Gallego Belén, Verdú José R, Carrascal Luis M, Lobo Jorge M
I.U.I. CIBIO, Universidad de Alicante, San Vicente del Raspeig, 03080 Alicante, Spain; Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales-CSIC, José Abascal 2, 28006 Madrid, Spain.
I.U.I. CIBIO, Universidad de Alicante, San Vicente del Raspeig, 03080 Alicante, Spain.
J Therm Biol. 2016 Feb;56:113-21. doi: 10.1016/j.jtherbio.2015.12.006. Epub 2016 Jan 20.
The study of insect responses to thermal stress has involved a variety of protocols and methodologies that hamper the ability to compare results between studies. For that reason, the development of a protocol to standardize thermal assays is necessary. In this sense, infrared thermography solves some of the problems allowing us to take continuous temperature measurements without handling the individuals, an important fact in cold-blooded organisms like insects. Here, we present a working protocol based on infrared thermography to estimate both cold and heat thermal stress in insects. We analyse both the change in the body temperature of individuals and their behavioural response. In addition, we used partial least squares regression for the statistical analysis of our data, a technique that solves the problem of having a large number of variables and few individuals, allowing us to work with rare or endemic species. To test our protocol, we chose two species of congeneric, narrowly distributed dung beetles that are endemic to the southeastern part of the Iberian Peninsula. With our protocol we have obtained five variables in the response to cold and twelve in the response to heat. With this methodology we discriminate between the two flightless species of Jekelius through their thermal response. In response to cold, Jekelius hernandezi showed a higher rate of cooling and reached higher temperatures of stupor and haemolymph freezing than Jekelius punctatolineatus. Both species displayed similar thermoregulation ranges before reaching lethal body temperature with heat stress. Overall, we have demonstrated that infrared thermography is a suitable method to assess insect thermal responses with a high degree of sensitivity, allowing for the discrimination between closely related species.
对昆虫热应激反应的研究涉及多种方案和方法，这妨碍了不同研究之间结果比较的能力。因此，制定标准化热分析方案很有必要。从这个意义上说，红外热成像解决了一些问题，使我们能够在不接触个体的情况下进行连续温度测量，这对于像昆虫这样的冷血生物来说是一个重要事实。在此，我们提出一种基于红外热成像的工作方案，用于估计昆虫的冷应激和热应激。我们分析了个体体温的变化及其行为反应。此外，我们使用偏最小二乘回归对数据进行统计分析，该技术解决了变量多而个体少的问题，使我们能够研究珍稀或特有物种。为了测试我们的方案，我们选择了两种同属的、分布狭窄的蜣螂，它们是伊比利亚半岛东南部特有的物种。通过我们的方案，我们在对冷应激的反应中获得了五个变量，在对热应激的反应中获得了十二个变量。通过这种方法，我们通过热反应区分了杰氏蜣螂属的两种无飞行能力的物种。在对冷应激的反应中，赫氏杰氏蜣螂的降温速率更高，达到昏迷和血淋巴冻结的温度也比点线杰氏蜣螂更高。在热应激达到致死体温之前，这两个物种都表现出相似的体温调节范围。总体而言，我们证明了红外热成像是一种以高灵敏度评估昆虫热反应的合适方法，能够区分亲缘关系密切的物种。
