Mechanisms of tritrophic effects of plant chemistry on a parasitoid

植物化学对拟寄生物的营养作用机制paul Ode1 and May berenbaum2众所周知，植物化学不仅对食草动物有影响，而且对这些食草动物的天敌也有影响。虽然植物化学对天敌寄主寻找和接受行为的影响在许多系统中得到了很好的研究，但相对而言，植物化学对其他适应度相关因子的影响以及天敌如何能够应对植物化学的负面影响知之甚少。寄生蜂（Copidosoma sosares）是植物和食草动物之间选择性相互作用的主要天敌。呋喃香豆素的生产由野生防风草植物，pasinaca sativa，选择了解毒能力的防风草网状蠕虫，pasinacella，一种专业的野生防风草食草动物。反过来，网虫的食草性选择了野生防风草对呋喃香豆素的抗性。这种营养系统原产于欧洲，现已被引入北美西部；野生防风草和防风草网虫遍布北美中西部，但它们实际上不含寄生虫。本项目的中心目标是研究野生防风草呋喃香豆素对索萨Copidosoma sosares生长和繁殖的影响。在美国西部人群中，防风草植物的呋喃香豆素谱及其与C. sosares适应度测量的相关性将被记录下来。实验室研究，操纵人工饲料中的黄毒素浓度，将直接检查呋喃香豆素对C. sosares适应性测量的影响。其他实验将检测C. sosares在其网络蠕虫宿主中遇到的呋喃香豆素水平，以及它们解毒任何遇到的呋喃香豆素的能力。最后，探讨呋喃香豆素的变化对红腹草繁殖决策的影响。美国中西部相对无寄生性种群的存在，以及欧洲和美国西部重度寄生性种群的存在，可以比较寄生性对网虫解毒能力和植物化学的影响。研究寄主植物化学对天敌的生理作用将有助于更全面地了解营养关系的作用机制。

Mechanisms of tritrophic effects of plant chemistry on a parasitoidPaul Ode1 and May Berenbaum21North Dakota State University2University of Illinois at Urbana-ChampaignPlant chemistry is well known to have impacts not only on herbivores, but also on natural enemies of these herbivores. While the effects of plant chemistry on host finding and acceptance behavior of natural enemies is well studied in many systems, comparatively little is known about effects of plant chemistry on other fitness correlates and how natural enemies are able to cope with negative effects of plant chemistry. The parasitic wasp, Copidosoma sosares, is the predominant natural enemy in a system where the selective interactions between plant and herbivore have been particularly well studied. Furanocoumarin production by wild parsnip plants, Pastinaca sativa, selects for detoxification capabilities of the parsnip webworm, Depressaria pastinacella, a specialist herbivore of the wild parsnip. In turn, herbivory by the webworms selects for furanocoumarin-based resistance by wild parsnips. This tritrophic system is native to Europe and has been introduced to western North America; wild parsnips and parsnip webworms are found throughout Midwestern North America, but are effectively parasitoid-free. The central goal of this project is to examine the impacts of wild parsnip furanocoumarins on growth and reproduction of Copidosoma sosares. Furanocoumarin profiles of parsnip plants and their correlation with C. sosares fitness measures in western US populations will be documented. Laboratory studies, manipulating xanthotoxin concentrations in artificial diets, will directly examine the effect of furanocoumarins on C. sosares fitness measures. Other experiments will examine levels of furanocoumarins encountered by C. sosares in their webworm hosts as well as their ability to detoxify any encountered furanocoumarins. Finally, the effects of furanocoumarin variation on reproductive decisions made by C. sosares will be examined. The existence of relatively parasitoid free populations in the Midwestern US and heavily parasitized European and western US populations allows comparison of parasitoid effects on webworm detoxification abilities as well as plant chemistry. Studying the physiological effects of host plant chemistry on natural enemies will allow for a more complete understanding of how trophic relationships function.