B.C. researchers discover parasitic wasps that hypnotize and feast on spiders

PhilippeFernandez-Fournierwas in Ecuador studying "social" spiders that typicallystay close to their colonies.

So, when one wandered off alone and started spinning a thick, cocoon-like web, he noticed.

"It was very odd ... so I started taking notes," said Fernandez-Fournier, aformer master's student in theUniversity of British Columbia's department of zoology.

Those first notes led to the discovery of a new species of wasp that transforms the sociablespiders into lifeless dronesthat abandon their own colonies to obey the wasp instead.

And, eventually, die to keep the wasp alive.

Egg comes first

The findings,published inEcological Entomologythis fall, detail the unusual parasite-host relationship between the Zatypota wasp and the spider.

It begins when an adult female wasp only about the size of a fingernail lays an egg on the spider's abdomen. When the larva hatches, it latches on to its unlucky host and starts feasting.

The larva slowly takes over the spider's body as it grows, keeping it alive until it'sready to move to a proper nest.

Then, itcommands itsspider to spin a dense, protectivecocoon not far from the colony.

The wasp then kills the spider, devours the corpseand crawls into thecage-like web. An adult waspemergesfully formedafter about 10 days.

Samantha Straus, co-author of the study and a PhD candidate in UBC's department of zoology,said it's not clear how the wasp takes over the spider's brain. Her best guesses are some kind of hormonal or viral influence.

She said the wasps essentially use the spiders to ensure their own survival.

"The environment in Ecuador is intense," Straussaid in a phone interview on Tuesday. "The web is basically a protective cage for the wasp to keep growing."

Parasitic wasps aren't entirely new, but theZatypotaspecies is the only one the authors believe can manipulatesocial spiders.

The Vancouver-based student described the wasphijacking, which was researched over six years,as one of the "coolest"things she's "ever worked on."

So cool, that Strausgot a tattoo of the wasp on her arm keeping with her tradition of getting some kind of tattoo in homage to her various field studies.

"I think they're beautiful," she said, adding:"You have to be a pretty big nerd to think this stuff is cool. WhichI am."