Susceptibility of brome grass to Russian wheat aphid (Homoptera: Aphididae)

Three annual Bromus species-cheat, B. secalinus L.; downy brome, B. tectorum L.; and Japanese brome, B.japonicus Thunberg--are associated with small-grain production and have life cycles similar to that of winter wheat, Triticum aestivum L. Objectives were to establish preferences of Russian wheat aphid for cheat, downy brome, Japanese brome, and wheat and to evaluate Bromus species indigenous to the central and western United States for their relative susceptibility to aphid feeding damage. Studies of nonpreference, aphid weight and fecundity, time to plant death, and plant damage were conducted in a greenhouse. The following order of decreasing acceptability was observed: wheat, downy brome, cheat, and Japanese brome. These data suggest that Russian wheat aphids prefer wheat in a wheat-annual brome mixture. Russian wheat aphid reared on wheat was on average 38% heavier and produced an average of 10.2 more nymphs per individual than when reared on annual brome species. Seedlings of wheat infested by Russian wheat aphid lived 6.7 d less than the brome species. B. inermis Leysser and B. pumpellianus Scribner suffered minor feeding damages. B. erectus Hudson and B. biebersteinii Roemer and Schultes sustained moderate damage from feeding aphids, and 14 other species received high levels of damage. Field studies are needed to determine the relationships of native plant communities, cereal crops, and Russian wheat aphids