Beewolf (wasp)

from Wikipedia, the free encyclopedia
Beewolf
Beewolf (Philanthus triangulum)

Beewolf ( Philanthus triangulum )

Systematics
Class : Insects (Insecta)
Order : Hymenoptera (Hymenoptera)
Family : Crabronidae
Subfamily : Philanthinae
Genre : Philanthus
Type : Beewolf
Scientific name
Philanthus triangulum
( Fabricius , 1775)

The Bee Wolf ( Philanthus triangulum ) belongs to the grave wasps family Crabronidae in the insect order Hymenoptera (Hymenoptera). From around mid-June the black and yellow insects can be observed, which can be recognized by their large heads, the thick antennae in the middle , the conspicuous burial bristles of the females and their hovering flight , similar to that of hoverflies . The length of the female beewolf, which is slightly larger than a bee, is 13 to 18 millimeters, but that of the males is only 8 to 10 millimeters.

habitat

The beewolf can be found in large parts of Europe as far as Siberia , on warm and dry heaths and grasslands that resemble the steppes . This biotope is progressively declining as a result of human action, so that the beewolf is becoming increasingly rare.

food

Male of the beewolf visiting a man litter inflorescence

In Central Europe, honeybees ( Apis mellifera ) serve almost exclusively as food for the larvae . In very rare cases, wild bees should also serve as prey. As with all digger wasps , they are only captured by the females. The victim is overwhelmed when visiting the flower after it has first been identified visually and then examined for smell by shaking in the air at a distance of a few centimeters. Due to the speed of the unexpected attack, no resistance is usually possible. The victim who is caught in the legs is immediately paralyzed by a stab between the front hip. The beewolf then presses the prey's abdomen together with the tip of its abdomen. As a result of this pressure on the bee's honey stomach, a drop of nectar emerges from its mouth, which the beewolf licks up. The prey is then turned on its back and transported in flight to the nest, which is located in sandy soil. During the flight the bee is clasped with all legs. A typical behavior when aiming for the opening of the nest is the persistent hovering flight and swinging back and forth in the air for a few seconds before the beewolf literally rushes into the mostly open nest entrance with its prey.

Note: The beewolf's rapid attack only occurs on an object with a bee scent , e.g. B. in the experiment on a similar size wooden block smeared with the scent of bees.

Unlike the larvae, adult beewolves feed on the nectar from the flowers of various plants. As described above, captured honey bees also serve as nectar suppliers for the hunting female.

Reproduction

Beewolves in the Old Botanical Garden of the University of Göttingen (29 seconds, 15.79 MB). The photos from the late summer of 2008 show, among other things, female animals digging and with prey.

The females dig a tube in the ground that can be up to a meter long. This ends in five to seven chambers into which three to four, but sometimes up to six paralyzed honey bees are usually brought. These serve to nourish the offspring, with future females needing one more bee than the males.

For a long time it was assumed that the stunned bees are preserved by the poison, which only has a paralyzing effect, and thus do not spoil. According to the findings of the research group around Erhard Strohm from the Biozentrum of the University of Würzburg, a series of tests was able to prove that the preservation takes place through a special treatment of the bees by the beewolf. The beewolf licked the bee intensely with his mouthparts. This special treatment keeps the bees unspoiled for several days. Untreated animals that were stunned by the beewolf's poison spoiled after a few hours (mold attack).

In slightly inclined or horizontal terrain, after each visit to the nest , it is locked to protect it from nest predators such as various beetles or parasitic wasps. In the vertical terrain the entrance is kept open at all times.

White, maggot-shaped larvae hatch from the eggs that are then laid . After the captured bees have eaten , the larvae pupate so skillfully on a silk stem that they do not touch the floor or walls; this also prevents the pupa (cocoon) from being attacked by fungi, aided by the moisture. Around the middle of June each year, the new generation of beewolves dig themselves out of their burrows in the ground.

Protection of the larvae with antibiotics

Recent research also shows that the beewolf cultivates Streptomyces bacteria. Female beewolves breed these bacteria in special glands on their antennae and smear them on the roof of their brood cells. The beehive larvae, in turn, ingest the bacteria, spin them into the silk of their cocoons and thus increase their chances of survival. The bacteria form antibiotic substances that protect the young beewolf from fungal and bacterial infections.

Opponent

The beewolf is parasitized by the golden wasp Hedychrum rutilans .

Individual evidence

  1. Strohm, E. and Linsenmair, KE: Females of the European beewolf preserve their honeybee prey against competing fungi , Ecological Entomology 26 (2001), 198-203
  2. J. Kroiss, et al .: Symbiotic streptomycetes provide antibiotic combination prophylaxis for wasp offspring , Nature Chemical Biology 2010, doi : 10.1038 / nchembio.331
  3. Bacteria protect young wasps from fungal attack in: Naturwissenschaftliche Rundschau , Volume 58, Issue 6, 2005.
  4. By means of imaging mass spectroscopy it was possible to show in vivo on the beewolf cocoon that the antibiotics produced by the bacteria are concentrated on the outer skin of the cocoon. Beewolf protects itself with antibiotics
  5. Scientists at the Max Planck Institute for Chemical Ecology in Jena, in collaboration with the University of Regensburg and the Jena Leibniz Institute for Natural Product Research - Hans Knöll Institute - discovered that the bacteria of the genus Streptomyces are a cocktail of nine different Produce antibiotics to ward off invading pests. [1]

literature

  • Nikolaas Tinbergen : About the orientation of the beewolf (Philanthus triangulum Fabr.). In: Journal of Comparative Physiology . Volume 16, 1932, pp. 305-334.
  • Nikolaas Tinbergen : About the orientation of the beewolf (Philanthus triangulum Fabr.). II. The bee hunt. In: Journal of Comparative Physiology. Volume 21, 1935, pp. 699-716.
  • Helgard Reichholf-Riehm: Insects. Mosaik, Munich 1984, pp. 204-205.
  • Heiko Bellmann : bees, wasps, ants. Hymenoptera of Central Europe. 2nd Edition. Franckh-Kosmos, Stuttgart 2005, pp. 173–177.
  • Rolf Witt: Wasps. 2nd revised and expanded edition. Vademecum-Verlag, Oldenburg 2009.

Web links

Commons : Beewolf  - Collection of images, videos and audio files