Scientists have discovered that the lancet liver fluke parasite, notorious for turning ants into “zombies” by manipulating their brains, is even more cunning than previously believed. Researchers from the University of Copenhagen in Denmark have found that this parasite has a remarkable ability to get infected ants to avoid the sun’s lethal rays when temperatures rise, allowing them to survive longer and spread the parasite further.
The study, recently published in the journal Behavioral Ecology, reveals that the liver fluke can compel ants to crawl back down the blade of grass during hot daytime temperatures. This behaviour helps the parasite ensure its survival by increasing the chances of the infected ant being consumed by grazing animals like cattle and deer.
“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,” said study co-author Brian Lund Fredensborg. “Our discovery reveals a parasite that is more sophisticated than we originally believed it to be.”
In this study, scientists tracked hundreds of infected ants in the Bidstrup Forests near Roskilde, Denmark, monitoring their behaviour in response to environmental conditions such as light, humidity, time of day, and temperature. They found a clear correlation between temperature and ant behaviour, with ants climbing higher on blades of grass in cooler temperatures and descending as temperatures rose.
“We found a clear correlation between temperature and ant behaviour. We joked about having found the ants’ zombie switch,” Dr. Fredensborg remarked.
Previous research has revealed that when the liver fluke infects an ant, hundreds of parasites enter the insect’s body, but only one makes its way to the brain. This single parasite influences the host’s behaviour while others conceal themselves in a capsule within the ant’s abdomen.
While the temperature was identified as a key factor in the parasite’s control of ant behaviour, researchers are still working to uncover the specific chemical substances the parasite uses to manipulate ants into becoming “zombies.”