The jewel wasp’s venom is potent on two levels. With the first stab of its stinger, the wasp paralyzes the much larger cockroach. The neurotransmitter GABA, inserted into the thorax of the cockroach, causes temporary paralysis by shutting down motor neurons. The paralysis allows for the second stab — a perfectly targeted attack on a specific area of the cockroach brain (the subesophageal and supraesophageal ganglion). Scientists think a dopamine-like compound in the venom causes the careful cleaning behavior, while the GABA again works to shut down neurons, to ensure the cockroach doesn’t run away. This guarantees it will be there waiting to be eaten alive by the wasp’s offspring. That’s a pretty horrific way to die!
For more info:
Kaiser, M., & Libersat, F. (2015). The role of the cerebral ganglia in the venom-induced behavioral manipulation of cockroaches stung by the parasitoid jewel wasp. Journal of Experimental Biology, 218(7), 1022-1027.