PARENT SESSION
Oral Session #72: Herbivory: Herbivore Response to Plants.
Presiding: C. Mitchell
Wednesday, August 7. 1:00 PM to 4:45 PM. Mesquite Room, Radisson.
Interactions between insect parasitoids and multiple herbivores on tomato plants.
Rodriguez-Saona, Cesar*,1, Thaler, Jennifer1, 1 Department of Botany, University of Toronto, Toronto, ON, Canada
ABSTRACT- Herbivore damage induces changes in plant phenotype that can affect the future colonization and performance of herbivores and their natural enemies. These changes can be induced by more than one species, against which plants may deploy differential defenses. We compared the chemical responses of tomato plants to damage by single and multiple herbivores and the consequences of these responses at different trophic levels. We damaged tomato plants with either the phloem feeding aphid Macrosiphum euphorbiae, the chewing caterpillar Spodoptera exigua, both herbivores, or neither. We then tested the performance and preference of S. exigua and its parasitic wasp, Cotesia marginiventris, on these plants. Parasitized and non-parasitized caterpillars were fed leaves from treated plants. Caterpillar damage to plants reduced the growth, development, survival, and food consumption of assay caterpillars compared to caterpillars reared on control plants. This effect was not altered by aphid feeding. Parasitoid survivorship mirrored caterpillar survivorship on the four treatments. In addition, choice experiments conducted to determine oviposition preference of moths to different treated plants indicate that moths oviposit higher number of eggs on aphid-damaged and control plants as compared to caterpillar-damaged plants.
KEY WORDS: Herbivory, Defenses, Tritrophic, Interactions