Acariformes

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Acariformes
Balaustium sp.  as a representative of the Acariformes

Balaustium sp. as a representative of the Acariformes

Systematics
Over trunk : Molting animals (Ecdysozoa)
Trunk : Arthropod (arthropoda)
Sub-stem : Jawbearers (Chelicerata)
Class : Arachnids (arachnida)
Subclass : Mites (acari)
Superordinate : Acariformes
Scientific name
Acariformes
Zakhvatkin
Orders

Acariformes are one of the two large groups of mites (Acari) next to Parasitiformes , which include ticks . Acariformes are an ancient group of arachnids with representatives that go back to the earliest terrestrial invertebrates. Well-known representatives of this group are the house dust mites (Dermatophagoides) and spider mites (Tetranychidae). There are currently around 30,000–32,000 different species described.

Due to the enormous reduction in body size, the success of the enormous spread of the Acariformes was made possible. Furthermore, the rapid development and the short generation duration predestine the diversity of the habitats.

anatomy

The habitus is very stocky and has a simplified physique. The four pairs of legs are also showing increasing regression. Above all, there was a reduction in the coxae (uppermost part of the leg), which have fused with the body. Especially their setae (specialized hair) distinguish the Acariformes from the other Acari. Probably the most important example are the setae with the optically active chitin derivative "actinopilin", which causes birefringence of polarized light. Because of this property, they are also called actinotrichida. In return, other mites (Parasitiformes) are called anactinotrichida. The trichobothria , also a special form of the setae, are sensitive to vibrations and air currents. Other sensory modified setae are Solenidia and Eupathidia. The variability of the Acariformes makes a visual division very difficult. The most common classification is as follows:

The Trombidiformes are probably the largest group of the Acari. They are only slightly sclerotized, have long bristles and their stigmata (body openings for the tracheal system) are located far in front of the body. They generally have a conspicuous body color, mostly they appear in different shades of red.

The Sarcoptiformes also have no armor. What is special is that they do not have any breathing openings; oxygen is absorbed through the cuticle and through food. In contrast to the Trombidiformes, they are light-skinned to white in color. An exception to the above-mentioned Sarcoptiformes is the subordination of the Oribatida , which are heavily armored. Their stigmata are at the bases of the legs where the coxes are attached. But they are covered by the plates of the tank. Their color ranges from brown to black.

habitat

Acariformes inhabit all imaginable biotic and abiotic habitats, from hot or hydrothermal springs, leaves, lizards, to the ears of the house cat. These include the well-known house dust mites , spider mites and itch mites as well as a huge selection of lesser known parasites, predators and fungus eaters.

The most important plant inhabitants among the Acariformes, such as the spider mites and Eriophyidae , are counted as plant pests among the Trombidiformes. One of the most conspicuous families of wild mites are the relatively large and bright red velvet mites that belong to the family Trombidiidae.

Some Acariformes live in association with vertebrates and nests. These include the well-known house dust mites, grave mites (sarcoptes), feather mites and some fur mites . Grave mites and other skin-dwelling mites (e.g. Psoroptidae ) cause scabies and mange .

nutrition

The diet types of the Acariformes are very heterogeneous .

Trombidiformes are mainly plant parasites and are responsible, among other things, for economic damage. But they also feed on animals fungi , predatory and parasitic .

Sarcoptiformes feed on solid foods. They are both fungivorous and saprovored and sometimes live in the nests of insects or vertebrates . The best known of them is probably the house dust mite.

The suborder Oribatida feeds on dead plant parts, fungi, algae, pollen and are therefore important for humus formation. It should be noted that they are not parasites.

Reproduction and development

Electron microscopy of an acariformes ( Aceria anthocoptes )

Which form of reproduction of the Acariformes depends on the species. This trait is astonishing in terms of its relatedness, as the arachnid class shows relatively little creativity in its methods of reproduction. Whether the male's sperm is transferred to the female with the help of specially modified organs (such as spermatophores ), via chelicerae loaded with sperm or directly via copulation , often varies from species to species. Mated females mostly lay eggs, but some of them are also viviparous. Furthermore, the form of reproduction of parthenogenesis (single-sex reproduction) can occur.

Until the larva hatches, the egg or praelarva remains inactive for about 6 days after ovulation . The activity of the six-legged larvae is particularly high in the first days of life. In this case, active means that the metabolism and mobility are particularly high in contrast to the inactive development periods.

This is followed by a 2–3 day period of rest, which is associated with the development of the protonymphs. In the case of the protonymphs, too, an active phase lasting 5–6 days is passed through first, which is followed by a 2–3 day resting phase. The resulting tritonymphs are active for another 7 days. Tritonymphs have two pairs of genital protuberances (papillae) whereas the protonymphs have only one pair. Another resting phase follows in which the sexually mature animals develop. The development is anamorphic, which means that body segments are added between the moults . Before molting, the legs for the later stage are formed inside the body and not inside the trunk of the legs of the previous stage. Mutual mating of males and females with subsequent oviposition of the females completes the whole cycle. A very widespread mating or copulation process is as follows: It begins with an attempt by the male to attach to the female. This is done with the help of his third pair of legs and the two suction cups. The male is then carried around by the female in this position for several hours so that the seeds can flow into the sexual opening, the bursa copulatrix .

