Deader, I think we have a winner! Yeah, i'm pretty shure this is the movie :D

[...On the surface, a colony of ants has gained a heightened level of intelligence and has apparently decided to drive out the local people. A group of surviving scientists, who were examining the ant phenomenon, rescue a wandering woman, and they become "trapped" in the "laboratory."...]

[...when the nutter scientist is consumed in a pit of ants..]

I remember it was not a film with a lot of action, but interesting story.