Disease Note.

The Russian Wheat Aphid, Diuraphis noxia, Confirmed as Vector of Brome Mosaic Virus in North America. V. D. Damsteegt, USDA-ARS, Fort Detrick, Building 1301, Frederick, MD 21701. A. D. Hewings, USDA-ARS, Fort Detrick, Building 1301, Frederick, MD 21701.. Plant Dis. 72:79. Accepted for publication 11 August 1987. Copyright 1988 The American Phytopathological Society. DOI: 10.1094/PD-72-0079.

Diuraphis noxia Mordw. causes serious losses of wheat (Triticum aestivum L.) in South Africa. The aphid was identified in Mexico in 1980 and the southern plains of the United States in 1986 and is considered to be a very damaging pest. D. noxia has been reported to transmit several grain viruses, including brome mosaic virus (BMV), which previously had no known insect vector (I). Nonpersistent and persistent modes of transmission of a Nebraska isolate of BMV were tested with a Texas clone of D. noxia on Baart wheat and Henry barley (Hordeum vulgare L.). Four weeks after inoculation, each test plant was harvested for ELISA analysis and for mechanical back inoculation to individual Henry seedlings. All 48 plants assayed in the persistent tests were symptomless, yet eight were positive for BMV by ELISA and six were positive when bioassayed on indicator hosts. BMV-infected indicator hosts showed typical linear yellow lesions. All plants that were positive by bioassay were positive by ELISA. No transmission was obtained in nonpersistent experiments. D. noxia appears to transmit BMV inefficiently in the persistent manner but is potentially a very threatening vector because of high natural populations in graminaceous hosts.

Reference: (I) M. B. von Wechmarand E. P. Rybicki. S. Afr. J. Sci. 77:488, 1981.