Behere Gajanan T, Tay Wee Tek, Russell Derek A, Heckel David G, Appleton Belinda R, Kranthi Keshav R, Batterham Philip
Centre for Environmental Stress and Adaptation Research, Department of Genetics, Bio21 Institute of Molecular Science and Biotechnology, The University of Melbourne, Parkville, Australia.
BMC Evol Biol. 2007 Jul 14;7:117. doi: 10.1186/1471-2148-7-117.
Helicoverpa armigera and H. zea are amongst the most significant polyphagous pest lepidopteran species in the Old and New Worlds respectively. Separation of H. armigera and H. zea is difficult and is usually only achieved through morphological differences in the genitalia. They are capable of interbreeding to produce fertile offspring. The single species status of H. armigera has been doubted, due to its wide distribution and plant host range across the Old World. This study explores the global genetic diversity of H. armigera and its evolutionary relationship to H zea.
We obtained partial (511 bp) mitochondrial DNA (mtDNA) Cytochrome Oxidase-I (COI) sequences for 249 individuals of H. armigera sampled from Australia, Burkina Faso, Uganda, China, India and Pakistan which were associated with various host plants. Single nucleotide polymorphisms (SNPs) within the partial COI gene differentiated H. armigera populations into 33 mtDNA haplotypes. Shared haplotypes between continents, low F-statistic values and low nucleotide diversity between countries (0.0017-0.0038) suggests high mobility in this pest. Phylogenetic analysis of four major Helicoverpa pest species indicates that H. punctigera is basal to H. assulta, which is in turn basal to H. armigera and H. zea. Samples from North and South America suggest that H. zea is also a single species across its distribution. Our data reveal short genetic distances between H. armigera and H. zea which seem to have been established via a founder event from H. armigera stock at around 1.5 million years ago.
Our mitochondrial DNA sequence data supports the single species status of H. armigera across Africa, Asia and Australia. The evidence for inter-continental gene flow observed in this study is consistent with published evidence of the capacity of this species to migrate over long distances. The finding of high genetic similarity between Old World H. armigera and New World H. zea emphasises the need to consider work on both pests when building pest management strategies for either.
棉铃虫和美洲棉铃虫分别是东半球和西半球最重要的多食性鳞翅目害虫。区分棉铃虫和美洲棉铃虫很困难，通常只能通过生殖器的形态差异来实现。它们能够杂交产生可育后代。由于棉铃虫在东半球分布广泛且寄主植物范围广，其单一物种的地位受到了质疑。本研究探讨了棉铃虫的全球遗传多样性及其与美洲棉铃虫的进化关系。
我们获得了从澳大利亚、布基纳法索、乌干达、中国、印度和巴基斯坦采集的249只棉铃虫个体的部分（511 bp）线粒体DNA（mtDNA）细胞色素氧化酶I（COI）序列，这些个体与各种寄主植物相关。部分COI基因内的单核苷酸多态性（SNP）将棉铃虫种群分为33种mtDNA单倍型。各大洲之间共享的单倍型、低F统计值以及各国之间较低的核苷酸多样性（0.0017 - 0.0038）表明这种害虫具有高流动性。对四种主要棉铃虫害虫物种的系统发育分析表明，点带棉铃虫位于烟青虫的基部，而烟青虫又位于棉铃虫和美洲棉铃虫的基部。来自北美洲和南美洲的样本表明，美洲棉铃虫在其分布范围内也是一个单一物种。我们的数据揭示了棉铃虫和美洲棉铃虫之间较短的遗传距离，这似乎是在大约150万年前通过一次由棉铃虫种群引发的奠基者事件而形成的。
我们的线粒体DNA序列数据支持棉铃虫在非洲、亚洲和澳大利亚的单一物种地位。本研究中观察到的洲际基因流动证据与已发表的该物种远距离迁移能力的证据一致。东半球棉铃虫和西半球美洲棉铃虫之间高度的遗传相似性这一发现强调，在为任何一种害虫制定害虫管理策略时，都需要考虑对这两种害虫的研究。
