15 new species of parasitic wasp discovered that "zombify" spiders
Consider yourself lucky that you’re not a spider. They may seem like they sit on top of the food chain in the bug world, but they’re vulnerable to an even worse fate than just being eaten: falling prey to parasitic wasps that infect and essentially “zombify” them. And now, researchers have discovered 15 new species of these wasps.
Parasitoid wasps prey on spiders in a particularly cruel way. Females are known to attack and sting a spider, which temporarily paralyzes it, allowing the wasp to lay an egg on its back. Once the larva hatches, it hijacks the nervous system of the poor host spider and forces it to build a special type of web that resembles a cocoon. The wasp larva then curls up in this protective web to pupate into an adult – but not before it eats the hapless spider.
And now, researchers from University of Turku and the Brazilian INPA (National Institute of Amazonian Research) have expanded the number of known species that practice this parasitic behavior. The genus Acrotaphus has now grown by 15 new species, more than doubling the 11 that were already known. These were all found living in the tropical Andes and the lowland rainforests of the Amazon.
“The Acrotaphus wasps we studied are very interesting as they are able to manipulate the behaviour of the host spider in a complex way,” says Ilari E. Sääksjärvi, an author of the study. “Host manipulation is a rare phenomenon in nature, which makes these parasitoid wasps very exciting in terms of their evolution.”
Rare as it may be, it’s not the only insect horror story we’ve heard. The crypt-keeper wasp, discovered in 2017, was found to lay its eggs in the nests of gall wasps. Normally the gall wasp will dig its way out through tree bark once it’s matured, but the crypt-keeper wasp has other plans. Its larvae will manipulate the gall wasp into making its tunnel too small, so that its head gets stuck when it tries to escape. Then the parasitic wasp will eat its unfortunate host, tunnelling through its body to freedom.
And then there’s the story of the “zombie ant” fungus. The parasitic fungus infects carpenter ants with spores, driving the insects to climb up into the plant canopy and find a nice spot on the underside of a leaf or stick. There the ant is forced to clamp its mandibles shut, latching on while the fungus devours the poor bug from the inside. Over the course of a few days, a stalk will grow out of the ant’s head, eventually releasing new spores down to the unsuspecting ants below, where the cycle is repeated.
Hollywood, if you're listening: nature is handing you some free horror movie ideas here.
The research was published in the journal Zootaxa.
Source: University of Turku