Abstract: 【Aim】 The rice planthopper (BPH), Nilaparvata lugens, is one of the important non-target insect pests of the Bt rice, and many insecticides could induce the resurgence of N. lugens. This study aims to understand the resurgence potential of N. lugens on Bt rice and non-Bt rice treated by different nitrogen regimes. 【Methods】 The indices of ecological fitness (nymphal duration, nymphal survival rates, female adult weight, the number of eggs laid per female and egg hatchability) of N. lugens treated with different concentrations of deltamethrin (0, 1, 3 and 6 mg/L) were evaluated on Bt rice lines (T1C-19 and T2A-1, harboring  cry1C* and cry2A* gene, respectively) and its parental non-Bt rice (MH63) applied with different application levels of nitrogen fertilizer (0, 100 and 250 kg N/hm²). 【Results】 The nymphal survival of N. lugens treated with the high concentration of deltamethrin (6 mg/L) was significantly lower than that in the untreated control, while the number of eggs laid per female was significantly higher than that in the untreated control. ANOVA results indicated that the interaction between nitrogen fertilizer and deltamethrin significantly affected the nymphal survival rate, female adult weight, number of eggs laid per female and egg hatchability. The fecundity did not significantly differ when N. lugens nymphs were reared on the Bt and non-Bt rice lines treated with deltamethrin under the nitrogen regime of 0 kg N/hm², while significantly increased with the increase of deltamethrin concentration on the rice lines under the nitrogen regimes of 100 kg N/hm² and 250 kg N/hm². The ecological fitness of N. lugens increased as the nitrogen fertilizer application level increased. The nymphal duration shortened and the nymphal survival rates, female adult weight, the number of eggs laid per female and egg hatchability increased as the nitrogen fertilizer application level increased. The values of the ecological fitness indices were not significantly different on the Bt and non-Bt rice lines treated with the same concentration of deltamethrin under the same nitrogen regime. 【Conclusion】 The results indicate that nitrogen fertilizer application can promote the resurgence of N. lugens induced by deltamethrin on Bt rice lines T2A-1 and T1C-19, and this effect does not differ between Bt rice lines and non-Bt rice.

Key words: Nilaparvata lugens, Bt rice, nitrogen fertilizer, deltamethrin, ecological fitness, resurgence