Among the piranhas, anacondas and jaguars of the Ecuadorian Amazon, a newly discovered species of parasitic wasp could be the scariest thing in the jungle.
The wasps "hijack" the brain of spiders living in common canvases and force them to abandon their colonies to protect the wasp larvae. Then, zombie spiders "patiently wait" for food, according to a recent study published in Ecological Entomology.
Researchers specializing in zoology at the University of British Columbia (UBC) have documented this strange relationship after observing the life cycle of parasitoids between the insect not yet described in the Zatypota kind of wasp, and the social Anelosimus eximius spider, in Ecuador. A wasp in the Zatypota Previously, we observed a genus modifying the behavior of a solitary spider. This is the first time a wasp is found zombifying a so-called "social" spider.
According to research, after an adult wasp has laid an egg on the belly of a spider, the larva hatches and attaches to the unlucky arachnid. The larva becomes bigger and more powerful as it feeds on the spider's hemolymph, the equivalent of blood in insects.
Through a behavior modification process, the larva becomes able to manipulate the
decision making spider. According to the study, host spiders appeared to be "zombified" and would "leave the colony and spin a cocoon for the larva before patiently waiting to be killed and consumed".
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Under the protection of the cocoon, the larva regales the dead spider and continues to grow. Nine to eleven days later, the larva emerges from the cocoon in the form of a completely formed wasp, ready to go out and zombie another unfortunate spider.
"Once the larva has become a completely formed wasp, she will go out looking for a companion," co-author Samantha Straus told me in a phone call. "Then the cycle continues."
For scientists, the brutal methods of parasitoid wasps are not a new concept in nature. According to a study published in 2018 in 2018, creatures that lay their eggs on or in the body of other insects and end up eating them are actually one of the most diverse animal groups on Earth. BMC Ecology. But the wasp newly identified in the Zatypota The genre is unique, even among this scary group.
"This behavior change is so difficult," Straus said in a UBC press release. "The wasp completely diverts the spider's behavior and brain and makes it do something it would never do, like leaving its nest and turning on a completely different structure. It's very dangerous for these little spiders.
Researchers suspect that wasps induce this unusual behavior in social spiders by injecting it with hormones that cause it to leave its colony and submit to the larva.
In addition, scientists believe that wasps target these social spiders as they can
provide a large stable host colony and a source of food. They discovered that wasps were more likely to target larger spider colonies.
Straus says she hopes to return to Ecuador to check if the wasps are returning to the same generation-to-generation spider colonies and, if so, what evolutionary benefits might be present.
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