Genetic dynamics and dispersion pattern changes of Aedes aegypti populations in Yunnan Province from 2016 to 2018

Background Aedes aegypti is the major vector for massive mosquito-borne viruses, including Dengue, ZIKV, etc., and threatens human health world-widely. The absence of efficient vaccine for those insect-borne diseases highlights the importance of monitoring of genetic changes of the Ae. aegypti populations. Methods The genetic variation and population structure of Ae. aegypti populations collected from three regions of Yunan province in China during 2016 to 2018 were investigated with 9 microsatellite loci and the mitochondrial coxI gene. Results From 2016 to 2018, the genetic diversity of Ae. aegypti populations in Yunnan province displayed a trend of initial increase followed by a decrease. The degree of inbreeding within the populations gradually shifted from heterozygous to moderately inbred. The clustering results indicated that, compared to the populations collected in 2016, those collected in 2017 and 2018 were genetically closer. Ten coxI haplotypes were detected, haplotypes H06 and H09 were detected nearly in all regions, while the others were only detected in single region or even single year. The population diffusion analysis indicated that the diffusion of Ae. aegypti populations among different locations exhibited a trend of first increasing and then decreasing. Meanwhile, the AMOVA analysis results also revealed that the source of variation in the Yunnan Ae. aegypti populations gradually shifted from mainly inter-individual to mainly inter-regional. The evolutionary scenario inference of the invasion and diffusion of Ae. aegypti indicated that the mosquito invaded and colonized Dehong Prefecture from Southeast Asian, and then diffused to Lincang City, and finally to Xishuangbanna Prefecture. Conclusion The results presented here indicate that the current mosquito-control strategies in Yunnan Province have effectively suppressed Ae. aegypti populations within regions. Rather than focusing primarily on preventing imported cases, greater attention should now be paid to intra-provincial spread of Ae. aegypti , particularly between port and urban areas.