Nephotettix cincticeps (rice green leafhopper)

Both nymphs and adults of N. cincticeps suck sap primarily from leaves and leaf sheaths of rice plants. Populations are rarely high enough to cause direct feeding damage. N. cincticeps is the vector of rice dwarf disease, rice yellow dwarf disease and transitory yellowing (Ou, 1985).

Cultural Control

In Japan, the cultivation of early-planted rice crops contributed to an increase in the importance of Rice dwarf virus disease (Kiritani, 1983). Hokyo (1976) advocated later planting of rice crops so that fewer immigrants would be able to colonize rice fields. This could be achieved by developing mechanical transplanting techniques for older seedlings. However, these measures were often not considered practical. Ploughing fallow rice fields in the winter is recommended with the objective of reducing numbers of overwintering adults and nymphs of N. cincticeps and thus reducing the incidence of Rice dwarf virus disease (Nakasuji and Kiritani, 1977). Widiarta et al. (1992) showed that ploughing during the peak oviposition period of N. cincticeps females was the most effective strategy to reduce the density of leafhoppers invading rice crops. In Korea, lower population densities of N. cincticeps were recorded in direct-seeded rice fields than in fields where machine transplanting was practised (Lee and Ma, 1997). Population development of rice leafhoppers and planthoppers is enhanced by the application of high levels of inorganic nitrogen fertilizer (Cook and Denno, 1994). Researchers in Japan reported that the density of N. cincticeps in an organically-farmed rice field was lower than that in a field where chemical inputs were used (Kajimura et al., 1993). Based on this and related studies it was suggested that fertilizer practices could be modified to manage populations of both leafhoppers and planthoppers in Japan (Kajimura et al., 1995).

Rice dwarf virus (RDV) and Rice gall dwarf virus (RGDV) are transmitted by N. cincticeps in a persistent manner (Sasaya et al., 2014). N. cincticeps is regarded as a major pest of rice in Japan, particularly in the south of the country where Rice dwarf virus disease is present (Kiritani, 1980). Direct feeding damage to the rice plant may occur as the insertion of the insect's stylets disrupts the translocation of water and photosynthetic products to the panicles (Naba, 1988). Potential yield loss is greater in early-maturing varieties, but field populations of N. cincticeps are rarely high enough to cause serious damage.

Few data are available for economic losses caused by Rice dwarf virus disease. Kiritani (1983) argued that changes in cultivation practices, such as the winter and spring ploughing of fallow rice fields, has contributed to a decline in the duration and frequency of Rice dwarf virus disease.