Maruthi M N, Rekha A R, Sseruwagi P, Hillocks R J
Natural Resources Institute, University of Greenwich, Central Avenue, Chatham Maritime, Kent ME4 4TB, UK.
Mol Biotechnol. 2007 Jan;35(1):31-40. doi: 10.1385/mb:35:1:31.
The whitefly, Bemisia afer (Hemiptera; Aleyrodidae), is emerging as a major agricultural pest. The current identification methods based on adult and pupal morphology are laborious and unreliable. A diagnostic polymerase chain reaction (PCR) protocol was developed for the first time in this study to discriminate B. afer from other whitefly species. Primers specific to mitochondrial cytochrome oxidase I gene (mtCOI) were designed to amplify a band of approx 650 bp. The PCR products were sequenced from B. afer samples collected from Malawi, Tanzania, Uganda, Zanzibar, and the United Kingdom. Phylogenetic analyses of mtCOI sequences and those of reference B. afer sequences clustered the African B. afer separately from the UK and Chinese populations and from other whitefly species. The African cluster was divided into two clades by parsimony and neighbor-joining methods. This indicates the existence of at least two genotypic clusters of B. afer, which are diverged by 0.8 to 3.2% nucleotide (nt) identities. Analysis of molecular variance indicated that these differences were the result of within population variation but were insufficient to identify discrete populations. Among the whitefly species used in the analysis, B. afer was equally dissimilar to Bemisia tabaci and Bemisia tuberculata (21.3-26.2% nt identities). As is the case for B. tabaci, these data show that mtCOI sequences are informative also for identifying B. afer variants, which lack distinguishing morphological features.
烟粉虱，非洲烟粉虱（半翅目；粉虱科），正成为一种主要的农业害虫。当前基于成虫和蛹形态的鉴定方法既费力又不可靠。本研究首次开发了一种诊断聚合酶链反应（PCR）方案，以将非洲烟粉虱与其他粉虱物种区分开来。设计了针对线粒体细胞色素氧化酶I基因（mtCOI）的特异性引物，以扩增一条约650 bp的条带。对从马拉维、坦桑尼亚、乌干达、桑给巴尔和英国采集的非洲烟粉虱样本的PCR产物进行了测序。对mtCOI序列以及参考非洲烟粉虱序列进行系统发育分析，结果表明非洲烟粉虱群体与英国和中国群体以及其他粉虱物种分别聚类。通过简约法和邻接法，非洲聚类被分为两个分支。这表明至少存在两个非洲烟粉虱基因型聚类，它们的核苷酸（nt）同一性差异为0.8%至3.2%。分子方差分析表明，这些差异是群体内变异的结果，但不足以识别离散群体。在分析中使用的粉虱物种中，非洲烟粉虱与烟粉虱和 tuberculata粉虱的差异程度相同（nt同一性为21.3 - 26.2%）。与烟粉虱的情况一样，这些数据表明mtCOI序列对于识别缺乏明显形态特征的非洲烟粉虱变种也具有信息价值。
