CHEMICAL ECOLOGY OF PLANT-MICROBE INTERACTIONS AND EFFECTS ON INSECT HERBIVORES

*Signatures are on file in the Graduate School iii Plants are central to most community interaction webs and thus the ability to coordinate responses to many simultaneous interactions is an essential adaptation. Interaction with one organism may make the plant more vulnerable or more resistant to attacks by very different organisms. Microorganisms can form intimate associations with plants with direct effects ranging from beneficial to antagonistic, but indirect effects of plant-microbe relationships on plant interactions with other organisms are not well understood. Here, we explore the influences of microorganisms and microbial products on herbivory and resulting plant defenses. We use the legume-rhizobia mutualism as a model-system to explore herbivore-plant interactions by first characterizing the effects of rhizobial inoculation on herbivore feeding and subsequent accumulation of plant defense signaling hormones. We found interactive effects of the legume-rhizobia mutualism on plant-herbivore interaction