中文摘要：

【目的】通过分析比较钝绥螨ITS基因片段,探讨其作为分子手段应用于种类鉴定,同时应用此分子标记来分析钝绥螨的亲缘关系,为研究其系统发育和完善分类系统提供参考。【方法】对采自江西桔园的尼氏真绥螨、江原钝绥螨、津川钝绥螨和东方钝绥螨进行总DNA提取,PCR扩增,测序,并从GenBank中下载5种钝绥螨的ITS序列,应用软件分析ITS片段长度、A＋T%含量、变异位点和进化关系。【结果】得到总长度为644—655 bp的ITS序列片段,序列中A＋T碱基比例较高,为58.2%。整个ITS基因片段存在204个碱基变异位点（ITS1：172;ITS2：22;5.8S：10）和32个碱基插入/缺失。真绥螨属的尼氏真绥螨和卵圆真绥螨的分类地位较近,遗传距离为0.013;而小新绥螨属的4个种与钝绥螨属的3个种在构建系统发育树时未能明显地分为2支,其中胡瓜新小绥螨和东方钝绥螨的遗传距离最近,为0.083。【结论】ITS序列片段分析结果支持尼氏真绥螨和卵圆真绥螨现在的分类地位,而小新绥螨属与钝绥螨属似乎未达到属间差异,其分类地位有待进一步确定。

英文摘要：

【Objective】The objective of this study is to analyze the phylogenetic relationships among phytoseiid mites in the citrus orchards by comparing their ITS gene fragments,finally improve the classification system of phytoseiid mites.【Method】The fragment sequences of ITS from 4 phytoseiid mites,Euseius nicholsi,Amblyseius eharai,A.tsugawai and A.orientalis,which collected from citrus orchards in Jiangxi province were analyzed by using softwares.【Result】Length of ITS from the 4 species are from 644-655 bp.The average A＋T content is 58.2%.There are 204 variable sites and 32 insertion/deletion in these sequences.Results demonstrated that ITS2 regions are much more conserved than ITS1.Aligned with the ITS sequence of other 5 phytoseiid species of citrus orchard from GenBank,data analysis shows that the relationship between E.nicholsi and E.ovalis is closer than others,their genetic distance is 0.013.Four species of Neoseiulus and 3 species of Amblyseius are clustered into the one branch in the phylogenetic tree,and the nearest genetic distance,which between N.cucumeris and A.orientali,is 0.083.【Conclusion】The results support the taxonomic status of E.nicholsi and E.ovalis,and show sufficient evidence that Neoseiulus and Amblyseius should not be assigned to two genera,which the taxonomic system needs to be further researched.