In a bizarre twist of nature, ants are finding themselves at the mercy of a parasite called the lancet liver fluke – a flatworm with an uncanny ability to control its host and turn ants into zombies.
A recent study from the University of Copenhagen has unveiled that the flatworm’s manipulation of ant behavior is far more complex than previously understood.
The lancet liver fluke’s life cycle is a marvel of evolution. The process begins when an infected ant, driven by the parasite residing in its brain, latches onto the tip of a blade of grass. This strategic position ensures that the ant will be consumed by grazing animals, such as cattle and deer, thereby allowing the fluke to move onto its next host.
However, it’s not just about climbing up. Researchers have observed that the fluke can influence the ant to move back down the blade of grass when temperatures soar.
Associate Professor Brian Lund Fredensborg, who led the study, commented, “Our discovery reveals a parasite that is more sophisticated than we originally believed it to be.” He captured this photograph showing the parasite and the zombie ant.
To investigate this behavior, researchers glued colors and numbers to infected ants in the Bidstrup Forests, Denmark. By tracking these ants, they discerned a clear relationship between temperature and the ant’s position on the grass.
“At lower temperatures, the ants clung to the grass tops. But as it warmed up, they descended,” Fredensborg remarked. The amusing analogy they derived from this was finding the ants’ “zombie switch” which the liver fluke seemingly toggles depending on the temperature.
The intricacies don’t end here. Although hundreds of parasite liver flukes reside in an infected ant, only one ventures into the brain, turning the ants into zombies.
This sole fluke dictates the ant’s behavior and eventually sacrifices itself during the transition to the next host. The remaining flukes, protected within capsules, are poised for the next stage of their journey after being ingested by a grazer.
Parasites, as Fredensborg notes, play a substantial role in the food chain by manipulating their host’s behavior. Despite their significance, they remain a relatively unstudied area due to their elusive nature.
“Parasitism is the most widespread life form,” he says, emphasizing the need for further studies. The influence of parasites on ecosystems is profound, affecting interactions between species and the broader balance of nature.
To better understand the liver fluke’s life cycle:
The fluke takes control of the ant, driving it to latch onto grass to be consumed by a grazer. Concurrently, a multitude of flukes in the ant’s abdomen await their turn.
Upon consuming the infected ant, the grazer becomes the fluke’s next host. While the controlling fluke succumbs to the grazer’s stomach acid, its brethren, protected by capsules, navigate to the liver to mature and reproduce.
The cycle continues when a snail consumes the fluke eggs excreted by the grazer. Inside the snail, the flukes proliferate.
In a bid to infect ants again, the flukes induce the snail to produce a mucus ball, a delicacy for ants, ensuring their ingestion and restarting the cycle.
As researchers continue to decipher the chemical concoctions the fluke uses to turn ants into zombies, one thing remains clear: the parasitic world holds mysteries waiting to be unraveled, revealing nature’s intricate and sometimes eerie strategies for survival.
The study of the parasite has just been published in the scientific journal Behavoral Ecology.
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