How ants detect and treat infections from their fellow ants

Megaponera analis Not an ant like the others. Whereas its approximately 13,000 cousin species enjoy a varied diet, it is picky and eats only termites. But, not giving up on the latter, workers’ raids present serious risks: about 22% of attackers are injured. In a remarkable thesis, elaborated by a book (Fight, save, healCNRS Editions, 2020) and a documentary (Life on our planet, streaming on Netflix), biologist Eric Frank of the University of Würzburg in Germany has already shown how the most affected ants sacrifice themselves to save the colony. But what happens to others? How are they cared for? To find out, the researcher spent three years between the Ivory Coast and his observation field at the University of Lausanne in Switzerland. Result published on 29th December, 2023 Nature Communications

is surprising.

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After returning, the injured ants are first medically examined. On the program: isolate those with sterile wounds, those likely to heal spontaneously, those with infected wounds. To do this, they use hydrocarbons present on the patient’s cuticle. This layer of lipid protects all insects against desiccation. In ants, it also creates a chemical signature. “It allows us to distinguish colony members and strangers, but also to know the status of each, nurse, predator, queen.”

, details Eric Frank. This “uniform of type” It does even better: it tells nurses — and this is the first new result of the article — whether an injured person has activated his or her immune system; That is, whether she is infected or not.

A German-Swiss team proved this by infecting ants with the bacteria at various high doses. Pseudomonas aeruginosa. At very high doses, the injured person is simply expelled from the anthill; In minimal doses, she is asked to protect herself. Between these two extremes, nurses take matters into their own hands. Starting with the dance, with all due respect to La Fontaine: in fact, they bend themselves to allow their legs – right, then left, then right, then left… – to reach the metapleural gland hidden in their back. Then they lick their paws and finally, apply with their mouths what really looks like a miraculous ointment.

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