Surviving changing climate conditions is particularly difficult for organisms such as insects that depend on environmental temperature to regulate their physiological functions. Insects are extremely threatened by global warming, since many do not have enough physiological tolerance even to survive continuous exposure to the current maximum temperatures experienced in their habitats. Here, we review literature on the physiological mechanisms that regulate responses to heat and provide heat tolerance in insects: (i) neuronal mechanisms to detect and respond to heat; (ii) metabolic responses to heat; (iii) thermoregulation; (iv) stress responses to tolerate heat; and (v) hormones that coordinate developmental and behavioural responses at warm temperatures. Our review shows that, apart from the stress response mediated by heat shock proteins, the physiological mechanisms of heat tolerance in insects remain poorly studied. Based on life‐history theory, we discuss the costs of heat tolerance and the potential evolutionary mechanisms driving insect adaptations to high temperatures. Some insects may deal with ongoing global warming by the joint action of phenotypic plasticity and genetic adaptation. Plastic responses are limited and may not be by themselves enough to withstand ongoing warming trends. Although the evidence is still scarce and deserves further research in different insect taxa, genetic adaptation to high temperatures may result from rapid evolution. Finally, we emphasize the importance of incorporating physiological information for modelling species distributions and ecological interactions under global warming scenarios. This review identifies several open questions to improve our understanding of how insects respond physiologically to heat and the evolutionary and ecological consequences of those responses. Further lines of research are suggested at the species, order and class levels, with experimental and analytical approaches such as artificial selection, quantitative genetics and comparative analyses.

中文翻译：

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昆虫对热的反应：变暖世界中的生理机制、进化和生态意义

对于依赖环境温度来调节其生理功能的昆虫等生物来说，在不断变化的气候条件下生存尤其困难。昆虫受到全球变暖的极大威胁，因为许多昆虫没有足够的生理耐受性，即使持续暴露在其栖息地当前的最高温度下也无法生存。在这里，我们回顾了有关调节热反应和提供昆虫耐热性的生理机制的文献：(i) 检测和响应热的神经元机制；(ii) 对热的代谢反应；(iii) 体温调节；(iv) 耐受热的应激反应；(v) 在温暖的温度下协调发育和行为反应的激素。我们的综述表明，除了由热休克蛋白介导的应激反应外，昆虫耐热的生理机制仍然缺乏研究。基于生命史理论，我们讨论了耐热性的成本和驱动昆虫适应高温的潜在进化机制。一些昆虫可能通过表型可塑性和遗传适应的共同作用来应对持续的全球变暖。塑料的反应是有限的，而且本身可能不足以承受持续的变暖趋势。尽管证据仍然很少，值得在不同昆虫类群中进一步研究，但对高温的遗传适应可能是快速进化的结果。最后，我们强调了在全球变暖情景下为物种分布和生态相互作用建模的生理信息的重要性。本综述确定了几个悬而未决的问题，以提高我们对昆虫对热的生理反应以及这些反应的进化和生态后果的理解。建议在物种、目和纲层面进行进一步的研究，采用实验和分析方法，如人工选择、数量遗传学和比较分析。