Multi-omics profiling reveals associations between gut microbiota and olfactory gene expression in mosquitoes

The interplay between gut microbiota and host physiological processes has been extensively studied in vertebrates, where it plays a crucial role in regulating appetite, emotion, immunity, and other physiological functions. However, whether a similar regulatory mechanism exists in insects remains unclear, especially regarding the long-distance regulation of olfactory function. This study focused on three Culex subspecies (Culex quinquefasciatus, Culex pipiens pallens, and Culex pipiens molestus) that are closely related but exhibit significant differences in olfaction-dependent ecological habits. By integrating antennal transcriptomic and gut metagenomic data, we systematically analyzed the expression characteristics of olfactory-related genes, the structure of gut microbial communities, and their intrinsic associations.

We integrated antennal transcriptomic and gut metagenomic sequencing to analyze olfactory-related gene expression, gut microbial community structure, and their intrinsic associations in male and female individuals of the three Culex subspecies. Bioinformatics analyses included differential gene screening, functional enrichment, microbial taxonomic annotation, and Spearman correlation analysis.

The results showed that a large number of sex-specific and species-specific differentially expressed genes (DEGs) were identified in the antennae of the three Culex subspecies. Among these, 345 DEGs were shared sex-specific genes across species, which were significantly enriched in pathways such as odor binding, signal transduction, and xenobiotic metabolism. At the phylum level, the gut microbial composition was dominated by Proteobacteria, Bacteroidetes, and Firmicutes, showing a conserved structure; at the genus level, 11 dominant genera (including Wolbachia, Elizabethkingia, and Asaia) exhibited distinct species-specific distribution patterns. Diversity analysis revealed that the gut microbial richness of male individuals was significantly higher than that of females, and the β-diversity showed an obvious "sex clustering" pattern.Correlation analysis further indicated that 152 DEGs were significantly correlated with 107 microbial genera. Among them, olfactory-related genes were closely associated with several core genera (e.g., Wolbachia, Asaia, Serratia). Gut microbes may remotely regulate the expression and function of olfactory genes in antennae through metabolites or signaling molecules, thereby influencing mosquito behaviors such as host localization, mating, and oviposition.

This study reveal the intrinsic association between gut microbes and olfactory function in Culex mosquitoes, providing a new perspective for understanding the "microbe-host" cross-organ regulatory mechanism and laying a theoretical foundation for the development of novel mosquito vector control strategies based on microbial or olfactory interference.