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

从长期来看，控制入侵性害虫的最佳方法是将卵产在昆虫体内的寄生性天敌。卵孵化并发育成幼虫，幼虫从昆虫宿主体内取食。因为这是一场你死我活的斗争，自然选择强烈地作用于寄主进化以逃避寄生，而作用于拟寄主克服宿主的防御。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拟寄生虫。预计在这种新的，无敌人的环境中，进化可能导致昆虫宿主具有较低的防御能力。寄主进化对寄生虫的反应是重要的，因为寄主的抗性影响生物控制计划。在这些项目中，有意引入来自本地的敌人来控制入侵的害虫。当昆虫宿主再次暴露于其拟寄生物时，自然选择将再次作出反应。这项研究调查了斑点翼果蝇的防御水平在其入侵北美后是如何变化的，以及这些防御在一种专门的寄生蜂从本土范围释放后是如何变化的。除了对生物防治的广泛影响外，该项目还有望对斑翼果蝇的防治产生具体的见解，斑翼果蝇是一种主要的农业害虫。斑翅果蝇的抗性较低，可能有助于生物防治，而抗性水平的增加或地理上的变化可能使生物防治不太成功或难以预测。本项目研究了一种经典的生物防治剂释放后，寄主-拟寄主相互作用的生态进化动力学，拟寄主黄蜂巴西加纳斯（Ganaspis brasiliensis）对抗入侵的斑点翅果蝇（drosophila suzukii）。与预期相反，在北美和欧洲的入侵范围内，斑点翼果蝇的抵抗力似乎有所增加而不是减少。这种增强的抗性可能源于外来范围内斑点翼果蝇的竞争减少和充足的资源，允许维持高水平的防御化合物。释放防虫剂前收集的初步数据表明，斑翅果蝇对巴西蠓的抗性较高，但变异较大，有13-48%的寄生性幼虫被寄主杀死。在这个项目中，巴西果蝇将被释放到密歇根州的八个地点，这些地点已经有了斑翼果蝇抗性水平的基线数据。随后的调查将允许评估在释放这种共同进化的专业天敌后的任何抗性变化。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.