Lethal time50 (LTime50) and lethal temp (LTemp50) are commonly used laboratory indices of arthropod cold tolerance, with the former often being employed to predict winter survival in the field. In the present study, we compare the cold tolerance of different life‐history stages (nondiapausing and diapausing females, as well as males and juveniles) of a major agricultural pest: the two‐spot spider mite Tetranychus urticae Koch (Acarina: Tetranychidae). Diapausing females from European populations of this species are shown to be freeze avoiding, supercooling to −23.6 ± 0.37 °C and with an LTemp50 of −23.2 °C. However, nondiapausing females [supercooling point (SCP) –19.1 ± 0.49 °C, LTemp50 –14.32 °C], males (SCP –21.27 ± 0.52 °C, LTemp50 –16 °C) and juveniles (SCP –25.34 ± 0.29 °C, LTemp50 –18.3 °C) are subclassified as strongly chill tolerant juveniles. LTime50 is 148.3 days for non‐acclimated diapausing females, whereas nondiapausing females, males and juveniles reach 50% mortality by 21.7 days. When individuals are acclimated at 10 °C for a period of 7 days, no effect is found. Cold tolerance is suggested to be a major contributor to the successful spread of T. urticae across temperate countries, although it is dependent on a diapause trait, suggesting a potential target for control. Winter field trial data from diapausing females indicate that LTime50 is a reliable indicator of winter survival even within diapause, supporting the use of these indices as a valuable component within environmental niche models for the prediction of future pest invasions.

中文翻译：

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二斑叶螨耐寒性的生活史变化：在害虫防治和定植风险评估中的应用

致死时间50 (LTime50) 和致死温度(LTemp50) 是节肢动物耐寒性实验室常用指标，前者常用于预测田间冬季存活率。在本研究中，我们比较了一种主要农业害虫：二斑叶螨 Tetranychus urticae Koch（螨类：叶螨科）不同生活史阶段（非滞育和滞育雌性，以及雄性和幼虫）的耐冷性。该物种欧洲种群的滞育雌性表现出避免冷冻的能力，过冷至-23.6 ± 0.37 °C，LTemp50 为-23.2 °C。然而，非滞育雌性[过冷点(SCP) –19.1 ± 0.49 °C，LTemp50 –14.32 °C]、雄性(SCP –21.27 ± 0.52 °C，LTemp50 –16 °C)和幼鱼(SCP –25.34 ± 0.29 °C) ，LTemp50 –18.3 °C）被细分为强耐寒幼体。对于未适应环境的滞育雌性，LTime50 为 148.3 天，而非滞育雌性、雄性和幼体在 21.7 天时死亡率达到 50%。当个体在 10°C 环境下适应 7 天时，没有发现任何影响。耐冷性被认为是二斑绦虫在温带国家成功传播的一个主要因素，尽管它依赖于滞育性状，这表明了潜在的控制目标。来自滞育雌性的冬季田间试验数据表明，即使在滞育期间，LTime50 也是冬季生存的可靠指标，支持使用这些指数作为环境生态位模型中预测未来害虫入侵的有价值的组成部分。