admin The lance leech, Dicrocoelium dendriticum, has a complex life cycle that begins with entrainment of the ant’s brain.
An unsuspecting ant climbs and clings to a blade of grass with its powerful jaws, making it more vulnerable to being eaten by grazing animals such as cattle and deer.
Scientists from the Department of Plant and Environmental Sciences at the University of Copenhagen have discovered that the parasite’s ability to fight ants is even more sophisticated than previously thought. Interestingly, the parasite can even force the ant to crawl on a blade of grass when it is too hot.
“Placing ants high in the grass while cattle or deer graze on cool mornings and evenings, and then moving them back to avoid the deadly rays of the sun is pretty smart.Our discovery reveals a more sophisticated parasite than we first thought. explains Associate Professor Brian Lund Fredensborg, who conducted the study with former student Simone Nordstrand Gasque, now a graduate student. Student at Wageningen University in the Netherlands.
The study of the parasite has been published in Behavioral Ecology.
Zombie ‘on/off switch’
Scientists have identified several hundred infected ants in the forests of Bidstrup, near Roskilde, Denmark.
“Putting colors and numbers on the hind segments of the ants required some skill, but made it possible to follow them over a long period of time”; said Brian Lund Fredensborg.
They then observed the behavior of the infected ants based on light, humidity, time of day and temperature. It was clear that temperature affected the ants’ behavior. At low temperatures, the ants were more likely to attach themselves to the tips of the blades of grass.As the temperature rose, the ants left the grass and crawled back down.
“We have found a clear connection between temperature and the behavior of ants. We joked that we had found ants. “Zombie Switch”; said Brian Lund Fredensborg.
Trojan horse
Once the liver fluke infects the ant, several hundred parasites invade the ant’s body. But only one makes its way to the brain, where it can influence the ant’s behavior. The rest of the liver flukes conceal themselves in the ant’s abdomen.
“Here, there can be hundreds of liver flukes waiting for the ant to get them into their next host. They are wrapped in a capsule which protects them from the consequent host’s stomach acid, while the liver fluke that took control of the ant, dies. You could say that it sacrifices itself for the others,” explains Brian Lund Fredensborg.
Animals infected with many liver flukes can suffer liver damage as the parasite moves around the host’s liver and bile ducts.
Nature’s biggest influencer
Brian Lund Fredensborg notes that there are many other examples of parasites altering animal behavior. Therefore, parasites that take control of the host’s behavior play a more important role in the food chain than one might think. According to Fredensborg, this new study sheds light on an extremely underestimated group of creatures.
“Historically, parasites have never received so much attention, although some scientific sources claim that parasites are the most widespread life form. This is partly because studying parasites is quite difficult.However, the hidden world of parasites is an important part of biodiversity, and by altering the behavior of their hosts, they can help determine who eats what in nature. That’s why it’s so important to understand them,” he says.
The small liver fluke is widespread in Denmark and other temperate regions of the world. The researcher and his colleagues will continue to study the parasite and investigate how exactly it penetrates ants
“Now we know that temperature determines when the parasite enters the ant’s brain.However, we still need to figure out what cocktail of chemicals the parasite uses to turn the ants into zombies, concludes Fredensborg.
Liver fluke life cycle
1. The zombie ant: The liver fluke infects an ant’s brain causing it to clamp onto a blade of grass so that its next host—a cow, sheep, deer or other grazer—eats it. Meanwhile, a large flock of flukes awaits transmission in the ant’s abdomen.
2.The grazer: Once the grazer ingests an infected ant, it becomes infected with the liver fluke also. The liver fluke that took control of the ant’s brain dies in the host’s stomach acid. The larger flock in the ant’s abdomen is protected by a capsule that only dissolves once in the host’s intestine. Here, the liver flukes find their way through the bile ducts into the liver, where they suck blood and develop into adult flukes that begin to lay eggs, which are then excreted via the host animal’s feces .
3.The snail: Once the fluke eggs have been excreted, they lie on the ground waiting for a snail to crawl by and consume the feces. Within the snail, the eggs develop into larval flukes that reproduce asexually, where they can multiply into several thousand.
4.The slime ball: To exit the snail and move on to their next host, the larval flukes cause the snail to cough, thereby expelling them in a lump of mucus. Ants are attracted to the ball of mucus and consume it, and in doing so, ingest the fluke larvae.
Provided by University of Copenhagen
