The effect of ecosystem simplification on arthropod predation in southeastern Minnesota

Naturally occurring insect predators can provide crucial herbivore regulatory services in both natural and managed ecosystem with little risk to human or environmental health. Limited understanding of how predation pressure varies based on ecosystem complexity is a major obstacle to optimizing this ecosystem service within simplified agroecosystems. Among growers, there is great potential for decreasing yield loss to pest species by determining what level of within plot diversity would promote the presence of natural predators. We used collard plants (Brassica oleracea) as a model system to explore the influence of ecosystem complexity of predation pressure within the southeastern Minnesota. Plants were placed in natural oak savannas, monoculture brassica plots, or polyculture brassica plots and baited with three common pest-herbivore species of brassicas (Myzus persicae, Plutella xylostella, and Trichoplusia ni.). Differences in herbivore survivorship between predator-excluded, caged and predator included, shamed-caged plants was used to assess level of predation within each site. Comparisons across levels of ecosystem complexity will be made and implications for within plot augmentation will be discussed.