bullhorn acacia and pseudomyrmex ant
A lot of bullhorn acacia, a thorny bush that is very common in Mesoamerica, can be found in the area of Guanacaste, Costa Rica. On its leaves and stems lives the pseudomyrmex ant. One of the first rules for the jungle dweller is not to get close to these bushes, as the bites of the ants and the stinging of the thorns are both very unpleasant.
It has been known since a while that these two are in a great state of mutualism: The ants are missing a certain enzyme, so they can`t digest certain sugar types from other plants and the bullhorn acacia is the only plant providing the right type of sugar for the little animals. In exchange the ants protect the plant with their quite poisonous bites, when other animals try to eat the plant. So lots of scientists have been praising this great win/win situation and the intelligence of nature.
However, recently a couple of German scientists (not mentioned in the English references so far!) did some research on the new born baby ants and discovered a strange thing: the babies are born without a defect. The enzyme, which is missing later, is produced by the young ants and they would be able to feed on other plants as well. But as they are born on the bullhorn acacia, the first food the young ants get, is the resin from these plants. The German scientists found out that the resin contains a chemical, that blocks a certain enzyme in the ants. Without this enzyme the baby ants cannot digest the nutrients from other plants and thus they stay dependent on the bullhorn acacia for their whole life.