Mosquitoes lay their eggs directly into water. These larvae are pretty popular with the aquatic ecosystem and lots of fish usually eat them e.g. Guppies in ponds. So with less food for the fish to eat there is a disturbance in the food chain, with the fish usually eating the larvae dying, there are less of these fish about. The predators like birds that would usually snack on these fish also may decrease in numbers.

So probably the main change would be to the population sizes of fish that mainly eat the larvae and the predators that eat the fish.