Us humans kill more ants with our exterminators, destruction of habitat, and accidentally(nukes, bombs, poisons, feet, etc).
You humans think you know war? Only us ants know the true meaning of war.
Ant colonies constantly wage war against each other for food and territory. Considering the amount of land the ants inhabit I would find it hard to believe that we could kill more with our pesticides and exterminators.
It has been estimated that there are 10 trillion individual ants alive at any one time (that's more than all human biomass combined). Their fast adapters, being able to digest food scraps and learning to occupy space where ever humans settle. A great majority of them kill each other for territory and resources in the wild.