This Tapeworm Hacks Ants' Biology to Live Longer Than Their Own Queen

A Parasite With an Unlikely Gift

A tapeworm fundamentally changes the lives of ants: workers of the species Temnothorax nylanderi infected with the tapeworm Anomotaenia brevis live several times longer than their uninfected nestmates. We're not talking about a modest bump in lifespan — infected workers exhibit prolonged lifespans comparable to that of queens, which live up to two decades. Meanwhile, the average worker ant toils for a fraction of that time. But this extraordinary longevity comes with a sinister catch: it's not for the ant's benefit at all.

The parasite just wants to keep its host lazy so it will be easy pickings for a giant predator — the bowels of which are the parasite's preferred breeding ground. For the tapeworm, this arrangement is advantageous because the ants serve as intermediate hosts. The parasite develops fully only in woodpeckers, its definitive hosts. The longer an infected ant survives, the better the odds that a woodpecker will eventually come along and eat it — completing the tapeworm's life cycle.

How the Infection Begins — and What It Does

When ant larvae are fed woodpecker droppings, they can become infected with the tapeworm Anomotaenia brevis — and so begins an insidious cycle. A single ant can be infected by up to 70 parasitic larvae, which survive in the body fluid. The transformation that follows is dramatic. The infected ants smell different from and are smaller than their nestmates, their cuticles turn yellow instead of the usual brown color, and they tend to stay sitting in the nest.

Uninfected ants do the worker's chores, carry infected ants around, feed them, and groom them for the rest of their days. These pampered ants barely leave the nest. Remarkably, this "royal treatment" mirrors the care normally reserved for the colony's queen. But this social favoritism comes at a real cost to the colony: worker ants burdened with looking after their infected peers die much earlier. And although neither the infected ants nor their attentive carers appeared to show physiological indicators of stress, workers gave their queens less loving care as they tended to the infected, which may spell trouble for the colony.

Scientists Finally Unravel the Molecular Mystery

A new study by Johannes Gutenberg University Mainz (JGU), published in the journal BMC Genomics, reveals the molecular basis of this unusual effect. In the laboratory, ants were assigned to three groups: queens, workers infected with the tapeworm, and uninfected workers. From the ants, the researchers dissected the brain and the fat body — a tissue in the abdomen important for metabolism and the immune system. They then used RNA sequencing to analyze which genes were active in each tissue.

The results were striking — and tissue-specific. "The effect of the infection is therefore tissue-specific," explained Giulia Blasi, first author of the study and a doctoral researcher. "In the fat body, we see a shift toward a queen-like metabolic profile. In the brain, by contrast, many signaling pathways linked to behavior and activity are dampened." In other words, the tapeworm reprograms the ant's body to age slowly while simultaneously dialing down the ant's drive to do anything useful for the colony.

"The data rather suggest that the parasite influences the ant indirectly by intervening in the host's own regulatory networks, which control metabolism, the immune system, aging, and behavior, among other processes," said Giulia Blasi. The tapeworm isn't injecting its own chemicals to fake the ant out — it's hijacking the ant's existing biological machinery and repurposing it entirely.

Why This Discovery Matters Beyond the Anthill

As Professor Foitzik noted, "Queens and workers of social insects share the same genetic basis, but differ greatly in lifestyle and lifespan. The fact that infected workers show a partly queen-like molecular profile in the fat body suggests that the parasite taps into existing biological programs of the ant." This raises a profound question: if a tapeworm can unlock longevity pathways already buried in an ant's genome, what does that tell us about the biology of aging more broadly?

Understanding how parasites hijack host longevity and behavioral pathways offers critical insights into the molecular mechanisms of aging and the broader evolutionary dynamics of parasitic manipulation. The Temnothorax–tapeworm system is now being studied as a model for how aging can be molecularly switched — not by adding something new, but by flipping switches that were always there. For scientists chasing the secrets of longevity, the answer may have been hiding in a forest floor acorn all along.