RAPID: Eco-evolutionary dynamics of host-parasite interactions in a novel environment

从长远来看，入侵害虫最好的控制方法是寄生天敌，即在昆虫体内产卵。卵孵化并发育成幼虫，幼虫从内部以昆虫宿主的身体为食。由于这是一场生死攸关的斗争，自然选择强烈地作用于宿主以进化以逃避寄生，并作用于寄生蜂以克服宿主防御。当害虫入侵一个新的地区时，它们通常会留下适应攻击它们的寄生蜂。预计在这种新的、没有敌人的环境中，进化可能会导致昆虫宿主的防御能力降低。寄主对寄生虫的响应进化很重要，因为寄主的抗性会影响生物控制程序。在这些节目中，故意引入原生范围的敌人来控制入侵的害虫。当昆虫宿主再次暴露在寄生蜂面前时，自然选择将再次做出反应。这项研究调查了斑点翼果蝇在入侵北美后防御水平如何变化，以及在从原生范围释放一只专业寄生蜂后这些防御水平可能会如何变化。除了对生物防治的广泛影响外，该项目还有望对斑点果蝇的控制产生具体的见解，斑点果蝇是一种主要的农业害虫。入侵斑点果蝇较低的抗性有助于最初的生物防治，而增加的或地理上可变的抗性水平可能会使生物防治在区域上更不成功或更难预测。本项目研究了经典生防剂--巴西小蜂对入侵斑点果蝇的寄主-寄生蜂相互作用的生态进化动力学。与预期相反，在北美和欧洲的入侵范围内，斑点果蝇的抵抗力似乎增加了，而不是减少了。这种抵抗力的增加可能源于斑点果蝇在外来范围内竞争的减少和充足的资源，从而允许维持高水平的防御性化合物。在生防剂释放前收集的初步数据表明，斑点果蝇对巴西赤眼蜂的寄生抗性相对较高，但也是高度可变的，13-48%的寄生幼虫被寄主杀死。在这个项目中，巴西球虫将在密歇根州的八个地点被释放，那里已经有关于斑点果蝇抵抗力水平的基线数据。随后的调查将允许评估在共同进化的专家天敌发布后阻力方面的任何变化。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Invasive insect pests are best controlled in the long term by parasitoid natural enemies that lay their eggs inside the insect. The eggs hatch and develop into larvae, which feed on the body of the insect host from the inside. Because this is a life-and-death struggle, natural selection acts strongly on the host to evolve to escape parasitism and on the parasitoid to overcome host defenses. When insect pests invade a new region, they usually leave behind the parasitoids that are adapted to attack them. It is expected that in this new, enemy-free environment, evolution could result in an insect host with lower defenses. Host evolution in response to parasites is important because host resistance impacts biological control programs. In these programs, enemies from native ranges are introduced intentionally to control invasive insect pests. When the insect host is once again exposed to its parasitoids, natural selection will once again respond. This study investigates how defense levels of the spotted wing drosophila have changed following its invasion of North America and how those defenses may change following the release of a specialist parasitoid from the native range. In addition to broad implications for biological control, the project promises to yield specific insights into control of spotted wing drosophila, which is a major agricultural pest. Lower resistance of invasive spotted wing drosophila could help biocontrol initially, while increased or geographically variable levels of resistance could render biocontrol less successful or less predictable regionally.This project investigates eco-evolutionary dynamics of host-parasitoid interactions following the release of a classical biocontrol agent, the parasitoid wasp Ganaspis brasiliensis against the invasive spotted wing drosophila (Drosophila suzukii). Contrary to expectations, the resistance of spotted wing drosophila seems to have increased instead of decreased in the invaded range in North America and Europe. This increased resistance may stem from reduced competition and ample resources for spotted wing drosophila in the exotic range, permitting maintenance of high levels of defensive compounds. Preliminary data collected prior to the release of the biocontrol agent show that spotted wing drosophila resistance to parasitism by G. brasiliensis is relatively high but also that it is highly variable with 13-48% of parasitoid larvae being killed by the host. In this project, G. brasiliensis will be released at eight sites in Michigan where there is already baseline data about resistance levels of spotted wing drosophila. Subsequent surveys will permit assessment of any changes in resistance following this release of a co-evolved specialist natural enemy.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.