Resistance Mornitoring Of Three Common Chemical Insecticides And Frequency Of Resistance Allele To Transgenic BT Cotton In Field Helico Verpa Armigera (Hubner)

The development of a resistant strain of Helicoverpa armigera and monitoring of resistance to Bt Cotton in the field populations of H. armigera were conducted in this study, The main aim is to monitor the early resistance to Bt cotton and provide basis for resistance management in H. armigera.1. Puration and maintaining of high resistant strain of H. armigera selected by transgenic Bt cottonThe resistant strain YCR was selected by Bt cotton leaves from126th to143th generation. The resistance ratio to Cry1Ac toxin increased from3242-fold to5423-fold. It provided the high resistance H. armigera for the F1screening.2. The frequencies of resistance allele monitoring of H. armigera by F1screening methodIn2010and2011, F1screening method was used to detect resistance alleles to Bt cotton in H. armigera from Qiu Country in Hebei Province and the frequencies of resistance allele of H. armigera were0.131(95%CI:0.101-0.162) and0.078(95%CI:0.034-0.122). The results suggested that significant increase in resistance allele frequencies had occurred in the field population of H. armigera in Qiu County in recent years.3. Resistance monitoring in the field populations of H. armigera to3kinds of chemical insecticidesResistance of six field populations of H. armigera, feed on transgenic Bt cotton, to three insecticides were determined by leaf dipping method in2010and2011. The resistance to cyhalothrin was in high level, the population in Siyang Jiangsu province were extremely high resistance (171.0fold), Resistance of populations in Wangjiang Anhui province, Xiao county from Anhui province, Zaoyang and Jingzhou from Hubei province were at moderate level (61.4fold to38.0fold,52.1fold to28.5fold, respectively) Dongtai Population from Jiangsu province in2011was at moderate level with33.5fold, while populations in Zaoyang Hubei province and Qiu country were at high level resistance (73.0fold to77.1fold,54.2fold to51.2fold, respectively). To phoxim, the resistances were low to moderate level:populations in Xiao county, Zaoyang were from low to moderate level resistance (8.1fold to15.4fold,6.6fold to12.0fold, respectively). Populations in Siyang, Wangjiang and Qiu countuy were at moderate level resistance (18.5fold (2010),14.2fold to20.5fold,17.7fold to23.7fold, respectively). Resistance of population in Jingzhou fell from moderate to low level (23.2fold to5.6fold). Dongtai Population was in low level resistance (8.8fold,2011). The resistance of emamectin benzoate were in sensistive to low level and there were no obvious difference in the two years. So emamectin benzoate can still be used to control H. armigera in the transgenic Bt cotton.