Pollen Associated Thrips Transmission of Tobacco streak virus (TSV) Causing Necrosis Disease in Urdbean and Mungbean in Andhra Pradesh

Tobacco streak virus (TSV) isolates of urdbean (Vigna mungo L. Hepper) and mungbean (Vigna radiata L. Wilczek) viz., TSV-BG and TSV-GG, were collected during a survey carried out in 2007–08 Kharif in Andhra Pradesh. The disease samples were bio-assayed on the indicator host, cowpea cv. C-152 which produced necrotic lesions three days post inoculation. The TSV isolates were confirmed by infectivity assays on urdbean cv. LBG-20, mungbean cv. K-851, groundnut cv. JL-24 as well as through DAC-ELISA tests using TSV polyclonal antiserum. Four thrip species viz., Frankliniella schultzei, Scirtothrips dorsalis, Megalurothrips usitatus and Thrips palmi, transmitted both TSV-BG and TSV-GG in presence of TSV-infected pollen. In laboratory tests, the thrips fed on infected leaves alone and the TSV infected pollen alone did not transmit the virus. All test plants that expressed symptoms were positive in DAC-ELISA tests confirming the transmission of TSV-BG and TSV-GG.