Student Poster Display
Plant-Insect Ecosystems
Student
Bijay Subedi
Graduate Research Assistant
The Pennsylvania State University
State College, Pennsylvania
Victoria Pocius
Field Scientist I
Douglas Products
State College, Pennsylvania
Monica Kersch-Becker
Assistant Professor
The Pennsylvania State University
University Park, Pennsylvania
Trophic cascades, where predators benefit plants by suppressing herbivore populations, are influenced by plant defenses, but the contribution of prey nutritional content remains overlooked. While it is known that plant defenses can affect predator behavior, a comprehensive mechanistic framework is lacking. Therefore, there is a need for identifying mechanisms influencing the strength of tri-trophic interactions and the success of biological control in agroecosystems. This study investigates the impact of phytohormone-mediated resistance on herbivore quality as prey and the subsequent effects on predation. Here, we manipulated plant resistance (Solanum lycopersicum)by exogenously applying benzothiadiazole, a salicylic acid analog, to examine how salicylate-mediated defenses affect the performance and nutritional composition of the potato aphid (Macrosiphum euphorbiae). Additionally, we assessed how changes in aphid nutritional quality as prey impact predation by the ladybug predator, Hippodamia convergens. We demonstrated that salicylate-mediated defenses reduced aphid performance and nutritional quality. This reduction in aphid quality triggered a compensatory feeding response in the predators, causing them to consume more aphids to meet their dietary needs. These findings demonstrate that the effects of phytohormone-mediated resistance propagates throughout the food web, reducing herbivore performance and altering predator consumption. By elucidating the complex interactions between plant defenses, herbivore nutritional quality, and predator feeding behavior, this study provides insights into the mechanisms driving tri-trophic interactions, highlighting the potential for optimizing biological control strategies and promoting sustainable agricultural practices.