There are studies. Killing some species of mosquitoes may be entirely beneficial. But if this happens to succeed, what will be next ? Will we use this technology to eradicate another specie and discover too late that this one was very important ? We are creating a precedent. I favor eradicating some species of mosquitoes, but this should stop there. My worry is that human is rarely able to stop after a success. What will be the failure that will cause us to stop ? How devastating will be this failure ?