18SrDNA序列与同翅目昆虫的分类系统

18S rDNA Sequences and Classification System of the Order Homoptera

大量文献资料分析发现，昆虫１８ＳｒＤＮＡ序列可以用作种上分类的指标。同翅目中所有胸喙亚目昆虫的１８ＳｒＤＮＡ序列（２２００～２５００ｂｐ）比头喙亚目及部分半翅目昆虫的１８ＳｒＤＮＡ序列（１９００～１９２５ｂｐ）长，是典型的分子分类特征。粉虱类１８ＳｒＤＮＡ序列最长，其碱基替换率比全半翅目（Ｅｕｈｅｍｉｐｔｅｒａ）的部分昆虫高３倍，蚜虫与蚧壳虫的碱基替换率比半翅目部分昆虫高１．５倍。胸喙类是单源起源，与头喙类和部分半翅目昆虫种类形成姐妹群。这些发现具有化石记录、繁殖生物学、地理分布。

It is indicated that by a great deal data analysised, 18S rDNA nucleotide sequences of insect can be regarded as superspecific classification index. The sequences of sternorrhyncha of the Order Homoptera are longer (2 200￣2 500 bp) than those of Auchenorrhycha and some insect of the order Hemiptera, which is typical molecular classification characteristic; The 18S rDNA of whiteflies is the longest recorded to data and has a base substitution rate of 3 times greater than partial of Hemiptera taxon examined. The aphid and scale insect have a substitution rate approximately 1.5 times greater than that of Auchenorrhynchans. The sternorrhyncha is monophyletic and forms a sister group to all other Homopteras and some of Hemipteras; This classification above is almost similar to fossil record and morphological classification.