FEEDING-BEHAVIOR OF THE RUSSIAN WHEAT APHID (HOMOPTERA, APHIDIDAE) ON WHEAT AND RESISTANT AND SUSCEPTIBLE SLENDER WHEATGRASS

Russian wheat aphid, Diuraphis noxia (Mordvilko), poses a serious threat to the yield and quality of wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.) production in the United States. Although, Land Grant College and Soil Conservation Service programs advocate the use of many cool- and warm-season forage grasses, many of these grasses serve as alternate hosts to the Russian wheat aphid. One form of cultural control is the development of grass cultivars resistant to Russian wheat aphid for use in such programs, which could eliminate oversummering host plants for the aphid. Prior studies have indicated that slender wheatgrass (Elymus trachycaulum (Link) Gould ex Shinners), a species commonly found in reclamation areas, offers several potentially resistant plant introductions for use in development of resistant cultivars. The nature of Russian wheat aphid resistance at the behavioral level was studied with four slender wheatgrass entries, 'Pryor', PI 387888, PI 440100, and PI 440102 and 'TAM W-101' wheat on electronic feeding monitors. Aphids on the resistant plant introductions and, to a lesser degree, on 'Pryor' spent more total time engaged in baseline behavior, less time in phloem-ingestion behavior, and more time in nonphloem-ingestion behavior than did aphids on the susceptible entries 'TAM W-101' wheat and slender wheatgrass PI 387888. These results indicate that PI 440100 and PI 440102 could be used in the development of slender wheatgrass cultivars resistant to Russian wheat aphid.