TY - JOUR
T1 - Flying, nectar-loaded honey bees conserve water and improve heat tolerance by reducing wingbeat frequency and metabolic heat production
AU - Glass, Jordan R.
AU - Burnett, Nicholas P.
AU - Combes, Stacey A.
AU - Weisman, Ethan
AU - Helbling, Alina
AU - Harrison, Jon F.
N1 - Publisher Copyright:
© 2024 the Author(s).
PY - 2024
Y1 - 2024
N2 - Heat waves are becoming increasingly common due to climate change, making it crucial to identify and understand the capacities for insect pollinators, such as honey bees, to avoid overheating. We examined the effects of hot, dry air temperatures on the physiological and behavioral mechanisms that honey bees use to fly when carrying nectar loads, to assess how foraging is limited by overheating or desiccation. We found that flight muscle temperatures increased linearly with load mass at air temperatures of 20 or 30°C, but, remarkably, there was no change with increasing nectar loads at an air temperature of 40°C. Flying, nectar-loaded bees were able to avoid overheating at 40°C by reducing their flight metabolic rates and increasing evaporative cooling. At high body temperatures, bees apparently increase flight efficiency by lowering their wingbeat frequency and increasing stroke amplitude to compensate, reducing the need for evaporative cooling. However, even with reductions in metabolic heat production, desiccation likely limits foraging at temperatures well below bees' critical thermal maxima in hot, dry conditions.
AB - Heat waves are becoming increasingly common due to climate change, making it crucial to identify and understand the capacities for insect pollinators, such as honey bees, to avoid overheating. We examined the effects of hot, dry air temperatures on the physiological and behavioral mechanisms that honey bees use to fly when carrying nectar loads, to assess how foraging is limited by overheating or desiccation. We found that flight muscle temperatures increased linearly with load mass at air temperatures of 20 or 30°C, but, remarkably, there was no change with increasing nectar loads at an air temperature of 40°C. Flying, nectar-loaded bees were able to avoid overheating at 40°C by reducing their flight metabolic rates and increasing evaporative cooling. At high body temperatures, bees apparently increase flight efficiency by lowering their wingbeat frequency and increasing stroke amplitude to compensate, reducing the need for evaporative cooling. However, even with reductions in metabolic heat production, desiccation likely limits foraging at temperatures well below bees' critical thermal maxima in hot, dry conditions.
KW - evaporative water loss
KW - flight energetics
KW - flight kinematics
KW - honey bee
KW - thermoregulation
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U2 - 10.1073/pnas.2311025121
DO - 10.1073/pnas.2311025121
M3 - Article
C2 - 38227669
AN - SCOPUS:85182610719
SN - 0027-8424
VL - 121
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 4
M1 - e2311025121
ER -