Resistance of soybean plant introductions to three colonies of soybean aphid (Hemiptera: Aphididae) biotype 4

Authors: CONZEMIUS, SOPHIA - South Dakota State University; Hesler, Louis; VARENHORST, ADAM - South Dakota State University; TILMON, KELLEY - The Ohio State University

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/8/2019
Publication Date: 5/13/2019
Citation: Conzemius, S., Hesler, L.S., Varenhorst, A., Tilmon, K. 2019. Resistance of soybean plant introductions to three colonies of soybean aphid (Hemiptera: Aphididae) biotype 4. Journal of Economic Entomology. https://doi.org/10.1093/jee/toz116.
DOI: https://doi.org/10.1093/jee/toz116

Interpretive Summary: Infestations of the soybean aphid on soybean may cause substantial yield loss, and control measures have led to a large dependence on insecticides against this pest throughout the Midwestern United States and southern Canada. However, several populations of pyrethroid-resistant soybean aphid have been found recently in these regions, highlighting the importance of alternative management approaches. One such alternative, host plant resistance, uses naturally-occurring plant defenses in crop cultivars to reduce the potential for yield loss from a pest population. Aphid-resistant cultivars do not protect against all forms of this pest due to the presence of highly injurious biotypes that overcome multiple resistance genes. In particular, soybean aphid biotype 4 overcomes resistance genes Rag1 and Rag2, both individually and in combination. However, we surmised that resistance to biotype 4 may exist in previously identified, but uncharacterized soybean plant introductions (PIs) that have shown resistance to less destructive soybean aphid biotypes. To test this, 51 PIs previously identified as resistant to other soybean aphid biotypes were evaluated in the laboratory for resistance to three separate colonies of biotype 4 aphids collected from Lomira, Wisconsin in 2013 and from Volga, South Dakota in 2015 and again in 2016. Free-choice tests preliminarily identified various PIs with resistance to the ‘Lomira13,’ ‘Volga15,’ and ‘Volga16’ colonies. Follow-up, no-choice tests with the resistant PIs corroborated two to three resistant PIs per colony, and PI 437696 was resistant to each of the three colonies, which could aid in breeding efforts and broader soybean aphid management.

Technical Abstract: Soybean aphid, Aphis glycines Matsumura, infestations on soybean, Glycine max (L.) Merr., and associated yield loss have led to a large dependence on insecticidal management in soybean throughout the Midwestern United States and southern Canada. However, several populations of pyrethroid-resistant soybean aphid have been found recently in these regions, highlighting the importance of alternative management approaches. One such alternative method, host plant resistance, uses naturally occurring plant defenses in crop cultivars to reduce the potential for yield loss from a pest population. Current soybean aphid resistant cultivars do not protect against all soybean aphids due to the presence of virulent biotypes. In particular, soybean aphid biotype 4 is virulent to Rag1 and Rag2 resistance genes both individually and in combination. However, we hypothesized that resistance to biotype 4 may exist in previously identified, but uncharacterized resistant soybean plant introductions (PIs). To test this, we evaluated 51 PIs that were previously found to be resistant to other soybean aphid biotypes in the laboratory for their resistance to colonies of biotype 4 soybean aphids collected in separate site-years (Lomira, WI 2013; Volga, SD 2015, 2016). Free-choice tests identified 14 PIs with putative resistance to ‘Lomira13,’ two to ‘Volga15,’ and eight to ‘Volga16’ soybean aphid colonies. Follow-up, no-choice tests with the putatively resistant PIs corroborated two to three resistant PIs per colony, and PI 437696 was resistant to each of the three colonies, which could aid in breeding efforts and broader soybean aphid management.