Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore-560089.
Abstracts of the papers presented at the 16th Annual Convention and International Symposium of Indian Virological Society on “Management of Vector-Borne Viruses” at International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Patancheru-502324, Hyderabad, India, February 7–10, 2006.
Watermelon bud necrosis virus (WBNV) causes serious epidemics on watermelon resulting in heavy yield loss. Thrips are reported to transmit the virus but the species involved are yet to be ascertained. Studies were carried out during 2002–03 at the Indian Institute of Horticultural Research to document the species of thrips on watermelon, relationship between thrips number and incidence WBNV and management of WBNV by controlling the thrips on watermelon. Thrips occurring on watermelon were sampled at fortnightly interval and species were identified. Among the species collected, Thrips palmi, Scirtothrips dorsalis and Frankliniella schultzei were found in more number. Thrips population was also monitored by installing the yellow funnel water traps. Seasonal variation in thrips number was monitored by monthly sowing the watermelon var. Arka Manik from December 2002 to June 2003. For every crop, two separate plots were maintained, one without any pesticide intervention (control) and the other treated with acephate 75 SP at 10 days interval. Comparison between the percent incidence of WBNV in the treated and control plots indicated that hundred percent incidence of WBNV at harvest irrespective of thrips number recorded. But delayed incidence of WBNV was noticed in treated plots. Thrips found on weeds around the watermelon plots were collected and identified to species level to record the reservoir hosts. Further, a field experiment was conducted to manage the thrips using combination of insecticides and black polythene mulch. Covering the soil with black polythene, seed treatment with imidacloprid (Gaucho 75 WS) and acephate spray at 10 day interval significantly reduced the WBNV incidence compared to other combinations of botanical and synthetic insecticides.
