During their evolution, ants adapted their social organization and developed defense mechanisms to counter disease, according to research from Swiss biologists.
All the factors that favor the spread of diseases are gathered in the anthill: a dense population and frequent contacts between individuals.
Biologist Nathalie Stroeymeyt and her colleagues at the University of Lausanne have discovered that they do not interact randomly with all their peers. Instead, they are organized into working groups, depending on their age and the tasks to be accomplished.
Thus, the young ants who look after the larvae inside the colony (workers / nannies) have very little contact with the elders who come out for food (workers / soldiers).
Study the spread of diseases
In order to understand the spread of diseases, biologists from the Department of Ecology and Evolution first put digital markers on 2266 black garden ants, divided into 22 colonies in its laboratories.
Then they took pictures every half-second to know very precisely the movements and positions of each individual.
The researchers then exposed 10% of the fodder workers to the spores of a pathogenic fungus, transmissible between ants by simple contact.
They then compared the properties of anthills before and after the introduction of the infective agent to find that these insects were able to detect the presence of the fungus and quickly adjust their behavior to enhance the colony’s defense mechanisms.
The fragmentation of the colony and the segregation between the different working groups have increased.
Thus, the nannies and the fodder have less interacted.
In addition, the fodder initially exposed to the fungus was isolated. They spent more time outdoors and reduced their movements once inside the colony. Healthy forage, which had not been exposed, reacted in the same way.
As for the nannies, they moved the brood (set of eggs, larvae and nymphs) deeper into the nest to make it safe.
The fact that unexposed ants are also able to adapt their behavior to the presence of a pathogen was unknown until now.
It has also been shown that the colony overprotects important insects when a threat arises.
For example, the queen (the only individual to breed) and nannies (young ants who still have many hours of work to offer to the community) were less exposed to the pathogen.
At the end of the 9-day experiment, “mortality was higher among fodder than nanny. And all the queens were still alive, “stresses Nathalie Stroeymeyt.
Common front against the disease
This study is the first to show that an animal community is able to actively modify its organization to reduce the spread of diseases.
Social insect groups have many similarities with human societies.
According to the researchers, the ability of ants to collectively cope with complex problems, such as the risk of an epidemic, could inspire the development of similar methods in humans, or even prevent pandemics on a global scale.
Ants know how to protect themselves against diseases for 100 million years. We, since a few centuries hardly.
The details of this study are published in the journal Science
