Experiments have shown that after eating and drinking, ants try to swallow a drop of their own acid in order to destroy microbes that have entered the digestive tract and protect themselves from diseases.
In many species of ants, the sex glands that are unnecessary for working individuals acquire a completely different function, producing poison, often based on the simplest organic acid, formic. It stands out, and sometimes shoots directly through the ducts that come out to the surface of the body on the abdomen of the insect. The acid allows the ant to defend itself and its nest from predators, but at the same time helps prevent infectious diseases. This is covered in a new article published in eLife magazine.
“As soon as ants swallow food or water, they immediately begin to lick their abdomen,” explains one of the authors of the work, Simon Tragust of the German Martin Luther University. "Judging by the fact that the reaction to water is the same as to food, this is not about digestion." To find out the essence of this behavior, scientists conducted experiments with the North American tree ants Camponotus floridanus.
Insects in the laboratory were given food and then prevented from licking the abdomen, simply temporarily laying on ice, in which they became practically immobile until they warmed up again. In doing so, scientists tracked the level of acidity (pH) in their digestive system. In ants, it is quite high, which is usually unusual for insects, but without the acid coming from the outside, the pH value became more neutral and unstable - this could no longer destroy bacterial cells.
The following experiments showed that the chances of survival for an ant that has eaten food with large amounts of pathogenic bacteria, if, after eating, the insect retains the ability to lick the abdomen and "pour" the required amount of acid into the gastrointestinal tract. Moreover, they did not transmit the infection to other family members with whom they actively exchange food. Recall that in the event of the spread of the disease in the ant colony, even quarantine can be practiced.
In general, ants are distinguished by an extremely low diversity and number of symbiotic microflora inhabiting their digestive tract, despite the fact that they feed directly "from the ground". Apparently, this is due precisely to the influence of formic acid. Only acetobacteria, which are widely found in the intestines of these insects and help them with the assimilation of food, are well protected from its action.