Wolbachia symbiosis in Chinese populations of Aedes albopictus (Skuse): implications for the incompatible and sterile insect techniques

Mosquito-borne diseases represent a significant public health challenge in China and globally, with Aedes mosquitoes transmitting over 99% of viral mosquito-borne diseases. Aedes albopictus (Skuse), the primary vector of dengue and chikungunya in China, is conventionally controlled through environmental, physical, and chemical methods increasingly compromised by insecticide resistance and environmental concerns. The Incompatible Insect Technique (IIT), which exploits Wolbachia -induced cytoplasmic incompatibility (CI), the Sterile Insect Technique (SIT) or their combination offers promising alternatives. This study comprehensively investigated the genetic diversity, Wolbachia infection characteristics, and induced CI among geographical Ae. albopictus strains across China. Crosses between different geographical strains either failed to induce CI or resulted in incomplete CI, with egg mortality rates ranging from 14.1 ± 9.0% to 86.8 ± 12.9%. Our results also revealed significant genetic differentiation. The Hainan (HN) population exhibited significant genetic distinctiveness (Hd = 0.644; π = 0.00132), whereas the Anhui (AH) population showed the highest genetic diversity (Hd = 0.711; π = 0.03127), serving as a phylogeographic hub. The data also indicated signatures of recent population expansion (Tajima’s D = −2.86, Fu’s Fs = −6.05). Wolbachia infection was nearly almost fixed (99.5%), featuring two main strains ( w AlbA and w AlbB) with remarkable sex-biased prevalence. ParaFit analysis indicated no significant host–symbiont coevolution, coupled with the observed incomplete CI levels, suggesting that purifying selection may drive loss-of-function in the cif genes determining CI. This study provides fundamental data for assessing the regional applicability of IIT or combined IIT/SIT strategies in China, guiding the selection of suitable mosquito populations for future vector control operations.