2009 Annual Report 1a.Objectives (from AD-416) The objective(s) of this cooperative research project is to establish study sites in the Rocky Mountain area of Colorado to study the ecology of Russian wheat aphid and related species to determine the role of sexual reproduction for overwinter survival and biotype development. This study will determine if the Russian wheat aphid, Diuraphis noxia, requires a sexual reproductive phase to successfully overwinter in its natural mountain habitat on grasses to elucidate the role of sexual reproduction in the development of Russian wheat aphid biotypes. Other Diuraphis species will also be studied and sexual morphs described in order to identify D. noxia sexual morphs and the conditions when sexual morphs occur in this genus. 1b.Approach (from AD-416) Natural populations of Diuraphis noxia, D. tritici, D. frequens, and D. nodulus will be located to determine host associations and to study the occurrence of sexual morphs and oviposition. Two sites will be established for each species to determine the grass species and hosts associated with each site. The period when sexual morphs occur will be determined, and specimens will be collected and described. 3.Progress Report Research plots containing plantings of mountain brome, blue wild rye, Canadian wild rye, and wheat were established in the fall of 2007, at the Upper Colorado Environmental Plant Center at Meeker, CO, and were sampled in the spring and fall to determine host range of Diuraphis spp., overwintering success, and information on each aphid's holocycle. Egg hatch for D. mexicana occurred April 15, 2008. Sexuals appear in mid-August and lay overwintering eggs beginning in September. Ten sites infested with Russian wheat aphid were located in the Colorado Plateau region for study of overwinter survival and biotypic diversity in the fall of 2008. These studies will continue through 2010, and information obtained from these studies will determine the extent of sexual reproduction in the Russian wheat aphid and its role in creating new biotypes. The ADODR monitored activities via periodic meetings and sampling trips with the cooperator. The cooperator also provided ecological information over the season, periodically collected samples, and coordinated field studies with farm managers and extension agents.