Zombie-like Parasite Manipulates Ants to Ensure Its Own Survival, Study Finds
Researchers at the University of Copenhagen have discovered the fascinating method by which the lancet liver fluke zombifies ants to alter their behavior. The parasite, which has a complex life cycle that involves infecting snails, ants, and grazing mammals, has a unique “on/off” switch that relies on temperature. The findings, published in the journal Behavioral Ecology, shed light on the hidden world of parasites and emphasize their importance in understanding ecosystems.
Liver flukes typically infect ants by hiding in their abdomen, protected by a capsule that shield them from stomach acid. However, one liver fluke attaches itself to the ant’s brain and compels the ant to clamp its mandibles at the top of a blade of grass. This behavior increases the chances of the ant being eaten by grazing animals such as cows, sheep, or deer. The protective capsule then dissolves inside the new host’s intestines, allowing the liver flukes to reach the liver through the bile ducts. The fluke attached to the ant’s brain dies, sacrificing itself for the sake of its parasitic companions.
Once inside the new host, the surviving liver flukes feed on the host’s blood, mature, and lay eggs. These eggs are excreted in the host’s feces, which are consumed by snails. The eggs hatch into larval flukes, which reproduce asexually and eventually find their way into ants through the mucus coughed up by the snails. This cycle ensures the continued survival of the liver flukes.
The researchers, led by Brian Lund Fredensborg, observed the effects of temperature on infected ants in the wild. Previous laboratory experiments had shown that infected ants were less likely to bite a leaf under hotter temperatures. In the latest study, Fredensborg and his team observed four anthills in the Bidstrup Forests near Copenhagen for 13 days, tracking temperature and humidity while monitoring the ants’ behavioral changes.
The results confirmed the earlier findings, revealing that infected ants were more likely to attach themselves to the top of a blade of grass in colder temperatures. They would return to the ground when the temperature rose and repeat this behavior when it dropped again. The researchers suggest that this strategy evolved to increase the liver fluke’s chances of transmission to a new host while protecting it from potentially lethal high temperatures.
“We found a clear correlation between temperature and ant behavior,” said Fredensborg. “Our discovery reveals a parasite that is more sophisticated than we originally believed it to be. But we still need to figure out which cocktail of chemical substances the parasite uses to turn ants into zombies.”
The study highlights the intricate and complex relationships that exist in nature and the importance of studying parasites. Understanding these relationships can provide valuable insights into ecosystems and help us appreciate the diversity of life on Earth.