One of the reasons mosquito populations are out of control is that we've killed off a lot of their predators. No mosquito anywhere is a keystone species, and you would only need to wipe out the vector species. Other, less harmful species of mosquito would fill in nicely with less competition.

At least, that's the theory. Previous theories included introducing mosquitofish to eat the larvae, but that backfired because the moquitofish are aggressive and don't eat as many mosquitos as local predators driven off by the mosquitofish.