Wasps create zombie spiders by laying their eggs inside them

Certain species of parasitoid wasps lay their eggs on spiders’ backs and their larvae can control their brains after hatching, according to a new study.

Soon after the larvae emerge they effectively take control over the spider’s mind and force it to build an unusual web which acts as a cocoon for the wasp larva. 

The young wasp eats the spider when the web is done and, when the arachnid serves no purpose, the insects encompass themselves with its before emerging as adult wasps.

It was already known that some species of wasps and spiders but how it takes control of their mind was not. 

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After eating the spider, this wasp is now in its pupal stage and hangs from the spider’s cocooning web (pictured). Researchers think that it will then use a hormone called ecdysone to change the spider’s behaviour so that it spins a special kind of web

Now researchers, from the Smithsonian Tropical Research Institute, suggest that the wasp takes on the hijacks the spiders’ molting behaviour. 

Molting in spiders is when they shed their exoskeletons to allow them to grow a larger cuticle exoskeleton.

The process usually takes place in a web as it makes them vulnerable to an attack by a predator because it takes a while for the soft exoskeleton to harden

The researchers said that spiders that had just built cocoon webs had high levels of a hormone called ecdysone in their bodies.

This hormone is known to play a big role in the spider’s moulting cycle.

In response, the spider builds a special, protective type of web before they are eaten by the wasp.

Now researchers, from the Smithsonian Tropical Research Institute, suggest that the wasp takes on the hijacks the spiders’ moulting behaviour. After the web is built, the wasp larva eats the hapless spider

Certain species of parasitoid wasps lay their eggs on spiders’ backs so that their larvae can control their brains, according to a study. Pictured, here, a wasp getting ready to attack a spider

The team suggest that the wasp larvae inject extra ecdysone into the creature, essentially tricking it into thinking it’s time to molt.

‘Now that we have a proposed mechanism, we can ask a new set of questions,’ said William Eberhard, co-author of the study. 

‘Because the lines in spider webs represent precise records of their behavior, we could study ‘zombification’ in unprecedented detail by looking at the lines in cocoon and molting webs. 

‘We discovered that both web types vary, and more importantly, that the variations only overlap partially. 

‘The larvae probably tweak the spider’s molting web construction behavior to gain added protection. 

‘The mechanisms by which these additional modifications are obtained may result from differences in the timing or amounts of ecdysone, or modifications in the ecdysone molecules themselves, but they remain to be documented.’  

The study was published in the Biological Journal of Linnean Society.

WHAT IS A PARASITOID?

Parasitoids are insects with parasitic larvae that eat their host – usually another insect – from the inside out.

They often employ a sharp tool known as an ovipositor to deposit eggs under the skin or exoskeleton of unsuspecting hosts.

After a short gestational period, the larvae hatch and begin consuming their host, normally reaching adulthood when the host has died.

Parasitoid species are mostly types of bee, wasp and ant, though some species of fly also employ the gruesome technique.

The biology of parasitoids has inspired several science fiction authors and scriptwriters to create parasitoidal aliens that kill human hosts, including the infamous Xenomorph in Ridley Scott’s 1979 film ‘Alien’.

Parasitoids are insects with parasitic larvae that eat their host – usually another inset – from the inside out. Pictured is a parasitic wasp that injects larvae into spiders and then sews the host into its nest to pin it down