Rhinoceros beetle

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Rhinoceros beetle
Rhinoceros beetle (Oryctes nasicornis), male

Rhinoceros beetle ( Oryctes nasicornis ), male

Systematics
Order : Beetle (Coleoptera)
Subordination : Polyphaga
Family : Scarab beetle (Scarabaeidae)
Subfamily : Giant beetle (Dynastinae)
Genre : Oryctes
Type : Rhinoceros beetle
Scientific name
Oryctes nasicornis
( Linnaeus , 1758)

The rhinoceros beetle ( Oryctes nasicornis ) is a beetle from the family of scarab beetles (Scarabaeidae).

description

The beetle is between 20 and 40 millimeters long, cylindrical and colored black or dark brown, often with maroon wing-coverts. The surface of the body, especially that of the elytra, is smooth and shiny; the wing covers have very fine rows of dots. While the upper side is bald, the underside is very noticeably hairy fox-red. The head has antennae with the three-part antennae lobe characteristic of the family, the upper jaws ( mandibles ) are leaf-like widened and clearly visible from above, the head is triangularly narrowed between them. The rails ( tibia ) of all three pairs of legs are transformed into grave legs; they are somewhat flattened and widened and roughly toothed on the outside.

The characteristic horn, which gives the species its name, sits on the top of the head. It is long and curved only in the male; the female has only a short horn or a hump in the same place. The pronotum is also built very differently between the sexes. In the male, it has a strip-shaped elevation in the rear half, which is bent up into three distinct humps in the middle. In the female these humps are missing, the pronotum has an indistinctly limited impression in front. As with many horn-bearing beetles, it is not uncommon for "female-shaped" males without a horn to appear (mostly small animals). These can be distinguished from females by the fact that the pygidium (that is the upper sclerite of the last abdomen segment that protrudes backwards over the wing covers is not covered by these), is bald in them, hairy in the females.

The larvae have the typical conglomerate shape of the scarab beetle larvae , they are very large, whitish-colored, cylindrical larvae that are curved in a C-shape towards the belly. The light brown head capsule and three relatively long, brown-colored pairs of legs can be seen at the front end. The body surface is segmented and also divided into separate ringlets (plicae); she wears small, brown colored sclerites .

Way of life

Rhinoceros beetle female - side view
bottom
Rhinoceros beetle larvae

The original habitat of the species is strongly decomposed, soft wooden sludge , as it accumulates inside dead tree trunks or thick branches of old deciduous trees. In the primeval forests of Europe without human influence, such sludge was widespread, a variety of beetle species specialize in it. But while numerous dump beetles are very rare today as "jungle relics" and are often threatened with extinction, the rhinoceros beetle has successfully made the transition to new, man-made substrates. The species is therefore no longer rare in Central Europe and can be found almost everywhere, it even seems to be spreading further. In the original habitat of Holzmulm, however, the rhinoceros beetle can be found extremely rarely; it may not have originally occurred here in Central Europe, but only migrated from the south. In southern Europe, too, evidence from tree hollows is rare. B. it was found here in old oaks in an Italian park.

The first man-made substrate was obviously oak wood as a residue from the tannery. Today the species is found regularly and in large quantities in piles of sawdust at sawmills and other wood processing companies and in piles of bark mulch, but also in ordinary compost heaps in gardens and allotments, provided that enough fibrous material has been deposited in them. It doesn't necessarily have to be wood. In a Belgian study, the best growth was seen in relatively fresh material populated with white rot fungi, while more decomposed material produced fewer and smaller beetles.

The rhinoceros beetle, like all related species, has three larval stages. The larvae then pupate in cocoons the size of a hen's egg made of clay and sawdust. The diet of the adult animals has not yet been fully clarified. If they eat at all in their short life, they probably feed on tree sap.

The adult male beetles actually use the conspicuous head horn in a rhinoceros-like manner when fighting against each other for females. As with related species, it can be assumed that small males remain polled in order to "camouflage" themselves as females from superior males. This allows them to smuggle themselves into the vicinity of the females unnoticed. However, direct evidence of this in the rhinoceros beetle itself is still pending.

