Ants learn how to farm mushroom as extra food source to support more population. Allow one extra building exceeding tc building limit.
They way this would work is that it would allow to make a building that would increase the building limit like tcs do (wouldn't be able to make unit itself), mushroom farm. That unit would be unique - meaning one per player.
This would allow insectoid to make a bit more units that other races, compensating for their weaker stats. The tech should be rather expensive tho.
Naturally this is referencing ant irl that can farm mushrooms in their anthills, look it up.
This has no relation to myconid race