Determination of Plutella xylostella (L.) Resistance to Nine Insecticides in Central China

Five field populations of diamondback moth,Plutella xylostella,including Luoyang in Henan Province,Yueyang in Hunan Province,and Wuxue,Yunmeng and Yichang in Hubei Province,were collected from the central China.P. xylostella populations had resistance to 9 insecticides as 2% abamectin EC,16 000 IU·mg-1 Bt WG-001 WP,20% beta-cypermethrin EC, 5% chlorantraniliprole EC, 2.5% spinosad SC,10% chlorfenapyr EC,5% chlorfluazuron EC, 20% diafenthiuron EC,5% indoxacarb EC.The bioassay results indicated that 5 populations exhibited high to extreme high level of resistance to abamectin,Bt,beta-cypermethrin,with the resistance ratio 44.5-92.0 fold,66.5-202.1 fold,and 76.2-146.4 fold,respectively.Moderate to high level of resistance to chlorfluazuron was found with the ratio 32.5-82.5 fold.As to spinosad,chlorantraniliprole,chlorfenapyr,indoxcarb,moderate and low resistance levels were proved with the ratio 6.5-19.4 fold,3.1-23.1 fold,2.6-22.3 fold,and 7.1-26.3 fold.The resistance ratio to diafenthiuron was ranged from 2.3-7.7 fold,showing sensitive or low resistance.Therefore,attention should be paid to insecticides rotation application between chlorantraniliprole, chlorfenapyr, diafenthiuron which were more sensitive and spinosad,indoxacarb, chlorfluazuron in central China, so as to delay the generation and development of insecticide resistance and achieve better control effect.