Exploitative competition mechanisms drive coexistence of Aphelinus nigritus and Lysiphlebus testaceipes on shared aphid hosts in cereal agroecosystems of the Central Great Plains

In the Central Great Plains of the United States, the solitary koinobiont endoparasitoids Lysiphlebus testaceipes Cresson (Hymenoptera: Braconidae) and Aphelinus nigritus Howard (Hymenoptera: Aphelinidae) compete for limited aphid hosts in annual cereal agroecosystems. Although these parasitoids reduce aphid pest populations in this region through parasitism, little is known about their competitive interactions and mechanisms of coexistence. This dissertation explores the mechanisms of coexistence and the outcomes of competitive interactions between A. nigritus and L. testaceipes. The mechanisms include differences in host specificity, host switching ability, searching efficiency, arrival time, and host discrimination ability. The information gained from these studies will add to our understanding of the overall structure and function of cereal aphid parasitoid communities of the Central Great Plains.