title: Change in Biotypic Diversity of Russian Wheat Aphid (Hemiptera: Aphididae) Populations in the United States.
abstract: A key component of Russian wheat aphid, Diuraphis noxia (Kurdjumov), management has been through planting resistant wheat cultivars. A new biotype, RWA2, appeared in 2003 which caused widespread damage to wheat cultivars containing the Dn4 gene. Biotypic diversity in Russian wheat aphid populations has not been addressed since 2005 when RWA2 dominated the biotype complex. Our objectives were to determine the biotypic diversity in the Central Great Plains and Colorado Plateau at regional (2010, 2011, 2013) and local (2012) levels and detect the presence of new Russian wheat aphid biotypes. Regional and within-field aphid collections were screened against Russian wheat aphid-resistant wheat genotypes containing genes Dn3, Dn4, Dn6, Dn7, Dn9, CI2401; and resistant barley STARS 9301B. In 2010, all aphid collections from Texas were avirulent to the Dn4 resistance gene in wheat. Regional results revealed Dn4 avirulent RWA6 was widespread (55-84%) in populations infesting wheat in both regions. Biotypes RWA1, 2, and 3/7 were equally represented with percentages<20% each while RWA8 was rarely detected. Combining percentages of RWA1, 6, and 8 across regions to estimate avirulence to Dn4 gene revealed high percentages for both 2011 (64-80%) and 2013 (69-90%). In contrast, the biotype structure at the local level differed where biotype percentages varied up to ≥2-fold between fields. No new biotypes were detected; therefore, Dn7, CI2401, and STARS9301B remained resistant to all known Russian wheat aphid biotypes. This study documents a shift to Dn4 avirulent biotypes and serves as a valuable baseline for biotypic diversity in Russian wheat aphid populations prior to the deployment of new Russian wheat aphid-resistant wheat cultivars.
authors.affiliation: Plant Science Research Laboratory, USDA-ARS, 1301 N. Western, Stillwater, OK 74074. gary.puterka@ars.usda.gov.
authors.forename: G J
authors.initials: GJ
authors.lastname: Puterka
authors.affiliation: Department of Entomology and Plant Pathology, Oklahoma State University, 27 Noble Research Center, Stillwater, OK 74078.
authors.forename: K L
authors.initials: KL
authors.lastname: Giles
authors.affiliation: Plant Science Research Laboratory, USDA-ARS, 1301 N. Western, Stillwater, OK 74074.
authors.forename: M J
authors.initials: MJ
authors.lastname: Brown
authors.affiliation: Plant Science Research Laboratory, USDA-ARS, 1301 N. Western, Stillwater, OK 74074.
authors.forename: S J
authors.initials: SJ
authors.lastname: Nicholson
authors.affiliation: Colorado State University, Tri River Area Extension, 2775 Hwy., 50 Grand Junction, CO 81502.
authors.forename: R W
authors.initials: RW
authors.lastname: Hammon
authors.affiliation: Department of Bioagricultural Sciences and Pest Management, 1177 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1177.
authors.forename: F B
authors.initials: FB
authors.lastname: Peairs
authors.affiliation: Department of Bioagricultural Sciences and Pest Management, 1177 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1177.
authors.forename: T L
authors.initials: TL
authors.lastname: Randolph
authors.affiliation: Texas A&M AgriLife Research and Extension Center, 6500 W. Amarillo Blvd., Amarillo, TX.
authors.forename: G J
authors.initials: GJ
authors.lastname: Michaels
authors.affiliation: Texas A&M AgriLife Research and Extension Center, 6500 W. Amarillo Blvd., Amarillo, TX.
authors.forename: E D
authors.initials: ED
authors.lastname: Bynum
authors.affiliation: USDA, ARS, SPA, Range and Pasture Research, 2000 18th St., Woodward, OK 73801.
authors.forename: T L
authors.initials: TL
authors.lastname: Springer
authors.affiliation: Plant Science Research Laboratory, USDA-ARS, 1301 N. Western, Stillwater, OK 74074.
authors.forename: J S
authors.initials: JS
authors.lastname: Armstrong
authors.affiliation: Plant Science Research Laboratory, USDA-ARS, 1301 N. Western, Stillwater, OK 74074.
authors.forename: D W
authors.initials: DW
authors.lastname: Mornhinweg
mesh_terms: D000818:Animals; D001042:Aphids / Q000145:classification / Q000502:physiology*; D001467:Hordeum; D014908:Triticum / Q000502:physiology*; D014481:United States
keywords: barley; host plant resistance; host race; sustainable resistance; wheat