Analysis Of The Larval Host Types For Cotton Bollworm (Helicoverpa Armigera) Population And Evaluate The Refuge In Northern Xinjiang

With the wide planting of Bt(Bacillus thuringiensis) cotton over a long period of time, there is the potential for the cotton bollworm(Helicoverpa armigera) to develop resistance. Bt-cotton is widely grown in Xinjiang Province, which is the biggest cotton-producing area in China, but no studies have been conducted on potential refuges in this region of China. In this study, Intelligent forecast light traps were set up to collect cotton bollworms from May to September2013in the147th and121th regiments of the Shihezi reclamation area, Shawa, Manasi located in northern Xinjiang. Wings from the males and females are collected at each site on each day were combined into one samples to explore the property sources (C3or C4), test the female wing and corresponding spermatophore which mated with the females to ensure the mating type and percentage of mating frequency between C3and C4by513C. Caluculate the percentage of refuge of cotton bollworm from2002to2012, evalute the refuge function. The results indicate that:1. Host use by cotton bollworm:In northern Xinjiang, a proportion of cotton bollworms originated from C4in the spring (late May) and in the autumn (early August to September), The C4property source was about50%, which was comparative to the C3property source. During July to June, The C4property source was approximate5%, most was C3property.16of June in147th, the C4property was54.46%, It may immigration from C4plant. Maize was considered as the most important natural refuge for Bt susceptible cotton bollworms in northern Xinjiang since maize is predominantly a C4host plant as compared to cotton, and can provide susceptible cotton bollworms in the autumn of a year and the spring of the next year. It is difference between males (percentage of is approximate50%) and females (percentage of is approximate5%) of property source in147th and Manasi, there is not significant difference of females and males in121th.2. Magration habits of cotton bollworm:mating number was significantly positively correlated with the development grade of moth ovaries (R=0.91949, p<0.0001), when ovary development to2lever, the cotton bollworm is mating, with the lever of ovary developed, the mating number is add, when the ovary development to5lever, It is to the the peak, at6lever, It is lose of mating number, cotton bollworm immigration had occurred at147th and Manasi in northern Xinjiang. The overwintering and2nd generation in147th and1st generation in Manasi is all emigration.3. Mating frequency and effective mating:There were about20%of females moth unmated, the reason is not sure accurately, It may relate with that physiological unmaturation period、or maturation period but unmated(mating failures), the mating frequency is higher during peak cotton bollworm, The percentage of effective matings of C3host plant and C4host plant was about10%(11.1%in the spring,8.3%and13.33%in Autumn), The simultaneous existence period of C3and C4cotton bollworms is short, so the percentage of effective matings between the two property sources is low. females is2in May and July,0.5in June, Cotton bollworm of C3host plant and C4host plant can mated but the mating rate of different larval host types is low, It indicated that corn refuge could dilute H. armigera resistant gene but not really effective. The cotton bollworm size of females was not significantly positively correlated with spermatophore size of males.4. The result indicated that there are not significant differences in Northern Xinjiang and Sourthern Xinjiang (F=0.071, P=0.795), there are significant differences in reclamation and the corresponding areas (F=10.013, P=0.009), the percentage of reclamation is9.1-9.6%, the percentage of the corresponding areas is22.9-25.9%. To explore the refuge function of maize for cotton bollworm in Xinjiang clearly in different cropping patterns of reclamation and areas,we needed meticulous work.