Abstract
The present paper deals with the results of inoculation feeding experiments with the mulberry dwarf agent by vector leafhopper, Hishimonus sellatus Uhler. Serial inoculation experiments indicated that there was latent period for the causal agent in the body of H. sellatus. Length of the latent period varied with the individuals from 13-28 days to 42-55 days. Shortest inoculation feeding period of the viruliferous leafhopper was 3 hours. The transmission rate by more than 3 days feeding increased remarkably. The leafhopper of which latent period in vector was passed over did not always show a continuous transmission. Most of individuals showed an intermittent transmission. The retention period in the insect was comparatively long. Under the experimental conditions, some individuals were able to retain the causal agent more than 60 days. It was considered that the period required between inoculation and the appearance of symptoms, i.e., latent period in mulberry seedling, varied with the individuals from 6-13 days (rather close to 13 days) to 82-87 days, without distinction of inoculation feeding period. Transovarial passage on H. sellatus was studied by using 260 individuals obtained from every mating of viruliferous and non-viruliferous male and female parents and the transovarial passage was not found.
