Effects of Ploughing of Fallow Paddy Fields on the Population Density of the Green Rice Leafhopper, Nephotettix cincticeps(UHLER)(Hemiptera:Cicadellidae)

Abstract

The green rice leafhopper, Nephotettix cincticeps, is an important vector of rice dwarf virus disease in southwestern Japan. The nymphs and adults of the overwintering generation as well as the first generation inhabit Alopecurus aequalis (SOBOL) in fallow paddy fields. The effects of ploughing fallow paddy fields on the population density of the first generation were investigated and compared to an unploughed field in Okayama, western Japan. Three treatments were used: ploughing once before the emergence of overwintering adults, ploughing once at the peak oviposition period of overwintering females, and ploughing at the times of both emergence and oviposition peaks. The density of eggs, immature stages and adults was significantly lower in the last two fields, although the density of all stages of the leafhopper between the two fields was not significantly different. Therefore, ploughing once at peak oviposition of the females is the most effective strategy to reduce density of the first generation.