When you get out of the cold or the flu, you can choose to keep your distance from other people to save them from such a snake fate – and they may turn away from you. According to a new study, people are not alone in their efforts to relieve the sick. In the presence of contagious pathogens, modest garden ants can also change their behavior to keep polluted creatures away from other members of the colony.
Ants are social beings. They live in large groups, communicate, and cooperate with each other to ensure that the colony functions properly. Since they are often in close contact, the ants are also vulnerable to contagious diseases. Studies have shown that ants are able to keep disease in the bay through a number of hygienic mechanisms, such as removing trash and bodies of dead members of the colony from their nests. Scientists suspect that insects can also change their social behavior to reduce the spread of infections, but until recently this hypothesis was difficult to prove.
"Amnesty colonies have hundreds of individuals," explains Nathalie Stroeymeyt, post-graduate researcher at the University of Lausanne, Switzerland, who explores collective behavior in dead colonies. "So far, there was simply no technical methodology to measure their interactions at the level of colonies over extended periods of time."
Fortunately, an automated tracking system developed by Swiss researchers in 2013 allows Stroeymeyt and her colleagues to examine in detail how 22 Muslims are kept in the laboratory when the disease is wasted among them. The team glued the small 2D barcodes onto the chest ants boilers, giving each insect a unique identifier – "just like a QR code," says Stroeymeyt. A camera above the boxes of ants broke two shots every second, and the algorithm opened and recorded the position of each barcode, giving the researchers plenty of data on ants' movements.
For four days the team let the ants walk around in the enclosure peacefully. As with colonies in the wild, some of the ants worked outside the nest to feed, and others like the queen and the "sisters" who tended to develop the birds in the nest. On the fifth day, researchers discovered some mushrooms, but not all, of the farmers in 11 colonies Metarhizium brunneum, which is often found in the soil of the habitats of the garden ants and is known to become ill. The blocks from the other 11 colonies were treated with a benign solution to serve as a control group.
It is essential that previous studies have shown that M. brunneum the fungi take at least 24 hours to infect the ants, which in turn gives researchers time to observe insects before they are really ill.
"We wanted to focus on that [this] period … so that we can distinguish the active reaction of the ants themselves from side effects of the disease or parasitic manipulation, "explains Stroeymeyt.
Writing in the journal science, the researchers reveal that when the oars were returned to their enclosure, the contaminated ants spend more time outside the nest, which means they have less contact with the most valuable members of the colony: the queen who puts all the eggs on the colony, and in-house workers who are younger than welders and therefore have more hours to contribute to the colony. (Older ants are loaded with risky out-of-the-box feeding jobs because, as Stroeymeyt said, they would "die in any case.")
But the main part of the study lies in the discovery that polluted ants were not the only ones to change their behavior. Foggers that were not exposed to the fungus also increased the time spent outside the nest. And the nurses in the nest moved younger inward and spent more time in them, "which can be seen as a spatial isolation from blacksmiths," says Stroeimit.
How is it known that the colony is in action to prevent disease before the fungal spores even infect some of them? Researchers are not sure, but the sense of anise smell can be key. The ants sweep around with their antennas, which constantly touch and pierce the insect environments. It is entirely possible, according to Stroeymeyt, that an ant can find a tickling fungus on one of its colony members just as easily as it might smell a pathogen on its body.
Why not polluted peanuts also reduced the time spent in the nest is another interesting question. As a first line of contact with their accomplices who might later become ill, they may have somehow known that they had given up important members of the colony. But it is also possible that after discovering pathogens to their colleagues, they just spent more time treating the infected workers outside the nest. Ants produce formic acid through the gland at the top of the gas or the abdomen; they can destroy the fungal spores from one another by picking up formic acid in their mouths and licking the bodies of their pathogenic friends.
Although researchers have noticed fewer interactions between employers and indoor workers, contacts have not ceased entirely – and this has led to another interesting revelation. When using simulations to model how fungal pathogens spread throughout the colony in the face of changes in the social network of ants, scientists have found that the queen and nurses have a potential fatal load on the fungus, but the probability that these important ants low load, have increased.
"This is similar to immunization or vaccination in humans," explains Stroeymeyt. "These low doses do not result in mortality but allow the ant to develop some protection against later exposure to the same pathogen. [finding] is something completely new. "
Moving forward, Stroeymeyt plans to investigate how pathogens cause social changes in wild marble colonies that can be hundreds of thousands; she suspects that segregation between indoor and outdoor workers may be even more pronounced in these large groups.
Megan Frederikson, an associate professor of ecology and evolutionary biology at the University of Toronto, who did not participate in the new study, called the researchers' conclusions "a new and exciting find" triggered by "state-of-the-art" methods. such technology can help scientists investigate whether ants also change their social networks to deliver useful microbes to one another. And Frederick thinks "the meaning [of the study] even goes beyond the ants. "
"I wonder," she says, "how often other social animals reorganize their networks to limit the spread of the disease."
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