The negative is you're disrupting the ecosystem. They reduce the mosquito lifespan's which might impact their population. Things that eat mosquitoes might have to adapt.
At this point I'm prepared to accept that though. The suffering these things cause is immeasurable. I hate mosquitoes so much I wish I could nuke them.
More likely, the targeted mosquitoes are outcompeted by other mosquito or small insect species that are just as useful to whatever was dependent on the targets. There's an obvious exception for if some plant is exclusively pollinated by some disease-carrying mosquito, or other bet specific relationship, but that seems unlikely and easy to detect in advance.
People in these discussions forget that there are lots of mosquito species, most of which don't transmit diseases.
In fact, there's certain belief in the Scientific community that (human biting, desease spreading) mosquitoes could safely be eradicated from the planet without impacting on the ecosystem.
The great thing about technology is that it's possible to have new things or ways of life that are strictly better than the ones they replace! We can move beyond the efficient frontier; progress is non-zero-sum.
* Golden Rice
* Unleaded gas
* HCFCs (over CFCs)
* etc
Yes it's possible, but we really need to be cautious.
In general it's a bad idea to underestimate adaptive systems. It's especially foolish to underestimate the ultimate adaptive system: natural ecosystems. We should be extremely humble and careful when we're toying with the unfathomably complex system that we depend on. We understand very, very, very little about these things except that they're hard to predict and we really need them to continue working well enough to maintain the parameters we need for survival.
How often do you hear about the downsides of malaria eradication in the United States (probably spraying most of Florida with DDT would be one…)? What about screwworm fly elimination in the United States and parts of Central America? That program is much more similar to the thing described in this article than spraying every puddle with insecticide.
DDT doesn't run the risk of "running away" out of control the way biological/bacterial/viral interventions do. This is my first time hearing about screwworm and 1) wow what a nasty looking infection, and 2) boy am I glad it looks like the eradication campaign is going well! And yes the screwworm program does seem really similar to this, so especially thrilled it seems to be going well!
Well, widespread spraying with DDT did essentially create a permanent reservoir of DDT-resistant mosquitoes, which also made them resistant to pyrethroids. Bit of a problem. Fun fact - DDT makes spider mites extra fertile.
I do agree however that the eradication efforts of both caused significantly more good than harm, no question.
At this point I'm prepared to accept that though. The suffering these things cause is immeasurable. I hate mosquitoes so much I wish I could nuke them.