Tuesday, 21 July 2009

Manipulation of Cockroach by Parasitic Wasp

A friend posted this on Facebook - so I repost it here.

The movie (adapted from "The wasp Ampulex compressa, a predator of the cockroach Periplaneta americana" by Wijnand Heitmans; University of Amsterdam, 1986) shows the main events in the life cycle of A. compressa and the manipulation of its cockroach host.
(1) Struggle: A parasitoid wasp locates a cockroach and grabs it by the pronotum. (2) Head sting: The wasp injects a venom cocktail into the prey's cerebral ganglia. The cockroach shown here was anaesthetized and tethered to allow filming from below. (3) Host feeding: The wasp cuts the cockroach's antennae and feeds off hemolymph from the cut end. Notice that the cockroach does not escape the wasp, although it is not paralyzed. (4) Host transportation: The wasp grabs the cockroach by the antenna stump and walks backward toward its nest, while the cockroach follows in a docile manner. Notice the expression of an alternating-tripod gait when the cockroach is following the wasp. (5) Host concealment: The cockroach is inserted into the wasp's nest without resisting or trying to escape. (6) Oviposition: The wasp lays one egg on the cockroach leg and exits the nest. The cockroach stays at the same spot, although it is not paralyzed. (7) Entombment: The wasp collects nearby pieces of paper and seals the entrance to the nest, while the cockroach waits inside. (8) Egg and larval development: A larva hatches from the egg, feeds on hemolymph (not shown), then penetrates the cockroach and consumes the internal organs. It is only at this stage that the cockroach dies and the larva pupates inside the cockroach abdomen. (9) Hatching: around 40 days after the egg has been laid, an adult wasp hatches from the cockroach's abdomen and exits the nest.

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