DeVries Zachary C, Kells Stephen A, Appel Arthur G
Department of Entomology and Plant Pathology, 301 Funchess Hall, Auburn University, Auburn, AL 36849, USA; Department of Entomology, Campus Box 7613, North Carolina State University, Raleigh, NC 27695-7613, USA.
Department of Entomology, 219 Hodson Hall, 1980 Folwell Ave., University of Minnesota, St. Paul, MN 55108, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2016 Jul;197:52-7. doi: 10.1016/j.cbpa.2016.03.003. Epub 2016 Mar 9.
Evaluating the critical thermal maximum (CTmax) in insects has provided a number of challenges. Visual observations of endpoints (onset of spasms, loss of righting response, etc.) can be difficult to measure consistently, especially with smaller insects. To resolve this problem, Lighton and Turner (2004) developed a new technique: thermolimit respirometry (TLR). TLR combines real time measurements of both metabolism (V·CO2) and activity to provide two independent, objective measures of CTmax. However, several questions still remain regarding the precision of TLR and how accurate it is in relation to traditional methods. Therefore, we evaluated CTmax of bed bugs using both traditional (visual) methods and TLR at three important metabolic periods following feeding (1d, 9d, and 21d). Both methods provided similar estimates of CTmax, although traditional methods produced consistently lower values (0.7-1°C lower than TLR). Despite similar levels of precision, TLR provided a more complete profile of thermal tolerance, describing changes in metabolism and activity leading up to the CTmax, not available through traditional methods. In addition, feeding status had a significant effect on bed bug CTmax, with bed bugs starved 9d (45.19[±0.20]°C) having the greatest thermal tolerance, followed by bed bugs starved 1d (44.64[±0.28]°C), and finally bed bugs starved 21d (44.12[±0.28]°C). Accuracy of traditional visual methods in relation to TLR is highly dependent on the selected endpoint; however, when performed correctly, both methods provide precise, accurate, and reliable estimations of CTmax.
评估昆虫的临界热最大值（CTmax）面临着诸多挑战。通过视觉观察终点指标（如痉挛发作、翻正反射丧失等）往往难以进行一致的测量，尤其是对于体型较小的昆虫。为了解决这个问题，莱顿和特纳（2004年）开发了一种新技术：热限呼吸测定法（TLR）。TLR结合了代谢（V·CO2）和活动的实时测量，以提供CTmax的两个独立、客观的测量指标。然而，关于TLR的精度以及它与传统方法相比的准确性，仍然存在几个问题。因此，我们在喂食后的三个重要代谢阶段（1天、9天和21天），使用传统（视觉）方法和TLR评估了臭虫的CTmax。两种方法得出的CTmax估计值相似，尽管传统方法得出的值始终较低（比TLR低0.7 - 1°C）。尽管精度水平相似，但TLR提供了更完整的热耐受性概况，描述了直至CTmax时代谢和活动的变化，而这是传统方法无法做到的。此外，喂食状态对臭虫的CTmax有显著影响，饥饿9天的臭虫（45.19[±0.20]°C）具有最大的热耐受性，其次是饥饿1天的臭虫（44.64[±0.28]°C），最后是饥饿21天的臭虫（44.12[±0.28]°C）。传统视觉方法相对于TLR的准确性高度依赖于所选的终点指标；然而，当操作正确时，两种方法都能提供精确、准确且可靠的CTmax估计值。
