Fish. Many species of fish think that mosquito larvae are delicious and will eat them. Some of these species will also thrive even in small bodies of water with little assistance.

Sterile insects. Male mosquitos don’t bite, and females only mate once, so releasing large numbers of sterile males will reduce the population.

Wolbachia. There are bacteria that live in mosquitoes, are quite effective at infecting the next generation, will not infect humans, and prevent malaria from living in the mosquito.

Bti. There’s a species of bacteria that produces a bunch of toxins that are very specific to mosquito larvae. I have no idea why it evolved to do this, but you can buy “mosquito dunks” and commercial preparations that will effectively kill mosquito larvae in water. They’re apparently entirely nontoxic to basically anything else. I expect that they’re too expensive for country-scale control, but they’re great for a backyard puddle.

You can kill mosquito pupae in water by spraying with an oil that makes a surface film for a few days. The pupae suffocate.