Welcome to Costa Rica, a country that has more ants than humans.
A country dominated by ants
My name is David Villanueva. I am a naturalist guide in the Corcovado National Park. And today I am going to introduce you ´´The amazing world of leaf cutter ants´´.
A world full of realities
The world is full of different realities, so many and so varied that it is impossible to list them. For instance, the realities in our human species are infinite. Furthermore, they change depending on the exposure to different natural environments, political conditions or languages, etc. Now, when, we compare our reality with some animals. We realize, there is a great diversity of ways of perceiving the environment.
It is not necessary to go very far, just look at our closest pets. ‘’ The dog’’ . Certainly, is a good example of a totally different way of perceiving the environment. For instance, we can remember and associate our memories mainly with images, colors and textures. However, the dog fails to appreciate the variety of colors that we do appreciate. It only sees in black and white. Yet, it surpasses us in variety of aromas and sounds. Surely, there are so many and so different that they create a whole world to counteract the world that we have of colors. But not only do we differ in the way we see, smell or hear the world. There are also differences in habits, ways of reproducing, raising, etc.
Today we are going to explore a world so different that looks it was taken from a science fiction book. The world of leaf cutter ants.
A science fiction world
Ants live in a world almost parallel to ours. In a world of chemical signals that for them would be like the sight, smell and hearing of ours. Even their life spam is way to different to ours. Since they only live 1 to 3 month.
When it comes to complexity, leaf-cutter ants are a whole universe. Not only in their way of perceiving the environment. But, also, in their way of reproducing, feeding, handling waste, among other things.
The leaf cutter ants (ants of the genus atta and acromyrmex). Along with humans create the largest societies in the world. A successful colony of these ants can contain more than 8 million individuals, more population than the one in Madrid. And they are the arthropods with the largest number of individuals in Costa Rica. In oder words, there is no other species that surpasses them in population. There are at least 4 billion ants in the country, a thousand times more than the 4.5 million Costa Ricans.
Are humans really the dominant species in our country?
An organize city
Either way, these ants, like humans, need to delegate functions. Which they do through the creation of roles. In order to carry out the tasks that are needed to keep their nest running. That is why they are divided into workers (non-breeding females), which in turn are divided into 4 castes; minimum, minor, medium and major. And breeding ants; females (queens) and males.
These ants feed on a fungus (leucocoprino sp) that they cultivate themselves with the leaves that they extract from the forest. The care and maintenance of this fungus is essential for its survival, so they divide functions to cultivate the fungus; extract the leaves, carry out quality inspections, among other things.
Furthermore, these ants also perform other functions such as caring for the eggs, nymphs and larvae, patrolling the nest for protection. And in the case of the minimum. They also climb on the leaves that the largest workers transport and protect them from a fly (phoridae) that are parasites. And lay eggs on the heads of some ants causing their death. So, you know if you see a small ant climbing on the leaf that carries a larger one. It is not that it is abusing its companion to take it back to the nest. But it is protecting it from the attack of a fly.
Without a doubt you can talk a lot about the roles within the ant colony. During my expeditions to the Corcovado national park I have been able to observe very interesting behaviors. One of them, and that I like to show my tourists. Is the way in which they expel the garbage from the nest and drop it in the river. I place the telescope from the bridge and through the lens you can see how small ants release the fungus residues into the river.
The explanation for this behavior is that the residues can generate another fungus that can contaminate the fungus that they feed on. And for this reason. It is not only important to keep the residues away from the nest nucleus. But also, to avoid that the ants in charge of the work, to indirectly contaminates it. Therefore, the workers dedicated to the extraction of waste ,are marginalized and cannot access the important parts of the colony.
Another interesting behavior I could see was a bloody war between colonies of leaf cutter ants to gain control over the bridge that spans one of the rivers near the Sirena Park Ranger Station. Initially both colonies took advantage of the bridge, each on its designated side. But one day for no reason that I know of. A conflict arose.
That day you could see how these ants, without fear of anything, killed each other, leaving the remains of heads and body parts all along the bridge. Then then older nest took the lead, causing the other to retreat further each day. Until they reach the point where they were all back in the nest. And they were frantically covering the entrances that give access to the core of their city. Finally, after a while, the older nest retired to its daily tasks and the ants in the new nest changed the place from where they extracted the leaves.
How do they reproduce?
Another interesting fact about these ants is their way of reproducing. Ants with reproductive organs (queens and males) have wings and are larger than workers. During certain seasons of the year these ants come out of their nests to be able to reproduce. In order to conquer new territories. Queens, which are larger than males, must obtain a strain of the fungus and store it in a special cavity inside their mouth. This strain is going to become the vestige of what will later be the cultivation of mushrooms.
Once the strain is obtaine. The queens leave their nest in search of males from different colonies with which they can reproduce. Their goal is to be able to obtain more than 300 million sperm to procreate thousands of ants daily. Once enough genetic variety has been obtained. The queens look for a safe place to dig in the ground, leave the strain of the fungus, lose their wings and start the production of thousands of ants that will start the new york rainforest. It is important to mention that less than 2.5% of queens achieve their goal.
Corcovado is full of different and varied stories and realities. I am incredibly grateful to be able to experience them daily and share them with my clients.