The endosymbiotic bacterium Wolbachia has been proposed to form the basis for an effective mosquito biocontrol strategy. Resident strains ofWolbachia inhibit viral replication inDrosophila fruit flies and induce a reproductive phenotype known as cytoplasmic incompatibility that allows rapid invasion of insect populations. Transinfection of Wolbachia strains into the principle mosquito vector of dengue virus, Stegomyia aegypti, has resulted in dengue-refractory mosquito lines with minimal effects on mosquito fitness.