Transmission of cucurbit potyviruses by Uroleucon pseudambrosiae (Homoptera: Aphididae), an aphid trapped during epidemics of watermelon mosaic virus 2 in Flordia

As part of epidemiological studies of watermelon mosaic virus 2 (WMV-2) in Florida, aphids were collected in green tile water traps in 1989 and 1990. A Uroleucon sp. accounted for 25% of the aphids trapped. The same aphid was found infesting most of the wild lettuce (Lactuca graminifolia Michaux.) and spiny-leaved sowthistle (Sonchus asper [L.] Hill) plants growing near plots of watermelon and was identified as Uroleucon pseudambrosiae (Olive) (formerly Dactynotus pseudambrosiae). The vector propensity of this aphid was estimated and compared with that of three other known vectors of WMV-2, both in arena tests and in tests using single aphids given limited acquisition and inoculation access. U. pseudambrosiae transmitted virus relatively inefficiently in controlled-access tests but was not significantly different from Aphis spiraecola Patch and Aphis illinoisensis Shimer in virus transmission in arena tests. Myzus persicae (Sulzer) was the most efficient vector in all tests. This is the first report of U. pseudambrosiae transmitting WMV-2. Based on its abundance and the estimate of its vector propensity, we think that this species could play an important role in the epidemiology of WMV-2 in areas in which both aphid and virus are commonly found