Ants that enslave other ants

Did you think slavery was over? Not for these ants. They force a species very close to them to work for them. They enslave their genetic relatives, so to speak. They’re the ants that enslave other ants.

These enslaver ants capture workers of other species. They then take them back to their colony to work for them. What are their functions? They take care of their young, help them defend themselves, find food for them. They even keep the colonies clean.

Ants that enslave other ants often capture larvae to train them.
Ants that enslave other ants often capture larvae for training.
Stealing larvae

Most often they capture the specimens in very early stages of development. That is, still in the form of larvae or pupae. They take them to their colony and turn them into worker ants. Thus, these begin to work for their mistresses. But in some species they capture adult workers.

How did the emergence of eusociality in ants come about? This is the name given to a certain development of complex societies. There are castes of individuals who perform different tasks (work, reproduction, defense). They cooperate with each other to maintain a colony and raise their offspring. And this was accompanied by a multiplication of genes encoding chemoreceptor molecules. They are responsible for both smell and taste. The proof of this is the great importance of chemical communication in these species.

Therefore, one particular fact is of special interest. And that is that the workers of slave ants are able to reproduce. It could be said that they have recovered this trait. This is attributed to the loss of the ability to sense and respond to the pheromones of the queen ant. Why should they stop doing so? Because they inhibit reproductive activity.

These ants make the other ants work for them.
These ants make the others work for them.
Insensitive parasites

In a recent study they have sequenced the genome of eight species of ants. Three parasitic, their three parasitized species and two non-parasitized species. They investigated whether chemoreceptors had been lost in these three parasitic species.

They found something interesting in the parasitized species. They had half as many taste receptors as the other five species. In addition, three quarters of the smell receptors. In other words, in those species, they have lost about 50% of their ability to taste. And the ability to smell has been lost by 25%. So, they identify much less substances than the parasitized ones do.

To what is the loss of taste receptors attributed? To the fact that these species no longer search for food. Of course, there’s already someone to do it for them. The parasitized ants are at their command. Therefore, they don’t need to receive and decode as much information that way.

Evolving

It is very unlikely that such things happen by chance. The consequence that follows is that this is an advantageous loss. That is, one that we say is of high adaptive value. It entails a cost that is not outweighed by an equivalent gain.

The metaphor is suggestive. In ants, the adoption of slavery entails the attenuation or loss of eusociality. And also of the sensory capacities that make it possible.

Evolution follows no temporal arrow. Human history surely doesn’t either. Ants enslaving other ants is a mirror of other things happening in our world.

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