Data from: Behavioural response to combined insecticide and temperature stress in natural populations of Drosophila melanogaster

Insecticide resistance evolves extremely rapidly, providing an illuminating model for the study of adaptation. With climate change reshaping species distribution, pest and disease vector control needs rethinking to include the effects of environmental variation and insect stress physiology. Here we assessed how both long term adaptation of populations to temperature and immediate temperature variation affects the genetic architecture of DDT insecticide response in Drosophila melanogaster. Mortality assays and behavioral assays based on continuous activity monitoring were used to assess the interaction between DDT and temperature on three field-derived populations from climate extremes (Raleigh for warm temperate, Tasmania for cold oceanic and Queensland for hot tropical). The Raleigh population showed the highest mortality to DDT whereas the Queensland population, epicentre for derived alleles of the resistance gene Cyp6g1, showed the lowest. Interaction between insecticide and temperature strongly affected mortality, particularly for the Tasmanian population. Activity profiles analyzed using self-organizing maps show the insecticide promoted an early response while elevated temperature promoted a later response. These distinctive early or later activity phases revealed similar responses to temperature and DDT dose alone but with more or less genetic variance depending on the population. This change in genetic variance among populations suggests that selection particularly depleted genetic variance for DDT response in the Queensland population. Finally, despite similar (co)variation between traits in benign conditions, the genetic responses across population differed under stressful conditions. This showed how stress-responsive genetic variation only reveals itself in specific conditions and thereby escapes potential trade-offs in benign environments.

杀虫剂抗药性的演化速度极快，为适应性研究提供了极具阐释价值的模型。随着气候变化重塑全球物种分布格局，病媒生物与害虫防控工作亟需重新调整思路，将环境波动与昆虫应激生理学的影响纳入考量范畴。本研究以黑腹果蝇（Drosophila melanogaster）为对象，评估了种群对温度的长期适应性以及即时温度波动如何影响其对DDT杀虫剂应答的遗传架构（genetic architecture）。研究采用死亡率测定法与基于连续活动监测的行为学测定法，针对3个源自极端气候区域的野外种群（罗利种群：暖温带；塔斯马尼亚种群：冷海洋性气候；昆士兰州种群：炎热热带气候），探究DDT与温度的交互作用。结果显示，罗利种群对DDT的死亡率最高，而作为抗药性基因Cyp6g1衍生等位基因起源中心的昆士兰州种群，死亡率最低。杀虫剂与温度的交互作用对死亡率存在显著影响，尤以塔斯马尼亚种群最为突出。通过自组织映射（self-organizing maps, SOM）分析活动谱可知，杀虫剂可诱导早期应答，而高温则会触发晚期应答。这些特征性的早期或晚期活动阶段表明，单一温度或单一DDT剂量下的应答模式相似，但不同种群的遗传方差存在增减差异。种群间遗传方差的此类变化提示，选择作用尤其耗竭了昆士兰州种群中与DDT应答相关的遗传方差。最后，尽管在适宜环境下各性状间的（共）方差模式相似，但不同种群在胁迫环境下的遗传应答存在显著差异。该结果揭示了应激响应性遗传变异仅在特定条件下才会显现，从而在适宜环境中规避了潜在的适应性权衡。