中国齿小蠹属昆虫的鉴定

Identification of Ips species(Coleoptera:Scolytinae)in China

【目的】齿小蠹属(Ips)(鞘翅目:小蠹亚科)昆虫是重要的针叶树蛀干害虫,在北半球广泛分布。本文在全国范围内调查的基础上,对采集到的齿小蠹成虫进行了种类鉴定,旨在厘清我国齿小蠹属的种类,并提供DNA分子数据。【方法】对我国东北、西北、西南地区9省(自治区)39个地点的针叶林中采集到的12062头齿小蠹成虫进行了形态特征观察,在初步鉴定到种的基础上,选取52个齿小蠹代表性样本进行mtDNA COⅠ基因测序和序列比对,并基于最大似然法、最大简约法和贝叶斯法将本研究代表性样本与齿小蠹属内所有已知物种进行种间系统发育关系的分析。【结果】依据形态学特征共鉴定出10种齿小蠹。基于序列比对的分子鉴定进一步验证了形态学鉴定结果,分别为中华齿小蠹(Ips chinensis)、重齿小蠹(I.duplicatus)、天山重齿小蠹(I.hauseri)、光臀八齿小蠹(I.nitidus)、东喜马拉雅云杉齿小蠹(I.schmutzenhoferi)、十二齿小蠹(I.sexdentatus)、香格里拉齿小蠹(I.shangrila)、西藏重齿小蠹(I.stebbingi)、落叶松八齿小蠹(I.subelongatus)和云杉八齿小蠹(I.typographus)。在包含世界范围内所有已知37种齿小蠹的系统发育分析中,本研究的样本与同种参考样本聚在了同一分支,进一步支持了形态鉴定和分子鉴定的结果。同时系统发育分析进一步表明:重齿小蠹与天山重齿小蠹为姊妹种;中华齿小蠹样本与该种已知的北方种群和南方种群有明显的遗传分化,独立为种内的第3个亚支;云杉八齿小蠹的新疆样本、东北-远东样本和欧洲样本分化为各自独立的3个亚支;我国东喜马拉雅云杉齿小蠹的样本与尼泊尔和巴基斯坦的样本分化为2个亚支;重齿小蠹、十二齿小蠹样本也与其各自对应的欧洲样本分化为2个亚支;新疆和东北的落叶松八齿小蠹样本没有表现出遗传分化。【结论】我国齿小蠹种类丰富,分布广泛,许多姊妹种之间形态特征十分相近,难以区分。基于形态特征结合mtDNA COⅠ基因的系统发育分析方法可以对齿小蠹属的种类进行准确鉴定。本研究发现的10种齿小蠹中包括我国的新纪录种——东喜马拉雅云杉齿小蠹。此外,本文更正了中华齿小蠹的鉴定,并发现7种齿小蠹存在明显的种下遗传分化特征。

【Objective】The bark beetles in the genus Ips(Coleoptera:Scolytinae)are severe stem borers of conifers,and widely distributed in the Northern Hemisphere.The purpose of this paper is to identify the species in genus Ips in China and provide DNA data based on a nationwide investigation.【Method】In this study,a total of 12062 Ips adult specimens were collected from 39 sites in the coniferous forests in 9 provinces(autonomous regions)in Northeast,Northwest and Southwest China.Based on the first preliminary identification of species level with the morphological characters recorded in literature,fifty-two representative samples were selected for mtDNA COⅠgene sequencing and sequence alignment.Phylogenetic trees containing all species in the genus and Chinese samples were constructed based on maximum likelihood,maximum parsimony and Bayesian methods.【Result】A total of 10 Ips species were identified based on their morphological characteristics.The molecular identification based on sequence comparisons further verified the morphological identification results,namely I.chinensis,I.duplicatus,I.hauseri,I.nitidus,I.schmutzenhoferi,I.sexdentatus,I.shangrila,I.stebbingi,I.subelongatus and I.typographus.In the phylogenetic analysis of all known 37 Ips species worldwide,the Chinese samples were clustered in the same branch with the same reference species,which further supported the results of morphological and molecular identifications.At the same time,phylogenetic analysis further showed that I.duplicatus and I.hauseri were sibling species.There was obvious genetic differentiation between the samples of I.chinensis and the known northern and southern populations of the species,and the samples were independently classified into the third subclade within the species.The I.typographus samples from Xinjiang,Northeast-Far East and Europe were divided into three separate subbranches.The I.schmutzenhoferi samples from China and those from Nepal and Pakistan were divided into two subbranches.The I.duplicatus and I.sexdentatus samples were divided into two subclades with their corresponding European samples.There was no genetic differentiation in I.subelongatus from Xinjiang and northeast China.【Conclusion】The species of Ips are abundant and widely distributed in China.The morphological characteristics of many sibling species are very similar,and difficult to distinguish solely based on morphology.Joint methods based on morphological characters and mtDNA COⅠgene sequence alignment and phylogenetic analysis can accurately identify Ips species.Among the 10 Ips species in this study,I.schmutzenhoferi is a new record species in China.In addition,the identification of I.chinensis was amended,and seven Ips species were found with subspecific genetic differentiations.