Abstract: Objective　To understand the genetic basis of the adaptation of Culex tritaeniorhynchus to different environmental ecology in Jining City, Shandong Province, so as to provide insights into understanding of the population structure or isolation pattern of Cx. tritaeniorhynchus in the city. Methods　Seven sampling sites were selected from urban, suburban and rural areas of Jining City, Shandong Province from June to August 2023, and mosquitoes were  collected using mosquito⁃trapping lamps. All collected adult mosquitoes were identified morphologically. Genomic DNA was extracted from a single female Cx. tritaeniorhynchus mosquito, and the mitochondrial cytochrome C oxidaseⅠ (COI) gene was amplified using a PCR assay, sequenced and subjected to molecular identification. The number of haplotypes, haplotype diversity (Hd), nucleotide diversity (Pi), and average number of nucleotide differences (K) of Cx. tritaeniorhynchus DNA sequences were estimated among different sampling sites using the software DnaSP 6, and a neutrality test was performed. The fixation index (FST), and gene flow (number of migrants, Nm) of Cx. tritaeniorhynchus populations were calculated using the software Arlequin 3.5.2, and subjected to analysis of molecular variance (AMOVA). In addition, a haplotype network diagrams and a phylogenetic tree of Cx. tritaeniorhynchus populations were created using the software PopART and MEGA 11, respectively. Results　A total of 420 sequences were successfully amplified from the COI gene of Cx. tritaeniorhynchus samples collected from 7 sampling sites in Jining City, and a gene fragment sequence with a length of 603 bp was obtained, with 55 variable sites and 46 haplotypes and without insertion or deletion mutations. Of the 46 haplotypes, H01 was the dominant shared haplotype, and the haplotype frequency increased gradually from urban areas (34.00%) to rural areas (47.00%). The mean Hd, Pi and K values of Cx. tritaeniorhynchus COI genes were 0.814, 0.024 and 14.129, 0.489, 0.016 and 7.941 and 0.641, 0.016 and10.393 in suburban, urban, and rural areas, respectively, with the highest population diversity of Cx. tritaeniorhynchus in suburban areas and the lowest in urban areas. Paired FST analysis among different types of sampling sites showed that the mean FST value was 0.029 between urban and suburban areas, indicating more frequent inter⁃population communication. AMOVA revealed that the percentage of intra⁃population variation (95.74%) was higher than that of inter⁃population variation (4.26%). Neutrality tests showed deviation from neutrality in Cx. tritaeniorhynchus populations collected from Nanyang Township (Tajima's D ＝ 2.793, Fu's Fs ＝ 6.429, both P values < 0.05). In addition, the mismatch distribution curves of Cx. tritaeniorhynchus COI gene appeared bimodal or multimodal patterns in Jining City, indicating a relatively stable overall population size. Conclusions　The mitochondrial COI gene may be used as a molecular marker to investigate the population genetic diversity of Cx. tritaeniorhynchus. The population genetic diversity of Cx. tritaeniorhynchus is higher in the suburban areas of Jining City than in rural and urban areas, and there are frequent genetic exchanges between Cx. tritaeniorhynchus populations from urban and suburban areas.

Key words: Culex tritaeniorhynchus, Cytochrome C oxidaseⅠ, Population diversity, Genetic diversity, Jining City

摘要： 目的　了解山东省济宁市三带喙库蚊适应不同环境生态的遗传基础，为其种群结构或隔离模式研究提供参考。方法　2023年6—8月，选择山东省济宁市城市、城郊及农村地区的7个采样点，采用诱蚊灯法采集蚊虫。对所采集的成蚊进行形态学鉴定，提取单只三带喙库蚊雌蚊基因组DNA，采用PCR法对细胞色素C氧化酶亚基Ⅰ（cytochrome C oxidase Ⅰ，COI）基因进行扩增、测序，并进行分子鉴定。使用DnaSP 6软件统计不同地区三带喙库蚊DNA序列的单倍型数量、单倍型多样性（haplotype diversity，Hd）、核苷酸多样性（nucleotide diversity，Pi）、序列间核苷酸差异的平均数量（average number of nucleotide differences，K）等指标，并进行中性检验。使用Arlequin 3.5.2软件计算种群固定指数（fixation index，FST）、基因流（number of migrants，Nm），并进行分子方差分析（analysis of molecular variance，AMOVA）。使用PopART和MEGA 11软件分别绘制种群单倍型网络图和系统进化树。结果　从济宁市7个采样点采集的三带喙库蚊样本COI基因中成功扩增出420条序列，获得长度为603 bp的基因片段序列，其中有55个可变位点和46个单倍型，无插入和缺失突变。46个单倍型中，H01为优势共享单倍型，单倍型频率从城市地区（34.00%）向农村地区（47.00%）递增。城郊、城市、农村地区三带喙库蚊COI基因平均Hd、Pi值和K值分别为0.814、0.024、14.129，0.489、0.016、7.941和0.641、0.016、10.393；城郊地区三带喙库蚊种群多样性最高，城市地区种群多样性最低。不同类型采样点之间的配对FST分析表明，城市地区与城郊地区FST平均值为0.029，其种群间交流更为频繁。AMOVA分析结果表明，济宁市三带喙库蚊群体内变异百分比（95.74%）高于群体间变异（4.26%）。中性检验结果表明，7个采样点中仅南阳镇采集的三带喙库蚊种群偏离中性（Tajima's D ＝ 2.793，Fu's Fs ＝ 6.429，P 均< 0.05）。济宁市三带喙库蚊COI基因错配分布图曲线呈双峰或多峰，表明种群整体数量相对较稳定。结论　线粒体COI基因可作为研究三带喙库蚊种群遗传多样性的分子标志。济宁市城郊地区三带喙库蚊种群遗传多样性高于农村和城市地区，城市和城郊地区三带喙库蚊种群间频繁发生遗传交换。

关键词: 三带喙库蚊, 细胞色素C氧化酶亚基Ⅰ, 种群多样性, 遗传多样性, 济宁市