|Mornhinweg, Dolores - Do|
Submitted to: North American Barley Research Workshop Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2008
Publication Date: 10/27/2008
Citation: Puterka, G.J., Mornhinweg, D.W. 2008. Distribution and diversity of Russian wheat aphid (Homoptera: Aphididae) biotypes in North America [abstract]. In: Proceedings of the 19th North American Barley Researchers Workshop, October 26-29, 2008, Madison, WI. Available: http://wheat.pw.usda.gov/ggpages/BarleyNewsletter/51/NABRW_2008_Proceedings.htm.
Technical Abstract: Wheat with Russian wheat aphid (RWA) resistance based on the Dn4 gene has been important in managing RWA since 1994. Currently, there are eight biotypes (RWA1 - RWA5) of this aphid that have been described based on their ability to differentially damage RWA resistance genes in wheat. RWA2, RWA4, and RWA5 are of great concern because they can kill wheat with Dn4 resistance. In 2005, 365 RWA clone colonies were made from collections taken from 98 fields of wheat or barley in Oklahoma, Texas, New Mexico, Colorado, Kansas, Nebraska, and Wyoming to determine their biotypic status. The biotype of each clone was determined through its ability to differentially damage four resistant and two susceptible wheat entries in two phases of screening. Only two biotypes, RWA1 and RWA2, were identified in this study. The biotype composition across all collection sites was 27.2% RWA1 and 72.8% RWA2. RWA biotype frequency by state indicated that RWA2 was the predominant biotype and composed 73 - 95% of the biotype complex in Texas, Oklahoma, Colorado, and Wyoming. Our study indicated that RWA2 is widely distributed and has rapidly dominated the biotype complex in wheat and barley within its primary range from Texas to Wyoming. Wheat with the Dn4 resistance gene will have little value in managing RWA in the United States, based on the predominance of RWA2. However, the two main sources of resistance in barley, STARS 9301B and 9577B, remain resistant to the eight known RWA biotypes.