Scientists in Denmark have discovered two new species of deadly mushrooms that devour from the inside, bursting from the abdomen of their prey still alive.
The parasites – Strongwellsea acerosa and Strongwellsea tigrinae – infect adult flies, which continue to buzz for days with massive holes in the body.
As they do, the mushrooms rain spores from these holes down on other unsuspected flies.
Thousands of torpedo-shaped spores can fire like a single-shot missile.
Researchers believe that flies are kept alive by powerful chemical-like drugs secreted by fungi, which also keep other microorganisms away from the wound.
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The corpse of a fly with two large holes in the abdomen, caused by the fungus Strongwellsea tigrinae. After carving through its host, the parasite keeps it alive and doped so that it can hum and throw spores on other unsuspected flies.
Researchers at the Museum of Natural History in Denmark and the Department of Plant and Environmental Sciences at the University of Copenhagen reported on the two new mushrooms.
“They work like small missiles,” University of Copenhagen ecologist Jørgen Eilenberg told The Guardian.
“They’re almost torpedo-shaped and designed to go fast.”
“If they land on another fly, they stick to the cuticle and then head for the abdomen, where they begin to proliferate.”
“Thousands of spores will be released from a single fly.”
Spongy Strongwellsea spores. Mushrooms go through cold Danish winters as thick-walled orange dormant spores and germinate in spring
One species, Strongwellsea acerosa, was discovered on Amager, the country’s most densely populated island and which hosts its capital, Copenhagen.
The other, Strongwellsea tigrinae, was found in Jægerspris, a more rural area in the north.
Host-specific fungi infect only two species of Danish flies, Coenosia testacea and Coenosia tigrina.
The host-specific fungus Strongwellsea tigrinae (bottom) infects only adult flies Coenosia tigrina. Researchers believe that only 3 to 5% of the fly population is infected, enough for the fungus to spread
As they do, they create a large hole in their host’s abdomen.
But the gaping wound does not kill the fly, it turns it into a “zombie”, which buzzes around, throwing more fungal spores into the air and fresh victims.
Mushrooms feed on the bodies of their hosts to the end.
After a few days, the fly finally gives way, falling on its back and spasming in the last hours before dying.
“This is an interesting and bizarre aspect of the biodiversity that we have discovered in Denmark,” said Eilenberg.
“In itself, this mapping of new and unknown biodiversity is valuable. But at the same time, this is a new basic knowledge, which can serve as a basis for experimental studies of the routes of infection and the bioactive substances involved.
Strongwellsea acerosa (bottom) from adult flies Coenosia testacea. Researchers believe the fungus secretes substances that keep its host alive and other living microorganisms fly away from the wound area
The mushrooms go through the cold Danish winters with the help of their thick-walled orange spores and germinate in the spring.
Eilenberg thinks it doesn’t infect a lot of flies, maybe three to five percent, just enough to spread.
“It’s fascinating how the life cycles of these mushrooms are so well adapted to the life of the flies they target,” he said.
Ironically, the horrible life cycle of these parasites could have health benefits for humans.
Researchers believe that mushrooms emit an amphetamine-like substance to keep their hosts up even while their insides are being devoured.
They also probably produce something that keeps other microorganisms away from the wounds of flies.
“We would certainly like to continue our research, as this has the potential to discover and use these substances later, probably in medicine,” said Eilenberg.
The findings were published in the Journal of Invertebrate Pathology.
This is not the only fungus that turns its fly host into a zombie: another genus, massospora, which uses cicadas in a similar way.
Another fungus, Cordyceps, also infects flies, but as a larva.
Another deadly fungus, Cordyceps, infects the fly larva. When the fly matures, it takes control of its muscles, forcing it on the top of the plant. It then sprouts antennae-like stems through its victim’s exoskeleton, which shoots spores on the ground below to infect more insects.
Once the fly matures, the fungus controls its body, forcing it to go to the top of a plant, to freeze and wait for it to die.
Cordyceps then sprouts antennae-like stems through its victim’s exoskeleton, which then shoots spores on the ground below, where the fungus can infect several insects.
Experts initially thought Cordyceps had infected the brains of its hosts, but research published this month showed that it was actually taking over the muscles of the victims.
The researchers described this behavior as “like a puppeteer pulling the strings to make a puppet move.”