Studies on cucurbit viruses in Madras state. II. Vector-virus relationships of the bittergourd mosaic virus

Abstract

Investigations carried out on the relationship of Bittergourd Mosaic virus and its vectors indicated that the pre-acquisition fasting threshold, acquisition threshold and inoculation feeding threshold were 15 minutes, 5 seconds and 60 seconds respectively forMyzus persicae; 15 minutes, 20 seconds and 5 minutes respectively for Aphis gossypii; 30 minutes 30 seconds and 5 minutes respectively for Aphis nerii and Brevicoryne brassicae; 30 minutes, 20 seconds and 5 minutes respectively for A. malvae. The optimum number of viruliferous aphids per plant for transmission was 15 for all the five aphid vectors; increasing the number of aphids above the optimum decreased the percentage of transmission. Persistence of the virus during fasting was 4 hours, 90, 60, 45 and 30 minutes respectively for M. persicae, A. gossypii, A. malvae, B. brassicae and A. nerii while persistence during feeding was 40, 30, 20, 15 and 10 minutes respectively for the same aphid vectors. Though both alate and apterous forms of the vectors transmitted the virus, the apterous forms were more efficient than the alate ones.