Social parasites in ant colonies
With the help of small means the ants have created simple yet effective ways of communicating. This is important to factors such as cooperation within the colony, but can also be a backdoor wide open to social parasites.
Imagine meeting a person you have never met before. The person in front of you claims to be one of your best friends. Naturally, you won’t fall for the trick – there are thousands of details proving the person wrong. You see a stranger. But to ants, the telling of a fraud is not as easy as for humans. This has paved the way for a bunch of highly developed social parasites.
Replacing the humans with ants, all that would be needed to make the trick work is the change of scent. A perfume of sorts – making the individual familiar. Because of the small brains of ants, they have developed simple yet effective ways of communicating. Friends are known by their smell, as well as foes (not smelling like friends of course!), making it easy for a fraud to copy the smell and blend in with the rest. (Read more: How Ants Communicate)
Ants as social parasites
There are several different types of social parasites. One example is ants exploiting other ants. The scientist Heinrich Kutter discovered one of the more extreme cases with the species of Teleutomyrmex schneideri in the French and Swiss alps. They spend most of their lives piggybacking a host ant, all made possible due to their tiny and concave body. They carry six large feet, used to keep them from falling off. They do not contribute to the colony and are dependant on nutrition and water from their host’s colony supplies. Through evolution they’ve completely infiltrated the species of Tetramorium caespitum and now lives a fuss-free life on their backs. The parasitic species has no workers, but are totally dependant on their hosts – they are well worth the name of social parasites. These queens are actually fed by the Tetramorium workers and are treated like offspring of the colony.
But a life on top of another ant comes with a price. In spite of their, at first glance, carefree and luxurious living conditions the species is plagued by weak bodies. They do not possess the glands that other ants use to feed their larvae or to exude anti-bacterial secretions. Hence, they are at high risk when it comes to decease. They can only eat liquids due to their weak jaws. If they are thrown off of their host ant, they will most probably die within days. The parasite is not strong enough to find and climb another host. (1)
Among the Scandinavian species, 37% are considered social parasites. A bunch of species found their colonies the parasitic way. A lone ant queen wanders into an established nest and eventually eliminates the ruling queen. The workers accepts the order of succession and keeps serving the colony like before. In time all the worker force is converted to the genes of the new queen, and no traces of the old colony members and their queen is left. (2)
1. Per Douwes, Johan Abenius, Björn Cederberg, Urban Wahlstedt (2012) Nationalnyckeln “Steklar: Myror-getingar. Hymenoptera: Formicidae-Vespidae” p. 36 (Swedish)
2. Bert Holldobler & Edward O. Wilson (1995) “Journey to the ants” p. 124-125