The Tapeworm That Helps Ants Live Absurdly Long Lives

The Never-Aging Ants With a Terrible Secret.  A parasite gives its hosts the appearance of youth, and an unmatched social power in the colony.

Deep in the forests of Germany, nestled neatly into the hollowed-out shells of acorns, live a smattering of ants who have stumbled upon a fountain of youth. They are born workers, but do not do much work. Their days are spent lollygagging about the nest, where their siblings shower them with gifts of food. They seem to elude the ravages of old age, retaining a durably adolescent physique, their outer shells soft and their hue distinctively tawny. Their scent, too, seems to shift, wafting out an alluring perfume that endears them to others. While their sisters, who have nearly identical genomes, perish within months of being born, these death-defying insects live on for years and years and years.

They are Temnothorax ants, and their elixirs of life are the tapeworms that teem within their bellies—parasites that paradoxically prolong the life of their host at a strange and terrible cost.

A few such life-lengthening partnerships have been documented between microbes and insects such as wasps, beetles, and mosquitoes. But what these ants experience is more extreme than anything that’s come before, says Susanne Foitzik, an entomologist at Johannes Gutenberg University Mainz, in Germany, who studies the ants and their tapeworms. Infected Temnothorax ants live at least three times longer than their siblings, and perhaps much more, she and her colleagues report in a study published today in Royal Society Open Science. No one is yet sure when the insects’ longevity tops out, but the answer is probably in excess of a decade, approaching or even matching that of ant queens, who can survive up to 20 years.

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The tapeworm-laden ants didn’t just outlive their siblings, the team found. They were coddled while they did it. They spent their days lounging in their nest, performing none of the tasks expected of workers. They were groomed, fed, and carried by their siblings, often receiving more attention than even the queen—unheard of in a typical ant society—and gave absolutely nothing in return.