Dynamics of an omnivore and its herbivorous prey on a shared, inducible host plant

Empirical studies have established that both omnivory and wound-inducible response systems in plants are common in Nature. These ecological areas are especially well-characterized for arthropod-plant interactions. While there are well-developed, discrete bodies of theory for the ecological and evolutionary dynamics of both omnivory and wound-inducible plant defenses, to date there is no formal theory exploring the interplay between them.  As a first step, we submit a simple model that explores a number of ecological situations in which an herbivore-omnivore pair occurs on an inducible plant.  Our model assumes the plant, herbivore, and omnivore have distinct fitness interests which may conflict. Each actor pursues its interests, and in doing so manipulates the plant’s inducible response system. This makes the plant more or less resistant to future herbivory.  Model results indicate that manipulation of the plant induced response system by the herbivore and omnivore can lead to qualitatively different effects on both arthropod population dynamics and plant performance.  We believe the interaction of induced plant responses and omnivory offers several interesting lines of empirical research, which could have important consequences for the understanding of predator-prey dynamics and integrated pest management.