利用核糖体ITS和3个线粒体基因序列研究几种常见肿腿蜂种类

Molecular identification of Sclerodermus species (Hymenoptera: Bethylidae), using the nuclear ribosomal ITS region sequence and partial sequences of the mitochondrial Cytb,12S,16S genes

硬皮肿腿蜂Sclerodermus spp.(Hymenoptera:Bethylidae)寄生低龄天牛幼虫和吉丁类蛀干害虫。本研究利用核糖体ITS序列和3个线粒体基因序列区分8种常见的肿腿蜂。测出8种肿腿蜂的核糖体间隔区ITS1-5.8S-ITS2序列全长2 060 bp。通过对ITS序列分析,根据ITS1序列1 319-1 333 bp位置处"CTTCT"的个数,将管氏肿腿蜂、川硬皮肿腿蜂、白蜡吉丁肿腿蜂、沙蒿吉丁肿腿蜂、苹小吉丁肿腿蜂、松脊吉丁肿腿蜂、落叶松吉丁肿腿蜂,这7种肿腿蜂分成两类,其中,管氏肿腿蜂、川硬皮肿腿蜂、白蜡吉丁肿腿蜂、沙蒿吉丁肿腿蜂为一类,有3个"CTTCT"单元,新发现的苹小吉丁肿腿蜂、松脊吉丁肿腿蜂、落叶松吉丁肿腿蜂为另一类有两个"CTTCT"单元,所以,ITS序列能够将苹小吉丁肿腿蜂、松脊吉丁肿腿蜂和落叶松吉丁肿腿蜂从已知种管氏肿腿蜂、川硬皮肿腿蜂和白蜡吉丁肿腿蜂中区分出来,也为这些新发现的肿腿蜂个体成为新物种提供理论依据;同时分析了8种肿腿蜂线粒体基因cytb,12S和16S 3个基因片段,并结合线粒体基因序列数据和系统发育树。所得的结果表明落叶松吉丁肿腿蜂的所有个体聚在一起形成一个单独的姐妹群,并且在所测的3个基因中落叶松吉丁肿腿蜂都有很高的自检支持率(90%以上)。cytb和12S基因也提供了有力的证明:松脊吉丁肿腿蜂的所有个体聚集为一个单独的类群(自检支持率在90%以上)。这种多个基因综合比较分析的方法,为肿腿蜂科硬皮肿腿蜂属的个体种类鉴定及线粒体基因的进化提供一定的理论依据,但最终肿腿蜂新种的鉴定仍需对其进行形态学鉴定。

The parasitoid wasps Sclerodermus (Hymenoptera: Bethylidae) are indigenous natural enemies, of the longhorned beetle pest. Using the nuclear ribosomal ITS region sequence and partial sequences of the mitochondrial Cytb , 12S, 16S genes to study molecular identification of Sclerodermus species (Hymenoptera: Bethylidae). Although the sequences of internal transcribed spacer of the nuclear ribosomal DNA (ITS1 and ITS2) of these parasitoids are very similar, according to the deletion of one CTTCT repeats between 1 319 and 1 333 bp on ITS1, we discover that the ITS sequences could separate eight Sclerodermus species into two groups, as well as one group is the known species, contained Sclerodermus guani , Sclerodermus sichuanensis , Sclerodermus pupariae, and Sclerodermus sp.(No.4), the other group is the unnamed species which are Sclerodermus sp.(No.1), Sclerodermus sp.(No.2) and Sclerodermus sp.(No.3). Thus the ITS sequence could identify the three unknown Sclerodermus ( Sclerodermus sp.(No.1), Sclerodermus sp.(No.2) and Sclerodermus sp.(No.3)) from the known species ( S. guani , S. sichuanensis, S. puparia ). So the ITS sequences could be an initial important basis for discovery new species. And to determine genetic variation and relationships among different species of Sclerodermus , we analyzed nucleotide sequence data for three mitochondrial DNA (mtDNA) genes (12S rDNA, cytb , 16S rDNA) using concatenated mtDNA data and two species tree inference methods (neighbor-joining and maximum likelihood). All analyses provide strong support for Sclerodermus sp.(No.3) merged into one haplogroup with the high bootstrap support for all three gene sequences. cytb and 12S gene analysis also strongly supported a single haplogroup for Sclerodermus sp.(No.2). This comparative gene analysis sheds light on the identification and evolution of mitochondrial genes in the genus Sclerodermus . But the morphological identification needs to be done for new Sclerodermus species.