Emerald cockroach wasp

Emerald cockroach wasp
Ampulex compressa
Scientific classification
Kingdom:Animalia
Clade:Euarthropoda
Class:Insecta
Order:Hymenoptera
Family:Ampulicidae
Genus:Ampulex
Species: A. compressa
Binomial name
Ampulex compressa
(Fabricius, 1781)
Synonyms
  • Ampulex sinensis Saussure, 1867
  • Chlorampulex striolata Saussure, 1892
  • Sphex compressus Fabricius, 1781

The emerald cockroach wasp or jewel wasp (Ampulex compressa) is a solitary wasp of the family Ampulicidae. It is known for its unusual reproductive behavior, which involves stinging a cockroach and using it as a host for its larvae. It thus belongs to the entomophagous parasites.

Distribution

The wasp is mostly found in the tropical regions of South Asia, Africa, and the Pacific islands. The flying wasps are more abundant in the warm seasons of the year.

A. compressa was introduced to Hawaii by F.X. Williams in 1941 as a method of biocontrol. This has been unsuccessful because of the territorial tendencies of the wasp, and the small scale on which they hunt.[1]

The species is also found in the Brazilian states of São Paulo and Rio de Janeiro. A. compressa likely arrived in the country through the ports of Santos and Rio de Janeiro.[2]

Description

The wasp has a metallic blue-green body, with the thighs of the second and third pair of legs red. The female is about 22 mm long; the male is smaller and lacks a stinger.[1]

Reproductive behavior and lifecycle

As early as the 1940s, female wasps of this species were reported to sting a cockroach (specifically a Periplaneta americana, Periplaneta australasiae, or Nauphoeta rhombifolia)[1] twice, delivering venom. A 2003 study[3] using radioactive labeling demonstrated that the wasp stings precisely into specific ganglia of the roach. It delivers an initial sting to a thoracic ganglion and injects venom to mildly and reversibly paralyze the front legs of its victim. The biochemical basis of this transient paralysis is discussed in a 2006 paper.[4] Temporary loss of mobility in the roach facilitates the second venomous sting at a precise spot in the victim's head ganglia (brain), in the section that controls the escape reflex. As a result of this sting, the roach will first groom extensively, and then become sluggish and fail to show normal escape responses.[5] In 2007, the venom of the wasp was reported to block receptors for the neurotransmitter octopamine.[6]

Wasp 'walking' a roach

The wasp proceeds to chew off half of each of the roach's antennae.[1] Researchers believe that the wasp chews off the antenna to replenish fluids or possibly to regulate the amount of venom because too much could kill and too little would let the victim recover before the larva has grown. The wasp, which is too small to carry the roach, then leads the victim to the wasp's burrow, by pulling one of the roach's antennae in a manner similar to a leash. In the burrow, the wasp lays a white egg, about 2 mm long, on the roach's abdomen. It then exits and proceeds to fill in the burrow entrance with pebbles, more to keep other predators out than to keep the roach in.

With its escape reflex disabled, the stung roach simply rests in the burrow as the wasp's egg hatches after about 3 days. The hatched larva lives and feeds for 4–5 days on the roach, then chews its way into its abdomen and proceeds to live as an endoparasitoid. Over a period of 8 days, the wasp larva consumes the roach's internal organs in an order which maximizes the likelihood that the roach will stay alive, at least until the larva enters the pupal stage and forms a cocoon inside the roach's body. Eventually, the fully grown wasp emerges from the roach's body to begin its adult life. Development is faster in the warm season.

Adults live for several months. Mating takes about a minute, and only one mating is necessary for a female wasp to successfully parasitize several dozen roaches.

