Plant-mediated competition among insect herbivores occurs when one species induces changes in plant biochemistry that render plants resistant to attack by the same or other species. We explored plant-mediated interspecific and intraspecific interactions between the beet armyworm (Spodoptera exigua) (BAW), the tobacco hornworm (Manducca sexta) (THW), and the western flower thrips (Frankliniella occidentalis) three important nightshade herbivores. This thrips is a major vector of the tomato spotted wilt virus and TSA is a potential reservoir. These studies were conducted in the context of the invasive noxious weed tropical soda apple (TSA). The consequences of beet armyworm-induced resistance for BAW, THW and thrips performance were studied in the greenhouse and lab cages. TSA plants were exposed to four densities of BAW (none, low, moderate, and high). The preference, performance, and survivorship of thrips were then measured on the four categories of induced plants in cage and greenhouse settings.