Digestion of cellulose fibers by the larva

Rhinoceros beetle larvae feed on wood and other plant fibers, which consist predominantly of cellulose (and hemicellulose ). This material is known to be difficult to digest by almost all animal species. In experiments it was possible to keep rhinoceros beetle larvae alive for weeks with the exclusive use of filter paper. The animals must therefore be able to actually digest the cellulose fibers. However, no cellulose-degrading enzymes ( cellulases ) could be found in the intestines of rhinoceros beetle larvae . The cellulose is only broken down in the rectum, which forms a fermentation chamber (similar to the rumen of ruminants ). The chemical bonds of the cellulose molecules are ultimately unlocked here by symbiotic types of bacteria. This takes place under strictly anaerobic conditions and in an alkaline environment. Methane is released as a breakdown product. The beetles' most important source of protein are the microorganisms themselves, some of which are digested.

distribution

The distribution area includes central and southern Europe to southern Scandinavia and the Baltic States, north Africa north of the Sahara, the Canary Islands and parts of central and east Asia, east to the Indian Himalayas. A number of subspecies are distinguished within the very large area. A total of 19 subspecies have been described, but their definition and differentiation from one another is questionable in many cases. Usually the subspecies is not given at all. The subspecies prolixus , endemic to the Canary Islands, is sometimes viewed as a separate species. The type subspecies Oryctus nasicornis nasicornis is widespread in Central Europe, but the (controversial) subspecies holdhausi and polonicus are already found in eastern Central Europe (Slovakia and Poland) . The subspecies corniculatus (syn. Laevigatus ) lives in northern Italy . Further subspecies are given for the Mediterranean area. The species first immigrated to Northern Europe, especially Scandinavia, in historical times. It is still missing in Great Britain to this day.

In Southeast Asia there are other species of the genus, some of which are bitterly fought as pests on palm species used. Occasional false reports found in the press or on the Internet about an occurrence in tropical East Asia, e.g. B. in Thailand, refer to these species. The rhinoceros beetle itself is economically insignificant. It is even recommended to promote its occurrence in compost heaps for better composting or to settle it there specifically.

Enemies

Dagger wasp species are sometimes specialized in rhinoceros beetle larvae as prey. The wasp lays an egg on the larva, the developing wasp larva eats on it from the outside, ultimately killing the beetle larva (idiobiont parasitoid ). The yellow-headed dagger wasp has become known as a specialized parasitoid of rhinoceros beetle larvae

Legal protection

The rhinoceros beetle is a "specially protected" animal species in Germany due to its inclusion in the Federal Species Protection Ordinance ( § 1 sentence 1 in conjunction with Appendix 1 BArtSchV). According to § 44 of the Federal Nature Conservation Act (BNatSchG), it is forbidden to "catch, injure or kill them or to take their forms of development from nature, to damage or destroy them" (§ 44 (1) of the BNatSchG). In addition, their "breeding or resting places" must not be damaged or destroyed; it is also prohibited to buy, sell, or possess them. The Lower Nature Conservation Authority can grant exceptions to the regulations upon request ( Section 45 BNatSchG). However, this does not involve any special protection of the animals in planning or approval procedures.

In Switzerland, the rhinoceros beetle is protected under Article 20 of the Ordinance on Nature Conservation and Homeland Conservation; it is included in the list of protected animals (Appendix 3).

Fossil evidence

Subfossil remains of the species were found during the archaeological record of the Stralsund town hall. Here around 1390 Gerberlohe was built into the vault cap as filler material, which contained numerous remains of beetles. This is important because the medieval occurrence of the species in northern Germany has often been doubted, e.g. B., because no real common name of the striking kind has come down to us.

