These mosquitos were created by genetics using their own self limiting genes. All of these GM mosquitos are male. They are released into the wild with the new genes where they breed with females. Once they mate, the genes are passed down to their children, who then die before they grow to be adults. The genes are injected into male mosquito eggs.
These GM mosquitos were created by the biotechnology firm, "Oxitec" to lessen the population of mosquitos that are famous for spreading diseases such as Malaria or the Zika Virus. They figured that by breeding, these genes will be passed down and it will decrease the number of mosquitos that may potentially carry a disease, so that it is not so big of a problem.
Pros: This is a new breakthrough to prevent serious diseases. It also keeps the mosquito population from getting too large and uncontrollable. Finally, it may help research in GMO experiments to cure other hard to treat diseases.
Cons: Since this is the first time GMOs have been used on mosquitos like this, the results of the GMO is unknown to scientists. Second, this may spread to other areas where these diseases are not a problem, and it could bring the disease to a new environment. Finally, this act is very controversial and may cause arguments as to whether or not this should be allowed.
Personally, I think that creating these GM mosquitos will be beneficial to preventing the diseases that foreign countries face. This is the first step to creating more GMO's that may one day help to prevent or decrease other diseases and not just ones spread through mosquitos. These mosquitos will help prevent Malaria and the Zika Virus, which can be fatal. This may be one of the only ways that we know of that can stop the spread of these diseases.
Sources: https://www.theatlantic.com/technology/archive/2016/04/genetically-modified-mosquitoes-zika/479793/ http://www.oxitec.com/our-solution/technology/