Florida carpenter ants have specialized jobs where they either "major" which are soldier or "minor" which forage for food. Shelby Berger injected the "major" ants with trichostatin A from 0,5, or 10 days after adulthood. This was injected in the brain and caused numerous of their genes to be expressed differently. Some had changes in behavior, but the ants that were injected at 10 days did not; suggesting that behavior flexibility has a very short time frame. This can cause soldier ants to behave as the foragers.
I think this is a very interesting study. I wonder if this can be done with ants, what other species this can affect as well. The test seemed to mainly turn the soldier ants into foragers, but I wonder if it could work the other way as well. I believe it would because it seems to alter their genetics, so it should be the same.