Zombie Wasps Found Infected With Different, Smaller Brain-Eating Wasps

Researchers with Rice University have detailed a new disturbing discovery involving one particular type of wasp and a different, smaller wasp variety that turns them into zombies. The victim is known as the 'crypt gall wasp,' a name given to a type of wasp that tricks live oak trees into forming small 'crypts' in their stems. The wasps' young are raised in these crypts, where they eventually gnaw their way to freedom, but a different parasitic wasp, it turns out, hijacks this process for its own purposes.

This turns out to be a case where one parasite — the wasp that manipulates the tree — is itself subject to a different parasite, one that manipulates the wasp. The gall wasp — also known as Bassettia pallida — grows to maturation within the crypt formed in the tree. Once fully mature, the wasp tunnels its way to freedom by gnawing through the wood into the outside world.

The other type of wasp, though, known as the 'crypt-keeper,' lays its eggs in these crypts, where they infect the gall wasp and manipulate it into tunneling through the tree earlier than usual. The gall wasp tunnels a hole that is just smaller than its head, so that when its tries to exit, its head gets stuck in the hole, blocking it so that critters on the outside can't get in.

Once this happens, the crypt-keeper wasp then eats the trapper gall wasp's organs, feeding itself as it grows in safety. After the crypt-keeper consumes its host, it eats its way through the dead wasp's head, escaping out the hole it manipulated the gall wasp into burrowing. How the crypt-keeper wasp manipulates its host into burrowing through the tree early, however, is unknown at this time.

SOURCE: The Royal Society, Rice University