|Budget Amount *help
¥4,100,000 (Direct Cost: ¥4,100,000)
Fiscal Year 1997: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1996: ¥2,400,000 (Direct Cost: ¥2,400,000)
The brown planthopper, Nilaparvata lugens has been broadly accepted to exhibit wing-dimorphism, depending mostly on nymphal density, but we have demonstrated the presence of genetic varieties in the field populations showing different responses to density and generated genetically genuine strains predominantly showing specific wing-form and body-color in broad range of density.
ln this research, we first used the two strains showing specific wing-from by topically applying juvenile hormone or anti-juvenile hormone, precocene to the nymphs in various developmental stages to know the effect of them on wing-from, ovarian development and metamorphosis. We found that juvenile hormone induced brachyptery in the macropterous strain and enhanced its ovarian development, while prococene induced macroptery in the brachypterous strain and retarded its ovarian development, when applied in specific developmental stage. Our results strongly supported that higher
The life history characteristics such as nymphal period, adult longevity, preoviposition period, fecundity, egg period were demonstrated to differ among four strains, i.e, blackish brachypterous strain, yellowish-brown brachypterous strain, blackish macropterous strain and yellowish-brown macropterous strain, suggesting the involvement of the genes for wing-form and body^color expression also to control these life history characteristics, possibly through regulation of the synthetic activity of juvenile hormone by corpora allata.