Integrated transcriptome-microbiome analysis reveals a host-microbe interplay associated with insecticide resistance in Aedes albopictus.

Introduction: Aedes albopictus is the primary vector of major arboviral diseases such as dengue fever, chikungunya fever, and Zika virus disease, and its control is highly dependent on chemical insecticides. However, the long-term use of pyrethroid insecticides has led to the development of insecticide resistance in Ae. albopictus, which severely undermines the efficacy of vector control programs.

Methods: Ae. albopictus populations were collected from five sites in Guangdong and Hainan provinces, China. Beta-cypermethrin resistance levels were determined via bioassays, with resistance ratios at the median lethal concentration (RR₅₀) calculated. Target-site resistance was evaluated via kdr mutation detection in the voltage-gated sodium channel (VGSC) gene. Transcriptome sequencing identified differentially expressed genes (DEGs), and 16S rRNA sequencing characterized gut microbiome alterations. Correlation analysis and Cedecea neteri dietary supplementation assays verified the role of gut microbiota in resistance.

Results: The results showed that all four populations (except the CP population) exhibited varying degrees of resistance to beta-cypermethrin, with resistance ratios at the median lethal concentration (RR₅₀) ranging from 2.84 to 29.18. Detection of kdr mutations revealed three mutations (F1534C, F1534L, F1534S) at codon 1534 of the voltage-gated sodium channel (VGSC) gene in all field populations, with mutation frequencies ranging from 49.4% to 100.0%, and a low-frequency V1016G mutation at codon 1016. Transcriptome analysis identified a total of 2,566 commonly upregulated genes and 994 commonly downregulated genes across the resistant populations. Gut microbiome analysis revealed a significant alteration in the intestinal microbial community structure of resistant populations; specifically, the relative abundance of the genus Cedecea differed significantly between resistant and susceptible populations and correlated strongly with the expression of most differentially expressed genes. Furthermore, dietary supplementation with Cedecea neteri significantly increased the survival rate of Ae. albopictus exposed to β-cypermethrin (73.86% vs 40.00%; P < 0.0001).

Discussion: From the perspectives of target-site mutations, gene expression regulation, and gut microbe interactions, this study providing a foundation for further studies on resistance mechanisms in Ae. albopictus, thereby providing a theoretical foundation for further dissection of resistance mechanisms and optimization of vector control strategies.