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Title: Biotypic diversity in Colorado Russian wheat aphid (Hemiptera: Aphididae) populations

Author
item WEILAND, AUBREY - CSU, BIOAGRIC. SCI.
item PEAIRS, FRANK - CSU, BIOAGRIC. SCI.
item RANDOLPH, TERRI - CSU, BIOAGRIC. SCI.
item RUDOLPH, JEFFREY - CSU, BIOAGRIC. SCI.
item HALEY, SCOTT - CSU, SOIL & CROP SCI
item Puterka, Gary

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/7/2007
Publication Date: 3/1/2008
Citation: Weiland, A.A., Peairs, F.B., Randolph, T.L., Rudolph, J.B., Haley, S.D., Puterka, G.J. 2008. Biotypic diversity in Colorado Russian wheat aphid (Hemiptera: Aphididae) populations. Journal of Economic Entomology. 101(2):569-574.

Interpretive Summary: The Russian wheat aphid (RWA) is an important aphid pest of wheat that has five biotypes (RWA1-RWA5) that differ in their ability to damage RWA resistance genes in wheat. New RWA isolates were collected from cultivated wheat, Triticum aestivum L. in Montezuma County, CO. (RWA6), another from Canada wildrye, Elymus canadensis L., in Baca County, CO. (RWA7), and another from crested wheatgrass, Agropyron cristatum (L.) Gaertn., in Montezuma County, CO. (RWA8). The response of 24 plant differentials (22 wheat lines and 2 barley lines) were assessed in standard screening flat trials and compared to RWA1 and RWA2. RWA1 was the least virulent of the isolates, killing only the susceptible entries. RWA8 also killed the susceptible entries, but expressed intermediate virulence on seven resistant wheat lines. RWA6, killed nine entries, and RWA7, killed eleven entries, both expressed an intermediate level of virulence overall, but differed in their level of virulence to 'CO03797' (Dn1 gene), 'Yumar' (Dn4 gene), and 'CO960293-2'. RWA2 was the most virulent isolate, killing fourteen entries, including Dn4- and Dny-resistance gene containing wheat lines. Four wheat lines, '94M370' (Dn7 gene), 'STARS 02RWA2414-11', CO03797, and 'CI2401', were resistant to the five isolates. The results of this screening confirm the presence of three new and unique Russian wheat aphid biotypes in Colorado.

Technical Abstract: The biotypic diversity of the Russian wheat aphid, Diuraphis noxia (Kurdjumov), was assessed in five isolates collected in Colorado. Three isolates, RWA 1, RWA 2, and an isolate from Montezuma County, CO designated RWA6, were originally collected from cultivated wheat, Triticum aestivum L. The fourth isolate, designated RWA7, was collected from Canada wildrye, Elymus canadensis L., in Baca County, CO. The fifth isolate, designated RWA8, was collected from crested wheatgrass, Agropyron cristatum (L.) Gaertn., in Montezuma County, CO. The four isolates were characterized in a standard seedling assay, using 24 plant differentials: 22 wheat lines and 2 barley, Hordeum vulgare L., lines. RWA1 was the least virulent of the isolates, killing only the susceptible entries. RWA8 also killed the susceptible entries, but expressed intermediate virulence on seven resistant wheat lines. RWA6, killed nine entries, and RWA7, killed eleven entries, both expressed an intermediate level of virulence overall, but differed in their level of virulence to ‘CO03797’ (Dn1), ‘Yumar’ (Dn4), and ‘CO960293-2’. RWA2 was the most virulent isolate, killing fourteen entries, including Dn4- and Dny-resistance gene containing wheat lines. Four wheat lines, ‘94M370’ (Dn7), ‘STARS 02RWA2414-11’, CO03797, and ‘CI2401’, were resistant to the five isolates. The results of this screening confirm the presence of five unique Russian wheat aphid biotypes in Colorado.