Exploring omnivory in native plant-herbivore-omnivore systems

Many of the 'predatory' insects used in modern biological control are actually omnivores, feeding at least in part upon host plant tissues in addition to consuming arthropod prey. Although plant-herbivore-omnivore interactions have been studied in agricultural systems, similar work has not been conducted in natural systems where the interacting species may have a long coevolutionary history. Using a few natural plant-herbivore-omnivore systems, I conducted simple manipulations to ask three questions: 1) how predatory are the plant-associated omnivores?, 2) can stable isotopes be used to accurately estimate the diet of the omnivores in the field?, and 3) what is the effect of the omnivore on herbivore abundance? Early experimental results and some basic system descriptions will be presented.