summary: Ants infected with the lancet liver fluke are forced into life-threatening situations to propagate the fluke’s complex life cycle. The researchers found that fluke manipulation is more complex than previously thought, with temperature acting as a trigger for the ants’ behavior.
Cold temperatures increase the chance that infected ants will cling to blades of grass and be eaten by herbivores. When temperatures rise, ants descend to protect themselves from the deadly heat.
Important facts:
- The lancet liver fluke controls the ant’s brain and forces it to attach to grass blades during cool weather, maximizing its chances of being eaten by herbivores.
- The study uncovers a temperature-triggered “zombie on/off switch” that controls when ants cling to grass or seek shelter.
- Of the hundreds of flukes inside an infected ant, only one controls the brain, while the rest wait in the ant’s abdomen for infection.
sauce: University of Copenhagen
Imagine yourself grasping the top of a swaying blade of grass with your chin, without knowing how it got there. This is the reality for ants infected with the lancet liver fluke, a small parasitic flatworm.
The liver fluke has a complex, almost insanely conceived life cycle that begins by taking over the ant’s brain. Unsuspecting ants climb up and lock their powerful jaws onto blades of grass, increasing their chances of being eaten by herbivores such as cows and deer.
Researchers at the University of Copenhagen’s Department of Plant and Environmental Sciences have discovered that the parasite’s ability to control ants is even more cunning than previously thought. Amazingly, this parasite can even make ants crawl out of blades of grass when it gets too hot.
“It is very wise to raise ants onto the grass during the cool hours of the morning and evening while cows and deer graze, and then come back down again to avoid the dangerous sun’s rays.” “Our findings reveal a more sophisticated parasite than we originally thought,” says Simone Nordstrand, a former graduate student and current doctoral student at Wageningen University in the Netherlands. Associate Professor Brian Lund Fredensborg, who worked with Gasquet, explains:
A study of this parasite has just been published in a scientific journal. behavioral ecology
Zombie “on/off switch”
Researchers tagged hundreds of infected ants in Bidstrup Forest near Roskilde, Denmark.
“Packing the colors and numbers on the backs of the ants required some dexterity, but it allowed us to track the ants for long periods of time,” says Brian Rand-Fredensborg.
Next, they observed the behavior of infected ants in relation to light, humidity, time of day, and temperature. It was clear that temperature affected the behavior of the ants. When temperatures are cold, ants are more likely to attach to the tops of grass blades. When the temperature warmed up, the ants let go of the grass and crawled back.
“We found a clear correlation between temperature and ant behavior. We joked that we had found a zombie switch for ants,” says Brian Rand Fredensborg. say.
trojan horse
When a liver fluke infects an ant, hundreds of parasites invade the ant’s body. However, he is the only one who can reach the brain and influence the ant’s behavior. The remaining liver fluke hides in the ant’s abdomen.
“Here, there can be hundreds of liver flukes waiting for the ant to ingest into its next host. The ants are encapsulated, which protects them from the host’s stomach acid, but the ants “The liver fluke that controls it dies. You can say that you are sacrificing yourself for the sake of others,” explains Brian Lund Fredensborg.
Animals infected with many liver flukes can develop liver damage as the parasite moves around the host’s liver and bile ducts.
Nature’s greatest influence
Brian Rand Fredensborg points out that there are many other examples of parasites altering animal behavior. Parasites that hijack the behavior of their hosts therefore have a greater impact on the food chain than many people realize. Fredensborg said the new research sheds light on a highly underappreciated group of creatures.
“Historically, parasites have never received much attention, despite the scientific evidence that they are the most widespread life form. Part of the reason is that parasites This is due to the fact that insects are extremely difficult to study. Nevertheless, the hidden world of parasites forms an important part of biodiversity, and by changing the behavior of their hosts, we can determine who and what they are in nature. “That’s why it’s important for us to understand them.”
This small liver fluke is widely distributed in temperate regions around the world, including Denmark. The researcher and his colleagues plan to continue studying the parasite and how it takes over the ant’s brain.
“We know that temperature determines when the parasite takes over an ant’s brain. But we need to figure out what mixture of chemicals the parasite uses to turn the ant into a zombie. ” concluded Fredensborg.
Box: Liver fluke life cycle
- Zombie ant: The liver fluke infects the ant’s brain and binds the ant to a blade of grass so that its next host, a herbivore such as a cow, sheep or deer, can eat it. Meanwhile, in the abdomen of the ant, a large swarm of fluke waits for transmission.
- Herbivores: When herbivores consume infected ants, they also become infected with the liver fluke. The liver fluke that took over the ant’s brain is killed by the host’s stomach acid. The large cluster in the ant’s abdomen is protected by a capsule that dissolves only once in the host’s intestine. Here, the liver fluke enters the liver through the bile duct, where it sucks blood, develops into an adult fluke, and begins to lay eggs, which are then excreted through the host animal’s feces.
- snails: Once the fluke eggs are excreted, they lie on the ground and wait for the snail to crawl over and eat the feces. Inside the snail’s body, the eggs develop into thousands of fluke larvae through asexual reproduction.
- Slime ball: To exit the snail and move on to the next host, the fluke larva causes the snail to cough, expelling the larva as a goop of mucus. The ants are attracted to the slime and consume it, ingesting the fluke larvae.
About this neuroscience research news
author: michael jensen
sauce: University of Copenhagen
contact: Michael Jensen – University of Copenhagen
image: Image credited to Neuroscience News
Original research: Closed access.
“The behavioral manifestations of zombie ants caused by flukes are strongly linked to temperature” by Brian Rand Fredensborg et al. behavioral ecology
abstract
The behavioral manifestations of zombie ants caused by flukes are strongly linked to temperature
It is a common phenomenon that changes in host behavior caused by parasites lead to increased transmission to subsequent hosts. However, field-based studies are rare and often do not consider the role of environmental factors in inducing host behavioral changes.
We investigated the effects of temperature, relative humidity (RH), time of day, date, and irradiation surrogates on behavioral changes in ants. formica polyctena (Förster, 1850) by the lancet liver fluke covering the brain. Dicrocoelium dendriticum (Rudolfi, 1819).
The fluke induces the ant to climb onto the vegetation in a temporary state of tetany and bite with its mandibles. In the Bidstrup Forest in Denmark, a total of 1,264 ants exhibiting altered behavior were observed over 13 nonconsecutive days of the year.
A subset of those ants (N= 172) were individually marked to track the attachment and release of infected ants in relation to changes in temperature. Infected ants primarily attached to vegetation early and late in the day in response to low temperatures and high relative humidity, likely coinciding with grazing activity of potential herbivorous definitive hosts. It is thought that there are.
Temperature was the single most important determinant for the induced phenotypic changes. On warm days, infected ants changed many times between manipulated and unmanipulated states, whereas on cool days, many infected ants remained attached to the vegetation throughout the day.
Our results demonstrate that the temperature sensitivity of infected ants exposes infected ants to their next host at the appropriate time, while at the same time protecting them from exposure to high temperatures that can increase host (and parasite) mortality. This suggests that it serves the dual purpose of protection.