Abstract: Experiments were carried out with the pure-bred strains of both macropterous (M) and brachypterous (B) brwn planthopper, Nilaparvata lugens (Stal) in order to know the effects of parents, rice growth stage and population density on the wing dimorphism. Under the same laboratory rearing condtion, the Fl progenies of B ♀×♂.B♀×M♂、M♀×B♂ and M♀×M♂provided 98%o. 92% 64% and 29% brachyptery adults respectively, and the ariance between each other was significant. At the density of more than 10 nymphs per plant, the percentages of both female and male macroptery adults whose nymphs were reared on yellow maturity rice were higher than those onmilk-filling stage rice. In single rear experiment, most of the female individuals turned out to be brachyptery, while males were dominated by macroptery, regardless of their parents and rice growth stage. Conclusion can be made from our studies that the wing dimorphism is controlled by a sex related gene expression regulation system affected bymany factors.

Key words: Nilaparvata lugens, wing dimorphism, genetic, gene expression regulation