PDF(Pubmed)
Abstract：
Advances in molecular ecology can overcome many challenges in understanding host-parasitoid interactions. Genetic characterization of the key-players in systems helps to confirm species and identify trophic linkages essential for ecological service delivery by biological control agents; however, relatively few agroecosystems have been explored using this approach. Pecan production consists of a large tree perennial system containing an assortment of seasonal pests and natural enemies. As a first step to characterizing host-parasitoid associations in pecan food webs, we focus on aphid species and their parasitoids. Based on DNA barcoding of field-collected and reared specimens, we confirmed the presence of 3 species of aphid, one family of primary parasitoids, and 5 species of hyperparasitoids. By applying metabarcoding to field-collected aphid mummies, we were able to identify multiple species within each aphid mummy to unravel a complex food web of 3 aphids, 2 primary parasitoids, and upward of 8 hyperparasitoid species. The results of this study demonstrate that multiple hyperparasitoid species attack a single primary parasitoid of pecan aphids, which may have negative consequences for successful aphid biological control. Although further research is needed on a broader spatial scale, our results suggest multiple species exist in this system and may suggest a complex set of interactions between parasitoids, hyperparasitoids, and the 3 aphid species. This was the first time that many of these species have been characterized and demonstrates the application of novel approaches to analyze the aphid-parasitoid food webs in pecans and other tree crop systems.
摘要：
分子生态学的进展可以克服理解宿主-寄生虫相互作用的许多挑战。系统中关键参与者的遗传特征有助于确认物种并确定生物控制剂提供生态服务所必需的营养联系；但是，使用这种方法探索的农业生态系统相对较少。山核桃生产由一个大树多年生系统组成，其中包含各种季节性害虫和天敌。作为表征山核桃食物网中宿主-寄生虫关联的第一步，我们关注蚜虫物种和它们的寄生虫。根据野外采集和饲养标本的DNA条形码，我们证实了3种蚜虫的存在，一个主要的寄生虫家族，和5种超寄生虫。通过对野外采集的蚜虫木乃伊应用元编码，我们能够在每个蚜虫木乃伊中识别出多个物种，以解开由3种蚜虫组成的复杂食物网，2个主要的寄生虫，以及8种超寄生虫物种的向上。这项研究的结果表明，多种超寄生虫物种攻击山核桃蚜虫的单个初级寄生虫，这可能会对成功的蚜虫生物防治产生负面影响。尽管需要在更广泛的空间尺度上进行进一步的研究，我们的结果表明，该系统中存在多种物种，并且可能表明寄生虫之间存在一组复杂的相互作用，超寄生虫，和3种蚜虫。这是首次对这些物种中的许多物种进行了表征，并展示了新方法在分析山核桃和其他树木作物系统中的蚜虫类食物网中的应用。
