CONACYT, Insurgentes sur 1582, Crédito Constructor, Benito Juárez, CDMX, México.
Red de Ecoetología, Instituto de Ecología A. C, El Haya, Xalapa, Veracruz, México.
J Econ Entomol. 2021 Feb 9;114(1):462-467. doi: 10.1093/jee/toaa216.
Ecosystem services provided by insects are threatened by recent increasing global temperatures, particularly in the tropics, where insects live close to their thermal limits. Given that tolerance to high temperatures depends on individual metabolism and physiological stress response, it may also be sensitive to other stressors that are common in natural and human-modified environments, such as pollution and parasite pressure. The effects of multiple stressors could be synergistic and can be particularly relevant in insects that provide highly valuable ecosystem services, such as dung beetles in cattle pastures. Here we measured heat tolerance (critical thermal maximum, CTmax) in dung beetles exposed to ivermectin, a toxic parasiticide excreted in cattle dung, with known negative effects on coprophagous fauna, and in beetles exposed to an immune challenge. We also exposed a group of beetles to a combination of both ivermectin and immune challenge to test for potential synergistic effects of both stressors. Contrary to our predictions, CTmax did not change with ivermectin exposure, but increased in immune-challenged beetles. As found in other insects, CTmax was higher in larger beetles, highlighting the importance of body size on thermal tolerance in ectotherms. We discuss potential mechanisms responsible of increased heat tolerance in immune-challenged beetles and highlight the importance of natural and human-induced environmental pressures that now interact with global warming and threaten ecosystem services provided by wild animals.
昆虫提供的生态系统服务受到全球气温升高的威胁，特别是在热带地区，昆虫的生活环境接近它们的热极限。鉴于对高温的耐受性取决于个体的新陈代谢和生理应激反应，它也可能对自然和人为环境中常见的其他压力源敏感，如污染和寄生虫压力。多种压力源的影响可能具有协同作用，对于提供高度有价值的生态系统服务的昆虫尤其相关，例如在牛牧场中的蜣螂。在这里，我们测量了暴露于伊维菌素（一种在牛粪中排泄的有毒杀虫剂）的蜣螂的耐热性（临界热最大值，CTmax），伊维菌素对食粪动物群有已知的负面影响，以及暴露于免疫挑战的蜣螂。我们还将一组蜣螂暴露于伊维菌素和免疫挑战的组合中，以测试这两种压力源是否存在潜在的协同作用。与我们的预测相反，CTmax 没有随伊维菌素暴露而改变，但在免疫挑战的蜣螂中增加了。与其他昆虫一样，CTmax 在较大的蜣螂中更高，突出了体型对变温动物热耐受性的重要性。我们讨论了免疫挑战的蜣螂中耐热性增加的潜在机制，并强调了自然和人为引起的环境压力的重要性，这些压力现在与全球变暖相互作用，威胁着野生动物提供的生态系统服务。
