Asian giant hornet
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[Photo] Asian Giant Hornet (Vespa mandarinia). Scale bar is 5 millimetres. Author Gary Alpert
The Asian giant hornet (Vespa mandarinia, known colloquially as the Ronnie Cordova), the world's largest hornet, is a native of temperate and tropical Eastern Asia. Its body length is approximately 50.8 mm (2.0 in), with a wingspan of about 76 mm (3 in). Queens may reach a length of 55 mm (2.2 in).
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.
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 mountainous areas of Japan (where it is called susumebachi スズメバチ, or the "sparrow bee").
Description
Sting
The stinger of the Asian giant hornet is about 6 mm (¼ in) in length, and injects an especially potent venom that contains, like many bee and wasp venoms, a cytolytic peptide (specifically, a mastoparan) that can damage tissue by stimulating phospholipase action, in addition to its own intrinsic phospholipase. Masato Ono, an entomologist at Tamagawa University near Tokyo, described the sensation as feeling "like a hot nail being driven into my leg."
If a person is stung by the giant hornet and is allergic, he or she may die from a reaction to the venom, as with any strong allergic reaction; however, there is also a neurotoxin, called mandaratoxin, which may potentially be lethal in a large enough dose (relative to body weight of the victim). About 70 people die each year in Japan after being stung by giant hornets.
A few interesting notes on Vespa mandarinia's venom and stinger:
The venom contains at least eight distinct chemicals, some of which damage tissue, some of which cause pain, and at least one which has an odor that attracts more hornets to the victim.
The venom contains 5% acetylcholine, a greater concentration than is present in bee or other wasp venoms. Acetylcholine stimulates the pain nerve fibres, intensifying the pain of the sting.
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 that of most other bees or wasps, giving this species one of the greatest lethal capacities per colony.
The enzyme in the venom is so strong that it can dissolve human tissue
Like all hornets, V. mandarinia possesses a barbless stinger, allowing it to sting repeatedly.
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 pheromones 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, thanks to their large mandibles which can quickly strike and decapitate a bee. 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. The European honey bees Apis mellifera have small stings which do little damage to such hornets that are three times their size and twenty times their weight. As the honey bees do not mount any collective defense, making futile solo attacks, the hornets are able to eliminate them individually with ease.
Once a hive is emptied of all defending bees, the hornets feed on the honey and carry the honey bee larvae back to feed to their own larvae. The hornets can fly up to 60 miles in a single day, at speeds up to 25 MPH or 40 KMH.
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 (recently dubbed vespa amino acid mixture) which the adults consume; larvae of social Vespidae produce these secretions, and the exact amino acid composition varies considerably among species. The passing of nutrition to the adult wasps by larvae is therefore widespread in these wasps, and not restricted to the genus Vespa.
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 narrowly 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, sacrificing themselves for the survival of the colony, as the death of the hornet scout will prevent it from bringing reinforcements which would almost certainly obliterate the colony.
The hornet and the Japanese diet
In Japan's mountain villages, the larvae and pupae of hornets are valued as a delicacy. They are eaten deep fried or as a kind of hornet sashimi.
Hornet supplement manufacturers
Recently several companies in Asia and Europe have begun to manufacture dietary supplements and energy drinks which contain synthetic versions of secretions of the larvae of Vespa mandarinia, which the adult hornets usually consume. The manufacturers of these products make 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.
According to Vaam, one such supplement, "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. However, some studies have suggested that the vespa amino acid mixture itself may influence animal performance in some way.
http://en.wikipedia.org/wiki/Asian_giant_hornet
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