January 26, 2017

New ‘Crypt keeper’ wasp species might be the creepiest thing we’ve ever seen

Researchers have found a new wasp species with a life cycle so unpleasant; they named it after Set, the Egyptian god of evil and mayhem.

Indigenous to the southeastern United States, the wasp, which scientists nicknamed the crypt-keeper, lays its egg within the small, wooden compartments a different wasp species, the gall wasp (Bassettia pallida), builds inside live sand oak trees.

As soon as the egg hatches, the E. set larva digs into the other wasp and takes control of its brain, compelling it to tunnel out of the tree, a task the crypt-keeper has a hard time doing by itself.

In a final cruel twist, the E. set larva then causes its host to punch out a hole not quite big enough for it to escape. After the bigger wasp is stuck in the hole it’s burrowed, the crypt-keeper eats its host from within, finally erupting from the host’s head and out into the world.

The wasp and its insidious behavior was detailed in two recently published papers: one in the journal ZooKeys and the other in the Proceedings of the Royal Society B.

How to study such an insidious creature

To see how effective E. set could tunnel on its own, study researchers taped slender strips of bark over the dead heads of the host wasp and waited. The trials revealed the crypt-keeper was around three times more prone to perish in the crypt if it had to burrow through both the head and the bark. The experiment revealed just how much the crypt-keeper needs a host.

"It could be the parasitoid (E. set larva) cues hosts to excavate early, but makes them do it less well than usual," study author Kelly Weinersmith, a research fellow at Rice University, said in a news release . "They only go part way and then they get stuck.

"That's what I love about parasite manipulation of host behavior," she said. "So many of the stories that have been uncovered are just as cool as the coolest science fiction movie."

The study team said they plan to investigate how E. set causes the change in Bassettia's behavior.

"One hard thing is that we can't see what's happening until they come out," Weinersmith said. "We're talking to people to see if we can CAT scan the branches in various stages."


Image credit: Ryan Ridenbaugh and Miles Zhang