The interactions between plants and insects are fundamental to terrestrial ecology. These interactions typically conjure images of bees pollinating flowers, and while pollination is important, herbivory on plants by insects has equally far-reaching effects. Specifically, I’m interested in tri-trophic interactions (interactions between a plant, an insect herbivore and insect parasitoids that attack herbivores): how they function, their broader ecological implications and their impacts on the evolution of each group. I’m currently working on a system involving the herbivorous tobacco hornworm (Manduca sexta), a suite of host-plants that it feeds on, and a parasitoid fly that attacks it in Arizona (Drino rhoeo). In southern Arizona, an attack by a parasitoid fly is typically a death-sentence for a caterpillar. I’m interested in how the type of plant a caterpillar eats affects it’s performance and immune function, and how this in turn affects a caterpillar’s ability to fend off an advancing parasitoid. This physiological-ecology approach has broad implications in agriculture, and will broaden our understanding of how herbivorous specialists and generalists co-evolve and cope with attacking parasitoids.