Bombardier beetle

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Bombardier beetle
Bombardier beetle of the genus Brachinus

Bombardier beetle of the genus Brachinus

Systematics
Superclass : Six-footed (Hexapoda)
Class : Insects (Insecta)
Order : Beetle (Coleoptera)
Subordination : Adephaga
incertae sedis
Subfamily : Bombardier beetle
Scientific name
Brachininae
Bonelli , 1810
Pheropsophus verticalis from Australia

The bombardier beetles (Brachininae) represent a subfamily in the family of ground beetles (Carabidae), which occur worldwide with about 500 species. In Central Europe they are represented by two genera and six species . There are 51 species across Europe . Some authors regard them as a separate family Brachinidae. The beetles can often be found in small groups under stones in the open.

features

The bombardier beetles are 5 to 15 millimeters long. Their bodies are elongated, their wings are shorter than their abdomen and straight or sloping inwardly at the end. They are usually blue or green, rarely they are also colored black. The large head and pronotum are usually red. They have completely hairy antennae . There is only one supraorbital bristle at the edge of the eye. The first three tarsal links of the front legs of the males are widened. The most important feature of these beetles is their explosion apparatus at the end of their abdomen, from which irritating and foul-smelling gases are blown out of two tubes directly towards the attacker if there is danger. A clear explosion bang can be heard.

Defense Mechanism

The bombardier beetles have an impressive defense system. If they are threatened by an enemy, they blow corrosive and foul-smelling gases directly at the attacker. The paired explosion apparatus at the end of the abdomen consists of a gland that produces secretion, a collection bladder and an explosion chamber. Hermann Schildknecht , a German chemist , examined the bombardier beetles and tried to research the course of this impressive chemical reaction. He found that the beetles make their explosives by mixing two very reactive chemicals ( hydroquinone and hydrogen peroxide ) just before blowing it out . When the beetles approach an enemy, such as an ants or a frog , they inject the chemicals stored in the collection bladder into the explosion chamber and add the enzymes catalase and peroxidase at exactly the right moment to accelerate the reaction. This catalyst oxidizes the hydroquinone to the toxic 1,4-benzoquinone and splits the hydrogen peroxide into water and oxygen . This leads to a violent chemical reaction that creates both heat and high pressure. As a result, a caustic gas mixture at around 100 ° C shoots with a bang from the abdomen at the attacker. A beetle can trigger this mechanism several times because a directed explosion does not use the entire chemical supply at once. In addition, the abdomen is very mobile, so that you can even shoot forward under the body. The mixture acts as a poisonous defense secretion .

The wall of the explosion chamber is provided with a thick cuticle and is equipped with spherical groups of unicellular enzyme glands. Bombardier beetles can not only use their weapon precisely, they can even shoot around corners. To do this, they have two disc-shaped reflectors on each side of the spray nozzle with which they can divert the gases. The explosion represents a defensive or at least frightening acoustic and visual signal.

Novid Beheshti and Andy McIntosh from the University of Leeds have examined the gas pressure-dependent inlet and outlet valves of the explosion chamber of the bombardier beetle and traced the exact process of this flash evaporation using equipment. Both the spray distance and the droplet size could be set in a controlled manner, both factors that play an important role in the administration of drugs by aerosolization .

Systematics

In Central Europe there are five species from two genera:

Individual evidence

  1. ↑ Brachininae. Fauna Europaea, accessed May 31, 2007 .
  2. ↑ H. Schildknecht, u. a .: The bombardier beetles and their explosion chemistry. In: Angewandte Chemie. 73, 1961, pp. 1-7.
  3. ↑ Werner Nachtigall, A. Wisser: Biological Design , Springer Berlin 2005, ISBN 978-3-540-22789-2 ( Google Books ).
  4. ↑ Gerhard G. Habermehl: Poison animals and their weapons. 5th edition. Springer, Berlin 1994, ISBN 978-3-540-56897-1 ( Google Books ).
  5. ↑ Rolf Froböse: When frogs fall from the sky. The craziest natural phenomena. Wiley-VCH, Weinheim 2007, ISBN 978-3-527-31659-5 ( Google Books ).
  6. ^ Bernhard Klausnitzer: Beetle. Nikol, Hamburg 2005, ISBN 3-937872-15-9 .
  7. ↑ Rolf Sauermost, Doris Outgoing (Editor): sheet to cistus oil. Spectrum, Heidelberg 2000, ISBN 3-8274-0328-6 ( Lexicon of Biology. Volume 3).
  8. ↑ Novid Beheshti, Andy C. McIntosh: The bombardier beetle and its use of a pressure relief valve system to deliver a periodic pulsed spray. In: Bioinspiration and Biomimetics. 2, No. 4, 2007, doi : 10.1088 / 1748-3182 / 2/4/001 .
  9. ↑ German summary

literature

  • Ekkehard Wachmann , Ralph Platen, Dieter Barndt: Ground beetles. Observation, way of life. Naturbuch, Augsburg 1995, ISBN 3-89440-125-7 .
  • Jiři Zahradnik, Irmgard Jung, Dieter Jung a. a .: Beetles of Central and Northwest Europe. Parey, Berlin 1985, ISBN 3-490-27118-1 .

Web links

Commons : Brachininae  - collection of images, videos and audio files