Bacterial community structure and diversity of common mosquito species in Chengdu: Insights from PacBio third-generation sequencing and public health implications

Mosquitoes, as critical vectors of diseases such as Japanese encephalitis, dengue fever, and yellow fever, pose significant public health risks in Chengdu, a subtropical city in southwestern China. The present study ecological surveillance and PacBio third-generation sequencing to characterize the symbiotic microbiota of four dominant mosquito species (Aedes albopictus, Culex pipiens quinquefasciatus, Culex tritaeniorhynchus, and Armigeres subalbatus) across urban and rural habitats. From 2020 to 2024, mosquito density monitoring revealed spatial heterogeneity(Aedes albopictus, Culex pipiens quinquefasciatus, Culex tritaeniorhynchus, and Anopheles sinensis), with outer ring areas exhibiting the highest density (34.69 mosquitoes per trap per night), while central urban zones had the lowest (3.60). Sequencing identified 717 high-quality Amplicon Sequence Variants (ASVs), with Aedes albopictus harboring the most unique bacterial species (191). Beta diversity analysis demonstrated distinct microbial clustering among species, driven by Pseudomonadota dominance (54.27-93.89%) and variations in secondary phyla (Bacteroidota, Campylobacterota). Functional prediction analysis via the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed significant disparities in the abundance of human disease-associated pathways across mosquito symbiotic microbiota (P = 0.049), with the disparities primarily observed in pathways related to bacterial, viral, and parasitic infections-categories of substantial public health relevance. Notably, Wolbachia (clade B) and Klebsiella variicola exhibited species-specific abundance patterns, underscoring their respective roles in potential pathogen suppression and public health risks. Unclassified taxa (norank_d__Bacteria, norank_p__Candidatus_Hydrogenedentes) clustered near novel mosquito-associated spirochetes, suggesting underexplored functional microbiota. This study establishes a foundational dataset for understanding mosquito-microbe interactions and inform the development of targeted strategies for mitigating vector-borne disease.