不同抗性水平棉铃虫地理种群的基因交流对抗性演化的影响

采自我国长江流域棉区的棉铃虫Helicoverpa armigera(Hubner)四川简阳种群、湖北武穴种群、湖南衡阳种群、江苏南京种群和浙江杭州种群对辛硫磷、三氟氯氰菊酯和硫丹的抗性水平分别为8.05～38.80、2.86～290.00和5.87～19.83倍。抗性较高的简阳种群和较低的杭州种群正、反交F₁代对上述3种农药的抗性为13.16和16.69倍、10.43和19.00倍及12.42和10.21倍，抗性遗传的显性系数为-0.2220、-0.2147和0.0700，表明对辛硫磷、三氟氯氰菊酯抗性呈不完全隐性方式遗传，而硫丹抗性则为半隐性遗传。P1自交F2代对辛硫磷、三氟氯氰菊酯和硫丹的抗性水平分别为17.66、7.57和9.03倍，F₁代对杭州种群回交F₂代的抗性倍数分别为8.79、3.Oo和6.61。其结果，高抗区和低抗区棉铃虫种群的基因流动将导致对三种农药抗性水平明显下降。

THE INFLUENCES OF GENE FLOW BETWEEN GEOGRAPHICAL POPULATIONS ON THE EVOLUTION OF INSECTICIDE RESISTANCE IN HELICOVERPA ARMIGERA

The resistance levels to phoxim, cyhalothrin and endosulfan of cotton bollworm, Helicoverpa arrnigera (Hubner), collected from Jianyang of Sichuan Province, Wuxue of Hubei Province, Hengyang of Hunan Province, Nanjing of Jiangsu Province and Hangzhou of Zhejiang Province, were determined as 8.05-38.80, 2.86-290.00 and 5.87-19.83-fold, respectively in comparison with a susceptible cotton bollwormpopulation. The Jianyang population ? and Hangzhou population (S) were crossed and backcrossed in the laboratory. The results showed that the resistance levels in the F₁ to phoxim, cyhalothrin and endosulfan were 13.16 and 16. 69, 10.43 and 19.00, and 12.42 and 10.21-fold, and the degrees of dominance in heredity of resistance to the three insecticides were estimated to be-0.2220,-0.2147 and 0.0700, respectively. It indicated that phoxim or cyhalothrin resistance was incompletely recessive, and endosulfan resistance was controlled by the semi-recessive gene. The resistance levels of progenies of F₁ breeding to phoxim, cyhalothrin and endosulfan were 17. 66, 7.57 and 9.03fold, respectively, and that in F₁ backcross with the Hangzhou population were 8. 79, 3.00 and 6.61-fold, respectively. Based on the results mentioned above, it is suggested that the gene flow between the resistant and susceptible populations would significantly reduce the resistance levels to the three insecticides.