My brother worked in a mosquito lab for a while and said that mosquitos lose these resistances pretty quickly (as a population) if they aren't regularly being dosed. In the absence of pesticide, the more efficient organism is generally the one without whatever metabolic fluke made it immune to the poison.

The lab helped inform the city's strategy for fighting mosquitos, which was to rotate pesticides. I believe they also bred and released neutered mosquitos.

Is it _far far_ worse though? It seems to me it should become just as worse as without any woking pesticide, only later.