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.

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.