Scientists have accidentally discovered a previously unknown species of parasitic wasp that grows inside the bodies of living flies before bursting out of their stomachs like a xenomorph from the ‘Alien’ movies.
A team of researchers stumbled upon this new wasp species – now named S. perlmani – while collecting fruit flies in their backyards in Mississippi.
This is the first wasp found to infect adult fruit flies. Other parasitic wasp species only target fruit flies during their early larva and pupa life stages.
S. perlmani use their needle-like ovipositor organ to stab into a fruit fly’s abdomen and deposit an egg inside. The egg then hatches into a wasp larva, which grows inside the fly for 18 days before exploding out of its host and leaving it to die.
S. perlmani is a newly discovered species of parasitic wasp that grows inside a fruit fly and then bursts out of its abdomen, leaving its host fatally wounded
‘It will effectively emerge out of the side of the fly,’ study lead author and Mississippi State University biologist Logan Moore told Live Science.
‘And just to add an additional layer of horror, the fly will normally remain alive for several hours after that.’
Moore and his team published their findings Wednesday in the journal Nature.
The researchers ultimately performed DNA analysis that revealed the wasps are present across the eastern US. What’s more, Moore and his colleagues were able to find them in Mississippi, Alabama and North Carolina.
But when they first stumbled upon this species in March 2023, they thought it was a fluke.
‘At the time we didn’t think it was real,’ Moore said. ‘If you dissect thousands of flies, you will see some things that are strange and odd, and you’ll never see them again.’
The team was actually hunting for a different parasite when they made their discovery – screening fruit flies for parasitic worms called nematodes.
But spiky-tailed wasp larvae in the abdomens of some of the flies caught their attention.
S. perlmani’s life strategy resembles that of the xenomorphs from the ‘Alien’ movies
The researchers collected these parasite-infected fruit flies and brought them to the lab to observe how the wasp larvae developed and study their DNA.
Once the larvae matured, the wasps exited their hosts, explored their new environment for a few hours and then buried themselves in a substrate provided by the researchers.
The wasps then entered a 23-day-long cocoon stage to finish their growth before emerging as adults.
The researchers paired the adult wasps with various species of fruit flies from the genus Drosophila to see which types of flies they would infect.
When the team first discovered the wasp larvae in their backyards, they had infected a species of fruit fly called Drosophila affinis. But they wanted to find out whether these wasps could infect other fruit fly species too.
After the lab-grown adult wasps emerged from their cocoon stage, the researchers paired them with different species of fruit flies from the genus Drosophila. They found that the wasps were also able to infect Drosophila acutilabella.
Adult S. perlmani wasps are able to parasitize multiple different species of fruit fly
The researchers also found the wasps’ DNA signature in a public database of Drosophila melanogaster genomic data, indicating that the wasp can parasitize this species too.
Scientists have using fruit flies as research subjects for centuries – mainly because they’re easy to find, breed and study.
This begs the question, why has a parasite that targets such a well-studied insect never been discovered until now?
‘I would say maybe the one thing that would explain why it’s gone undiscovered for so long is because nobody is expecting it,’ Moore said.
‘No parasitoid wasp has been known to infect the adult stage of not just Drosophila, but of flies in general.’
That’s because the early stages of insects, such as larvae and pupae, are much more vulnerable to parasitic attacks. They don’t have an exoskeleton to protect them, and they don’t have wings to help them escape, Moore explained.
Scientists still have much to learn about this new wasp species.
‘This is all around us, infecting one of the most well-studied animals on the planet,’ Moore said. ‘It just leaves you wondering what else is out there on our doormat right now.’
