title: The Inheritance of the Pheromone Sensory System in TwoHelicoverpaSpecies: Dominance ofH. armigeraand Possible Introgression fromH. assulta.
abstract: Hybridization of sympatric closely related species may sometimes lead to introgression and speciation. The sister speciesHelicoverpa armigeraandHelicoverpa assultaboth use (Z)-11-hexadecenal and (Z)-9-hexadecenal as sex pheromone components but in reversed ratios. FemaleH. armigeraand maleH. assultacould hybridize and produce fertile male hybrids, which can then backcross with females of the two parent species to get backcross lines in the laboratory. In this study, we compared the olfactory responses to pheromone compounds in the periphery and in the antennal lobes (ALs) of males of the two species, as well as of their hybrids and backcrosses. Single-sensillum recordings were carried out to explore characteristics of male-specific sensilla on the antennae, andin vivocalcium imaging combined with digital 3D-reconstruction was used to describe what happens in the macroglomerular complex (MGC) of the AL. The results show that the population ratio of the two male-specific types of olfactory sensory neurons responding to two sex pheromone components are controlled by a major gene, and that the allele ofH. armigerais dominant. Consistently, the study of the representative areas activated by sex pheromone components in the ALs further support the dominance ofH. armigera. However, the topological structure of the MGC in the hybrid was similar but not identical to that inH. armigera. All subtypes of male-specific sensilla identified in the two species were found in the male hybrids and backcrosses. Moreover, two new subtypes with broader response spectra (the expanded A subtype and the expanded C subtype) emerged in the hybrids. Based on the inheritance pattern of the pheromone sensory system, we predict that when hybridization of femaleH. armigeraand maleH. assultaoccurs in the field, male hybrids would readily backcross with femaleH. armigera, and introgression might occur fromH. assultaintoH. armigerathrough repeated backcrossing.
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijing, China; College of Life Sciences, University of Chinese Academy of SciencesBeijing, China.
authors.forename: Meng
authors.initials: M
authors.lastname: Xu
authors.affiliation: College of Forestry, Henan University of Science and Technology Luoyang, China.
authors.forename: Jun-Feng
authors.initials: JF
authors.lastname: Dong
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences Beijing, China.
authors.forename: Han
authors.initials: H
authors.lastname: Wu
authors.affiliation: Department of Entomology, College of Plant Protection, Henan Agricultural University Zhengzhou, China.
authors.forename: Xin-Cheng
authors.initials: XC
authors.lastname: Zhao
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences Beijing, China.
authors.forename: Ling-Qiao
authors.initials: LQ
authors.lastname: Huang
authors.affiliation: State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of SciencesBeijing, China; College of Life Sciences, University of Chinese Academy of SciencesBeijing, China.
authors.forename: Chen-Zhu
authors.initials: CZ
authors.lastname: Wang
keywords: Helicoverpa armigera; Helicoverpa assulta; antennal lobes; intraspecific hybridization; olfactory sensory neurons; sex pheromone