By creating sterile mosquitoes:
Current technologies we use against mosquitoes simply are not adequate: existing measures are losing the war. None are easy and even fewer are affordable for vulnerable individuals and governments charged with mosquito control. They do not fully protect, and their use entails direct risks to human health and the environment. So the choice of implementing [genetically modified] mosquitoes is not a choice of no risk versus risk, it is a matter of choosing the least risky among all existing choices in a war against very real continuing disease risk.
Others are less sanguine. Awhile back Rory Lynott tallied some of the ridiculous things scientists are trying in order to bring down the mosquito population.
The Dish 