Parasitic Crypt-Keeper Wasp Manipulates the Minds of Seven Fellow Insect Species

Crypt-keeper wasps are masters of manipulation.

As researchers reported in 2017, the insect is one of the few parasites capable of altering the behavior of similarly insidious parasites—a practice fittingly dubbed hypermanipulation. Now, a new study published in the journal Biology Letters suggests the crypt-keeper, or Euderus set, is even more powerful than previously believed: In total, the wasp can possess at least seven other insect species.

Per National Geographic’s Jason Bittel, E. set typically lays its eggs in oak tree burrows carved out by Bassettia pallida, a type of parasitic gall wasp. Upon hatching, the larva assumes control of its parasite neighbor, compelling the hapless gall wasp to chew through the wood in a bid for freedom. Unfortunately for the brainwashed wasp, the larva has no intention of letting its victim escape. By forcing the host to create a hole just large enough to expose its head, the crypt-keeper guarantees its own safety—and sustenance—until adulthood.

Needless to say, Kelly Weinersmith—a parasitologist at Rice University who co-authored the original 2017 study describing the crypt-keeper—tells National Geographic, the experience is highly unpleasant for gall wasps. “[Imagine] being stuck inside of a tight tunnel with no room to move, all the while having your insides eaten out,” she says.

Once fully grown, the crypt-keeper leaves the burrow by snacking its way through the gall wasp’s head. Finally, Bittel writes, E. set—named after Set, the Egyptian god of war and chaos—”erupt[s] from B. pallida’s forehead out into the world.”

Insidious wasp gets ahead by tunneling through host's head

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According to New Scientist’s Michael Le Page, researchers initially thought the crypt-keeper targeted just one species of gall wasp. But when a team led by Anna Ward, a biologist at the University of Iowa, collected 23,000 galls as part of a broader study, they realized the true scope of the hypermanipulator’s sway extended to at least 7 out of 100 gall wasp species.

As Eva Frederick reports for Science magazine, Ward and her colleagues counted crypt-keepers parasitizing 305 wasps included in the sample.

Crucially, the biologist tells Le Page, “What we found is that [the crypt-keeper] is attacking different hosts that don’t seem to be closely related.”

Frederick writes that the parasites’ hosts belonged to five diverse genesus. Still, the study notes, victims appeared to share certain characteristics—namely, ones “that may make them vulnerable to attack by E. set.” (Per Science, the wasps generally chose gall hosts lacking fur and spikes.)

According to Cosmos, the scientists’ findings indicate that hosts’ phenotypes, or observable physical properties, may influence crypt-keepers’ victim selection more than the manipulative parasite’s own specialized skill set.

E. set’s name is apt given its proclivity for possessing others. As Weinersmith, co-author of the 2017 study, explains to the Atlantic’s Ed Yong, “Set was the god of chaos and evil, and he was said to control other evil beings. He also locked his brother Osiris in a crypt for him to die.”

Weinersmith concludes, “It kind of blew our minds how many cool connections we could find.”

Meilan Solly | | READ MORE

Meilan Solly is Smithsonian magazine's associate digital editor, history.