Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Agronomy, Horticulture, and Plant Science

First Advisor

Adam Varenhorst


pest management, wild soybean


Soybean aphid, Aphis glycines Matsumura, is a major pest to soybean, Glycine max (L.) Merr. Host plant resistance is a management tactic that uses naturally occurring soybean plant defenses to limit soybean aphid pest damage. Virulent soybean aphid biotypes are able to successfully colonize on certain aphid resistant soybean. Soybean aphid biotype 4 is most virulent, overcoming all commercially available soybean aphid resistant soybeans (Rag1, Rag2, and Rag1+Rag2). Additional sources of resistance to avirulent biotypes have been identified in soja and soybean plant introductions (PIs). This study examined those resistant soja and soybean for resistance to the newly found soybean aphid biotype 4, using iso-female colonies of soybean aphid from three different site-years. Free-choice tests examined 20 soja and 50 soybean PIs for putative resistance to the three soybean aphid biotype 4 colonies. Promising PIs continued on in a follow-up, caged no-choice test with its respective colony. Soja PI 65549 and PI 101404A and soybean PI 437696 were found highly resistant to each of the three soybean aphid biotype 4 colonies and should be explored further as valuable sources of soybean aphid resistance.

Library of Congress Subject Headings

Soybean -- Disease and pest resistance.
Host plants.
Natural immunity.


Includes bibliographical references



Number of Pages



South Dakota State University

Conzemius-Sophia-2018-PACLA.pdf (187 kB)
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Rights Statement

In Copyright