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Vector Relations

Barley and Oats as Reservoirs for an Aphid Virus and the Influence on Barley Yellow Dwarf Virus Transmission. F. E. Gildow, Assistant professor, Department of Plant Pathology, The Pennsylvania State University, University Park 16802; C. J. D’Arcy, associate professor, Department of Plant Pathology, University of Illinois, Urbana 61801 Phytopathology 78:811-816. Accepted for publication 7 January 1988. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/Phyto-78-811.

The role of small grain cereals in horizontal transmission of the isometric Rhopalosiphum padi virus (RhPV) among aphid populations of R. padi and Schizaphis graminum was examined. Results of four types of RhPV transmission studies suggested that aphids acquired RhPV from plant tissues during feeding. RhPV was detected in 65 of 120 S. graminum when uninfected S. graminum were reared 5 days on plants coinfested with RhPV-infected R. padi. When uninfected aphids were given a 24-hr feeding on washed leaf tissue previously fed on by RhPV-infected aphids, 41 of 80 aphids became infected. Transport of RhPV through plants was suggested by aphid acquisition of RhPV from plant tissues not directly fed on by RhPV-infected aphids. When uninfected S. graminum or R. padi and RhPV-infected R. padi were fed on opposite ends of leaves for 7 days, 36 of 80 uninfected aphids became infected. Transmission tests indicated that virus in the plant tissue did not remain available for acquisition indefinitely. Results of enzyme immunoassays for RhPV in four barley cultivars and dsRNA analysis of oats and barley used to rear RhPV-infected R. padi failed to detect evidence of RhPV replication in plants. RhPV infection of R. padi or S. graminum had no effect on barley yellow dwarf virus (BYDV) transmission efficiency or vector-specificity when tested with the RPV, RMV, MAV, and PAV isolates of BYDV. Similarities in the virus-vector-plant interactions between RhPV and BYDV are discussed.