Book printer (beetle)
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Letterpress ( Ips typographus ), Imago |
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| Ips typographus | ||||||||||||
| ( Linnaeus , 1758) |
The letterpress or large eight-toothed spruce bark beetle ( Ips typographus ) is a species of beetle from the subfamily of the bark beetles (Scolytinae). Since it creates its breeding systems in the bark of the host trees, it is counted among the bark breeders . It is considered a major forest pest .
The German name comes from the beetle's larval ducts (see picture below), the top view of which is similar to Arabic characters . Each wing cover is studded with four teeth at the edge of the fall, so a total of eight, hence the second name, which is also common.
features
The beetles have a 4.2 to 5.5 millimeter long, cylindrical, dark brown, long yellowish to brownish hairy body, slightly widened at the back. The head is not visible from above because the pronotum towers over it. The uniformly arched pronotum is bumpy in front, long hairy and dotted at the base.
The third foot link is cylindrical.
The seams of the antenna lobes are strongly drawn forward in the middle.
The tip edge of the wing-coverts is double, the inner edge encompasses the abdomen , the outer edge delimits the fall. The second tooth on the fall is a bevel tooth. The fall falls from the middle of the wing covers towards the end. It is dull (not shiny), indistinctly dotted and not hairy. It forms a shallow depression. The first gap in the rows of dots next to the seam has a row of grains before the crash.
The male has a more developed frontal cusp and stronger teeth at the fall as well as shorter hair in the middle of the seventh sternite ( sexual dimorphism ).
Harmful effect
Infestation
The printer mainly attacks spruce , preferably the common spruce ( Picea abies ), but also larches ( Larix ), Douglas firs ( Pseudotsuga ), white pine ( Pinus strobus ), black pine ( Pinus nigra ) and silver fir ( Abies alba ). Normally, the spruce can repel insects by secreting resin , which can also be toxic . But if it is weakened in any way, it can be overwhelmed by relatively few bark beetles. With suitable weather conditions (optimal: dry, hot, calm), such breeding foci serve as a starting point for a mass increase, which then, regardless of their vitality, can destroy entire stands (compare dead wood ).
Printer in Meyers Konversations-Lexikon 1888
Book printer on softwood
Book printer who was fended off with resin by a spruce.
Printer's strategy
Even weakened spruce trees cannot be overwhelmed by individual beetles. The attackers need to concentrate more closely. Fragrances play a decisive role in this. First of all, ailing spruce trees are approached according to their smell, followed by “boring in” (in itself a “eating in”) for the establishment of breeding systems (the establishment of the male's chamber ). The spruce defends itself by sticky and poisonous resin flow, which the first attackers fall victim to. The spruce bark beetles convert resin constituents into fragrances. This increases the attractiveness of the tree, which in turn results in an increased intensity of attack. If this rises above the resilience of the spruce, the first breeding systems (starting from the ramming chamber, the creation of mother tunnels by the females) are created with further release of attractants. In addition to the further settlement of the breeding site, the neighboring trees are also attacked. In the event of over-settlement, this is also reported by scent. This small, weak insect has a sophisticated strategy for overpowering an enemy that is overpowering for the individual.
The beetles can (depending on the weather) fly actively for up to three kilometers, but the wind can also blow them over considerably longer distances.
Infestation symptoms
As the first visible symptom, resin droplets can emerge as a result of the drilling, which sometimes also turn into weak resin paths. The resin droplets or trajectories are not always visible, so they are not a necessary feature.
Only and always when the ramming chamber and the mother tunnels are installed, light brown drilling dust is reliably ejected. It is therefore the earliest and very reliable indication of the infestation. Because the boring dust is blown away by the wind and washed away by the rain, it will become harder to find over time.
Woodpeckers can notice the infestation and look for the beetles and larvae. They knock off parts of the bark . As a result, the previously gray bark glows red, or if the bark has been cut down to the wood, the trunks glow whitish. The cut pieces of bark can be found under the infested trees.
By interrupting the flow of sap, the needles in the crown of infested trees usually turn red from bottom to top. The red crowns are visible from afar. With a good water supply or during the vegetation-free period, green needles also fall off the tree (“chute”). These can then be found en masse under the infested trees. The audible trickling of the needles can also be an indication of the infestation.
damage
| year | Thousand fm | % |
|---|---|---|
| 2014 | 1,636 | 6.1 |
| 2015 | 3,179 | 10.1 |
| 2016 | 4,439 | 16.8 |
| 2017 | 5,592 | 19.4 |
| 2018 | 10,781 | 27.3 |
| 2019 | 27,221 | 63.0 |
| Damaged logging caused by insects in Germany
% = Share of total spruce harvested |
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When the beetles eat, but mainly the larvae, the phloem's assimilate flow, which descends in the bark, is interrupted. As a result, the assimilates accumulate in the crown area and the roots are no longer supplied with assimilates. This leads to the death of the tree if the infestation is intense enough.
