If you're interested in this you may like to check out Radiolab's "Kill 'em all" - http://www.radiolab.org/story/kill-em-all/. There is an organisation breeding a strain of mosquito that when released into wild populations causes all offspring to be infertile. This causes mosquito populations to be eradicated very quickly.

One of the presenters was asked if there are any benefits of having mosquitos around. After looking high and low, his conclusion was that they've stopped humans from coming in and destroying precious ecosystems, for instance in jungles, forests and swamplands.