I will give a pass on viruses, some are good most are bad. However, when man has introduced a species into an environment they are not indiginous to for the purpose of controlling another species it doesn't have the desired affects after the targeted species is controlled. The introduced species then becomes a problem and the whole process starts again until one day we are the targeted species.
Controlling the wolf comes to mind. Eradicate wolf. Other species it preyed on populations explode. These species suffer overpopulation and competition for food. We re-intro the wolf and now it is eating not only deer/elk/others it is eating cattle and sheep as the wolf is flourishing. Now we talk again about controlling its population.
When man does not learn from history he is doomed to repeat it.
Man should stick to what he knows and trying to fool Mother Nature isn't one of them.
Introducing a new species is worrisome, even for a technophile like me, but they are not introducing a new species, but merely sterilized mosquitoes of the same species that is already there. Playing God? That's like saying you play God when you reach for the fly swatter..