The double-edged sword effect of expanding Wolbachia deployment in dengue endemic settings

M. G. Pavan, G. A. Garcia, M. R. David and R. Maciel-de-Freitas,  The Lancet Regional Health - Americas,  27:100610. 2023.

We can use Brazil as a showcase to foresee and avoid a double-edged sword effect associated with Wolbachia releases. Insecticide resistance of native Ae. aegypti populations is spread worldwide (, and positive results should boost Wolbachia deployment in other dengue endemic settings around the world. Aedes aegypti populations are heterogeneous and nationwide releases of a Wolbachia strain whose genetic backcross belong to a specific locality would produce an unsought homogenization of vector populations. Aedes aegypti homogenisation at large geographic scales could impose additional undesirable consequences in the long-term by promoting genetic hitchhiking of traits such as higher vector competence, lower susceptibility to repellents and insecticides, or more avid host-seeking and biting behaviour. Available data has shown that ensuring adherence to local characteristics, specially a matching genetic between native and released mosquitoes, is critical to enhance the likelihood of achieving a faster introgression in the field, realizing cost and time savings over the globe. Probably there are a myriad of yet undiscovered traits beyond insecticide resistance that may influence vector local adaptation and would affect the success of released strains. Therefore, neglecting the genetic diversity in favour of centralising the rearing of mosquitoes with Wolbachia for nationwide releases could represent a drawback for future releases. Long-term studies regarding the consequences of releasing mosquitoes with homogenous genotypes in diverse ecological and epidemiological scenarios remain a critical research priority, essential for informed decision-making and sustainable management of mosquito-borne diseases.

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