Department of Entomology, Center for Pollinator Research, Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, State College, PA 16802, USA.
Department of Biology, Center for Pollinator Research, Pennsylvania State University, University Park, PA 16802, USA.
J Exp Biol. 2023 Sep 1;226(17). doi: 10.1242/jeb.245924. Epub 2023 Sep 12.
Climate change poses a threat to organisms across the world, with cold-adapted species such as bumble bees (Bombus spp.) at particularly high risk. Understanding how organisms respond to extreme heat events associated with climate change as well as the factors that increase resilience or prime organisms for future stress can inform conservation actions. We investigated the effects of heat stress within different contexts (duration, periodicity, with and without access to food, and in the laboratory versus field) on bumble bee (Bombus impatiens) survival and heat tolerance. We found that both prolonged (5 h) heat stress and nutrition limitation were negatively correlated with worker bee survival and thermal tolerance. However, the effects of these acute stressors were not long lasting (no difference in thermal tolerance among treatment groups after 24 h). Additionally, intermittent heat stress, which more closely simulates the forager behavior of leaving and returning to the nest, was not negatively correlated with worker thermal tolerance. Thus, short respites may allow foragers to recover from thermal stress. Moreover, these results suggest there is no priming effect resulting from short- or long-duration exposure to heat - bees remained equally sensitive to heat in subsequent exposures. In field-caught bumble bees, foragers collected during warmer versus cooler conditions exhibited similar thermal tolerance after being allowed to recover in the lab for 16 h. These studies offer insight into the impacts of a key bumble bee stressor and highlight the importance of recovery duration, stressor periodicity and context on bumble bee thermal tolerance outcomes.
气候变化对世界各地的生物构成威胁，耐寒物种（如大黄蜂属（Bombus spp.））面临着特别高的风险。了解生物如何应对与气候变化相关的极端高温事件，以及哪些因素可以提高生物的适应能力或使其为未来的压力做好准备，可以为保护行动提供信息。我们研究了不同环境（持续时间、周期性、有无食物以及实验室与野外）下的热应激对大黄蜂（Bombus impatiens）生存和耐热性的影响。我们发现，长时间（5 小时）的热应激和营养限制与工蜂的存活率和耐热性呈负相关。然而，这些急性应激源的影响并不持久（处理组之间的热耐受性在 24 小时后没有差异）。此外，更接近离开和返回巢穴的觅食者行为的间歇性热应激与工蜂的耐热性没有负相关。因此，短暂的休息可能使觅食者能够从热应激中恢复。此外，这些结果表明，短时间或长时间暴露于热应激不会产生启动效应——蜜蜂在随后的暴露中对热的敏感性仍然相同。在野外捕获的大黄蜂中，在温暖条件下采集的觅食者与在凉爽条件下采集的觅食者在实验室中恢复 16 小时后表现出相似的耐热性。这些研究深入了解了大黄蜂的一个关键应激源的影响，并强调了恢复时间、应激源周期性和背景对大黄蜂耐热性结果的重要性。
