For starters, you cannot say "mosquitoes" - as others have pointed out, there are ~3500 separate mosquito species, only ~100 bite humans, and only several dozen transmit disease.

I don't see any reason to only target those that transmit diseases. Target ones that are simply annoying because they string the average person, gives everyone a clear reason to support the proposal. There are also people with allergies or who simply don't heal the stinged area very well.

Also, I don't think country-level eradication plans (even for a single species) have the slightest chance of working long-term due to persistent re-invasion risk.

If you have to continue paying a few million each year to keep the mosquito population near zero that's no problem for any industrialized country if there's public will.

Narrowness is a virtue here, and this level of biological imprecision could alienate potential allies who will take you as reckless and uninformed.

Don't worry as far as biological imprecision goes. I don't invest the kind of effort required for being precise for a LW post to explore the idea but I would certainly invest the necessary effort if I wrote an actual petition and tried to make it viral.

I also made a choice against immediately crossposting to the effective altruism board or other venues to be able to iterate based on feedback.

(A related point is that the most promising interventions for eradication (like the sterile insect technique) are species specific, so it makes sense to start with the highest-priority target. Because [complex chain of reasoning to fill in later], I think aedes albopictus is likely the best bet.)

According to the map on Wikipedia we don't have any aedes albopictus in Germany but 4 neighboring countries have them. That means that it's not a valid target for German activism. Otherwise do you disagree with that map?