A book printer attack causes economic damage due to the decrease in value of the wood. Printers wear fungal spores on their bodies, which they transfer to the infested trees. This leads to the typical blue coloration of the sapwood, which is visible on the trunk jacket and the end faces of the trunk sections. The color of the sawn timber remains, which is why it can only be used to a limited extent for visible construction. That is why wood infected by the book printer is traded at reduced prices; it is sorted into the lowest quality class D in the framework agreement for the raw wood trade in Germany. The technical properties of the wood are not reduced by the beetle infestation.
If the book printer appears en masse, this can lead to an oversupply of spruce wood. The consequences are then falling prices for round timber in "Beetle years".
The infestation by book printers can disrupt the orderly, planned forest management. If the infestation occurs in parts of the forest that have not yet been rejuvenated, bare areas arise that either have to be reforested or often remain unproductive for a long time.
Beetle infestation on trees that are necessary to protect the stands behind (e.g. south or west edges) often results in further damage from storms or extensive beetle infestations.
Special periods of damage known as bark calamities or beetle years
- From 1768 to 1799 there were significant losses in the Harz ("30,000 hectares of forest in the Harz region destroyed") due to a bark beetle plague, which subsequently became known as "The great worm dryness" .
- For the period 1947-1949 a strong increase in the number of printers is known, which at the time was attributed to mild weather conditions. In the period from 1940 to 1950 there were 1.5 million solid cubic meters of damaged wood in the Harz Mountains , caused by the bark beetle infestation and in connection with "storm, shortage of workers and the chaos of war".
- 2018 came 11 years after the hurricane Kyrill for intense low Friederike , significant amounts of windblown trees left. The following year 2018 is known to be particularly low in precipitation until December. Spruce stands in particular showed reduced resistance to attack by bark beetles. After a mild winter, there was considerable damage to German, Austrian and Swiss tree populations in the spring of 2019, which was responded to with extensive removal of spruce. Since the processing capacities in Europe were insufficient to utilize the wood, there were extensive exports of the beetle wood to China. In the German state of North Rhine-Westphalia, the amount of damaged wood caused by the bark beetle species, book printer and engraver, was around 5.5 million cubic meters in 2019, far higher than in 2018 (0.8 million cubic meters). In locations below 400 meters above sea level, extensive extinction of most of the spruce forests occurred.
Reproduction
Pheromone biology
All the attractants ( pheromones ) used by the book printer are known. During the swarming flight ( dispersion flight ) of the bark beetle, the swarming males receive odor signals from the surrounding trees. Signal substances ( kairomones ) are absorbed by the antennae (primary attraction ), especially of weakened spruces, and induce the males to approach the potential host trees. If the olfactory stimuli received correspond to mechanical characteristics (e.g. bark structure), the pioneering males begin with the secondary attraction of their conspecifics of both sexes. The host's own monoterpene (-) - alpha-pinene is absorbed via the printer's tracheal system and converted into cis-verbenol, which is released via the abdomen as an aggregation pheromone (defecation). Ipsdienol and methane butenol are also released , with Ipsdienol aimed particularly at attracting females.
After the mating has ended and the host tree has been completely colonized, pheromones with a repellent effect are now being distributed by the book printers. They prevent over-colonization of the tree and thus secure the chances of survival of the growing brood. Pheromones with an inhibitory effect are verbenone, which, like cis-verbenol, is oxidized from (+) - alpha-pinene or (-) - alpha-pinene, and ipsenol.
Multiplication
A well-developed breeding system may contain 40 larval ducts. Assuming a sex ratio of 1: 1, 20 females can hatch. Assuming a 50 percent success of these females, the number of females increases tenfold with each generation.
In favorable years there is an education of three generations, i.e. a thousandfold increase in the population . The development of the brood is strongly temperature dependent. The development takes place from a threshold value of 12 to 15 degrees Celsius. Thus, when it comes to the question of whether or not a mass increase occurs, the temperature profile from April onwards is of decisive importance.
