You're asking a question that nobody has or can have the answer to, because the only way to have that answer is to actually make these genetic alterations, release the modified fauna, and observe what happens. What is true is that in the case of mosquitoes, the scientists who have studied them and their genes are able, with a very high probability, to say that if they alter a particular set of genes, that will cause the mosquitoes to behave in a particular way. And they rigorously test the actual behaviour, repeatedly, using small sample groups, before they're allowed to even consider letting GM mosquitoes into the wild.
Of course, there is the problem of what happens when, inevitably, there are unforeseen consequences. Should there be a kill switch of some kind? What does that entail? What happens if it malfunctions? It's a very slippery slope that will only get more slippery as the human population continues to expand, we continue to encroach on areas that were previously without humans, and gengineering becomes something that any government has the capabilities for.
Personally I'd much prefer the pest problem to be one solved by medical, not gengineering, technology. In other words, develop a vaccine against malaria instead of modifying the mosquitoes to be unable to breed, and similarly for Lyme disease and ticks. Yes, mosquito and tick bites are gross and annoying but they're also not a problem if the dieases these insects carry are no longer a problem.
A Dick head sold the idea of putting lead in fuel to stop knocking, he sciences the shit and Proved it was safe.
Midgley did nothing of the sort; he knew the evidence but simply didn't believe that lead was harmful, so he perpetuated lies about its safety as a fuel additive because he wanted to make money. And this was nearly a century ago, when peer review and corporate responsibility weren't a thing; the same s**t would not fly today in any way shape or form.
If you want an example of what happens to scientific frauds today, look no further than Andrew Wakefield's lies about vaccines and autism and his resulting blacklist from any reputable scientific journal or group. The British government even went so far as to ban him from practicing medicine ever again. There are still idiots who believe his nonsense, but they're the same idiots that believe 5G causes cancer.
The incidence of parasitic disease among humans has decreased every decade since the industrial revolution began. The sky isn't falling. As for "fish patterns", warmer water means a larger overall fish population. i.e. more food for all. That's a good thing too.
As for the belief that cold, dry climates are best for us, a quick question: would you rather be dropped alone on a warm tropical island, or Antarctica? There's a reason they built Disney World in south Florida, not Saskatchewan. Likewise, there's also a reason the human species began in Africa, not Siberia.
So many lies in one post. Take them elsewhere.
Genetic alterations in any organism have extremely high likelihood of having unforeseen secondary consequences. We are rarely if ever sure that specific functions of specific genes are the only ones and that the genes we're attempting to modify don't serve any additional purposes that could have very complex mechanisms behind them.
Most likely outcome: they won't survive for long after modifications. Second most likely: they survive while being permanently impaired one additional way or another.
You really think that the scientists who've been studying mosquitoes and their genome for
literally decades don't know this, huh? Boy have I got some news for you.