Nature can get disturbingly weird and scary. One of essentially the most ghastly animal behaviors we all know of is that of the ‘zombie ant fungus’ which takes management of dwelling ants with a purpose to unfold its spores to different people. Scientists have studied by this disturbing technique for greater than 100 years, and so they’re nonetheless studying extra about it. A brand new examine discovered that the fungus is definitely even sneakier than beforehand thought. Penn State researchers report that the parasite controls its hosts with out truly infecting the mind. Instead, like a masterful puppeteer, the fungus takes management of the ant’s limbs, forcing the host to behave in opposition to its personal will. That’s only a entire new degree of wickedness.
The bizarre parasite, often known as Ophiocordyceps unilateralis sensu lato, was first found by the British naturalist Alfred Russel Wallace in 1859, and is at present discovered predominantly within the tropical forests of Thailand but additionally Brazil’s rainforests. Once it infects a carpenter or employee ant, the parasite forces its host’s muscle groups to seize a leaf (or one thing else) when, the place, and the way the fungus desires it. They additionally power the ant to wander round in a drunken haze till it clamps its jaws on the underside of a leaf in what can solely be referred to as an ant zombie graveyard. The lifeless ant has now change into meals, serving to the fungus to develop right into a stalk out of the host’s head, which releases spores within the floor beneath the place it ought to infect different ants. The cycle repeats and the fungus income.
Previously, badysis confirmed that whereas holding on to the leaf with the demise grip, the heads of diseased ants are crammed with fungal cells and the muscle groups which function the ant’s jaw are atrophied. Mandibles that usually open and shut have now change into unidirectional — they will solely shut. This retains the ant from loosening its grip or dropping the leaf. Another factor the fungus does is suck all of the calcium from the ant’s muscle groups, inflicting a situation just like rigor mortis.
Penn State researchers have uncovered one thing completely different, although, after they painstakingly studied the corpses of contaminated ants in unprecedented element. The scientists first contaminated ants with both the dreaded mind-control fungus or another benign fungus with a purpose to badess the mobile interactions distinctive to Ophiocordyceps u.
“The fungus is known to secrete tissue-specific metabolites and cause changes in host gene expression as well as atrophy in the mandible muscles of its ant host. The altered host behavior is an extended phenotype of the microbial parasite’s genes being expressed through the body of its host. But it’s unknown how the fungus coordinates these effects to manipulate the host’s behavior,” stated Penn State’s Maridel Fredericksen, lead creator of the examine.
Each contaminated ant was lower into quite a few 50-nanometer slices of tissue which had been imaged with scanning electron microscopy, then stacked to create a high-res Three-D picture. A clbady machine studying algorithm then badyzed the slices to shortly and precisely recognized fungal cells amongst ant cells.
3D picture of an ant mandible adductor muscle (purple) surrounded by parasitic fungal cells (yellow). Credit: Hughes Laboratory/Penn State.
Surprisingly, the evaluation confirmed that whereas the fungal cells had been unfold all through the ant’s physique (head, thorax, stomach, and legs), these had been absent from the mind. However, fungal cells did cluster across the outskirts of the mind with which it interacted chemically, as reported within the Proceedings of the National Academy of Sciences.
“Normally in animals, behavior is controlled by the brain sending signals to the muscles, but our results suggest that the parasite is controlling host behavior peripherally,” says David Hughes, senior creator of the examine. “Almost like a puppeteer pulls the strings to make a marionette move, the fungus controls the ant’s muscles to manipulate the host’s legs and mandibles.”
This method, the researchers say, the fungus can take management of the ant whereas nonetheless protecting it alive — or not less than till it’s served its function.
“We hypothesize that the fungus may be preserving the brain so the host can survive until it performs its final biting behavior – that critical moment for fungal reproduction,” says Hughes. “But we need to conduct additional research to determine the brain’s role and how much control the fungus exercises over it.”
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