Description:	Bumble bee populations across the globe are experiencing substantial declines due to climate change, with major consequences for pollination services in both natural and agricultural settings. Using an economically-important species, Bombus impatiens, we explored the physiological mechanisms that may cause susceptibility to extreme heat events. We tested the hypothesis that heat exposure limits the activity of the pentose phosphate pathway (PPP) – a parallel pathway to glycolysis that can use nectar sugar to generate antioxidant potential and combat oxidative stress. Using isotopically-labeled glucose, we tracked PPP activity in B. impatiens at rest, during exercise, and during a post-exercise recovery period under two different temperature regimes (22ºC and 32ºC). We found that the PPP is routinely used by B. impatiens at moderate temperatures, but that its activity is markedly reduced when ATP demands are high, such as during periods of exercise and heat exposure. We also exposed B. impatiens to either 22ºC or 32ºC for 5 hours and assessed levels of oxidative damage (lipid peroxidation, protein carbonyls) and antioxidant potential (reduced (GSH) and oxidized (GSSG) glutathione concentrations). Interestingly, bees exhibited little oxidative damage after the thermal exposure, but we found a lower GSH:GSSG ratio in 32ºC-exposed bees, reflecting lower antioxidant potential. Overall, our study demonstrates that acute heat stress severely limits PPP activity and may constrain antioxidant potential in B. impatiens. The repeated attenuation of this pathway in a warming climate may have more severe physiological consequences for this species, with potential implications for pollination services across North America.
Authors:	Rossi, Giulia; McMaster University; University of Toronto; 0000-0002-4812-8869
Keywords:	glucose oxidative stress climate change thermal stress pollinators metabolic pathways
Field of Research:	Biological sciences > Animal physiology > Animal physiology, environmental stress
Publication Date:	2024-03-26
Publisher:	Federated Research Data Repository / dépôt fédéré de données de recherche
Funder:	Natural Sciences and Engineering Research Council of Canada
URI:	https://doi.org/10.20383/103.0919
Geographic Coverage:	Place Name Southern Ontario Province / Province / Territory Ontario Territory   Country Canada