Physogastry

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Photography, dorsal view
Egg-laying termite queen
Photography, half dorsal, half lateral
Egg-laying queen ant

Physogastry (from the Greek physa: bladder and gaster: belly) denotes in entomology the swelling of the abdomen , usually due to increased growth of the ovaries and the fat body of the females. The shape with a normal, not swollen abdomen is sometimes called stenogastric.

Ants, wasps, bees

Physogastry is typical of the queens of social insects. It often occurs in queens of termites and ants , and to a lesser extent in social wasps (social wasps ) and bees . Exceptionally, they are also found in workers, for example those of the honeydew ants , where the swollen free abdomen ( gaster ) does not take up eggs, but a supply of food.

Termites

In termite queens, physogastry occurs mainly in the "higher" termites, the Termitidae family , but is also known from a number of other families. When the colony was founded, the future queen's abdomen was still normal. With the queens of the genus Macrotermes it can reach five hundred times the volume when fully developed, with Cephalotermes it can reach a thousand times. The growth takes place gradually over several years, whereby the number of ovarioles does not increase, but these mature gradually from front to back and increase in size. The abdomen could not absorb this amount even when stretched to the maximum. This is why there is even a real growth of the cuticle in the imaginal animal and without molting processes in the termite queens, a great exception among insects . This growth, which is often but not always associated with physogastry, is known as neosomy .

Two-winged beetles

In addition to the termites themselves, physogastry is widespread in a number of species that live as parasites or kleptoparasites in termite burrows (collectively referred to as "Einlieter" or Inquilinen ). Physogastry in termite inquillins occurs mainly in the larvae and adults of various two-winged beetles (Diptera) and beetles (Coleoptera), examples would be the termite flies (belonging to the Phoridae or humpback flies), many short-winged beetles (Staphylinidae). Many physogastric species have special glands, the secretion of which attracts and soothes termites; they often lick their abdomen. The association was created by Erich Wasmann as a special form of symbiosis called "Symphilie".

Mites

Graphic, dorsal
Left: female. Pot Belly mite Pyemotes ventricosus ( Newp. , 1850)

In addition to insects, physogastry also exists in some species of mites . The females of Scutacarus acarorum show through their physogastric body that they are egg-laying females and no longer potentially phoretic females. The latter tend to climb on bumblebee queens to overwinter in this transport community. In species of the genus Pyemotes , particularly well investigated in the species Pyemotes herfsi , a parasite of the clothes moth , the female stings a moth caterpillar, which is then paralyzed. Then it liquefies the body and sucks it out. The abdomen swells to a spherical shape and reaches a diameter of about one millimeter, while the ovaries mature at the same time. Before that, the whole animal reaches a length of only 0.2 to 0.32 millimeters.

Individual evidence

  1. ↑ Mary Ann Basinger Maggenti, Armand R. Maggenti, Scott Gardner: Online Dictionary of Invertebrate Zoology: P. ( PDF , 1.28 MB), accessed on September 8 2016th
  2. ^ Bert Hölldobler, Edward O. Wilson: The Ants. Harvard University Press, 1990, ISBN 0-674-04075-9 , p. 641: Glossary.
  3. ^ Charles Noirot: Sexual Castes and Reproductive Strategies in Termites. Chapter 1 In: Wolf Engels (Ed.): Social Insects: An Evolutionary Approach to Castes and Reproduction. Springer Verlag, 2012, ISBN 978-3-642-74490-7 .
  4. ↑ Frank J. Radovsky: Neosomy. In: Vincent H. Resh, Ring T. Cardé (Ed.): Encyclopedia of Insects. Academic Press, 2009, ISBN 978-0-08-092090-0 , p. 685.
  5. ↑ many examples in William Morton Wheeler: The Social Insects: Their Origin and Evolution. K. Paul, Trench, Trubner & Co., London 1928, p. 226 ff.
  6. ↑ Nathan Banks: The Acarina or Mites. A Review of the Group for the Use of Economic Entomologists. In: Report No. 108 , United States Department of Agriculture, Bureau of Entomology, LO Howard (Ed.), 105, Washington 1915, book online , accessed September 20, 2016.
  7. ↑ Christian Schousboe: On the Biology of Scutacarus acarorum Goeze (Acarina: trombidiformes). In: Acarologia. T. 27, Fasc. 2, 1986, pp. 151-158. ( PDF online , 924 kB), accessed on September 7, 2016.
  8. ↑ M. Moritz: Arachnata, 10th order Acari. In: HE Gruner, M. Moritz, W. Dunger: Textbook of special zoology. (founded by Alfred Kaestner). Volume I, Part 4: Arthropoda (without Insecta). Gustav Fischer Verlag, Jena 1993, ISBN 3-334-60404-7 , p. 368/369.
  9. ↑ Spectrum Academic Publishing House (ed.): Lexicon of Biology. Bulbous mites. In: Spektrum.de, Heidelberg 1999, accessed on September 8, 2016.

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