If the book printer finds temperatures of at least 15 degrees from mid-April (as in 2007), he goes through the development process from oviposition to sexually mature insect within six weeks. If a sexually mature second generation is found in mid-June, a mass increase is to be expected. The first generation forms a "sibling brood" after egg-laying and subsequent regeneration feeding (about 14 days). This usually makes it impossible to recognize exact "swarm waves" in the course of the season. Rather, the swarming phases of the second generation with sibling broods are blurred, and so there is often a persistent swarming flight and, consequently, a constant new infestation.
In the first generation, the letterpress prefers to attack wood due to the reduced sap pressure, and from the second and third generation onwards, it attacks almost exclusively standing wood. The later in the year and the worse the water supply to the host trees, the more vital trees the beetles look for. When it is very dry, they often infest in the depths of a stand, which is then recognized too late by the operating personnel.
As a rule, a mass increase takes place over several years and then ebbs away again. The starting point is often storms, the amount of damaged wood of which provides the bark beetle with sufficient breeding material. The table above supports this experience, the starting point was hurricane Niklas in spring 2015.
Combat
Basically the only effective control method so far is the removal of the infested trees and the subsequent rendering harmless of the various stages of the printer (eggs, larvae, pupae, beetles)
Clean forest management
"Clean forest management" means the withdrawal of material suitable for breeding and the removal of infested trees.
The search for the infested trees is crucial. For this purpose, the drill dust ejected by the parent animals at the hatchery is searched for at the base of the trunk. If drilling dust is found, it can be assumed that the trunk concerned is infected, can no longer be saved and should be removed.
Since the drill dust is not always easy to see and can only be seen up close, a systematic search is made around endangered areas (damaged wood that has been left behind, torn stand edges, previous infestation areas). This method is most effective in the spring, when the first beetle brood is started, as the number of infected strains is lowest during the year. In the later course of the year, every time beetles dig in and create mother tunnels, drilling dust accumulates and is a sure indicator of the infestation.
Later in the year it is easier to find infected trees due to the clear symptoms, but often the first young beetles have already flown out by then. Therefore all neighboring trees are searched for drill dust. If drilling dust is found, the other neighboring trees are searched until no drilling dust is found on any. All trees on which drilling dust is found are removed and rendered harmless.
After the infested trees have been removed, follow-up inspections of the infested areas should be carried out according to the activity of the beetles.
Making the various beetle stages harmless
If the beetles are moved to places where they cannot find any suitable material for breeding, they cannot cause any further damage. Eggs and larvae can be rendered harmless by debarking. Beetles can at least partially survive debarking and attack other trees. If there are beetles in the bark, it must also be removed from the forest for effective control or destroyed (e.g. burned).
In order to render the beetles harmless, contact insecticides can also be applied to the trunks in an emergency, which kill the beetles when they are drilled in or out. Nets that are treated with contact insecticides and that cover the felled wood have a similar function.
Catch trees
With "catch trees" an attempt is made to reduce the starting stock. For this purpose, trees are felled in spring (March / April, before the first swarming flight), which are transported from the forest or debarked if they are infested. It is doubtful whether the trapping trees are so attractive to the beetles that they can distract the beetles and prevent the infestation of standing trees.
Self-regulation
As studies in the Bavarian Forest National Park show, antagonists such as the three-toed woodpecker have only a minor influence on the mass reproduction of beetles. The gradation ends only after - if possible several - cold summers or the infestation of all trees.
Other sources attach much greater importance to self-regulation and consider the fight against the book printer through “clean forest management” to be counterproductive. According to this, spruce trees with a high density of infestation by the book printer lead to mass infections and mass deaths to the book printer by fungi, sporozoa, bacilli and viruses. Beetles that still fly out carry the infection and the population collapses. The spread of this infection would be prevented if the infected trees were removed from the forest.
Attractant traps
The attractants (pheromones) of the book printer are chemically modeled and are also offered for sale by some manufacturers and are used as attractant strips or pheromone dispensers in attractant traps ("beetle traps"). The term is misleading, however, as beetle traps do not prevent book printer attacks. Rather, the traps are used to monitor swarms. It is assumed that high numbers of catches in the traps indicate a correspondingly stronger infestation in the forest stands. In addition, conclusions can be drawn about the development of the beetles and their broods (beginning of infestation in spring, escape of the various broods, breeding success, proportion of old and young beetles, etc.).
