Master and Slave

I am constantly impressed with nature's ability to put humans in their place (that is, we are not as special as we think we are). The source of this amazement is frequently ants. Anyone not impressed by ants, just hasn't done enough research. One feature of ant society that is completely fascinating is ant slavery. That's right, ants enslave other ants. The nature of the enslavement varies, but in general it involves either killing the queen and hijacking the nest or kidnapping pupae. In the genus Polyergus, commonly called Legionnaire ants, workers are incapable of carrying out even rudimentary brood care, care for their queen, or even acquiring food. Polyergus species subsist solely as a ruling caste, maintaining a worker force by capturing ants of the closely related species in massive colony-to-colony raids and have evolved to efficiently capture slaves.

Photo Credit: Alex Wild

Photo Credit: Alex Wild

As the stolen brood matures, the captured ants imprint on their captors' colony and perform the usual labor of foraging, brood care, and nest maintenance as they would for their own colonies. Polyergus ants are obligate parasites that cannot survive without the labor of the ants they enslave. Below the red slave-raiding Polyergus species is shown living with black/silvery slave ants, Formica argentea.

Photo Credit: Alex Wild

So, do slaves ever fight back? Commonly, the queen and workers of the raided Formica colony evacuate to nearby vegetation to wait out the raid, but there is documentation of some species trying to fight off raiders. There is also evidence that post-enslavement resistance has also evolved. In studies conducted by Susanne Foitzik of Ludwig-Maximilians University in Munich, slave nursemaids killed some 80 percent of their captors' young queens and some 60 percent of the young workers. Nature loves an arms race.