The lancet liver fluke, scientifically known as Dicrocoelium dendriticum, possesses a remarkably intricate life cycle that commences with the subjugation of an unsuspecting ant’s cognitive faculties.
Unbeknownst to the ant, it ascends to the summit of a blade of grass, clamping its formidable mandibles onto the grass’s apex. This involuntary behavior enhances the ant’s probability of being consumed by herbivores like cattle and deer. Researchers hailing from the Department of Plant and Environmental Sciences at the University of Copenhagen have uncovered that the parasite’s capacity to manipulate the ant is even more devious than initially assumed. Astonishingly, this parasitic entity can compel the ant to descend from the grass when the temperature surges, shielding it from the sun’s lethal rays.
Associate Professor Brian Lund Fredensborg, who helmed the study alongside former graduate student Simone Nordstrand Gasque (now a Ph.D. candidate at Wageningen University in the Netherlands), elucidated, “The stratagem of elevating ants into the grass during the cool morning and evening hours, where they are more likely to encounter grazing cattle or deer, and guiding them down to escape the sun’s scorching rays, showcases the parasite’s astute cunning. Our discovery exposes a level of sophistication within the parasite that surpasses our initial conjectures.”
This groundbreaking research on the parasite has been published in Behavioral Ecology.
The Researchers employed a meticulous tagging procedure on several hundred infected ants within the Bidstrup Forests near Roskilde, Denmark. Brian Lund Fredensborg commented on the process, saying, “Applying colors and numbers to the rear segments of the ants demanded nimbleness, but it facilitated long-term tracking.”
Subsequently, the team observed the behavior of these infected ants concerning factors such as light, humidity, time of day, and temperature. A discernible pattern emerged, indicating that temperature significantly influenced ant behavior. When temperatures were low, the ants exhibited a penchant for clinging to the grass’s pinnacle. Conversely, when temperatures escalated, the ants relinquished their grassy perches and descended.
Brian Lund Fredensborg humorously remarked, “We uncovered a conspicuous correlation between temperature and ant behavior. We playfully referred to it as the ‘zombie switch’ of the ants.”
Once the liver fluke infiltrates an ant, a multitude of parasites invades the ant’s body. However, only one manages to infiltrate the ant’s brain, where it exerts control over the ant’s actions. The remaining liver flukes hide within the ant’s abdomen. Brian Lund Fredensborg elaborated, “Within the abdomen, there can be hundreds of liver flukes, awaiting the opportunity to transition to their next host. They encase themselves in a protective capsule, shielding them from the host’s stomach acid, while the liver fluke controlling the ant ultimately meets its demise. You could say it sacrifices itself for the greater good.”
Animals harboring numerous liver flukes may suffer from liver damage as the parasites navigate the host’s liver and bile ducts.
Brian Lund Fredensborg emphasized that numerous examples exist of parasites altering animal behavior. Consequently, parasites capable of commandeering their host’s behavior wield substantial influence within the food chain. According to Fredensborg, this study illuminates a vastly underappreciated group of organisms. He asserted, “Throughout history, parasites have not received the attention they merit, despite scientific evidence indicating that parasitism is one of the most prevalent life forms. This oversight can be attributed, in part, to the inherent difficulty in studying parasites. Nevertheless, the hidden realm of parasites constitutes a significant component of biodiversity, and by manipulating host behavior, they play a pivotal role in shaping the natural order of who consumes whom. Hence, understanding them is imperative.”
The diminutive liver fluke exhibits a wide distribution in Denmark and other temperate regions globally. Fredensborg and his colleagues intend to continue their investigation into the parasite, delving deeper into the mechanisms by which it seizes control of an ant’s brain. He concluded, “We now understand that temperature governs the moment when the parasite assumes command over the ant’s brain. Nonetheless, we still aspire to unravel the precise concoction of chemical substances employed by the parasite to transform ants into obedient ‘zombies.'”
Source: University of Copenhagen