Abstract: Using rice cultivars Zhejing 88 and Yongyou 18 as materials， the effects of modified schedules of fertilizer application on the population of leaffolder and its natural enemies in rice field， and yields had been evaluated. Local farmers traditional fertilization in Yuyao and Linhai in Zhejiang province were used as control. Modified schedules of fertilizer application include reducing application of nitrogen fertilizer， postponing nitrogen technique， and NPK coordinated application. The results indicated that there were no significant difference on the rate of roll leaf， the population of main predators and parasitoids in the rice field at all growth period between modified fertilizer application schedule and control. However， the population of leaffolder larvae at tillering and panicle stage with modified fertilizer application schedule was significantly lower than those in control. Furthermore， nitrogen fertilizer usage， rice production and economic output in Zhejing 88 and Yongyou 18 followed with modified fertilizer application schedule were reduced by 2689% and 1268%， increased by 985% and 1258%， and increased 1551 Yuan·667m-2 and 2118 Yuan·667m-2than those in control， respectively. The fertilizer regulation scheme was presented in this paper can effectively reduce nitrogen fertilizer usage and relieve the larval population of rice leaffolder in paddy field. It is a useful tactic to control agricultural pollution and ensure food security in China.

Key words: fertilizer regulation, rice, nitrogen fertilizer, Cnaphalocrocts medinalis, yield