School of Biological Sciences, Illinois State University, Normal, Illinois, USA.
J Anim Ecol. 2024 Feb;93(2):171-182. doi: 10.1111/1365-2656.14041. Epub 2024 Jan 5.
As a consequence of ongoing climate change, heatwaves are predicted to increase in frequency, intensity, and duration in many regions. Such extreme events can shift organisms from thermal optima for physiology and behaviour, with the thermal stress hypothesis predicting reduced performance at temperatures where the maintenance of biological functions is energetically costly. Performance includes the ability to resist biotic stressors, including infectious diseases, with increased exposure to extreme temperatures having the potential to synergise with parasite infection. Climate change is a proposed threat to native bee pollinators, directly and through indirect effects on floral resources, but the thermal stress hypothesis, particularly pertaining to infectious disease resistance, has received limited attention. We exposed adult Bombus impatiens bumblebee workers to simulated, ecologically relevant heatwave or control thermal regimes and assessed longevity, immunity, and resistance to concurrent or future parasite infections. We demonstrate that survival and induced antibacterial immunity are reduced following heatwaves. Supporting that heatwave exposure compromised immunity, the cost of immune activation was thermal regime dependent, with survival costs in control but not heatwave exposed bees. However, in the face of real infections, an inability to mount an optimal immune response will be detrimental, which was reflected by increased trypanosomatid parasite infections following heatwave exposure. These results demonstrate interactions between heatwave exposure and bumblebee performance, including immune and infection outcomes. Thus, the health of bumblebee pollinator populations may be affected through altered interactions with parasites and pathogens, in addition to other effects of extreme manifestations of climate change.
由于持续的气候变化，预计许多地区的热浪将变得更加频繁、强烈和持久。这种极端事件可能会使生物从生理和行为的热最佳状态转移，热应激假说预测在维持生物功能需要大量能量的温度下，生物表现会下降。性能包括抵抗生物胁迫的能力，包括传染病，增加暴露于极端温度的可能性与寄生虫感染产生协同作用。气候变化被认为是对本地蜜蜂传粉媒介的直接威胁，通过对花卉资源的间接影响，但热应激假说，特别是与传染病抵抗力有关的假说，受到的关注有限。我们让成年大黄蜂（Bombus impatiens）工蜂暴露于模拟的、生态相关的热浪或对照热环境中，并评估其寿命、免疫力和对同时或未来寄生虫感染的抵抗力。我们证明，热浪后蜜蜂的存活率和诱导的抗菌免疫能力降低。热浪暴露削弱免疫力的说法得到了支持，免疫激活的成本取决于热环境，在对照条件下而不是在热浪暴露条件下的蜜蜂有生存成本。然而，面对真实的感染，如果不能产生最佳的免疫反应，将是有害的，这反映在热浪暴露后，锥虫原生动物寄生虫感染的增加。这些结果表明，热浪暴露与大黄蜂表现之间存在相互作用，包括免疫和感染结果。因此，除了气候变化极端表现的其他影响外，蜜蜂传粉媒介种群的健康可能会因与寄生虫和病原体的相互作用改变而受到影响。
