Interspecific hybridization ofHelicoverpa armigera andH. assulta (Lepidoptera: Noctuidae)

Reciprocal hybridization betweenHelicoverpa armigera (Hübner) andH. assulta Guenee followed by back-crossing of the hybrids (F₁) withH. armigera produced backcross (BC) lines consisting of fertile females and males. The F₁ ofH armigera female andH. assulta male had only male, no female sex. In this case Haldane’s rule applies, and therefore it is proved that the sex chromosomes ofHelicoverpa species are of ZW type, and the female is the heterozygous sex. This hybrid also showed significant heterosis with the heaviest pupal weight, and when it was back-crossed withH. armigera female, the sex ratio of the BC off-spring was distorted as 1 : 4. The potential utilization of this hybrid in genetic controllingH. armigera was finally discussed.