Mongolia.

>It's cheaper in the long run.

Is it? A human that survives to reproduce that would have otherwise died from malaria uses more non-renewable resources than a human that dies from malaria over the course of their lifetime, and continues to do so after their death by way of their progeny.

In terms of how much time we have as a species before running out of non-renewables on earth, killing the mosquitos might cost more than our blue marble can afford.

Perhaps certain natural population controls ought not be tampered with.

The benefits of human population control through disease, isn't much of a benefit at all, as child mortality and fertility tends to be correlated. The less chance of your kids dying, the less kids you'll have, in general. This probably means that while we might see a population boom in an adjustment period, we'd probably soon see drops in fertility.