Impact of Alien Plants on Insect Communities

在整个北美，外来植物正在迅速取代本地物种。大规模替代本地植被有几个后果，但外来植物对昆虫食草动物的影响很少受到关注。只能吃几种植物的昆虫应该不能在与它们没有共同进化历史的植物上生长和繁殖。因为大多数昆虫食草动物都是这样的专家，外来植物的入侵应该减少当地的生物多样性，这反过来可能会降低生态系统的稳定性和生产力。然而，专家们可能能够采用与本地植物宿主密切相关的外来物种，而几乎没有负面影响。相比之下，能够利用许多植物物种的昆虫应该不受外来物种的影响，并可能弥补专家的损失。现有的数据很少，但它们都不支持这两种预测。鉴于食草昆虫在植物向其他动物传递能量方面的关键作用，有必要了解外来植物如何影响食草昆虫的生产和多样性。该项目通过量化解决了这一需求：1)专家转向与其本国东道主相关的外国人的程度；2)多面手在外来和本地植物上的成功；③专才和通才对待外来生物的行为如何受到生境外来生物量比例的影响。一名研究生和几名本科生将接受野外种群抽样和昆虫分类方面的培训，并将获得对日益增长的生物入侵领域的宝贵接触。这项研究还将有助于填补长期以来我们对植物-昆虫相互作用知识的空白，例如通才是否比专家更能推动食物网。这项研究的结果将在主要文献和大众科学出版物中传播，以环境意识的公众为目标。

Alien plants are rapidly replacing native species throughout North America. Large-scale replacement of native vegetation has several consequences, but one that has received little attention is the effect of alien plants on insect herbivores. Insects capable of eating only a few types of plants should be unable to grow and reproduce on plants with which they share no evolutionary history. Because most insect herbivores are such specialists, alien plant invasions should reduce local biodiversity, which in turn may reduce ecosystem stability and productivity. Specialists may, however, be able to adopt alien species that are closely related to their native plant host with few negative effects. Insects that are able to use many plant species, in contrast, should be unaffected by aliens and may compensate for the loss of specialists. Existing data are few but they support neither of these predictions. In view of the critical role of herbivorous insects in transferring energy from plants to other animals, it is essential to understand how alien plants affect the production and diversity of insect herbivores. This project addresses this need by quantifying 1) the degree to which specialists switch to aliens related to their native hosts; 2) the success of generalists on alien and native plants; and 3) how the behavior of specialists and generalists toward aliens is affected by the proportion of alien biomass in the habitat. A graduate student and several undergraduates will be trained in field population sampling and insect taxonomy and will gain valuable exposure to the growing field of biological invasions. This study will also help to fill long-standing gaps in our knowledge of plant-insect interactions, such as whether generalists drive food webs more than specialists. The results of this study will be disseminated in the primary literature and also in popular-science publications to target the environmentally-minded public.