I've read somewhere that they killed mosquito breed with diesel oil in South America, after some invaded through planes and started to spread.
Wouldn't ground Sapindus nuts be an option too? They contain saponine which relaxes the water surface. Afaik. the larvae need the tension to stick to the surface and breathe.
Sapindus nuts shouldn't contain any long living environment poisons, people use them for washing cloths. They make you puke but they don't kill you when you eat them.
It needed to be checked how this treatment affects other animals though, like water spiders, water bugs and beetles. I'm sure they at least have less side effects than diesel oil.
p.s.: I don't know much about those things, it is just an idea.