Biotypic Diversity in Colorado Russian Wheat Aphid (Hemiptera: Aphididae) Populations

Abstract

The biotypic diversity of the Russian wheat aphid, Diuraphis noxia (Kurdjumov) (Hemiptera: Aphididae), was assessed in five isolates collected in Colorado. Three isolates, RWA 1, RWA 2, and an isolate from Montezuma County, CO, designated RWA 6, were originally collected from cultivated wheat, Triticum aestivum L., and obtained from established colonies at Colorado State University. The fourth isolate, designated RWA 7, was collected from Canada wildrye, Elymus canadensis L., in Baca County, CO. The fifth isolate, designated RWA 8, was collected from crested wheatgrass, Agropyron cristatum (L.) Gaertn., in Montezuma County, CO. The four isolates were characterized in a standard seedling assay, by using 24 plant differentials, 22 wheat lines and two barley, Hordeum vulgare L., lines. RWA 1 was the least virulent of the isolates, killing only the four susceptible entries. RWA 8 also killed only the four susceptible entries, but it expressed intermediate virulence on seven wheat lines. RWA 6, killing nine entries, and RWA 7, killing 11 entries, both expressed an intermediate level of virulence overall, but differed in their level of virulence to 'CO03797' (Dn1), 'Yumar' (Dn4), and 'CO960293-2'. RWA 2 was the most virulent isolate, killing 14 entries, including Dn4- and Dny-containing wheat. 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.

Biotype Differences for Resistance to Russian Wheat Aphid in Barley

“…At least eight biotypes are present in the United Sates (USA1-8; Burd et al, 2006;Haley et al, 2004;Puterka et al, 2006;Weiland et al, 2008). At least eight biotypes are present in the United Sates (USA1-8; Burd et al, 2006;Haley et al, 2004;Puterka et al, 2006;Weiland et al, 2008).…”

“…Additional biotypes have been identified in South Africa, Hungary, Chile, Ethiopia, Argentina, and the Czech Republic that differentially affect resistance in wheat (Basky, 2003;Ricci et al, 2012;Smith et al, 2004). Resistance genes in wheat appear to function in a biotype-specific manner with single genes providing resistance to one or more biotypes (Weiland et al, 2008;Puterka et al, 2007). Resistance genes in wheat appear to function in a biotype-specific manner with single genes providing resistance to one or more biotypes (Weiland et al, 2008;Puterka et al, 2007).…”

“…So far, only USA1 and USA2 are prevalent in the seven western states most affected by RWA (Puterka et al, 2007). In contrast, the two most widely-used barley germplasm lines for breeding resistant cultivars, STARS9301B and STARS9577B, show resistance to all eight United States biotypes (as defined by their differential reactions on wheat; Puterka et al, 2006;Weiland et al, 2008). In contrast, the two most widely-used barley germplasm lines for breeding resistant cultivars, STARS9301B and STARS9577B, show resistance to all eight United States biotypes (as defined by their differential reactions on wheat; Puterka et al, 2006;Weiland et al, 2008).…”

Seasonal Presence of the Russian Wheat Aphid (Hemiptera: Aphididae) on Alternate Hosts in Colorado

“…Russian wheat aphids from all over the world as well as from local North American populations were routinely evaluated (Puterka et al 1992, Shufran et al 1997. Recent studies have confirmed the presence of five unique Russian wheat aphid biotypes in Colorado (Haley et al 2004, Weiland et al 2008, two of which were found on noncultivated grasses. This study confirms that while the Russian wheat aphid has undergone many changes as a species, the important grass hosts have not changed.…”

Registration of Eight Six‐Rowed Feed Barley Germplasm Lines Resistant to Both Russian Wheat Aphid and Greenbug

“…STARS 9301B, STARS 9577B, STARS 0501B‐0507B, and STARS 0601B‐0643B were resistant to biotypes RWA1 to RWA5 (Puterka et al, 2006). Only germplasm STARS 9301B and STARS 9577B have been tested with RWA6, RWA7, and RWA8, and they were found to be resistant (Weiland et al, 2008). STARS 1006B, STARS 1008B, STARS 1009B, and STARS 1013B have resistance from the same sources as the STARS lines that were found to be resistant to RWA1 to RWA5.…”