Zombie Ants: Nature’s Puppet Show Directed by Liver Flukes

Summary: Ants infected with the lancet liver fluke are forced into life-threatening scenarios, all to propagate the fluke’s complex life cycle. Researchers have uncovered that the fluke’s manipulation is even more intricate than previously thought, with temperature serving as a trigger for the ant’s behavior.

At cooler temperatures, infected ants cling to grass blades, heightening their chance of being consumed by grazers. As the temperature rises, the ants climb down, protecting themselves from lethal heat.

Key Facts:

1. The lancet liver fluke takes control of an ant’s brain, compelling it to attach to grass blades during cooler periods, maximizing its chance of being consumed by grazers.
2. The research revealed a temperature-driven “zombie on/off switch”, controlling when the ant clings to grass or seeks shelter.
3. Out of hundreds of flukes inside an infected ant, only one controls the brain, while the rest await transmission in the ant’s abdomen.

Source: University of Copenhagen

Imagine coming-to, jaws gripping the top of a swaying blade of grass, unaware of how you got there. That’s the reality for ants infected with the lancet liver fluke, a tiny parasitic flatworm.

Liver flukes have a complicated, almost insanely conceived life cycle, which begins with the hijacking of the ant’s brain. The unsuspecting ant climbs up and clamps its powerful jaws onto the top of a blade of grass, making it more likely to be eaten by grazers such as cattle and deer.

Researchers from the University of Copenhagen’s Department of Plant and Environmental Sciences have discovered that the parasite’s ability to control the ant is even more cunning than previously believed. Impressively, the parasite can even get the ant to crawl back down the blade of grass when it gets too hot.

“Getting the ants high up in the grass for when cattle or deer graze during the cool morning and evening hours, and then down again to avoid the sun’s deadly rays, is quite smart. Our discovery reveals a parasite that is more sophisticated than we originally believed it to be,” explains Associate Professor Brian Lund Fredensborg, who conducted the study together with former graduate student Simone Nordstrand Gasque,  now a PhD student at Wageningen University in the Netherlands.

The study of the parasite has just been published in the scientific journal Behavoral Ecology 

Zombie “on/off switch”

The researchers tagged several hundred infected ants in the Bidstrup Forests near Roskilde, Denmark.

“It took some dexterity to glue colors and numbers onto the rear segments of the ants, but it allowed us to keep track of them for longer periods of time,” says Brian Lund Fredensborg.

They then observed the infected ants’ behavior in relation to light, humidity, time of day and temperature. It was clear that temperature had an effect on ant behavior. When the temperature was low, the ants were more likely to be attached to the top of a blade of grass. When the temperature rose, the ants relinquished the grass and crawled back down.

“We found…