Abstract
The deleterious effects of the rice dwarf virus upon its vector Nephotettix cincticeps, were studied as a factor affecting inter-generation changes in the percentage of the infected individuals in a vector population. Developmental period and survival rate of nymphs, longevity of adults, and preoviposition period and fecundity of female adults were compared between infected and non-infected insects reared in isolation under various temperatures. Inter-generation changes in percentage of infected females in experimental populations were also examined at 20°C, 25°C and 30°C. Virulency of insects was tested by using the rice seedling as a test plant or by the serological method. The virus was harmful to the vector with respect to all biotic preformances examined, especially, to the fecundity of females. An appreciable reduction in fecundity of infected females was observed as compared with that of non-infected ones in summer or in the 3rd generation. Decreases in the percentage of infected females in experimental populations were greater at 25°C and 30°C than at 20°C from the parent to F1 generation. Based on these facts, it is suggested that temperature is one of the factors involved in the inter-generation changes in the percentage of infected N. cincticeps.
