High genomic stability of w Mel Wolbachia after introgression in three geographically distinct Aedes aegypti populations

The introgression of w Mel Wolbachia into Aedes aegypti populations is being used for the biocontrol of arboviruses such as dengue and chikungunya in 15 countries to date. A w Mel infection in Ae. aegypti both reduces the transmission of viruses by the mosquito and causes a reproductive manipulation that aids w Mel introgression into naïve populations. However, a critical concern is whether w Mel could evolve over time, potentially diminishing these desired phenotypes. Here, we investigated the stability of the w Mel genome in Ae. aegypti released for biocontrol in Colombia, Indonesia, and Vietnam. We sequenced the w Mel genome at the start of releases and up to six years after w Mel introgression into each population. Our study identifies very few genomic changes, suggesting the w Mel genome is not rapidly evolving despite its release into three geographically different field sites and subsequent exposure to novel environments. These results align with previous w Mel sequencing studies from Australia and provide strong evidence for the long-term genomic stability of w Mel, reinforcing its potential as a reliable biocontrol tool against Ae. aegypti -transmitted arboviruses.