Abstract: 【Aim】 Decoyinine (DCY) is a new plant growth regulator. The aim of this study is to explore the effects of seed soaking with DCY on the resistance of commercial rice varieties Xudao 10 and Xiangliangyou 900 to the brown planthopper, Nilaparvata lugens. 【Methods】 After the newly hatched nymphs fed on Xudao 10 and Xiangliangyou 900 rice plants pretreated with different concentrations ［0(clean water as the control), 25, 50 and 100 mg/L］ of DCY by seed soaking, the growth and development, adult fecundity and population life table parameters of N. lugens were determined and compared by age-stage, two-sex life table, and the population growth was simulated within 60 d. The effects of seed soaking with 100 mg/L DCY on the honeydew excretion, body weight, and feeding and oviposition preference of the female adults of N. lugens were also investigated. 【Results】 When N. lugens fed on rice variety Xudao 10 pretreated with different concentrations of DCY by seed soaking, the nymphal duration was significantly prolonged, the fecundity (number of eggs laid per female) was significantly decreased, the population parameters including net reproductive rate R₀, intrinsic rate of increase rm and finite rate of increase λ were significantly decreased, and the mean generation time T and doubling time DT were significantly increased, as compared with those in the control. When N. lugens fed on Xiangliangyou 900 rice plants pretreated with different concentrations of DCY by seed soaking, the nymphal duration was significantly shortened, the number of eggs laid per female was significantly decreased, and only the mean generation time T was significantly increased, while the other population parameters showed no significant change, as compared with those in the control. The results of 60-d population simulation showed that the population size of the three treatment groups was smaller than that of the control group. The honeydew excretion and body weight of female adults of N. lugens after feeding on Xudao 10 and Xiangliangyou 900 rice plants pretreated with 100 mg/L DCY by seed soaking were significantly lower than those of female adults feeding on rice plants of the control group. The feeding and oviposition preference tests indicated that the female adults of N. lugens preferred to feed and oviposit on the control rice plants. 【Conclusion】 The resistance of commercial rice varieties Xudao 10 and Xiangliangyou 900 to N. lugens is enhanced by seed soaking treatment with DCY.

Key words: Nilaparvata lugens, rice, decoyinine, age-stage, two-sex life table, insect resistance