Abstract: Laboratory screenings were conducted for obtaining resistant population of cotton bollworm (CBW) Helicoverpa armigera (Hübner) to Bt transgenic cotton. The mode of inheritance of resistance in this population was also studied. The results showed that after selection for 16 generations, the WLC₅₀ (mean weight loss concentration) of CBW to Bt transgenic cotton was 43.3 times as many as that of the 1st generation. Owing to that the weights of the 7-day old larvae and emergence rate of adults, when fed on diets containing Bt transgenic cotton, changed significantly, these two characters were regarded as the resistance standards for screening in this study. The degrees of dominance of cross and reciprocal-cross between the resistant and susceptible populations were less than 0 according to Stone's formula. The sex ratios of the descendants of the cross and backcross groups were 1∶1 approximately. The χ² values were low as if the resistance of CBW to Bt transgenic cotton was controlled by a single gene. It is suggested that the inheritance of resistance to Bt transgenic cotton in CBW is controlled by single autosomal incomplete recessive allele.

Key words: Helicoverpa armigera (Hübner), Bt transgenic cotton, resistance, resistance inheritance mode