Terrifying new wasp discovered in the Ecuadorian, Amazon turns spiders into zombies to house its larvae that eats them alive from the inside.
The wasp “hijacks” the brains of spiders known to live in communal webs and force them to abandon their colonies and protect the wasp’s larva for them. Then, the zombie spiders “wait patiently” to be eaten, according to a recent study published in Ecological Entomology.
“Wasps manipulating the behaviour of spiders has been observed before, but not at a level as complex as this,” said University of British Columbia researcher Philippe Fernandez-Fournier.
The social Anelosimus eximius spider in its colony Credit: PHILIPPE FERNANDEZ-FOURNIER
“Not only is this wasp targeting a social species of spider but it’s making it leave its colony, which it rarely does.”
Researchers specialising in zoology from the University of British Columbia (UBC) documented this bizarre relationship after observing the parasitoid life cycle between the previously undescribed insect in the Zatypota genus of wasp, and the social Anelosimus eximius spider, in Ecuador.
A wasp in the Zatypota genus was previously observed modifying the behaviour of a solitary spider, this is the first time a wasp has been found zombifying a so-called “social” spider.
These spiders are notable for living together in large colonies, cooperating on prey capture, sharing parental duties and rarely straying from their basket-shaped nests.
Anelosimus eximius spider with wasp larvae on it abdomen Credit: PHILIPPE FERNANDEZ-FOURNIER
Researchers noticed some of the spiders were infected with a parasitic larva and were seen wandering away from their colonies to spin enclosed webs.
Intrigued, he carefully took a few of the structures, known as ‘cocoon webs’ back to his lab to see what would emerge from the depths. To his surprise, it was a parasitic wasp.
"It was very odd because they don’t normally do that, so I started taking notes," said Fernandez-Fournier.
According to the research, after an adult female wasp lays an egg on the abdomen of a spider, the larva hatches and attaches itself to the unlucky arachnid. The larva grows larger and more powerful as it proceeds to feed on the spider’s hemolymph, the equivalent to blood in insects.
The spiders then spins a protective cocoon for the wasp's larvae Credit: PHILIPPE FERNANDEZ-FOURNIER
Through a behaviour-altering process, the larva becomes capable of manipulating the spider’s decision-making. Host spiders appeared to be “zombified,” according to the study, and would “exit the colony and spin a cocoon for the larva before patiently waiting to be killed and consumed." The cocoon is of a completely different structure to the webs the spider would usually spin.
It's not known how the wasps do this, but scientists believe it may be caused by an injection of hormones that make the spider think it's in a different life-stage and cause it to disperse from the colony. The scientists think the wasps are targeting these social spiders because they can provide a large, stable host colony and food source. They found that wasps were more likely to target larger spider colonies.