1Division of Entomology and Nematology, Indian Institute of Horticultural Research, Hessaraghatta Lake Post, Bangalore-560089.
2Division of Seed Technology, 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.
A number of viruses have been reported to infect cucurbits. Among them, Papaya ring spot virus- W (PRSV-W) synonymously referred as Watermelon mosaic virus-1 (WMV-1) is of great economic importance in cucumber, watermelon, pumpkin and squash. More than twenty species of aphids are reported as vectors of this virus. In India, the species involved in the epidemiology of virus, dynamics of PRSV-W as influenced by the dynamics of aphid population and extent of yield loss due to virus infection are not understood. Hence field study was conducted to document the vectors involved in the spread of PRSV-W, identify the relation between vector number and virus incidence in pumpkin, spatial and temporal spread of virus and extent of yield loss due to PRSV-W infection. Aphid population were monitored every 24 hrs by setting yellow funnel water traps in pumpkin field and by sampling the pumpkin plants at weekly interval. Aphis gossypii Glover and A. craccivora Koch were recorded in yellow funnel traps. Aphis gossypii was found to be the predominant species. Numerically lower populations of A. craccivora were caught in yellow funnel traps. No aphid colonization was observed on pumpkin. Disease assessment was made at weekly intervals by tagging the infected plants. Significant correlation was observed between number of aphids caught in yellow funnel traps and incidence of PRSV-W. Disease progression and spatial distribution was quantified by variance to mean ratio and Lloyds patchiness index. Aggregation indices indicated random to clustering of virus diseased plants. The time of infection found to play a major role in deciding the weight of the fruit. Early infection significantly reduced the weight of the pumpkin than infections occurred at later stage of the crop. The implications of the study in the epidemiology of PRSV-W are discussed.
