Parasitoid wasps are the bodysnatchers of the natural world. This rich array of colorful spindly wasps survives by laying eggs in their host's body and hijacking their nervous system, before popping out their chest like a creature from the movie Alien.
Well, arachnids of the world, we’ve got some bad news for you. Scientists from the University of Turku in Finland have recently discovered over a dozen new species of parasitoid wasp in South America that use spiders as their hosts.
Strangest of all, the wasps are able to profoundly manipulate the behavior of the host spiders, effectively turning them into “zombies” and forcing them to spin a unique web that protects the developing pupa.
“The Acrotaphus wasps we studied are very interesting as they are able to manipulate the behavior of the host spider in a complex way," Ilari E Sääksjärvi, professor of biodiversity research at the University of Turku, said in a statement. "During the time period preceding the host spider’s death, it does not spin a normal web for catching prey. Instead, the parasitoid wasp manipulates it into spinning a special web which protects the developing pupa from predators.
“Host manipulation is a rare phenomenon in nature, which makes these parasitoid wasps very exciting in terms of their evolution.”
As described in the journal Zootaxa last week, the 15 new species, which belong to the genus Acrotaphus, were discovered in the lowland rainforests of the Amazon and the cloud forests of the Andes.
The parasitoid Acrotaphus wasps exclusively parasitize spiders. It starts when a female wasp infiltrates a web and temporarily paralyzes the spider with a venomous sting. The wasp then lays a single egg on the spider, which eventually hatches into a larva. The larva gradually consumes the spider's body and exercises its surprisingly complex ability to control its host’s behavior. Eventually, it pupates and breaks out of the spider using saw-like teeth to eat its way through the arachnid's thick skin.
There could be over 100,000 different species of parasitoid wasp, making them one of the most species-rich animal taxa on Earth. However, like many insect species, scientists have not formally described a huge number of them. As a testament to this, the new study has more than doubled the number of known species in the Acrotaphus genus.
“Acrotaphus wasps are fascinating because they are very sizeable parasitoids. The largest species can grow multiple centimeters in length and are also very colorful,” added Diego Pádua, study lead author from Brazil's National Institute of Amazon Research (INPA) and the University of Turku.
“Previously, only 11 species of the genus were known, so this new research gives significant new information on the diversity of insects in rainforests.”