Project Number: 1926-22000-024-00
Project Type: Appropriated

Start Date: Nov 04, 2010
End Date: Nov 03, 2015

Objective:
1 - Determine the behavioral, physiological, and genetic basis for host specificity of parasitoids of pest insects, such as soybean aphid (Aphis glycines) on soybean, Russian wheat aphid (Diuraphis noxia) on small grains, cherry vinegar fly (Drosophila suzukii) on soft fruits, and other invasive insects, and of insect herbivores, such as noctuid moths in the genus Heliothis on cotton and other crops. 1.1 – Determine the genetic architecture underlying differences in host specificity. 1.2 – Test whether parasitoids introduced against insect pests have evolved to parasitize endemic species and whether parasitoids resident prior to introductions have evolved to parasitize exotic pests. 1.3 – Test how the host acceptance behavior of parasitoids depends on their physiological state, aphid defenses, and ecological factors. 1.4 - Determine the role of bacterial endosymbionts in protecting insects from parasitoids. 2 - Determine the identity and phylogenetic relationships among species of parasitoids proposed for introduction against pest insects, such as soybean aphid, Russian wheat aphid, and cherry vinegar fly. 3 - Screen, introduce, and evaluate impact of candidates for biological control introductions against pest insects, such as the soybean aphid on soybean, the Russian wheat aphid on small grains, cherry vinegar fly on soft fruits, and other invasive insects. 3.1 – Biological control introductions against soybean aphid. 3.2 – Biological control introductions against Russian wheat aphid. 3.3 – Biological control introductions against cherry vinegar fly.

Approach:
Safe and effective biological control depends on using narrowly host-specific agents, and host specificity depends on internal physiological state and previous experience, as well as ecological factors. Furthermore, the likelihood that a host-specific insect will evolve to attack a novel host species depends on the genetic architecture of host use. We will determine the behavioral and genetic bases for host shifts in the herbivores in the genus HELIOTHIS and aphid parasitoids in the genus APHELINUS using laboratory experiments on host use behavior and quantitative genetics/genomics analyses of inter and intraspecific crosses to map and identify genetic architecture. We will also test whether introduced aphid parasitoids have evolved to parasitize endemic species and whether aphid parasitoids resident prior to introductions have evolved to parasitize invasive pests. To do this, we compare host ranges parasitoids before and after introduction in laboratory experiments. Cryptic species are closely related species that differ little in the morphology, but differ critically in traits like host specificity, and studies on host range have often confounded cryptic species. Using modern methods of molecular phylogenetics, morphometrics, and behavioral biology, we develop robust phylogenies and identification keys for species complexes of aphid parasitoids important in biocontrol. We will use the knowledge and methods from the above research to screen specificity of candidates proposed for biocontrol introductions against soybean aphid, Russian wheat aphid, and other invasive pests. We will introduce the most promising candidates and evaluate their impact on target and non-target species with field exclosures, surveys, and analyses of population dynamics.