BOTTOM-UP TROPHIC CASCADES: HOW A CHANGING CLIMATE CAN SHIFT PLANT-PEST-NATURAL ENEMY DYNAMICS

Abiotic stressors linked to global climate change frequently alter plant defensive trait expression, subsequently affecting a plant's susceptibility to insect herbivores. Using soybeans and soybean aphids (Aphis glycines) as a model system, this project will explore the longer-term evolutionary consequences of these biotic - abiotic interactions, particularly the differential impact of host plant water stress on virulent (i.e. resistant to natural plant defenses) and avirulent (i.e. susceptible to natural plant defenses) insect biotypes. Long term, this work will expand our understanding about the potential risk for abiotic stress to accelerate selection for insect virulence. Drawing upon a combined experimental and mathematical modeling approach, this project will address four main objectives:1) Compare the effect of host plant water stress on virulent and avirulent soybean aphid fitness2) Evaluate how host plant water stress impacts aphid interactions with a parasitoid wasp3) Track changes in virulent and avirulent aphid frequency under different water stress scenarios within experimental mesocosms4) Develop mathematical models to simulate changes in aphid population dynamics over the course of an entire growing season and in response to a wider array of biotic and abiotic stressors