Damage and Yield Response of Wheat Lines with Dn4 and Dn7 Genes Resistant to Russian Wheat Aphid Biotype RWA2

Plant damage and yield responses to three infestation levels (0, 1, and 10x) of biotype RWA2 Russian wheat aphid, Diuraphis noxia (Kurdjumov), were compared in winter wheat, Triticum aestivum L., during the 2010-11, 2011-12, and 2012-13 growing seasons at two sites in eastern Colorado. Wheat lines contained either no resistance gene (Yuma), Dn4 resistance (Yumar), or the Dn7 resistance gene (CO08RWA050). Fewer Russian wheat aphids and symptomatic tillers were on CO08RWA050 at any infestation. Yuma and Yumar tillers had an average of seven times more aphids present than CO08RWA050. Yields decreased as infestation increased in Yuma and Yumar, but yield was not less in CO08RWA050 at any infestation level. Kernel weights of Yuma and Yumar, but not CO08RWA050, were less with greater infestation. Data from the study suggested that resistance conferred by the Dn7 gene would be effective in reducing Russian wheat aphid abundance, and ultimately benefit wheat producers during outbreak years.