Infected ant workers of the species Temnothorax nylanderi live up to ten times longer than their uninfected nestmates and receive royal treatment—including grooming, feeding, and transport—after consuming tapeworm (Anomotaenia brevis) eggs found in woodpecker droppings, according to a study published in the journal BMC Genomics. While the parasite radically alters host physiology to ensure it is eaten by a definitive avian predator, researchers at Johannes Gutenberg University of Mainz and Zhejiang University discovered the manipulation occurs without the tapeworm directly hacking the ant’s brain.
How Tapeworms Alter Ant Physiology and Lifespan
When ant larvae ingest tapeworm eggs from woodpecker droppings, the resulting infection fundamentally shifts their physical traits and behavior. According to the study published in BMC Genomics, infected workers turn a pale yellow rather than their normal dark brown, stay smaller than nestmates, and emit distinct pheromones. These chemical signals mimic a queen ant, prompting healthy nest workers to roll out the red carpet. Uninfected ants bring food, carry their infected peers around, and groom them at the expense of the wider colony.
Biologists from Johannes Gutenberg University of Mainz (JGU) in Germany and Zhejiang University in China investigated this phenomenon by examining gene expression in the ants’ brains and fat bodies—tissues responsible for metabolic and immune functions. Lead author Susanne Foitzik, a behavioral ecologist at JGU, noted that the genetic analyses show the infection alters host physiology in a highly targeted way rather than simply making the insects sick. At the molecular level, infected workers display a profile that is partially queen-like, with alterations linked to metabolism, immune response, stress, and aging.
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Unlike the tapeworm’s indirect control over Temnothorax nylanderi, the cordyceps fungus directly hacks the nervous system of its victims, turning them into ‘zombies’ that climb plants and lock their mandibles onto leaves before a spore-spreading stalk erupts from their heads.
Inside the Ant Brain: Suppressed Signaling Without Direct Hacking
While fat body gene expression closely mirrored that of actual queens, the similarities vanished when researchers examined the ants’ brains. According to first author Giulia Blasi, a biologist at JGU, infected ants showed suppressed signaling molecules and receptors. This suppression likely explains why the infected insects completely lose the industrious work ethic characteristic of the species, spending their extended lives ignoring chores and rarely leaving the nest.
Surprisingly, the signaling molecules found in the brains of infected ants do not match those produced by the parasite. This disconnect rules out the hypothesis that tapeworms use their own peptides to directly hack the host brain. Instead, the data suggest that the parasite acts indirectly by intervening in the ant’s own regulatory networks, which control behavior, aging, metabolism, and immune function.
The Evolutionary Payoff for the Parasite
The altered lifestyle of infected Temnothorax nylanderi ants serves a precise evolutionary purpose for Anomotaenia brevis. While healthy ants scatter when a woodpecker approaches, infected workers remain helpless and stationary, providing an easy snack for the giant predator. Once inside the woodpecker’s gut, the tapeworm larvae develop into adults, breed, and lay eggs that pass out in the bird’s droppings, restarting the entire cycle.
Frequently Asked Questions
How do ant larvae become infected with the tapeworm?
According to research published in BMC Genomics, ant larvae become infected when they feed on woodpecker droppings containing Anomotaenia brevis tapeworm eggs.
Do tapeworms directly control the ant’s brain?
Why do uninfected ants treat infected workers like royalty?
Infected ants emit distinct pheromones that other workers interpret as coming from a queen, causing healthy ants to feed, groom, and carry them.
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