While a number of venomous animals paralyze prey as live food for their young, A. compressa is different in that it initially leaves the roach mobile and modifies its behavior in a unique way. Several other species of the genus Ampulex show a similar behavior of preying on cockroaches.[1] The wasp's predation appears only to affect the cockroach's escape responses. While a stung roach exhibits drastically reduced survival instincts (such as swimming, or avoiding pain) for about 72 hours, motor abilities such as flight or flipping over are unimpaired.[7][8]

Biomechanics

The first sting is delivered to the prothoracic ganglion (mass of nerve tissue) which causes a 2– to 3-minute paralysis of the front legs. This sting injects significant quantities of γ amino-butyric acid (GABA) and complementary agonists taurine and β alanine. The concoction temporarily blocks the motor action potentials in the prothoracic ganglion by depressing cholinergic transmission through the increased chloride conductance across nerve synapses. Individually, all of these substances induce short-term paralysis of the cockroach. When they are injected together in a ratio of 10:7:4, the effect was longer lasting. GABA activates ligand-gated chloride channels by binding to GABA receptors. Taurine and beta-alanine likely extend the duration of the paralytic affect by slowing the uptake of GABA by the synaptic cleft. Combined, this cocktail of compounds prevents the cockroach from moving and defending itself while the wasp administers the second sting/series of stings.

The second sting is administered to the subesophageal ganglion (SEG) and is much more precise, hence the need for paralysis and is significantly longer. The wasp actively searches for the SEG during this sting. The second sting inhibits the cockroach's ability to walk spontaneously, or of its own will, but cockroaches can right themselves and swim while under the influence, and when startled, will jump but not run. It also causes excessive grooming and alterations in the metabolism of the cockroach. The metabolic change is thought to preserve nutrients for the wasp larva. Researchers have simulated this zombie state by injecting procaine into the SEG. They also determined using extracellular bipolar electrodes that neuronal activity was less in stung cockroaches. The venom may disturb the octopaminergic modulation in structures within the roach's ganglion. Basically, it limits the effectiveness of octopamine, the neurotransmitter that controls muscle contraction in sudden movements.[9][10]

See also

References

  1. 1 2 3 4 5 Williams, F. X. (1942). "Ampulex compressa (Fabr.), a cockroach-hunting wasp introduced from New Caledonia into Hawaii". Proc. Hawaiian Entomological Society. 11: 221–233.
  2. ↑ "Vespa Joia". Insetologia. 8 October 2012. Retrieved 7 December 2017.
  3. ↑ Haspel, Gal; Ann Rosenberg, Lior; Libersat, Frederic (2003). "Direct Injection of Venom by a Predatory Wasp into Cockroach Brain" (PDF). Journal of Neurobiology. 56 (4): 287–292. doi:10.1002/neu.10238.
  4. ↑ Moore, Eugene L.; Haspel, Gal; Libersat, Frederic; Adams, Michael E. (July 2006). "Parasitoid wasp sting: A cocktail of GABA, taurine, and β-alanine opens chloride channels for central synaptic block and transient paralysis of a cockroach host". Journal of Neurobiology. 66 (8): 811–820. doi:10.1002/neu.20262.
  5. ↑ Gal, Ram; Rosenberg, Lior Ann; Libersat, Frederic (22 November 2005). "Parasitoid wasp uses a venom cocktail injected into the brain to manipulate the behavior and metabolism of its cockroach prey". Archives of Insect Biochemistry and Physiology. 60 (4): 198–208. doi:10.1002/arch.20092. PMID 16304619.
  6. ↑ How to make a zombie cockroach, Nature News, 29 September 2007
  7. ↑ Yong, Ed (June 5, 2008). "The wasp that walks cockroaches". Not Exactly Rocket Science News. Archived from the original on 2008-06-12. Retrieved 2008-07-14.
  8. ↑ Libersat, Frederic (June 27, 2003). "Wasp uses venom cocktail to manipulate the behavior of its cockroach prey" (PDF). Journal of Comparative Physiology. Springer-Verlag. 189: 497–508. doi:10.1007/s00359-003-0432-0.
  9. ↑ Jewel Wasps. YouTube. YouTube, 19 Feb. 2009. Web. 10 Dec. 2012.
  10. ↑ Banks, CN; Adams, ME. "Biogenic amines in the nervous system of the cockroach, Periplaneta americana following Envenomation by the Jewel Wasp, Ampulex Compressa". Toxicon. 59: 320–328. doi:10.1016/j.toxicon.2011.10.011. PMID 22085538.
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