Biogenic amines in the nervous system of the cockroach, Periplaneta americana following envenomation by the jewel wasp, Ampulex compressa

Abstract

The emerald jewel wasp, Ampulex compressa, exploits the American cockroach, Periplaneta americana, as a host for its progeny. The wasp subdues the host by stinging directly into the brain and subesophageal ganglion, inducing long-term hypokinesia. The hypokinesic host lacks normal escape behavior and motivation to walk, making it easy for subjugation by the wasp. The mechanism underlying hypokinesia induction is not known, but depletion of monoamines induces behavior resembling venom-induced hypokinesia. To test whether amine depletion occurs in stung animals, we used high-performance liquid chromatography with electrochemical detection (HPLC-ED) to measure quantitatively amine levels in the central nervous system. Our data show clearly that levels of dopamine, serotonin, octopamine and tyramine remain unchanged in stung animals, whereas animals treated with reserpine exhibited marked depletion of all amines sampled. Furthermore, stung animals treated with reserpine show depletion of amines, demonstrating that envenomation also does not interfere with amine release. These results show that hypokinesia induced by Ampulex venom does not result from amine depletion or inability to release monoamines in the central nervous system.