Natural Enemy Diversity and Biological Control

外来害虫或因人类的疏忽或故意而传播到世界各地。该提案评估了两个相互关联的问题：(1)这些害虫入侵的能力是否取决于它们遇到的新生态系统的生物多样性？(2)生物贫乏的生态系统是否更容易受到入侵？拟议的研究将在遭受多种外来有害生物侵害的农业系统中解决这些问题。大豆蚜虫（Aphis glycine）是一种非常成功的害虫，2000年在北美首次被发现。在上中西部地区，这种入侵者达到了爆发的程度，成为大豆田昆虫贫乏社区中唯一的严重害虫。相比之下，在苜蓿作物中，豌豆蚜虫（Acyrthosiphon pisum）是一种潜在的害虫，但它从未达到爆发的水平。与大豆田的低生物多样性不同，紫花苜蓿的无脊椎动物多样性很高，包括食草动物和食肉动物。我的研究将测试大豆群落相对于苜蓿群落的低多样性是否有利于大豆蚜虫的入侵和爆发，而捕食者不断控制豌豆蚜虫。试验将在大豆和苜蓿作物之间切换无脊椎动物群落，从而迫使大豆蚜虫面对苜蓿中发现的物种群落，反过来使豌豆蚜虫面对大豆中物种贫乏的群落。如果大豆作物的低生物多样性对大豆蚜虫的成功入侵至关重要，那么当放置在高度多样化的苜蓿作物群落中时，大豆蚜虫应该受到抑制。

Exotic pests are spread throughout the world either inadvertently or intentionally by humans. This proposal evaluates two inter-related questions: (1) does the ability of these pests to invade depend on the biodiversity of the new ecosystems they encounter, and (2) are biologically impoverished ecosystems more susceptible to invasion? The proposed research will address these questions in agricultural systems that have been subjected to numerous types of exotic pest. A dramatically successful pest, the soybean aphid, Aphis glycines, was first identified in North America in 2000. In the Upper Midwest, this invader reached outbreak levels, becoming the only serious insect pest in the otherwise insect-poor community found in soybean fields. In contrast, in alfalfa crops the pea aphid, Acyrthosiphon pisum, is a potential pest, but it never reaches outbreak levels. Unlike the low biodiversity of soybean fields, alfalfa has a high diversity of invertebrates, both herbivores and predators. My research will test whether the low diversity of the soybean community relative to the alfalfa community facilitates the invasion and outbreak of the soybean aphid, whereas predators continuously control pea aphids. Experiments will be performed to switch the invertebrate communities between soybean and alfalfa crops, thereby forcing soybean aphids to face the community of species found in alfalfa, and conversely making pea aphids face the species-poor community from soybeans. If low biodiversity of soybean crops is essential for the successful invasion of the soybean aphid, then when placed in the highly diverse community of alfalfa crops, the soybean aphid should be suppressed.