September 26, 2012
Evidence Shows Slave Ants Rebel Against Oppressors
Michael Harper for redOrbit.com — Your Universe Online
There´s new evidence today ants that have been captured and made slaves by other ants aren´t simply taking their plights lying down. According to a new study, these slave ants are prone to try and take down their oppressors by sabotaging their families.
The first signs of this kind of ant rebellion were noted by Johannes Gutenberg University Mainz (JGU) research professor Dr. Susanne Foitzik in 2009. However, in the nearly 3 years since this discovery, Dr. Foitzik says this behavior occurs frequently among enslaved ants and has become quite widespread. For example, enslaved ants in Ohio, New York and West Virginia were all found to neglect and even kill the offspring of their oppressors, rather than care and provide for them as they should. By systematically killing off the young, these slave ants have been able to ensure only 45% of the ruling ants´ offspring survive long enough to become adult ants. This kind of “long con” by the slave ants will one day weaken the other species, increasing the chances of the survival of the slave ants and their colonies.
According to a statement made by Dr. Foitzik, this sort of parasitic relationship isn´t uncommon and slave ants are often observed taking advantage or sabotaging the host species.
Normally, the slave-making ants begin the process by attacking the nests of another ant colony. During these attacks, the slave-making ants will kill the adults of the other ant colony and steal their offspring. These slave-making ants will then bring the soon-to-be slaves back to their nests of hollowed acorns or nutshells and raise them to do their bidding.
However, when these slaves begin caring for the next generation of slave-maker baby ants, they begin to notice the difference between the two species and begin to lash out against the host species.
"Probably at first the slaves cannot tell that the larvae belong to another species," says Dr. Foitzik, saying these ants will normally care for their oppressors offspring up to a certain point. When the larvae reach pupae stage, things begin to look a little differently.
"The pupae, which already look like ants, bear chemical cues on their cuticles that can apparently be detected. We have been able to show that a high fraction of the slave-maker pupae are killed by slave workers."
These slaves will either completely neglect these pupae or even actively attack them, ripping them to shreds. In Dr. Foitzik´s research, she observed several slave ants attack one single defenseless pupae. Ants in the pupae stage are unable to move or defend themselves and are unprotected by cocoons.
In West Virginia, only 27% of the slave-maker ants survived after undergoing the “care” of their servants. In a New York colony, only 49% of these pupae survived. Ohio´s host ant survival rate was highest in Dr. Foitzik´s research at 58%, though this is much lower than the national average of 85% in slave-free nests.
While these slave ants are reducing the numbers of their slave-making counterparts, they aren´t necessarily building their numbers instead.
"The enslaved workers do not directly benefit from the killings because they do not reproduce," said Dr. Foitzik. Though they aren´t planning hostile takeovers, these slave ants are ensuring their relatives remain safe from other similar takeovers.