应用DNA条形码技术鉴别谷实夜蛾与棉铃虫

Using DNA barcodes to identify two morphologically alike species: the cotton bollworm and corn earworm

仅依靠外部形态鉴定特征难以区分谷实夜蛾和棉铃虫,本文尝试应用DNA条形码技术鉴别这两个种。本研究测定了谷实夜蛾、棉铃虫、烟青虫及外群斜纹夜蛾的细胞色素氧化酶亚基I(COI)片段序列,通过比对分析34个样品并构建分子系统进化树,结果显示种间遗传距离大于3%,NJ进化树显示谷实夜蛾、棉铃虫与烟青虫分别形成稳定的单一支系。通过核苷酸多态性分析得出12个单倍型,其中种内单倍型之间少于3个核苷酸替代,而谷实夜蛾与棉铃虫的单倍型最少存在14个核苷酸替代;分析得到了13个特异的核苷酸鉴别位点用于区分谷实夜蛾与棉铃虫。研究结果显示通过DNA条形码技术可以鉴别近缘种类谷实夜蛾和棉铃虫。

Since the limited morphological difference, the two closely related species, the cotton bollworm Helicoverpa armigera （Htibner） and corn earworm Helicoverpa zea （Boddie） are difficult to distinguish. In this study, we using the mitochondrial cytochrome C oxidase subunit I （COI） gene sequence as DNA barcodes. We obtained partial COI sequence for 9 individuals of H. armigera, 13 individuals of H. zea, 10 individuals of H. assulta and 2 individuals Spodoptera litura （as outgroup）. The results indicate that genetic distance between species is more than 3% ; three closely related species of H. armigera, H. zea and H. assulta form stable monophyly respective- ly. Twelve haplotypes are identified in all samples. Haplotypes of the same species differed from each other by no more than three nucleotide substitutions. However, each haplotype of H. arrnigera differed from that of H. zea by at least 14 nucleotide substitutions. 13 unique diagnostic nucleotides were identified to distinguish H. arrnigera and H. zea. The results show that DNA bareodes can distinguish the two morphologically alike species efficiently.