Tapeworm infection makes worker ants live longer, behave like queens

A tiny tapeworm has been found to dramatically change the lives of ants, making ordinary worker ants live much longer and behave more like queens. According to a new study published in BMC Genomics, the parasite rewires their bodies in ways that help them survive for much longer while becoming less active. Scientists believe these changes also benefit the parasite by increasing its chances of completing its life cycle.

A parasite that transforms worker ants

Researchers from Johannes Gutenberg University Mainz (JGU) studied the ant species Temnothorax nylanderi, which can become infected by the tapeworm Anomotaenia brevis.

Normally, worker ants in this species live for only one to two years, while queens can survive for up to 20 years. However, earlier research showed that infected worker ants can live almost as long as queens.

How the scientists studied the ants

The research team collected ants from the Lenneberg Forest near Mainz, Germany, and divided them into three groups:

Queen ants

Worker ants infected with the tapeworm

Healthy worker ants

The scientists examined two important parts of the ants' bodies:

The brain, which controls behavior.

The fat body, an organ that helps regulate metabolism, immunity and energy storage.

Using advanced RNA sequencing, they looked at which genes were active in each group. They also analyzed the tapeworm's own genetic material to see whether it was producing chemicals that copied the ants' natural signaling molecules.

Infected ants become more like queens

Researchers found that infected worker ants had gene activity that looked surprisingly similar to that of queen ants.

"Our genetic analyses show that the infection does not simply make the ants sick, but alters their physiology in a highly targeted way," said Foitzik. "At the molecular level, infected workers showed a profile that was partially queen-like."

She added, "There, we found clear overlaps between infected workers and queens."

The affected genes were linked to:

Metabolism

Immune system

Stress resistance

Aging

Scientists believe these changes may explain why infected workers live much longer than healthy workers.

Their brains tell a different story

While the ants' bodies became more queen-like, their brains showed a different pattern. Researchers discovered that many neuropeptides—chemical messengers that influence feeding, activity and social behavior—became much less active.

This could explain why infected ants move less and no longer behave like typical worker ants.

"The effect of the infection is therefore tissue-specific," explained Giulia Blasi, first author of the study and a doctoral researcher at iomE. "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."

The tapeworm isn't copying the ants

Scientists also investigated whether the parasite tricks ants by producing molecules that imitate the ants' own signaling chemicals.

However, they found no evidence that this was happening.

Instead, the parasite appears to influence the ants in a more indirect way by changing the ants' own biological control systems.

"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 Blasi.

Why the parasite benefits

The tapeworm uses ants as an intermediate host, but it can only complete its life cycle after being eaten by woodpeckers, which are its final hosts.

Scientists think keeping infected ants alive for much longer—and making them less active—may improve the parasite's chances of eventually reaching a woodpecker.

Instead of quickly dying like ordinary workers, infected ants remain alive for years, giving the parasite more time to complete its journey.

A new model for studying aging

The findings could help scientists better understand how parasites manipulate their hosts and even provide clues about aging itself.

"Queens and workers of social insects share the same genetic basis, but differ greatly in lifestyle and lifespan," said Foitzik. "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."

Researchers say this unusual ant–tapeworm relationship offers an important model for studying how parasites can influence lifespan, metabolism and behavior by altering existing biological pathways rather than creating entirely new ones.