following acute heat exposure simulating a heat wave. Average estimate of CTMax varied among species and increased with body size but did not significantly shift in response to acclimation treatment except in the sweat bee Lasioglossum malachurum. Acclimation capacity averaged 9% among species and it was not significantly associated with body size or CTMax. Similarly, the average CTMax did not increase following acute heat exposure. These results indicate that bees might have limited capacity to enhance heat tolerance via acclimation or in response to prior heat exposure, rendering them physiologically sensitive to rapid temperature changes during extreme weather events. These findings reinforce the idea that insects, like other ectotherms, generally express weak plasticity in CTMax, underscoring the critical role of behavioral thermoregulation for avoidance of extreme temperatures. Conserving and restoring native vegetation can provide bees temporary thermal refuges during extreme weather events.
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Affiliation(s)
- Victor H. Gonzalez
- Undergraduate Biology Program and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045, USA
| | - Natalie Herbison
- Undergraduate Biology Program and Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045, USA
| | | | - Trisha Panganiban
- Department of Biological Sciences, California State University, Los Angeles, CA, 35229, USA
| | - Laura Haefner
- Biology Department, Waynesburg University, PA, 47243, USA
| | - Thomas Tscheulin
- Laboratory of Biogeography and Ecology, Department of Geography, University of the Aegean, University Hill, Mytilene, 81100, Greece
| | - Theodora Petanidou
- Laboratory of Biogeography and Ecology, Department of Geography, University of the Aegean, University Hill, Mytilene, 81100, Greece
| | - John Hranitz
- Department of Biology, Commonwealth University of Pennsylvania, Bloomsburg, 17815 PA, USA
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Gonzalez VH, Manweiler R, Smith AR, Oyen K, Cardona D, Wcislo WT. Low heat tolerance and high desiccation resistance in nocturnal bees and the implications for nocturnal pollination under climate change. Sci Rep 2023; 13:22320. [PMID: 38102400 PMCID: PMC10724170 DOI: 10.1038/s41598-023-49815-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2023] [Accepted: 12/12/2023] [Indexed: 12/17/2023] Open
Abstract
Predicting insect responses to climate change is essential for preserving ecosystem services and biodiversity. Due to high daytime temperatures and low humidity levels, nocturnal insects are expected to have lower heat and desiccation tolerance compared to diurnal species. We estimated the lower (CTMin) and upper (CTMax) thermal limits of Megalopta, a group of neotropical, forest-dwelling bees. We calculated warming tolerance (WT) as a metric to assess vulnerability to global warming and measured survival rates during simulated heatwaves and desiccation stress events. We also assessed the impact of body size and reproductive status (ovary area) on bees' thermal limits. Megalopta displayed lower CTMin, CTMax, and WTs than diurnal bees (stingless bees, orchid bees, and carpenter bees), but exhibited similar mortality during simulated heatwave and higher desiccation tolerance. CTMin increased with increasing body size across all bees but decreased with increasing body size and ovary area in Megalopta, suggesting a reproductive cost or differences in thermal environments. CTMax did not increase with increasing body size or ovary area. These results indicate a greater sensitivity of Megalopta to temperature than humidity and reinforce the idea that nocturnal insects are thermally constrained, which might threaten pollination services in nocturnal contexts during global warming.
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Affiliation(s)
- Victor H Gonzalez
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045, USA.
| | - Rachel Manweiler
- Department of Ecology and Evolutionary Biology, University of Kansas, Lawrence, KS, 66045, USA
| | - Adam R Smith
- Department of Biological Sciences, George Washington University, Washington, District of Columbia, USA
| | - Kennan Oyen
- Animal Disease Research Unit, Agricultural Research Service, United States Department of Agriculture, Pullman, WA, 99164, USA
| | - David Cardona
- Smithsonian Tropical Research Institute, Panama, Republic of Panama
| | - William T Wcislo
- Smithsonian Tropical Research Institute, Panama, Republic of Panama
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