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Wasp masters manipulate zombie spider slaves

Wasp vs spider Larvae of a clever, yet ruthless, wasp turn their spider victim into a zombie before forcing it to frantically build them a home -- and then kill it, a new study has found.

The discovery, which is reported in The Journal of Experimental Biology , represents one of the most extreme acts of host manipulation by a parasite.

The wasp's secret weapon is what the authors describe as an "unusual concentration" of "a manipulative substance," which they suspect is a hormone.

Keizo Takasuka of Kobe Universityand colleagues made the determination after collecting spiders from the species Cyclosa argenteoalba.

The researchers found the spiders at shrines in the cities of Tamba and Sasayama in Japan. Once captured, the spiders were brought back to a lab and observed.

The researchers noticed that some of the spiders had previously been parasitised by the wasp Reclinervellus Nielseni. To do this, the wasp laid eggs either on or within the spider's body.

Then, something really strange happened.

Each of the wasp-infected spiders worked tirelessly for around 10 hours to build an incredibly strong web, complete with a cocoon and even glistening silken "web decorations." All of this happened just before the wasp's larvae were about to pupate.

The webs contained so many fibres that they were anywhere from 2.7- 40 times stronger than the spider's usual webs, meaning the ones that the spider normally creates for itself to rest on and to catch prey.

Once the special webs were built, the wasp larvae moved in, using the spider-made cocoon to pupate. They then lured the spider to the hub of the web. Once there, the hapless spider was killed.

Takasuka and the other researchers suspect the wasp larvae inject a compound into their spider victim. It is comparable to one that the spider naturally produces.

The authors write that "the manipulative substance may react with the spider's endocrine system," leading to the hyperactive and unusual web-building behaviour.

Other parasites control the behaviour of their hosts for selfish reasons. For example, horsehair worms develop inside the bodies of crickets and grasshoppers. The worm parasites manipulate the behaviour of their hosts, often causing them to jump into streams, where the adult worm emerges and goes off on its own before starting the whole cycle again.

In humans, certain parasites can multiply in the brain, leading to behavioural changes that may include everything from memory loss to self-mutilation.

Related: Fungus turns Amazonian ants into zombies

This article originally appeared on DiscoveryNews.com