Fossil beetles, which were assigned to the recent species, have been found in Germany in Pliocene sediments ( Willershausen clay pit , southern Lower Saxony)

  • Rhinoceros beetle pupae

  • Life cycle of the rhinoceros beetle from egg to larvae, pupae to adult animal; from Edmund Reitter's Fauna Germanica. The beetles of the German Empire. Volume II. (1908)

  • Rhinoceros beetle from the front. The paper squares are 5 × 5 mm in size.

literature

Individual evidence

  1. ↑ a b Hans Henschel: The rhinoceros beetle. (= Die Neue Brehm-Bücherei. Volume 301). 2nd edition, Westarp Wissenschaft-Verlagsgesellschaft, Hohenwarsleben 2003, ISBN 3-894-32239-X (reprint of the first edition from 1962).
  2. ↑ Giuseppe Maria Carpaneto, Adriano Mazziotta, Giorgia Coletti, Luca Luiselli, Paolo Audisio (2010): Conflict between insect conservation and public safety: the case study of a saproxylic beetle (Osmoderma eremita) in urban parks. Journal of Insect Conservation 14: 555-565. doi : 10.1007 / s10841-010-9283-5
  3. ^ A b Paul Minck (1916): The influence of culture on the conditions of existence of the rhinoceros beetle (Oryctes nasicornis L.) in Germany. Archives for Natural History 82 (5): 147-163.
  4. ↑ Peter Helmstetter: Rhinoceros beetle on the move: resettlement campaign in Middle Franconia. LWF aktuell 47 (2004), p. 26. PDF
  5. ↑ Paul Hendriks (2007): Ontwikkeling van de neushoornkever, Oryctes nasicornis (Coleoptera: Scarabaeidae), in verschillende soorten organisch materiaal. Entomological Reports 67 (1-2): 53-57.
  6. ^ William G. Eberhard (1982): Beetle horn dimorphism: making the best of a bad lot. American Naturalist 119 (3): 420-426.
  7. ↑ Colette Bayon, Jocelyne Mathelin (1980): Carbohydrate fermentation and by-product absorption studied with labeled cellulose in Oryctes nasicornis larvae (Coleoptera: Scarabaeidae). Journal of Insect Physiology Volume 26, Issue 12: 833-840. doi : 10.1016 / 0022-1910 (80) 90100-6
  8. ↑ Colette Bayon, P. Etiévant (1980): Methanic fermentation in the digestive tract of a xylophagous insect: Oryctes nasicornis L. larva (Coleoptera; Scarabaeidae). Cellular and Molecular Life Sciences Volume 36, Number 2: 154-155. doi : 10.1007 / BF01953702
  9. ↑ ME Rössler (1961): Nutritional studies on scarabaeiden larvae (Oryctes nasicornis L., Melolontha melolontha L.). Journal of Insect Physiology Volume 6, Issue 1: 62-74.
  10. ↑ K.Chandra & VP Uniyal (2007): On a collection of pleurostict Scarabaeidae (Coleoptera) from the Great Himalayan National Park, Himachal Pradesh, India. Zoos Print Journal 22 (9): 2821-2823.
  11. ↑ Frank-Thorsten Krell (2002): On nomenclature and synonymy of of Old World Dynastinae (Coleoptera, Scarabaeidae). Entomological Sheets 98: 37-46.
  12. ↑ cf. The scarabs of the Levant
  13. ↑ Geoffrey O. Bedford (1980): Biology, Ecology, and Control of Palm Rhinoceros Beetles. Annual Review of Entomology Vol. 25: 309-339 doi : 10.1146 / annurev.en.25.010180.001521
  14. ↑ Rhinoceros beetles - great helpers in compost
  15. ^ GE Mach (1940): The Species Composition of the Hosts of the Most Important European Species of Scoliids. Bulletin of Plant Protection No. 4: 93-101.
  16. ↑ Wolfgang Schedl (2006): The dagger wasps of South Tyrol. Gredleriana 6: 343-350.
  17. ↑ Appendix 3: List of protected animals
  18. ↑ Jörg Ansorge & Peter Frenzel: Paleontological studies on invertebrates from archaeological excavations in Mecklenburg-Western Pomerania. In: Reitner, Joachim, Reich, Mike and Schmidt, Gabriele (Ed.): Geobiology. 74th Annual Conference of the Palaeontological Society, Göttingen October 2 to 8, 2004. Abstracts of the lectures and posters, pp. 43–44.
  19. ^ Frank-Thorsten Krell (2006): Fossil record and evolution of Scarabaeoidea (Coleoptera: Polyphaga). Coleopterists Society Monograph Number 5: 120-143.

Web links

Commons : Rhinoceros Beetle  - Album with pictures, videos and audio files