Degree Type


Date of Award


Degree Name

Master of Science




Entomology; Sustainable Agriculture

First Advisor

Erin W. Hodgson

Second Advisor

Matthew E. O'Neal


Soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is the most economically damaging insect pest of soybean, (Glycine max (L.) Merr.). Since soybean aphids were discovered in the United States in 2000, a substantial effort has been made to identify mechanisms for managing soybean aphid populations. Soybean aphid populations can be impacted by biocontrol, insecticides, and host plant resistance. Additionally, soybean susceptibility to soybean aphid can be influenced by soybean health and nutrient availability within phloem, which can be impacted through agricultural management practices. The focus of this research is three-fold. The first, was to evaluate how a three gene pyramid of Rag genes compared to four soybean varieties of varying resistance to soybean aphids. The second, was to demonstrate on a commercial scale, how soybean aphid populations and soybean yield differed between soybean aphid resistant and soybean aphid susceptible varieties on Iowa farms. The third, was to evaluate how crop rotation and soybean growth stage influenced soybean susceptibility to soybean aphid. We conducted our research in small plot cage studies, small plot studies, and on a commercial scale in central and northern Iowa. Cumulatively, our results suggest soybean aphid resistant varieties provide protection against soybean aphids with no consequence to yield, with host plant quality for soybean aphid being affected by crop rotation at the early reproductive growth stage.

Copyright Owner

Erika Rodbell



File Format


File Size

93 pages

Included in

Entomology Commons