Population characteristics of the brown planthopper, Nilaparvata lugens (Hemiptera: Delphacidae), with special reference to differences in Japan and the tropics.
Light-trap records showed that Nilaparvata lugens (Stal), an important pest of rice, is prevalent in the southwestern part of Japan. Populations that were studied in Zentsuji, Japan, developed from sparsely distributed macropterous colonisers and then multiplied approximately ten-fold each generation. In Kalugomuwa, Sri Lanka, N. lugens populations never multiplied as rapidly as this. Population stability seemed to be associated with production of many macropterous females. In Indonesia, serious damage was usually observed in rice at the peak of tillering. Populations in some infested fields included a surprisingly large number of macropterous females. In contrast to the field-wide injury observed in Indonesia, in Japan N. lugens caused large patches of damaged plants. The formation of patches is explained on the basis of earlier population processes. The relation of mean crowding of N. lugens adult females to mean density was so complex that their spatial distribution patterns could not always be explained by existing mathematical models.