Eggs are laid two to three days after copulation. Depending on various conditions, a female lays up to four eggs a day and up to 300 eggs during her lifetime. While the male representatives remain sexually active throughout their adult stage, the females are only fertile in the first half of their lives. The entire development phase usually takes 23 to 30 days. However, the developing mites are only active about 60% of that time. The further development ( metamorphosis ) takes place in five stages. In poor living conditions, the development time is extended. This can be expressed by the fact that the mite remains in the resting phase correspondingly longer ( diapause ), preferably with the protonymphe. A greatly reduced metabolism and a lower susceptibility to environmental influences are typical features of such immobile stages.

Systematics and taxonomy

The Acariformes can be divided into two orders - Sarcoptiformes and Trombidiformes. In addition, there is a paraphyletic grouping that includes primitive forms; the end ostigmata, which has already been declared extinct.

In the past, a classification of the Acariformes was also based on diet, this classification method is now considered out of date and has been replaced by more modern methods, such as genetic determinations. One example of this are end ostigmata, which were previously divided into a separate group and are now also counted among the sarcoptiformes. This classification makes both groups monophyletic . In general, the systematics of the Acariformes has not yet been finally clarified, but it is increasingly assumed that it is a sister group of the Solifugae .

literature

  • John B. Kethley, Roy A. Norton, Patricia M. Bonamo, William A. Shear: A Terrestrial Alicorhagiid Mite (Acari: Acariformes) from the Devonian of New York. In: Micropaleontology. Volume 35, No. 4, 1989, pp. 367-373, doi: 10.2307 / 1485678 .
  • Roy A. Norton, John B. Kethley, Donald E. Johnston, Barry M. OConnor: Phylogenetic perspectives on genetic systems and reproductive modes of mites. In: Dana L. Wrensch, Mercedes A. Ebbert (Ed.): Evolution and diversity of sex ratio in insects and mites. Chapman & Hall, New York NY et al. a. 1993, ISBN 0-412-02211-7 , pp. 8-99.
  • Barry M. OConnor: Phylogenetic relationships among higher taxa in the Acariformes, with particular reference to the Astigmata. In: Donald A. Griffiths, Clive E. Bowman (Eds.): Acarology VI. Volume 1. Ellis Horwood et al. a., Chichester 1984, ISBN 0-85312-603-8 , pp. 19-27.
  • Tomoyo Sakata, Roy A. Norton: Opisthonotal gland chemistry of early-derivative oribatid mites (Acari) and its relevance to systematic relationships of Astigmata. In: International Journal of Acarology. Vol. 27, No. 4, 2001, pp. 281-292, doi: 10.1080 / 01647950108684268 .
  • David Evans Walter, Heather Coreen Proctor: Mites. Ecology, Evolution and Behavior. NSW Press u. a., Sydney et al. a. 1999, ISBN 0-86840-529-9 .
  • Tyler A. Woolley: Acarology. Mites and Human Welfare. John Wiley and Sons, New York et al. a. 1988, ISBN 0-471-04168-8 .

Web links

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

Individual evidence

  1. ^ Mark S. Harvey: The neglected cousins: What do we know about the smaller arachnid orders? In: Journal of Arachnology . Vol. 30, No. 2, 2002, pp. 357-372, doi : 10.1636 / 0161-8202 (2002) 030 [0357: TNCWDW] 2.0.CO; 2 .
  2. a b c Wilfried Westheide , Reinhard Rieger (Ed.): Special Zoology. Volume 1: Protozoa and invertebrates. Fischer u. a., Stuttgart a. a. 1996, ISBN 3-437-20515-3 , p. 489 ff.
  3. Katharina Munk (Ed.): Zoologie. Georg Thieme, Stuttgart a. a. 2011, ISBN 978-3-13-144841-5 .
  4. Actinopilin . Brussels Museum of Natural Sciences
  5. ^ Richard Lucius, Brigitte Loos-Frank: Biology of Parasites. 2nd Edition. Springer, Berlin a. a. 2007, ISBN 978-3-540-37707-8 , p. 426 ff.
  6. Trombidiformes. eol.org. Retrieved September 23, 2015.
  7. a b Facts about Mites. eol.org. Retrieved September 23, 2015.
  8. a b Acari . Wiki of the Arachnological Society. Retrieved April 3, 2019.
  9. Development stages of mites , Mitbenmeister.de - Retrieved on April 2, 2019.
  10. Evert E. Lindquist: Current theories on the evolution of major groups of Acari and on their relationships with other groups of Arachnida, with consequent implications for their classification. In: Donald A. Griffiths, Clive E. Bowman (Eds.): Acarology VI. Volume 1. Ellis Horwood et al. a., Chichester 1984, ISBN 0-85312-603-8 , pp. 28-62.
  11. Almir R. Pepato, Carlos EF da Rocha, Jason A. Dunlop: Phylogenetic position of the acariform mites: sensitivity to homology assessment under total evidence . In: BMC Evolutionary Biology . tape 10 , no. 1 , August 2010, p. 235 , doi : 10.1186 / 1471-2148-10-235 ( biomedcentral.com [PDF]).