Data from: Behavioral 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.

杀虫剂抗性的演化速率极快，是开展适应性演化研究的极佳模型体系。随着气候变化重塑全球物种分布格局，害虫与病媒生物的防控策略亟需革新，需将环境变异与昆虫应激生理学的影响纳入考量范畴。本研究针对黑腹果蝇（Drosophila melanogaster），探究了种群对温度的长期适应性演化与即时温度波动，分别如何影响其对滴滴涕（DDT）杀虫剂应答的遗传架构。实验采用死亡率测定与基于连续活动监测的行为测定两种手段，对3株源自极端气候区域的野外采集种群展开分析：罗利种群（Raleigh）取自暖温带区域，塔斯马尼亚种群（Tasmania）取自寒冷海洋性气候区域，昆士兰种群（Queensland）取自炎热热带区域，以此探究滴滴涕与温度间的交互作用。结果显示，罗利种群对滴滴涕的死亡率最高；而昆士兰种群作为抗性基因Cyp6g1衍生等位基因的核心分布种群，其死亡率最低。杀虫剂与温度的交互作用对死亡率存在显著影响，该效应在塔斯马尼亚种群中尤为突出。采用自组织映射（self-organizing maps）分析活动谱后发现，滴滴涕可诱导早期应激应答，而高温则诱导后期应激应答。这些特征鲜明的早期或后期活动阶段表明，单独施加温度或滴滴涕剂量时，不同种群的应答模式相似，但遗传方差的大小因种群而异。种群间遗传方差的此类变化提示，选择作用尤其降低了昆士兰种群中针对滴滴涕应答的遗传方差。最后，尽管在良性环境条件下，不同性状间的（共）方差模式较为相似，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型遗传变异仅在特定条件下才会显现，从而在良性环境中规避了潜在的进化权衡。