Erika Rodbell, Iowa State University, Department of Entomology
M.S. defense seminar.
Abstract. Soybean aphid (SBA), Aphis glycines Matsumura (Hemiptera: Aphididae), is the most economically damaging insect pest of soybean, (Glycine max (L.) Merr.). Soybean susceptibility is influenced by Rag genes, soybean health and nutrient availability within phloem. The focus of our research is two-fold. The first is to demonstrate on a commercial scale how SBA populations and soybean yield differ between SBA resistant and susceptible varieties on Iowa farms. The second is to evaluate how crop rotation and soybean growth stage influences soybean susceptibility to soybean aphid. We evaluated SBA populations and yield for five different varieties of soybean, including three SBA-resistant varieties and two susceptible varieties. The crop rotation project investigated, across three soybean growth stages,how a conventionally managed two-year rotation differed from more diverse three-year and four-year crop rotations, with respect to soybean nutrient concentrations and SBA populations. Cumulatively, our results suggest SBA resistant soybean provide season long protection against SBA with no consequence to yield. In addition, our results suggest soybean susceptibility to SBA was impacted by soybean crop rotation scheme at the early vegetative growth stage and nutrient concentrations in soybean tissue.