Whitefly Transmission of Sweetpotato chlorotic stunt virus

The genus Crinivirus of the plant virus family Closteroviridae include members that are bipartite and whitefly-transmitted (2). The Crinivirus, Sweetpotato chlorotic stunt virus (SPCSV), was described from sweetpotato (Ipomoea batatas) in Nigeria (1). Vector transmission studies of SPCSV were conducted using two whitefly species, the sweetpotato whitefly (Bemisia tabaci biotype B) and the bandedwinged whitefly (Trialeurodes abutilonea). Whitefly colonies were reared in the laboratory on cotton plants in plexiglass cages. To evaluate transmission efficiency, single whiteflies were used in all experiments. Whiteflies were given 2-day acquisition access periods on I. batatas cv. White Bunch co-infected with SPCSV and Sweetpotato feathery mottle virus (SPFMV). Single whiteflies were then placed on individual healthy I. nil cv. Scarlet O'Hara seedlings for 2-day inoculation access periods. Plants then were sprayed with imidacloprid insecticide and placed in the greenhouse. Four independent tests were performed with each whitefly species. Seven to 10 days after exposing test plants to B. tabaci, 6 of 35, 4 of 28, 5 of 30, and 3 of 25 I. nil plants showed symptoms that consisted of leaf distortion and yellowing. In similar experiments conducted with T. abutilonea, 1 of 33, 0 of 32, 1 of 30, and 2 of 28 I. nil plants showed symptoms. Two weeks after inoculations, reverse transcription- polymerase chain reaction assays were performed with all 22 symptomatic and five randomly selected symptomless plants using primers that amplify the SPCSV heat shock protein 70 (HSP70) homolog gene fragment (446 bp). All 22 symptomatic plants were positive while the five symptomless plants tested were negative. Lower transmission rates were obtained with T. abutilonea (3.2%) when compared with B. tabaci (15.2%). These two whiteflies are present in sweetpotato fields in Louisiana and may play an important role in the spread of SPCSV. This represents the first report of transmission of SPCSV by the bandedwinged whitefly References: (1) S. Winter et al. Phytopathology 82:869-875, 1992. (2) G. C. Wisler et al. Plant Dis. 82:270-280, 1998.