Tuesday, February 14, 2012

Ampulex Compressa: Roach Assassin

Introduction: The female Ampulex Compressa, more commonly known as the emerald jewel wasp lays her eggs on the abdomen a living Periplaneta Americana (American cockroach), where they hatch and invade the cockroach to feed on its internal organs until it reaches maturity [2]. This parasitoid relationship begins with two very precise stings from the wasp that induce a zombie-like state in the host. The A. Compressa specifically parasitizes the P Americana, causes no diseases, and is commonly found in South Asia, Africa, and the Pacific Islands [1].

Symbiont Description: A. Compressa is of the family Ampulicidae and much smaller than the American cockroach that it infects; however, due to the toxic, but non-lethal, effects of its venom, the wasp can control it's host with two strategic stings first to the prothoracic region and then to the brain of its host. Only the female wasps carry out this process. The first sting paralyzes the front legs of the roach for two to three minutes allowing the roach time to inject its venom into the roach's head ganglia [2]. This second sting causes the roach to be compliant to the wasps, which will lead the roach into a burrow by pulling one of its antennae in a "dog on a leash" fashion [3]. Once in the burrow, the adult female wasp will lay her egg on the abdomen of the roach and barricade the roach in the burrow. After the egg hatches, the larva invades body cavity of the live roach and begins feeding on the internal organs as it matures.


Host: The Periplaneta Americana, American cockroach,  is the only host of the A. Compressa; therefore, the emerald jewel wasp is a holoxenous parasite [4]. The wasp will reach sexual maturity within the host, however, it will not reproduce within the host. The roach will die due to it being inhabited by the wasp making this a parasitoid relationship.

Life Cycle: The A. Compressa, as previously stated will lay its egg on the abdomen of the P. Americana and barricade the roach into a burrow. With the roach still alive, but subdued by the adult female wasp's venom, it will serve as a great source of nourishment for the larva after the egg hatches. This larvae will invade the roach's body and begin eating its internal organs. The larva will reach maturity while hollowing out and killing the roach. After about six weeks, the A. Compressa will reach full maturity and leave the roach's body to find other wasps to mate and continue the cycle [1].

Ecology: Since the A. Compressa only infects the  P. Americana, there is not a great deal of distribution of the wasp species. As previously stated the wasp is mostly in South Asia, Africa, and the Pacific Islands. No diseases are caused by this wasp, only the "zombie effect" it has over its host [2]. This effect is only caused by the injection of its highly specialized venom into the brain of the roach [1]. Humans are not affected by this parasite; however, these wasps were introduced to some Pacific Islands in hope of diminishing the roach population. These attempts failed due to the extremely territorial behavior of the A. Compressa [2].

An example of closed compatibility filter and parasitoidism: Because the A. Compressa is highly specialized to parasitize the American cockroach, the compatibility filter is closed to all other animals. The encounter filter is still open to other animals who share an environment with the wasp; however, the compatibility filter is closed and other species cannot be affected by the wasp [4].  The relationship between A. Compressa and P. Americana is a great example of parasitoidism, in which a parasites infection of a host directly leads to the host's death.

Video about the emerald jewel wasp:

[1] Haspel, Gal, Lior Ann Rosenberg, and Frederic Libersat. "Direct Injection of Venom by a Predatory                                               Wasp into Cockroach Brain." Journal of Neurobiology 56.3 (2003): 287-92.    

[2] Hopkin, Michael. "How to Make a Zombie Cockroach : Nature News." Nature Publishing Group : Science Journals, Jobs, and Information. Web. 14 Feb. 2012. 

            [3] Keasar, Tamar, Noa Sheffer, Gustavo Glusman, and Frederic Libersat. "Host-Handling Behavior: An Innate   Component of Foraging Behavior in the Parasitoid Wasp Ampulex Compressa." Ethology 112.7 (2006): 699-706. Print.

[4] Combes, Claude. Parasitism: The Ecology and Evolution of Intimate Interactions. Chicago: 2001.

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