Dopamine in Venom of a Parasitoid Wasp Induces Prolonged Grooming in the Cockroach

We are studying the mechanism by which a wasp venom induces a complex behavior when injected into the CNS of its prey. The parasitoid wasp, Ampulex compressa, injects its venom into the head of its prey, the cockroach, Periplaneta americana. The sting is directed towards, and probably penetrates, the subesophageal ganglion (SEG). The venom induces prolonged grooming which lasts for about 30 min alter the injection; control animals groom for only 7 min. This intense grooming behavior is followed by hypokinesia which lasts for several weeks. The goal of this study is to examine whether the venom elicits
grooming via a neuromodulatory system in the cockroach and, if so, to find which neuromodulatory system is affected by the venom. Reserpme, which causes massive release of monoamines, mimics the effect of the venom, inducing excessive grooming. Injection of monoamines into the hemolymph shows that dopamine induces significantly more grooming than serotonin, octopamine, or saline. The dopamine agonist, SKF 82958, induces prolonged grooming when injected directly into the SEG. The dopamine antagonist, flupenthixol, significantly reduces induction of prolonged grooming by the venom. Using GC/MS, we have found that one of the numerous components of
the venom is, in thct, dopamine. We suggest that the venom induces excessive grooming predominantly by acting on a dopaminergic system.