Asian giant hornet
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| Vespa mandarinia Smith, 1852 |
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For general information see hornet, and the related European hornet.
The Asian giant hornet (Vespa mandarinia, known colloquially as the Yak Killer hornet), the world's largest wasp, is a native of temperate and tropical Eastern Asia. Its body length is between 27 mm (1.1 inches) and 45 mm (1.8 inches), with a wingspan of about 76 mm (3 inches). Queens may reach a length of 55 mm (2.2 inches).
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[edit] Anatomy
The head of the hornet is orange and quite wide in comparison to other hornet species. The compound eyes and ocelli are dark brown, and the antennae are dark brown with orange scapes. The clypeus (the shield-like plate on the front of the head) is orange and coarsely punctured; the posterior side of the clypeus has narrow, rounded lobes. The mandible is large and orange with a black tooth (inner biting surface).
The thorax and propodeum (the segment which forms the posterior part of the thorax) of the Asian giant hornet has a distinctive golden tint and a large scutellum (a shield-like scale on the thorax) that has a deeply-impressed medial line; the postscutellum (the plate behind the scutellum) bulges and overhangs the propodeum. The hornet's forelegs are orange with dark brown tarsi (the distal - furthest down - part of the leg); the midlegs and hindlegs are dark brown. Wings are a dark brownish-gray. The tegulae are brown.
The gaster (the portion of the abdomen behind the thorax-abdomen connection) is dark brown with a white, powdery covering; with narrow yellow bands at the posterior margins of the tergite, the sixth segment is entirely yellow.
[edit] Geographic distribution
It can be found in Primorsky Krai, Korea, China, Taiwan (where it is called the "tiger bee"), Indochina, Nepal, India and Sri Lanka, but is most common in Japanese mountains. One was also spotted in a warehouse in Hanwell, West London.
[edit] "Hornets From Hell"
[edit] Sting
The stinger of the Asian giant hornet is about a quarter-inch (6 mm) in length, and injects an especially potent venom that contains an enzyme so strong that it can dissolve human tissue. Masato Ono, an entomologist at Tamagawa University near Tokyo, described the sensation as feeling "like a hot nail through my leg." [1].
If a person is stung by the giant hornet and does not receive prompt medical treatment, he or she may die from a reaction to the venom. About 40 people die each year after being stung by giant hornets, mainly as a result of an allergic reaction to the venom.
A couple of interesting notes on Vespa mandarinia's venom and stinger:
- The venom contains 5% acetylcholine, which stimulates the pain nerve fibres more than bee or other wasp venoms, so that it is a bit more painful.
- Vespa mandarinia uses its large crushing mandibles, rather than its sting, to kill prey.
- The venom of the Asian giant hornet is more toxic than most other bees or wasps, and has one of the greatest lethal capacities per colony
- Like all hornets, V. mandarinia possesses a barbless stinger, allowing it to sting repeatedly, as it does when preying on bees and other insects.
[edit] Predation
The Asian giant hornet is a relentless hunter that preys on other large insects such as bees, other hornet species, and praying mantises.
The hornets often attack honey bee hives with the goal of obtaining the honey bee larvae. A single scout, sometimes two or three, will cautiously approach the nest, giving off phermones which will lead the other hornets to the hive's location. The hornets can devastate a colony of honey bees: a single hornet can kill as many as 40 honey bees per minute; it takes only a few of these hornets a few hours to exterminate the population of a 30,000-member hive, leaving a trail of severed insect heads and limbs. Once a hive is emptied of all defending bees, the hornets carry the honey bee larvae back to feed to their own larvae.
Rather than consume their kills directly, the hornets chew them into a paste and feed them to their larvae (adult hornets being unable to digest solid protein). The hornet larvae, in return, produce a clear liquid called vespa amino acid mixture which the adults consume[1]. It is believed this high-energy food may play a part in the adults' performance: they can fly up to 60 miles in a single day, at speeds up to 25 MPH[1][2].
[edit] Native Honey Bees
Although a handful of Asian giant hornets can easily defeat the defenses of honey bees, whose correspondingly small sting cannot inflict much damage against such a large predator as the giant hornet, the Japanese honey bee (Apis cerana japonica) has evolved a method of defending against the much larger predator.
When a hornet scout locates a Japanese honey bee hive and approaches the nest, the scout will emit specific pheromonal hunting signals. When the honey bees detect these pheromones, a hundred or so will gather near the entrance of the nest and keep it open, apparently to draw the hornet further into the hive or allow it to enter on its own. As the hornet enters the nest, a large mob of about five hundred honey bees surround the hornet, completely covering it and preventing it from moving, and begin quickly vibrating their flight muscles. This has the effect of raising the temperature of the honey bee mass to 47 °C (117 °F). Though the honey bees can tolerate such a temperature, it is fatal to the intruder, which can handle a maximum temperature of about 45 °C (113 °F), and is effectively baked to death by the large mass of vibrating bees. Often several bees perish along with the intruder in this way, having sacrificed themselves for the good of the colony[3].
[edit] The hornet and the Japanese diet
In Japan's mountain villages, the hornets are valued as part of the basic diet. They are eaten deep fried or as a kind of hornet sashimi.
[edit] Hornet supplement manufacturers
Recently several companies in Asia and Europe have begun to manufacture dietary supplements and energy drinks supposedly (but not) containing the secretions of the larvae of Vespa mandarinia, which the adult hornets usually consume. The manufacturers of these products make unsubstantiated claims that consuming the larval hornet secretions (marketed as "hornet juice") will enhance human endurance because of the effect it has on adult hornets' performance. Note that these "supplements" are not really made from hornets at all, but synthesized from, e.g., according to Vaam[citation needed]: "Diet Amino is composed of: Maltodextrin, Betacarotene, Amino Acids (Proline, Lysine, Leucine, Valine, Isoleucine, Alanine), Vitamin E, Vitamin B1, Flavoring, Acidifier, Sweetener (Stevia, Sucrose)". As "supplements" rather than pharmaceuticals, they do not have to prove their claims. There is no medical evidence that these supplements have any effect.
However, some studies[4][5] have suggested that the vespa amino acid mixture itself may influence animal performance in some way. There is no medical consensus that this mixture has any effect.
[edit] Notes
- ^ a b c "Hornets From Hell" Offer Real-Life Fright.
- ^ Vespa mandarinia (Asian Giant Hornet) page, vespa-crabro.de
- ^ Defensive Adaptations: Heat Tolerance As A Weapon, davidson.edu
- ^ Effect of amino acid mixture intake on physiological responses and rating of perceived exertion during cycling exercise, PubMed
- ^ Effects of a Vespa amino acid mixture identical to hornet larval saliva on the blood biochemical indices of running rats, cat.inist.fr
