SGER: A Unique Opportunity to Document Chemical Coevolution Following Reassociation Between Introduced Weeds and a Specialist Moth

贸易全球化加剧了入侵植物的问题；当杂草物种入侵新的地区时，它们会造成巨大的经济和生态破坏。在许多情况下，有毒化学物质促进了这些杂草形成的过程，但关于植物毒素含量的进化变化的信息很少，这些变化是在植物被引入非本地地区并与长期的昆虫伙伴相互作用释放后发生的。当共同进化的天敌重新与非土著地区的寄主植物相互作用时，毒素含量的变化就更少了。在新西兰出现了一个独特的机会来调查这一进程。欧洲防风草网虫原产于欧洲，它以三种含有有毒呋喃香豆素的植物为食。这三种寄主植物在37至138年前入侵新西兰，直到两年前才摆脱了旧世界的食草动物，当时据报道，防风草网虫首次在新西兰南岛茁壮成长。该项目的目标是确定新西兰尚未被网虫感染的种群中呋喃香豆素的水平是否低于与网虫有长期联系的北美和欧洲种群的水平，并确定重新与防风草网虫联系的新西兰种群是否会经历定向选择以增加毒性。更广泛的影响：这种情况提供了一个非凡的机会来记录杂草物种的入侵程度取决于其毒性化学。由于传统的生物控制涉及引入食草动物来控制入侵杂草，本研究的结果也将提供关于杂草在与控制剂重新结合后如何进化的基本信息，并将在涉及引入共同进化的食草动物的生物控制计划的决策过程中有用。

Globalization of trade has exacerbated the problem of invasive plants; when weed species invade new areas, they can cause enormous economic and ecological damage. In many cases, toxic chemistry facilitates the process by which these weeds become established, but little information is available on the evolutionary changes in toxin content of plants that occur after introduction into a non-indigenous area and release from interactions with longtime insect associates. Even less is known about changes in toxin content that ensue when coevolved natural enemies resume interacting with a hostplant in a non-indigenous area. A unique opportunity has arisen in New Zealand to investigate this process as it unfolds. The parsnip webworm Depressaria pastinacella is native to Europe where it feeds on three plant species that contain toxic furanocoumarins. These three host plants invaded New Zealand 37 to 138 years ago and have been free of Old World herbivores until two years ago, when parsnip webworms were reported for the first time to be thriving on the South Island of NZ. The goals of this project are to determine whether furanocoumarin levels in New Zealand populations not yet infested by webworms are lower than levels in North American and European populations with a long history of webworm association and to determine whether New Zealand populations reassociated with parsnip webworms will experience directional selection for increased toxicity. Broader Impacts: This situation provides an extraordinary opportunity to document the extent to which an invasion by a weed species depends on its toxic chemistry. As classical biological control involves introduction of herbivores to control invasive weeds, the results of this study will also provide essential information about how weeds might evolve subsequent to reassociation with a control agent and will be useful in the decision-making process involved in biological control programs involving introduction of coevolved herbivores.