Genetic basis of sex pheromone blend difference between Helicoverpa armigera (Hübner) and Helicoverpa assulta (Guenée) (Lepidoptera: Noctuidae).

The two closely related moth species, Helicoverpa armigera and H. assulta, are sympatric in China. Both species use a mixture of (Z)-11-hexadecenal (Z11-16:Ald) and (Z)-9-hexadecenal (Z9-16:Ald) as their sex pheromones but in widely different ratios. Hybridization and backcrossing experiments between H. armigera and H. assulta were conducted and sex pheromone compositions of the parent species, their F(1) hybrids and backcrosses were compared to study the genetic basis of the production of their sex pheromone blend composition. Results show that the difference in sex pheromone blend ratios of these Helicoverpa species is mainly controlled by an autosomal locus with two alleles, with the allele from H. armigera being almost completely dominant over that derived from H. assulta.