A special thanks to Christoph Röhrs for helping me finding the wasps in captivity and to Franco Casini for the same help about finding the cockroaches (this last task could seem easier, but it’s not!)

The wasps with the passion for horror: Ampulex compressa

Sometimes the microcosm tells stories that could stir the imagination of every horror movie maker. And when it comes to parasites and parasitoids, no fantasy monster could rival the real ones created by nature in millions years of evolution.

They’re called “wasps” because of their appearance, but they’re more precisely a type of bee (Superfamily Apoidea): the Emerald or Jewel wasp Ampulex compressa. The female needs big and heavy cockroaches (mainly Periplaneta americana) to feed its larva, but can’t carry it to the burrow like other wasps do with their hosts. So it transports it by…. a leash! This species evolved a really amazing behaviour, being able to grasp the roach with powerful jaws and sting it directly on two precise parts of the nervous system. The first one partially and reversibly paralyzes the first pair of legs while the second “magic” one obliterates JUST the escape reflexes, leaving the cockroach unharmed but converted in a sort of zombie. In this way she will be able to pick it at one antenna and take it to a burrow, where she will deposit an egg and then bury the roach aliveto avoid predation by bigger animals. After a few days the larva emerges and starts feeding on the roach from the outside like a vampire. But when it will be bigger, it will eventually enter in the roach’s body and eat it from inside. In the end the big fat larva in the empty dead roach will pupate to give birth in a month to a new and beautiful Emerald wasp, which will emerge from the roach’s body like an Alien of the famous movie series.

related articles:
– Libersat, Frederic (June 27, 2003). “Wasp uses venom cocktail to manipulate the behavior of its cockroach prey” (PDF). Journal of Comparative Physiology (Springer-Verlag) 189.
– How to make a zombie cockroachNature News, 29 September 2007
– Gal, Ram; Rosenberg, Lior Ann; Libersat, Frederic (22 November 2005). “Parasitoid wasp uses a venom cocktail injected into the brain to manipulate the behavior and metabolism of its cockroach prey”Archives of Insect Biochemistry and Physiology 60 (4): 198–208.

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