Parasitic fungus that infects and kills spiders discovered in Brazil
March 17, 2023 - The Guardian
Scientists believe they have discovered a new parasitic fungus which preys on trapdoor spiders in Brazil’s Atlantic rainforest.
The rare organism, which is purple, belongs to a group of fungi that infect invertebrates and take over the host. A closeup image shows the fungus wrapped around the body of a trapdoor spider, poking out of the burrow from which the arachnid grabs insects.
Researchers said there was no evidence that the new parasitic fungus controlled the behaviour of trapdoor spiders before killing them, like their zombie-ant fungi relatives, which overcome the insects and trick them into leaving their nests to go to places where they can spread their spores and have been made famous by the post-apocalyptic TV drama The Last of Us.
The fungus was found in November during a field trip to forests north of Rio de Janeiro to document the area’s biodiversity and search for new species. It will need a formal scientific description before it is confirmed as a new species.
“It’s a really beautiful thing,” said Dr João Araújo, a Brazilian mycologist with the New York Botanical Garden, who made the discovery but has not yet decided on a name. “They infect trapdoor spiders, and it’s one of the very few cordyceps that are purple, which is a cool feature.
“We don’t know much about this fungal group because it’s very understudied. This kind of fungus has been collected very few times in the world, mostly in Thailand. This will likely be the first time we sequence a species like this from Brazil.”
The Atlantic rainforest is one of the most threatened ecosystems in the world. It once covered 15% of Brazil but has become highly fragmented, with only 20% of the original area now left. A biodiversity hotspot, it boasts several species that are found nowhere else on Earth, including the golden lion tamarin monkey and the painted tree rat.
The expedition, which was a collaboration between Royal Botanic Gardens, Kew, the New York Botanical Garden, Rio de Janeiro Botanical Garden and other organisations, included experts on plants, fungi, frogs, snakes and birds who wanted to see what remained in the forest. Scientists used the latest portable technology to sequence the genome of the fungus on site.
They believe they made more discoveries of fungal parasites on the trip, but need to do more checks. They include a parasitic fungus that preys on a harvestman spider, and another that attacks dung beetles.
“The new species that attacks trapdoor spiders belongs to a mega-diverse group of fungi,” said Araújo. “We know about 1% of its diversity, so we know very little. Foundational scientific work is needed so we can, perhaps, investigate new medical compounds or use them to protect against pests in crops.”
Lead researcher, Dr Oscar Alejandro Pérez Escobar, and Dr Natalia Przelomska, who conducted in-the-field sequencing, said their work would back up the new species hypothesis and could be used to speed up the identification of other species in threatened ecosystems.
Przelomska said: “Here at Kew, we have access to big DNA sequencing machines and all sorts of ways to produce data. That is often so much harder in biodiverse countries.
“So what was really special about the field trip was that we could go and use some of the newest DNA sequencing technologies with the people working there. It’s one small step in this really big problem of unequal access.”