Interaction webs in agroecosystems: beyond who eats whom

Studies of insect communities in agroecosystems have historically focused on a food web approach: who eats whom. Recent research has highlighted the importance of indirect effects in determining the abundance and distribution of insects and their effects on other insects and plants. These indirect interactions include apparent competition where an herbivore indirectly suppresses another herbivore by attracting shared predators, cases where predators or even other herbivores alter the behavior and/or physiology of herbivores in ways that result in decreased plant consumption, and mutualisms that can generate a network of indirect effects that alter the abundance of many species within a community. The consequences of these indirect interactions have been modeled and proof-of-concept studies have demonstrated their potential importance, but studies of the consequences of these interactions on crop yield are sorely needed. Documenting the prevalence and consequences of these indirect effects in multiple crops will allow researchers to compare and contrast responses across systems and identify key species or characteristics of agroecosystems that dictate when and where these effects are important. This research will ultimately allow growers to manipulate these interactions to increase ecosystem services provided by insects and increase crop yield.