Date of Award
Master of Science
Matthew E. O'Neal
The manipulation of beneficial insects can be done through purposeful releases of biological control organisms, or through manipulation of non-crop habitat. Both mechanisms are explored in various agroecosystems. In chapter 2, I determine if the parasitoid waspBinodoxys communis, imported from China, is able to colonize, and suppress soybean aphid, Aphis glycines in Iowa soybean fields. In addition, the effects of initial soybean aphid densities are measured. Binodoxys communis successfully colonized soybean aphids in Iowa soybean fields, but is not always effective at suppressing soybean aphid populations. Abiotic and biotic factors were more important for the suppression of soybean aphid. In addition, Binodoxys communis acts in a density-dependent manner when soybean aphid populations are lower. Thus, augmentative releases when soybean aphid populations are lower may limit soybean aphid populations. In chapter 3, I examined conservation of natural enemies (and other arthropod guilds) as part of a larger interdisciplinary study. Prairie vegetative strips were planted in various treatment amounts (0% to 20%), and distributions (0 to 3 strips) within watershed catchments devoted to annual crop production. Arthropods were significantly more abundant within prairie land cover than crop, but the various treatments had no effect on arthropod abundance. When examining the most commonly collected natural enemy taxa, we find that most taxa are more abundant within prairie over the entire season. At different sampling dates throughout the season, these natural enemy taxa responded in varying ways to the availability of alternative prey and resources available within prairie land cover. Within this system, prairie integration had a significant impact on the abundance and diversity of arthropods; however the surrounding matrix of each site was dominated by prairie, and likely silenced the treatment effects.
Hessel, Rene, "Classical and conservation biological control of pest insects within prairie and crop systems" (2013). Graduate Theses and Dissertations. 13539.