When you come down with a cold or flu, you can choose to stay away from others to save them…
When you come down with a cold or flu, you can choose to stay away from others to save them from a similar snowfly fate – and they may, in turn, be right for you. According to a new study, people are not alone in their efforts to sequestrate the sick. In the presence of contagious pathogens, humble tree ants can also change their behavior to keep contaminated robbers away from other colonies.
Ants are social creatures. They live in large groups, communicate and collaborate with each other to ensure that the colony works properly. Because they are often in close contact, ants are also prone to communicable diseases. Studies have shown that ants are able to cope with disease through a number of hygienic mechanisms, such as removing rubbish and bodies from dead colonists from their bonfires. Researchers suspected that the insects could also adapt their social behavior to reduce the spread of the infection, but this hypothesis was until recently difficult to prove.
“Dark colonies have hundreds of individuals,” explains Nathalie Stroeymeyt, a postdoctoral researcher at Lausanne University in Switzerland, studying collective behavior in ant colonies. “So far, it was just not the technical method to measure their interactions at colonial levels for longer periods.”
Fortunately, an automatic tracking system developed by Swiss researchers in 201
3 let Stroeymeyt and her colleagues have a detailed look at how 22 laboratory-born dark colonies behave when the disease is percolating in their midst. The team glued small 2D barcodes on the marsh’s chest, giving each insect a unique identifier – “just like a QR code”, says Stroeymeyt. A camera placed above the envelope’s casing pushed two pictures every second, and an algorithm detected and recorded each barcode position, giving researchers a wealth of data about the movements of the ants.
For four days, the team let the ants scream about in their containment undisturbed. As with colonies in nature, some ants worked outside the estate to grow food, while others – like the queen and “nurses” who tend to develop bride-stayed inside the estate. On the fifth day, the researchers exposed some, but not all, of the parents of 11 colonies to the mushroom Metarhizium brunneum which are often found in the soil of the tree myrtle habitats and are known to make them sick. Publishers from the other 11 colonies were treated with a benign solution to serve as a control group.
Important studies have shown that M. brunneum fungus takes at least 24 hours to infect ants, which in turn gave researchers time to observe the insects before they were actually sick.
“We wanted to focus on [this] period … so that we could distinguish Myran’s active response itself from side effects of disease or parasitic manipulation,” says Stroeymeyt.
Writing Science reveals the researchers that when the drivers are put back in their casing, polluted ants spent more time outside the estate, which meant they had less contact with the colonial’s most valuable members: the queen who puts the entire colony’s eggs and indoor workers, who are younger than the perpetrators, and therefore have more hours to contribute to the colony. (Older ants are exposed to risky confiscating jobs outside the estate because, as Stroeymeyt simply says, “will they die anyway.”)
But the essence of the study finds that the contaminated ants were not the only ones to change their behavior. Feeders that have not been exposed to the fungus also increased the time spent away from the estate. And the nurses inside the estate moved the kid further inward and spent more time overlapping with those who “could be seen as a spatial isolation from the parents,” says Stroeymeyt.
How did the colony feel disease-threatening? Prevention of fungal spores had even infected some traitors? The researchers are not sure, but the delicate sense of the ants can be the key. Ants spin around with their antennas, which constantly stir and sample the insects’ surroundings. It is quite possible, according to Stroeymeyt, that an ant could detect a festering fungus on one of its colonies, as easily as it could smell a pathogen on its own body.
Why non-contaminated feeders also reduced the time spent in the estate another interesting question. As the first line of contact with their soon-to-be-sick colleagues, they may in some way be known to stay away from important colonial members. But it is also possible that, after discovering pathogens on their other parents, they only spent more time treating the polluted workers outside the estate. Ants produce formic acid through a gland on the tip of their goats, or the abdomen; They can kill fungal spores on each other by picking up formic acid in their mouths and licking their pathogen-laden friends.
Although the researchers recorded fewer interactions between traitors and indoor workers, the contact ended did not completely lead to another interesting revelation. When using simulations to model how fungal pathogens spread across the colony in the face of myran’s social networking changes, researchers found that the likelihood of the queen and nurse who had a potentially lethal load of the fungus went down but the likelihood of these important ants got a low load .
“It is similar to immunization or vaccination in humans,” explains Stroeymeyt. “These low doses do not lead to mortality, but they allow the ant to develop some form of protection against later exposure with the same pathogen. [finding] is also something completely new.”
Moving forward, Stroeymeyt plans to investigate how pathogens triggers social changes in wild dark colonies, which can count into hundreds of thousands she suspects that segregation between indoor and outdoor workers can be even more pronounced in these large groups.
Megan Frederickson, a professor of ecology and evolutionary biology at the University of Toronto, who was not involved in the new study, calls the researchers “conclusions” a new and exciting discovery “caused by” groundbreaking methods. “She adds that similar technologies can help Researchers to study whether ants also switch their social networks to transfer beneficial microbes to each other. And Frederickson believes that “the meaning [of the study] goes beyond ants.”
“I wonder,” she musks, “how often do other social animals reorganize