Engraver (beetle)
| Engraver | ||||||||||||
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Pityogenes chalcographus , |
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| Scientific name | ||||||||||||
| Pityogenes chalcographus | ||||||||||||
| ( Linnaeus , 1761) |
The copper engraver ( Pityogenes chalcographus ), also known as the common copper engraver or six-toothed spruce bark beetle , is a weevil from the subfamily of the bark beetle (Scolytinae). Since it creates its breeding systems in the bark of the host trees, it is counted among the bark breeders.
features
The beetles are 1.6 to 2.9 millimeters long and have a brown-black, cylindrical body. Freshly hatched animals are brightly colored. The pronotum is longer than it is wide, has a fine crown of cusps at the front, is evenly arched, has a dotted base and covers the head when viewed from above. It has a shiny central keel and shiny surfaces on the sides. The base of the pronotum is unrimmed. It has a smooth, flat longitudinal callus at the back. Seen from below, the tip edge of the elytra is simple, immediately surrounding the abdomen . The elytra are parallel, blackish at the base and the edges, otherwise reddish brown in color and shiny, the rows of dots are weakly developed, very indistinct at the sides in front of the end. The fall begins in the middle of the wing cover and runs diagonally downwards. The abdomen remains straight from the second sternite towards the end. The third tarsal link is cylindrical in shape. The antennae are yellow, the legs are brown, the tarsi are lighter in color.
Male and female adults differ from each other ( sexual dimorphism ). The male wing covers each have three large conical teeth (they are clearly visible when looking at them with a magnifying glass) and the forehead has small cusps. The females have a pit on their foreheads, and only three small bumps can be found on the fall.
distribution
The species is widespread in Europe and Asia to the far north. They are rare in the British Isles . You can find them in coniferous forests from the plains to the mountains, but also in parks.
Way of life
The engraver comes across spruce ( Picea ) and occasionally Douglas fir ( Pseudotsuge menziesii ), Siberian larch ( Larix sibirica ), European larch ( Larix decidua ), pine ( Pinus ), white fir ( Abies alba ) and Siberian fir ( Abies sibirica ) in front. It colonizes the bark of the trees and feeds on the bast and bark tissue . Young trees that have been damaged by wind or snow are preferred. Older trees are populated in the upper trunk parts and the branches with thinner bark.
The feeding pattern shows a ramming chamber , mostly hidden in the bark , from which three to six mother tunnels branch off in a star shape. These are about six inches long and one millimeter wide. The numerous, closely spaced larval ducts are two to four centimeters long. The heavy population often creates confusing feeding pictures that resemble copper engravings, hence the name.
The animals are polygamous . All stages of the beetle in the breeding picture can overwinter under the bark. The engraver usually flies a little later than the printer ( Ips typographus ). One to a maximum of two complete generations are formed per year, with the flight time in April / May and from July to August, rarely also until September. If the trunk occurs in competition with the printer, the infestation is mostly limited to the thin trunk part ( breeding space competition ). Due to its size, the beetle can open up breeding spaces here that the printer cannot. Both types can coexist in transitional areas. The beetles send chalcogran (2-ethyl-1,6-dioxaspiro [4.4] nonane) and 1-hexanol as aggregation pheromones .
Economical meaning
Infestation
The reasons for a strong infestation by the engraver can be long-lasting, high temperatures above 20 ° C, a high proportion of damaged wood, among other things due to wind, infestation by the printer or previously damaged or otherwise weakened host plants. Like the printer, the engraver also attacks standing spruce trees. But the bark beetle can also breed successfully in branches and tree tops lying on the ground.
Damage
The infestation can be recognized by the very small drill holes. Other signs are brown and red discoloration of the tree crown and loss of needles. At this stage the young beetles have already flown out. Most endangered are spruce trees of the age of poles ; when the population density is high, freshly sown young spruces are also attacked and subsequently die. Loss of growth and consequential damage occur due to dying branches, tree tops or individual trees, which can attract fungal infections and other species that breed with bark and wood. The species is a primary pest on young trees, while in old trees it is associated with other species of the subfamily.
prevention
In contrast to the book printer, the copper engraver can hardly be checked using drilling dust. The infestation is usually recognized too late. It is advisable to process infested trees as quickly as possible, to carry out regular checks in the summer months and to destroy branch and crown material. Since there is always material that can be brood due to natural occurrences, the best prevention is to only cultivate the species suitable as host trees in the form of mixed forests in their natural distribution area . Even there (then less) damage is to be expected. Outside of their natural range, the host trees are highly endangered if they cannot grow under optimal conditions. This is the case with spruce trees that are grown below 600 m .
Synonyms
The following synonyms are known from the literature for Pityogenes chalcographus :
- Dermestes chalcographus Linnaeus, 1761
- Ips spinosus De Geer, 1775
- Scolytus sexdentatus Olivier, 1795
- Bostrichus xylographus Sahlberg, 1836
- Bostrichus bicolor Chevrolat, 1838
Individual evidence
- ^ Pityogenes chalcographus (Linné 1761). Fauna Europaea, Version 2.5, July 23, 2012, accessed on February 17, 2013 .
literature
- Sabine Green : Manual for the determination of the European bark beetle Verlag M. & H. Schaper, Hanover 1979, ISBN 3-7944-0103-4
- Fritz Schwerdtfeger : A contribution to the reproductive biology of the bark beetle Pityogenes chalcographus L. Dissertation. Hann.-Münden 1928
- Fritz Schwerdtfeger: The forest diseases. Textbook of forest pathology and forest protection . 4th, revised edition. Parey, Hamburg and Berlin 1981, ISBN 3-490-09116-7
- Wolfgang Schwenke (Hrsg.) Among others: The forest pests of Europe. A manual in 5 volumes. Volume 2: Beetles. Parey, Hamburg and Berlin 1974, ISBN 3-490-11016-1
- Edmund Reitter : Fauna Germanica - The beetles of the German Empire. Volume 5 p. 299, KG Lutz, Stuttgart 1916
- Edmund Reitter: Fauna Germanica - The beetles of the German Empire. 5 volumes, Stuttgart KG Lutz 1908–1916, digital library volume 134, Directmedia Publishing GmbH, Berlin 2006, ISBN 3-89853-534-7
- Jiři Zahradnik, Irmgard Jung, Dieter Jung et al .: Beetles of Central and Northwestern Europe. Parey, Berlin 1985, ISBN 3-490-27118-1 .
Web links
- Numerous pictures at Forestry Images
- Videos on Pityogenes chalcographus published by the Institute for Scientific Film . Provided in the AV portal of the technical information library .