1Key Laboratory of Monitoring and Management of Plant Diseases and Insects, Ministry of Agriculture/Department of Pesticide Science, College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China;2 Chinaredsun Company, Nanjing 211303, China; *Corresponding author, E-mail: email@example.com
Seventeen populations of Chilo suppressalis Walker were collected from the drainage area of the Yangtze River, including Zhejiang, Jiangsu, Anhui, Hubei, Hunan, Sichuan, and Henan Provinces, China and the resistance of the populations to monosultap, triazophos, chlorpyrifos, fipronil, and abamectin was monitored using topical application in 2008 and 2009. The resistance levels of the 17 populations to the five insecticides varied with the collection regions. The populations from Cangnan, Rui′an, Jiangshan in southern Zhejiang Province (highlevel resistance region) developed extremely high to high level resistance to monosultap (resistance ratio was 43.2 to 177.0fold), triazophos (238.7 to 728.1fold), and chlorpyrifos (31.7 to 57.8fold). At the same time, they had moderate or low level resistance to fipronil (11.2 to 24.7fold) and abamectin (5.9 to 7.1fold) which were widely used in recent years. The populations from Lujiang (Anhui Province), Youxian (Hunan Province) and Gaochun (Jiangsu Province) (moderatelevel resistance region) had extremely high level resistance to triazophos (203.2 to 379.0fold), high to moderate level resistance to monosultap (18.3 to 48.8fold) and chlorpyrifos (29.8fold), and low susceptibility to fipronil (4.4fold) and abamectin (4.1 to 4.7fold). The populations from Yizheng (Jiangsu Province), Hexian (Anhui Province)(low resistance region) showed high level resistance to chlorpyrifos (45.2fold) and triazophos (50.0fold), but moderate level resistance to susceptibility to the other insecticides. The populations from Xinyang (Henan Province), Lianyungang (Jiangsu Province) and Wusheng (Sichuan Province) (susceptibility region) displayed low susceptibility or susceptibility to most of the tested insecticides except monosultap. It is suggested that insecticide resistance management should be based on the local situation of insecticide resistance of C. suppressalis.