Ecological Effects of a Host Range Expansion by a Weevil Imported for Biological Control

研究人员提议测量为控制外来蓟而释放的花头象鼻虫（Rhinocyllus conicus）对本地植物及其相关昆虫的影响。实验将测量本地蓟花期对象鼻虫影响的影响，象鼻虫对本地蓟种子产量的影响，以及引进象鼻虫的优越竞争能力是否导致本地昆虫数量下降。预期结果包括：记录外来象鼻虫对大平原上两种本地植物取食的程度和影响，评估植物生长模式对象鼻虫使用和影响的作用，确定故意引入昆虫改变寄主使用的直接生态后果。为了控制外来杂草，一种昆虫被故意引入美国，这种昆虫无意中取食了当地的寄主植物，这项研究将首次通过实验评估其生态后果。杂草的生物防治越来越被提倡作为除草剂的环保替代品。然而，很少有数据可以用来评估引入外来昆虫在生物控制计划中的环境风险。这项研究将提供重要的数据，说明发生转移时的后果，从而说明与杂草的传统生物控制有关的潜在生态风险。这些信息在未来控制外来入侵杂草的尝试中将被证明是有用的。

9615299 LOUDA The investigators propose to measure the impact of the flowerhead weevil (Rhinocyllus conicus), released for biological control of exotic thistles, on native plants and the insects associated with them. Experiments will measure the effects of the timing of flowering by native thistles on the impact of weevils, the effect of the weevil on seed production of native thistles, and whether superior competitive ability of the introduced weevil is responsible for the population decline of native insects. The expected outcomes include: documentation of the extent and impact of the feeding by the exotic weevil on two native plants in the upper Great Plains, assessment of the role of plant growth patterns on weevil use and impact, and determination of the direct ecological consequences of shifting host use by a deliberately introduced insect. The study will be the first to experimentally assess the ecological consequences of unintended feeding on native host plants by an insect deliberately introduced into the USA to control exotic weeds. Biological control of weeds is increasingly advocated as an environmental alternative to herbicides. Yet, few data are available with which to evaluate environmental risks of introducing exotic insects in biological control programs. The study will provide important data on such consequences when transference occurs and, thus, on potential ecological risks associated with classical biological control of weeds. Such information should prove useful in future attempts to control invasive exotic weeds.