Enslaved worker ants fight back through acts of sabotage

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Enslaved worker ants fight back through acts of sabotage

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Geographic distribution of the anti-parasite trait “slave rebellion”

Abstract

Social parasites exploit the brood care behavior of other species and can exert strong selection pressures on their hosts. As a consequence, hosts have developed defenses to circumvent or to lower the costs of parasitism. Recently, a novel, indirect defense trait, termed slave rebellion, has been described for hosts of a slave-making ant: Enslaved Temnothorax longispinosus workers reduce local parasite pressure by regularly killing pupae of their obligatory slavemaking parasite Protomognathus americanus. Subsequently, growth of social parasite nests is reduced, which leads to fewer raids and likely increases fitness of neighboring related host colonies. In this study, we investigate the presence and expression the slave rebellion trait in four communities. We report its presence in all parasitized communities, document strong variation in its expression between different geographic sites and discuss potential explanations for this observed variation.


It would appear that ants that are kept as slaves by more powerful species aren’t as helpless as they might appear. New research from Gutenberg University Mainz in Germany shows that enslaved ants conduct their own form of civil disobedience, by neglecting and killing the offspring of their oppressors. And by doing so, the ants may be preventing their comrades outside the nest from being enslaved themselves.

This discovery was made by ant researcher Susanne Foitzik who started to observe this behavior back in 2009. But what she has since discovered is that this is not an isolated trick limited to one species; over the course of her studies, Foitzik has observed at least three different ant populations in which these acts of rebellion occur. It would appear, therefore, that it may be a fairly common way for enslaved ants to fight back.

Ants such as Temnothorax longispinosus become enslaved when workers from the slave-making ant colony, Protomognathus americanus, attack their nests. The parasitic master ants kill the adults of the subjugated population, and steal their offspring. Once back at their nest, the master ants force the new generation to feed and clean their larvae, thus compelling them to raise the offspring of their oppressors (what’s called "brood parasitism").

At least up until a certain point — but it would appear that the enslaved ants have evolved a fairly potent countermeasure.

Foitzik observed that 95% of the brood survives the larval stage — but things change dramatically once the larvae starts to pupate. At this point, the pupae give off a chemical signature that the enslaved ant recognizes as being foreign. In turn, the slave ants ignore and even outright kill the baby ants by tearing them apart — as much as 65% of them (normally, 15% don’t survive). Foitzik’s research even showed some survival rates that were as low as 27%.

Clearly, the slave ants are making a difference — and at no benefit to themselves. But their free relatives back home (as much as it can be said that ants are "free") are clearly benefiting from their enslaved brethren working behind the front lines.

http://io9.com/5947040/enslaved-worker-ants-fight-back-through-acts-of-sabotagehttp://www.redicecreations.com/article.php?id=30505http://link.springer.com/article/10.1007/s10682-012-9584-0?null