Muluvhahothe Mulalo M, Joubert Elsje, Foord Stefan H
SARChI-Chair on Biodiversity Value and Change, Department of Biological Sciences, Faculty of Science, Engineering and Agriculture, University of Venda, Private Bag X5050, Thohoyandou, 0950, South Africa.
Levubu Centre for Excellence, PO Box 121, Levubu, 0929, South Africa.
J Therm Biol. 2023 Jan;111:103395. doi: 10.1016/j.jtherbio.2022.103395. Epub 2022 Dec 5.
Temperature tolerance is an essential component of insect fitness, and its understanding can provide a predictive framework for their distribution and abundance. The two-spotted stink bug, Bathycoelia distincta Distant, is a significant pest of macadamia. The main goal of this study was to investigate the thermal tolerance of B. distincta across different life stages. Thermal tolerance indices investigated included critical thermal maximum (CT), critical thermal minimum (CT), effects of acclimation on CT and CT at 20, 25, and 30 °C, and rapid heat hardening (RHH), and rapid cold hardening (RCH). The Kruskal-Wallis test was used to explore the effects of life stage and acclimation on CT and CT and Generalized Linear Models (GLM) for the probability of survival after pre-exposure to RHH at 41 °C for 2 h and RCH at -8 °C for 2 h. CT and CT varied significantly between life stages at all acclimation temperatures, but CT (3.5 °C) varied more than CT (2.1 °C). Higher acclimation temperatures resulted in larger variations between life stages for both CT and CT. A significant acclimation response was observed for the CT of instar 2 (1.7 °C) and CT of females (2.7 °C) across acclimation temperatures (20-30 °C). Pre-exposure significantly improved the heat and cold survival probability of instar 2 and the cold survival probability of instar 3 and males. The response between life stages was more variable in RCH than in RHH. Instar 2 appeared to be the most thermally plastic life stage of B. distincta. These results suggest that the thermal plastic traits of B. distincta life stages may enable this pest to survive in temperature regimes under the ongoing climate change, with early life stages (except for instar 2) more temperature sensitive than later life stages.
温度耐受性是昆虫适应性的一个重要组成部分，对其的了解可以为昆虫的分布和数量提供一个预测框架。双斑臭虫（Bathycoelia distincta Distant）是澳洲坚果的一种重要害虫。本研究的主要目的是调查双斑臭虫在不同生命阶段的热耐受性。所研究的热耐受性指标包括临界热最大值（CTmax）、临界热最小值（CTmin）、驯化对20、25和30°C下CTmax和CTmin的影响，以及快速热硬化（RHH）和快速冷硬化（RCH）。Kruskal-Wallis检验用于探讨生命阶段和驯化对CTmax和CTmin的影响，以及广义线性模型（GLM）用于在41°C下暴露2小时的RHH和在-8°C下暴露2小时的RCH预处理后存活概率的分析。在所有驯化温度下，CTmax和CTmin在不同生命阶段之间存在显著差异，但CTmax（3.5°C）的变化比CTmin（2.1°C）更大。较高的驯化温度导致CTmax和CTmin在不同生命阶段之间的差异更大。在20 - 30°C的驯化温度范围内，观察到二龄若虫的CTmax（1.7°C）和雌虫的CTmin（2.7°C）有显著的驯化反应。预处理显著提高了二龄若虫的热存活概率和冷存活概率，以及三龄若虫和雄虫的冷存活概率。在RCH中生命阶段之间的反应比在RHH中更具变异性。二龄若虫似乎是双斑臭虫热可塑性最强的生命阶段。这些结果表明，双斑臭虫生命阶段的热可塑性特征可能使这种害虫能够在当前气候变化下的温度环境中生存，早期生命阶段（二龄若虫除外）比后期生命阶段对温度更敏感。
