The crypt-keeper wasp, Euderus set.

Ryan Ridenbaugh and Miles Zhang

Crypt keeper wasp is a parasite of a parasite

You can’t play a player, but you can parasitize a parasite. That’s what researchers discovered was happening to the crypt gall wasp (Bassettia pallida), which lays eggs in the stems of certain oaks. The larvae’s presence causes compartments dubbed crypts to form and protect them until they chew through the stem to emerge in adulthood. But just as the crypt gall wasp manipulates this plant to become its home, a newly discovered species also seems to manipulate the crypt gall wasp to do its bidding. The new species—known as the crypt keeper wasp (Euderus set, pictured) deposits its egg within the crypt—likely inside the adult crypt gall wasp—and triggers the crypt gall wasp host to stop digging through the stem, plugging its exit hole with its own head partway out of the tree. The adult crypt keeper wasp then pops out of the tree with very little effort of its own, after consuming the crypt gall wasp from the inside out. The extra help appears critical for the crypt keeper’s survival—those that had to leave the tree by digging through bark themselves were almost three times more likely to die trapped in the crypt, the scientists report today in the Proceedings of the Royal Society B. In future research, the scientists hope to verify that the crypt keeper is really the puppet master behind its host’s strange behavior by uncovering exactly how it pulls the strings.