Insect bacterial symbionts and short term adaptation of aphids to abiotic and biotic stress

现代进化论认为，动植物的微生物共生体是帮助宿主适应资源、天敌和气候条件快速生态变化的关键媒介。我们将在对照实验中使用称为蚜虫的小昆虫和它们的寄生黄蜂，以检验这样一个假设，即蚜虫严重依赖其细菌共生体的快速进化潜力来生存，以应对它们在日常生活中面临的生态压力，维管植物被用作它们的食物和栖息地。一个众所周知的物种，豌豆蚜虫，将在不同的生态压力模式下暴露于实验进化中，施加在它们身上的要么是或多或少致命的寄生虫，要么是在不同宜居的寄主植物物种之间转移，或者是它们在炎热的夏天经常面临的高温应激，而它们以空中植物部分为食。在历代逆境过程中，将利用分子技术对四种已知的母系遗传的蚜虫细菌共生体进行密切监测，以记录在特定逆境条件下蚜虫细菌群落的适应性变化。我们的发现应该有助于理解蚜虫在压力下是否通过调节其细菌体的大小和组成来对特定的生态威胁做出快速和适应性的反应，这是可以预期的，因为与昆虫相比，细菌的繁殖速度更快。我们的研究系统在对自然陆地食物网的四个层面进行仔细审查方面是独一无二的，在那里我们将试验植物、小型昆虫食草动物、它们的共生细菌联盟，以及将它们作为天敌攻击的寄生黄蜂。

Modern theories of evolution consider microbial symbionts of animals and plants as key mediators helping their host to adapt to rapid ecological change in their resources, natural enemies, and climatic conditions. We will use small insects called aphids and their parasitic wasps in controlled experiments, to test the hypothesis that aphids critically depend on the rapid evolutionary potential of their bacterial symbionts to survive to ecological stress that they face as part of their daily life on vascular plants used as their food and habitat. A well known species, the pea aphid, will be exposed to experimental evolution in distinct regimes of ecological stress imposed on them either as more or less virulent parasites, shifts between differently hospitable host plant species, or as a high temperature stress which they often face daily in hot summer while feeding on aerial plant parts. Four species of aphid bacterial symbionts among the best known to be maternally inherited in these aphids will be monitored closely using molecular techniques during the course of successive generations of stress, to document adaptive changes in the aphid bacterial community under particular stress regimes. Our findings should help to understand if aphids under stress respond quickly and adaptively to specific ecological threats, by modulating the size and composition of their bacteriome, which can be expected because of the fast rate of multiplication of bacteria compared to insects. Our study system is unique in bringing under scrutiny four levels of a natural terrestrial food web, where we will experiment with plants, small insect herbivores, their consortia of symbiotic bacteria, and parasitic wasps attacking them as natural enemies.