Is this safe? I hope it doesn't affect the ecology in worse ways we won't foresee, it has happened before

Principal Skinner: Well, I was wrong. The lizards are a godsend.

Lisa: But isn't that a bit short-sighted? What happens when we're overrun by lizards?

Principal Skinner: No problem. We simply unleash wave after wave of Chinese needle snakes. They'll wipe out the lizards.

Lisa: But aren't the snakes even worse?

Principal Skinner: Yes, but we're prepared for that. We've lined up a fabulous type of gorilla that thrives on snake meat.

Lisa: Then we're stuck with gorillas!

Principal Skinner: No, that's the beautiful part. When wintertime rolls around, the gorillas simply freeze to death.

This was tested in Singapore 10 years ago and successfully reduced the spread of Dengue fever by 77% and has not negatively impacted the ecosystem.

This isn't a project to eliminate all mosquitos. There are over 3600 species of mosquito - this project is only targeting one: Aedes aegypti, which spreads many diseases, and is in fact an invasive species. Anywhere you see an Aedes aegypti outside of North Africa, it was humans who brought it there in the first place. This project is just trying to undo that.

In the FAQ they discuss how in most of its range this particular species is invasive, feeds almost exclusively on humans, and is not believed to be a major food source for predators.

It's impossible to prove this (or really anything in human health/global ecology) is safe. We cannot reliably predict what the true short and long term outcomes will be, but by and large, this seems like one of the less unsafe ecological modification projects based on the underlying technology.