Ants Take Sick Days to Protect Their Colonies from Disease

If you have the flu, it will benefit you—and your colleagues—to stay home until you recover. The same concept apparently applies to ants, which essentially take a sick day when they've been exposed to harmful pathogens, Newsweek reports.

These new findings, published in the journal Science, come from a team of researchers in Austria and Switzerland. The researchers used infrared cameras to track the movements of more than 2200 garden ants in 22 different colonies. Ten percent of the insects were exposed to Metarhizium brunneum spores—a type of fungus that served as a pathogen among the ants.

Ants that had been exposed to the fungus altered their interactions with other ants to prevent the spread of a potentially fatal disease throughout the colony. "The cliques among ants become even stronger, and contact between cliques is reduced," Sylvia Cremer of the Institute of Science and Technology Austria said in a statement. "Foragers interact more with foragers, and nurses more with nurses. This is a response by the whole colony—animals who are not themselves treated with spores also change their behavior."

In other words, the exposed ants change their behavior to protect their cohorts, especially valuable members like the queen and nurse ants (young worker ants which help care for infant ants). They don't eliminate the exposure entirely, but merely limit it. This actually works in the ants' favor. A low dose of the pathogen can help the other ants build up immunity, which "can be compared to the process of vaccination in humans," lead author Nathalie Stroeymeyt told Newsweek. A high dose, on the other hand, can kill an ant within nine days.

It's unclear whether the ants actually stopped working during the experiment because only their locations, not their specific behaviors, were studied. But Stroeymeyt said their habit of isolating themselves "would be comparable to taking a day off work in the sense that they decreased their contacts with contaminated co-workers."