Proc. Natl Acad. Sci. USA doi: 10.1073/pnas.0809423105 (2008)

South American fire ants (Solenopsis invicta) have been shown to invade Florida's extensive pine flatwoods only where human activities such as mowing or ploughing create a disturbance.

Joshua King and Walter Tschinkel of Florida State University in Tallahassee set up several types of plot: undisturbed, mowed and ploughed, and added fire ants to some of each plot type. Fire ants can't displace native ants on their own; instead, disturbance makes this possible by reducing native ant populations and creating habitats in which fire ants do particularly well.