'Zombie' spiders infected by never-before-seen fungus discovered on grounds of destroyed Irish castle

Scientists have discovered a never-before-seen mind-controlling fungus that creates spider "zombies" after it was stumbled upon in a Victorian gunpowder store on the grounds of a destroyed Irish castle.

The fluffy white fungus, similar to the zombie-ant fungus that inspired the "The Last of Us" video game and TV series, likely uses chemical signals to direct cave spiders out of their lairs and into the open. The fungus then kills the spiders and uses their corpses to release its spores, according to a new study.

Members of BBC's nature documentary TV series Winterwatch first discovered the fungus in a gunpowder storeroom at Castle Espie wetland reserve in Northern Ireland in 2021. Scientists analyzed the fungus and found it is new to science. They describe the species, named Gibellula attenboroughii to honor Sir David Attenborough, in a study published Friday (Jan. 24) in the journal Fungal Systematics and Evolution.

The G. attenboroughii found in the gunpowder store was on a dead orb-weaving cave spider (Metellina merianae). As their name suggests, these spiders usually live in caves but will also inhabit dark human-made areas such as cellars and old storerooms.

Related: Horrifying photo captures moment parasitic fungus bursts from huge spider's body

Following the chance discovery in 2021, study co-author Tim Fogg, a caving specialist, found more examples of the fungus in cave systems in Northern Ireland and the Republic of Ireland, including on another cave spider species, Meta menardi, according to the study.

Cave spiders are usually concealed in lairs or webs, yet all of the infected individuals were exposed on the roofs and walls of the caves in which they were found — the gunpowder spider was on the storeroom's ceiling. The researchers proposed that the fungus altered the spiders' behavior, sending them out into the open and exposing them to air currents that dispersed G. attenboroughii spores.

Study lead author Harry Evans, an emeritus fellow who researches fungi at CABI, an international nonprofit focussed on agriculture and the environment, told Live Science that the fungus infection process is complex and G. attenboroughii would have evolved alongside the cave spiders.

Evans explained that G. attenboroughii spores penetrate the spider and infect its hemocoel — a cavity that holds the invertebrate equivalent of blood. After the spider leaves its lair, G. attenboroughii produces a toxin to kill its host, then uses antibiotics — antimicrobial substances that kill bacteria — to preserve the corpse whilst mummifying it. The fungus absorbs all of the spider's nutrients and when conditions are right, like high humidity in the cave, G. attenboroughii grows long structures on the spider to disperse its spores.

"Medicinal treasure chest"

While the relationship between the fungus and spiders is interesting, Evans noted the endpoint of this research should be the potential human medicines that could come from the antibiotics and other substances the fungus produces. "It's a medicinal treasure chest," he said.

Evans and his colleagues extracted DNA from the fungus to confirm it was a previously unknown species. So far, it's only been found in Ireland, but the researchers also suspect that G. attenboroughii infects orb-weaving cave spiders in Wales, based on photographs of what appeared to be the same fungus.

The study highlighted that there is a hidden diversity of parasitic fungi in the British Isles and likely many more species to be discovered. Fungi are one of the five kingdoms that make up all living things — the other kingdoms are plants, animals, protoctista and monera.

"There's a lot more fungi to find," Evans said. "The fungal kingdom could be up to 10, 20 million species, making it the biggest kingdom by far, but only 1% have been described."

G. attenboroughii was originally going to be called G. bangbangus — "bangbangus" being a nod to the gunpowder store where the fungus was found. However, the study authors changed the species name to honor Attenborough instead.