Natural Enemy Diversity and Biological Control

外来害虫在世界各地传播，无论是无意的还是有意的。 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，以及（2）生物贫乏的生态系统是否更容易受到入侵？ 拟议的研究将解决这些问题，在农业系统已受到许多类型的外来害虫。 大豆蚜虫是一种非常成功的害虫，2000年首次在北美发现。 在上中西部，这种入侵者达到爆发水平，成为大豆田中发现的昆虫贫乏社区中唯一严重的害虫。相比之下，在苜蓿作物中，豌豆蚜（Acyrthosiphon pisum）是一种潜在的害虫，但从未达到爆发水平。 与大豆田的低生物多样性不同，苜蓿具有高多样性的无脊椎动物，包括食草动物和捕食者。 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，而捕食者持续控制豌豆蚜虫。 将进行实验，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，反之，使豌豆蚜虫面对大豆中的物种贫乏群落。 如果大豆作物的低生物多样性是大豆蚜虫成功入侵的必要条件，那么当置于高度多样性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.