2007 Annual Report 1a.Objectives (from AD-416) Improve integrated pest management (IPM) practices for cereal aphids in wheat, sorghum, and barley in the United States by developing knowledge and tools to enhance the role of host plant resistance and natural enemies in crop management strategies. This will involve: (1) developing fundamental knowledge of the biology and ecology of cereal aphids; (2) developing an understanding of how aphid biotypic variation is generated and maintained; (3) determining the population breeding structure of cereal aphids in North America and its relationship to evolutionary/genetic basis for aphid biotypes; and (4) developing principles, techniques, and decision support tools for managing cereal aphids and their natural enemies. 1b.Approach (from AD-416) Field and laboratory experiments will be conducted to: (1) characterize the biotypic composition of greenbug populations occurring on non-cultivated hosts; (2) assess the role of grass species associated with cereal cropping systems in harboring pest aphids and their natural enemies; (3) monitor and characterize the biotypic structure of Russian wheat aphid populations on cultivated and non-cultivated hosts; (4) characterize holocyclic reproduction in the Russian wheat aphid and its role in biotype evolution; (5) determine the degree of genetic variation and the breeding structure of the Russian wheat aphid populations in the United States; (6) determine the genome size and organizational complexity of the Russian wheat aphid; (7) develop and test a natural enemy threshold for Coccinellidae against the greenbug in winter wheat; (8) develop airborne multi-spectral remote sensing techniques for monitoring greenbug infestations in wheat; and (9) develop computer programs to deliver pest management programs. 4.Accomplishments Russian wheat aphid biotype composition determined: Characterization of Russian wheat aphid (RWA) biotypes and determination of their composition in the field has provided key information to assist cereal breeders in identifying resistance sources and determinating which sources should be regionally deployed. The USDA-ARS Wheat, Peanut and Other Field Crops Research Unit at Stillwater, OK, in conjunction with collaborators from the Texas Agricultural Experiment Station, Colorado State University, Colorado State Extension Service, and USDA-NRCS have successfully characterized RWA biotypes RWA1 – RWA7, determined the extant biotype composition in the field, and assessed the regional occurrence of RWA sexual forms and functional holocycle to account for the genetic recombination responsible for the appearance of newly discovered RWA biotypes. The ecological and environmental conditions that regulate sexual reproduction (holocycle) were documented for three sympatric Diuraphis spp. (D. tritici, D. Frequens, D. nodulus). This accomplishment is important because it provides wheat and barley breeders the necessary information to select resistance sources for the development of RWA-resistant cultivars and also serves as the foremost guide for the study of the RWA holocycle and biotype development. (NP 304; Component V, Pest Control Strategies, Vb, Breeding for Host Plant Resistance) Remote sensing technology developed to monitor aphids: There exists a need for improved methods for monitoring Russian wheat aphid and greenbug infestations in wheat fields for purposes of making control decisions. At the USDA-ARS Wheat, Peanut and Other Field Crops Research Unit, Stillwater, OK, in conjunction with collaborators from the Texas Agricultural Experiment Station and SST Development Group Inc., we are developing remote sensing technology to detect and monitor infestations of these aphids in winter wheat. During FY 2007 we elucidated relationships between elevation, slope, aspect, and soil type within wheat fields to the spatially varying density of Russian wheat aphid infestations within the fields by means of regression modeling. We think that knowledge of the relationship between aphid density and within-field environmental variability will improve the ability to use remote sensing to efficiently detect and delineate infestations at an earlier stage of their development than would otherwise be possible. (NP 304; Component III, Plant, Pest and Natural Enemy Interactions and Ecology, Component IIIb, Population Studies/Ecology) Mitochondrial DNA analysis confirms suspected country of origin of RWA introduced into the US: The source of the RWA biotype RWA2 is unclear, that is whether it represents a new introduction from another country or if it arose from the extant population in the U.S. We sequenced mitochondrial DNA (mtDNA) from Russian wheat aphid collected in the U.S. from 1986 through 2006. Also included were specimens from Mexico and South Africa. No DNA sequence variation was found in US populations over this 20-year period. U.S. populations' DNA were identical to those from Mexico and South Africa. No unique DNA sequences were found, suggesting that biotype RWA2 did not represent a second introduction from a genetically distinct population from another country. The data are consistent with a single introduction from South Africa, and no other introductions of virulent biotypes into the U.S. occurred since 1986. This knowledge contributes significantly to the understanding of RWA biotype development. (NP 304; Component III, Plant, Pest and Natural Enemy Interactions and Ecology, Component IIIb, Population Studies/Ecology) 6.Technology Transfer Number of new CRADAs and MTAs 3 Number of active CRADAs and MTAs 7 Number of web sites managed 1 Number of non-peer reviewed presentations and proceedings 8 Review Publications Burd, J.D., Porter, D.R., Puterka, G.J., Haley, S.D., Peairs, F.B. 2006. Biotypic variation amoung North American Russian wheat aphid (Homoptera: Aphididae) populations. Journal of Economic Entomology. 99(5):1862-1866. Puterka, G.J., Burd, J.D., Mornhinweg, D.W., Haley, S.D., Peairs, F.B. 2006. Response of resistant and susceptible barley to infestations of five Diuraphis noxia (Homoptera: Aphididae) biotypes. Journal of Economic Entomology. 99(6):2151-2155. Elliott, N.C., Tao, F.L., Fuentes-Granados, R., Giles, K.L., Elliott, D.T., Greenstone, M.H., Shufran, K.A., Royer, T.A. 2006. D-vac sampling for predatory arthropods in winter wheat. Biological Control. 38:325-330.