title: Using COI gene sequence to barcode two morphologically alike species: the cotton bollworm and the oriental tobacco budworm (Lepidoptera: Noctuidae).
abstract: Due to limited morphological difference, the two closely related sister species, the cotton bollworm, Helicoverpa armigera (Hübner) and the oriental tobacco budworm, H. assulta (Guenée) (Lepidoptera: Noctuidae), are very difficult to distinguish, especially at the larvae stage. Recently, DNA sequence has been widely used as a bio-barcode for species identification. In this study, we attempted to distinguish H. armigera and H. assulta using the mitochondrial cytochrome C oxidase subunit I gene (COI) gene sequence as the barcode. We determined a 658 bp segment of the COI gene for 28 individuals of H. armigera, 8 individuals of H. assulta, and 10 individuals of Mamestra brassicae (as the outgroup) in Yunnan Province, southwest of P. R. China, together with one H. assulta and two H. armigera reported sequences from GenBank. Twenty-three haplotypes were identified in all 49 samples. As expected, network analysis of the haplotypes of the three species presented a clustering pattern consistent with the respective species status. Haplotypes of the same species differed from each other by no more than three nucleotide substitutions. However, each haplotype of H. armigera differed from that of H. assulta by at least 22 nucleotide substitutions. Both species differed from M. brassicae by more than 50 nucleotide substitutions. 17 unique diagnostic nucleotides were also used to discriminate the two species. The finding of large COI sequence differences between H. armigera and H. assulta suggested that it could be used to distinguish the two morphologically alike species and be employed for quick species identification during pest control.
authors.affiliation: Life Science College, Yunnan Normal University, 650092 Kunming, Yunnan, China.
authors.forename: Qing-Qing
authors.initials: QQ
authors.lastname: Li
authors.forename: Di-Yan
authors.initials: DY
authors.lastname: Li
authors.forename: Hui
authors.initials: H
authors.lastname: Ye
authors.forename: Xiao-Fei
authors.initials: XF
authors.lastname: Liu
authors.forename: Wei
authors.initials: W
authors.lastname: Shi
authors.forename: Neng
authors.initials: N
authors.lastname: Cao
authors.forename: Yan-Qing
authors.initials: YQ
authors.lastname: Duan
mesh_terms: D000818:Animals; D001483:Base Sequence; D002681:China; D058893:DNA Barcoding, Taxonomic / Q000379:methods*; D003576:Electron Transport Complex IV / Q000235:genetics*; D005843:Geography; D003368:Gossypium / Q000469:parasitology*; D006239:Haplotypes / Q000235:genetics; D008969:Molecular Sequence Data; D009036:Moths / Q000033:anatomy & histology* / Q000201:enzymology / Q000235:genetics*; D013045:Species Specificity; D014026:Nicotiana / Q000469:parasitology*
chemical_list: D003576:Electron Transport Complex IV