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Fungus-infected 'zombie spiders' found in Irish caves

Louise Cullen
BBC News NI Agriculture & Environment Correspondent
Tim Fogg A spider upside down on a ceiling. The spider's shadow is above it on a white background. The spider is brown and black with spindly long legs and a white fluffy face. Tim Fogg
The infected spiders - seen here with the fungus over its head and body - have been found in several cave systems across the island of Ireland

It's the stuff of nightmares - or even the hit TV show and video game The Last of Us: a novel fungus that turns its hosts into "zombies".

Thankfully, so far, it's only been found in spiders located in several cave systems across the island of Ireland, including the Whitefathers' Caves on the Fermanagh/Cavan border.

Named after Sir David Attenborough, Gibellula attenboroughii was first discovered in County Down during the filming of BBC Winterwatch in 2021.

The fungus changes the spider's behaviour, making it leave its concealed lair or web to die in an exposed position on the roof or walls of a cave.

Centre for Agriculture and Biosciences International A yellow fungus that looks like a yellow hand sized octopus, on a green leaf.Centre for Agriculture and Biosciences International
Gibellula attenboroughii was first discovered in County Down in 2021

It does this using dopamine, the brain's happy chemical, to make the spider favour the dispersal of the fungal spores over preserving its own life.

Scientists say the behaviour of the fungus mirrors that of ants infected by fungi of the genus Ophiocordyceps, previously reported from the Atlantic rainforest of Brazil.

The story of the "zombie ants" led to a number of zombie-fungus themed books, as well as the hugely popular The Last of Us video game.

The game, which takes place in a post-apocalyptic world overrun by fungus-infected zombie humans, was later adapted into an award-winning TV show starring Pedro Pascal and Bella Ramsey.

EPA On the left is a man with short dark hair and stubble. He has black glasses and is wearing a black shirt and black jacket. To the right is a young woman, in a light pink jacket and light-coloured shirt. She has shoulder-length dark hair. They are posing at the premiere of the TV show The Last of Us, and are standing in front of a background that features the logo for the show and that of streaming service HBO Max. EPA
Pedro Pascal and Bella Ramsey star in The Last of Us

After finding the fungus on a spider in the gunpowder store at Castle Espie in County Down, a team of scientists led by Dr Harry Evans from the Centre for Agriculture and Biosciences International (CABI), began to look for more specimens.

Dr Evans and his team used a speleologist - a cave explorer - to help their research.

That work led them to the conclusion that this was a native fungus specific to indigenous cave-dwelling spider species.

The fungus favours man-made habitats like culverts, tunnels and cellars.

A stream flows out of a low cave entrance, which is covered in trees and ivy
An entrance to the Whitefathers' Caves in County Cavan

It has been found on two species of spider occupying different types of environments in the cave systems.

Both Metellina merianae (Tetragnathidae: Araneae) and Meta menardi are reclusive, orb or circular web-weaving cave spiders that favour dark, damp places.

Centre for Agriculture and Biosciences International Two circular test tubes labelled with numbers and dates from 2022. The left test tube is a circular size of a tennis ball and has the yellow strawy octopus looking fungus in it. The right test tube is twice its size and is filled with a dark urine colour and four mushroom looking white fungi. Centre for Agriculture and Biosciences International
More research is needed to understand just how the fungus succeeds

Dr Evans' team's work has been published in the journal Fungal Systematics and Evolution.

He said more research is needed to understand just how the fungus succeeds.

But human beings needn't worry - at least yet.