Toxic aphids: how bacterial symbionts influence coccinellid defense and biological control of Aphis craccivora

Our overall goal is to understand the intertwined relationship between host plant usage, bacterial symbionts, and natural \enemy defense in A. craccivora. Our specific objectives are 1) to determine whether bacterial symbionts play a causal role in host plant association patterns in A. craccivora, 2) to characterize the predator-defensive properties of locust-origin A. craccivora with the particular hypothesis that the symbiont Arsenophonus is the causal agent for predator mortality, and 3) to examine the ecological and evolutionary interactions of differentially protected aphid strains and their natural enemies within a common environment. Our approach will be to use isoline clones of A. craccivora originating from different hosts in which we have manipulated symbiont infection through microinjection. We will use laboratory assays to evaluate the fitness of differentially infected aphid lineages across a variety of host plants. We will also use laboratory assays to assess ladybeetle fitness on the differentially infected aphid lineages. Finally, we will conduct laboratory, field population cage, and open field studies to evaluate the evolutionary trajectory, population dynamics, and community interactions of differentially protected A. craccivora.