This Parasite Deploys Mucus Slime Balls to Make ‘Zombie Ants’

Credits: Brian Lund Fredensborg

As the eerie season approaches, researchers have delved deeper into the workings of a minuscule parasitic flatworm, the lancet liver fluke, and its intriguing control over ant brains. Utilizing an intricate four-phase mechanism, these flukes may be ingeniously adapted to daily temperature fluctuations to expand their host range.

This recent discovery was shared in the Behavioral Ecology journal. When an ant consumes a globule of snail slime laden with fluke larvae, the parasite seizes control of its brain. Inside the brain, the larvae grow, allowing the parasite to compel the ant to ascend a grass blade and bite down on it.

This elevated position facilitates the fluke’s transfer to its next probable host, be it a cow, sheep, deer, or another grazer, which ingests the fluke, providing it with a new habitat and breeding ground.

The study even unveiled that the liver fluke can prompt the ant to retreat down the grass blade if the temperature rises too much. The research was carried out by Fredensborg, in collaboration with his ex-graduate pupil Simone Nordstrand Gasque, who is currently pursuing her PhD at Wageningen University in the Netherlands.

For their investigation, they marked numerous ants infected with the parasite in the Bidstrup Woods close to Roskilde, Denmark. The behavior of these infected ants in relation to humidity, luminosity, day period, and particularly temperature was meticulously observed.

It was evident that temperature played a role in their actions. In chillier conditions, ants were more prone to clinging to a grass blade’s peak. As the temperature escalated, ants released the blade and made their descent. Upon infection by the liver fluke, the ant becomes host to several hundred parasites.

A singular fluke navigates to the brain and modifies the ant’s actions. The other liver flukes hide within the ant’s gut situated in its belly. Inside, they journey through bile passages, reaching the liver where they drink blood and mature into egg-producing adults. These eggs are eventually expelled via the host’s waste.

Lying on the soil post-excretion, these fluke eggs await a passing snail to consume them. Inside the snail, these eggs transform into fluke larvae, which can reproduce without mating and proliferate into thousands.

For these young flukes to exit their snail host and find their subsequent victim, they induce a snail to expel them wrapped in mucus. Ants, drawn to this damp cluster, consume it, unintentionally swallowing more fluke larvae, setting the cycle in motion again.

The diminutive liver fluke is prevalent in Denmark and various global temperate zones and scholars persist in unraveling the intricacies of their brain-hijacking abilities.