Objective　To understand the infection status and typing of Wolbachia in Culex pipiens pallens population in coastal areas of Shandong Province, and to provide new research directions and theoretical basis for the prevention and control of mosquito-borne diseases. Methods　From June 2022 to August 2023, mosquito samples were collected from 8 sites in four coastal cities of Yantai, Qingdao, Rizhao, and Dongying in Shandong Province by light lure method. The collected samples were identified as Culex pipiens pallens by combining morphological and molecular methods. Then, using the PCR detection method established by the Wolbachia surface protein (wsp) gene sequence, the Wolbachia infection rate of Culex pipiens pallens collected in the field from 8 sites along the coast of Shandong Province was detected. In addition, the representative strain of Wolbachia was downloaded from the GenBank database, and the obtained gene sequences were subjected to phylogenetic analysis using Mega5.2 software for typing. Results　Wolbachia infection was found in all four coastal areas of Shandong Province, with an average infection rate of 80.8% (261/323). Among them, Yanti had the highest infection rate of 100% (46/46), while Wulian County, Rizhao City had the lowest infection rate of 60.6% (20/33). A total of 12 wsp haplotypes were identified, with 92.5% infection rates for Hap1, 70.0% for Hap2, and lower rates for Hap3 to Hap12. From the perspective of haplotype sources, Hap1 was detected in all 8 sampling sites, while other haplotypes were only detected in some geographical populations of sampling sites. Among them, Dongying District, Dongying City had the highest haplotype diversity, with six haplotypes detected. Phylogenetic tree analysis concluded that the Wolbachia strains found in all eight sampling points belonged to group B. Conclusions　Infection of Wolbachia group B is common in Culex pipiens pallens in coastal areas of Shandong Province. Still, there are certain differences in the haplotypes of Wolbachia infections in different regions. This provides a valuable theoretical basis for targeted prevention and control of specific mosquito-borne diseases in the region．

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 oxidase I (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 (F_ST), 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 and 10.393 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 F_ST analysis among different types of sampling sites showed that the mean F_ST 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.