Abstract: A sudden increase of Nilaparvata lugens appeared in the rice area at Jiaxing and Hangzhou when typhoon Kanu crossed Zhejiang and Jiangsu Province and subsequently headed to the East China Sea from the night of September 11th to the early morning of September 13th in 2005.Results showed that the sudden increase of Nilaparvata lugens was highly associated with Kanu.Firstly,on the evening of both Sep11th and Sep 12th,the weather conditions of Nilaparvata lugens' source area(Changjiang-Huaihe region) were favorable for their flying-off.Secondly,the strong convergent stream near the center of Kanu on the night of Sep 11th and the northerly current at the rear of Kanu on the night of Sep 12th were also advantageous to the transportation of Nilaparvata lugens in the air.Thirdly,the typhoon and the rainstorm on the night of Sep 11th at Jiaxing and the 850 hPa-level shear line on the night of Sep 12th were beneficial to Nilaparvata lugens' landing.Based on the effects of typhoon Kanu on the sudden increase of Nilaparvata lugens,more actions should be taken to prevent Nilaparvata lugens increase after the typhoon center pass by the rice area in the middle ten days of September.

Key words: Nilaparvata lugens, Nilaparvata lugens, Typhoon Kanu, Sudden increase, Weather conditions