Systemic control
In the 1990s, attempts were made with the systemic agent Methamidophos , with which an entire host tree becomes toxic to the beetle. The active ingredient is applied to the bast and leads to one hundred percent mortality of the larvae in the first six weeks. After that, the concentration of the active substance gradually decreases. The sensitive larvae, however, do not survive in the poisoned tree all year round. The standing trapping tree is interesting for the flight of beetles due to an attractant strip at a height of about ten meters.
literature
- Johann Friedrich Gmelin: J. Fr. Gmelin's Abhandlung über die Wurmtrocknis , Leipzig, Verlag der Grusiusisschen Buchhandlung, 1787, ( online via Googlebooks )
- Sabine Green : Manual for the determination of the European bark beetle Verlag M. & H. Schaper, Hanover 1979, ISBN 3-7944-0103-4
- Bavarian Forest National Park (publisher): Forest development in mountain forests after windthrow and bark beetle infestation (PDF; 9.6 MB), Scientific Series, Volume 14, Grafenau 2001, ISBN 3-930977-26-5
- 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
- Karl-Heinz Otto: Never been there before - the extreme mass reproduction of the large eight-toothed spruce bark beetle 2018 , published in GeKo Aktuell 1/2019, publisher: Geographical Commission for Westphalia, Landschaftsverband Westfalen-Lippe (LWL), ISSN 1869-4861. ( PDF file, digitized online )
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Wolfgang Schwenke (Ed.) U. a .: Europe's forest pests. A manual in 5 volumes
- Volume 2: Beetles . Parey, Hamburg and Berlin 1974, ISBN 3-490-11016-1
- Julius Theodor Christian Ratzeburg: The forest insects or illustration and description of the insects that have become known to be harmful or useful in the forests of Prussia and neighboring states , Nicolai, 1839, section "Harmful beetles", page 162, online via Googlebooks
- Helgard Reicholf-Riehm: Insects . Munich 1984
- Hans von Rudloff: The fluctuations and oscillations of the climate in Europe since the beginning of regular instrument observations (1670) , Volume 122 of Die Wissenschaft, Springer-Verlag, 2013, page 182, ISBN 978-3-663-07041-2
Web links
- Everything about book printers, engravers & Co. - Info from the LWF
- The printer (Ips typographus): The most important bark beetle in Switzerland on www.wsl.ch
- Letterpress ( Ips typographus ) at www.forestryimages.org
- Biology of Book Printer Species - WSL Leaflet for Practice PDF (464 kB)
- Helmut Klein: Threat to bark beetles PDF (2633 kB)
- Videos on Ips typographus published by the Institute for Scientific Film . Provided in the AV portal of the technical information library .
Individual evidence
- ↑ Bilder-Conversations-Lexikon for the German people . A guide to community knowledge dissemination and entertainment. FA Brockhaus , Leipzig 1837 ( zeno.org [accessed on June 11, 2019] Lexicon entry "Bark beetle").
- ↑ Felling caused by damage according to the cause of the felling and the type of forest ownership
- ↑ “ Wood that has been infected or overlaid by bark brooders, which is blue, predominantly without firm bark, is dry or red-streaked, is sorted into quality class D. ". Framework agreement for the raw wood trade in Germany (RVR), the German Forestry Council and the German Wood Management Council. 2nd edition 2015. download
- ↑ a b Michael Habermann, NW-FVA Göttingen, Bark beetle control in the Harz NP (online PDF file) ( Memento from March 11, 2019 in the Internet Archive )
- ^ Johann Friedrich Gmelin: J. Fr. Gmelin's treatise on worm drying
- ↑ Rudloff, page 182
- ↑ Die Zeit, March 8th, 2019 , "The forest teaches us to act in the long term" ( Memento of March 10, 2019 in the Internet Archive )
- ↑ Frankfurter neue Presse (FNP), February 25, 2019 , "Taunus spruces for China: Storm damage and bark beetle infestation: oversupply depresses the market price" ( Memento from March 10, 2019 in the Internet Archive )
- ↑ Landesbetrieb Wald und Holz Nordrhein-Westfalen, Forest Protection - Information message No. 6/2018 from October 12, 2018, (online PDF file) ( Memento from March 11, 2019 in the Internet Archive )
- ^ Mathias Niesar, S. Glück, Friedrich Louen, Michael Cescotti; Annette Köhne-Dolcinelli, WUH editorial team, January 21, 2019, spruces - bark beetles - mass reproduction with unprecedented intensity ( memento of March 11, 2019 in the Internet Archive )
- ↑ Federal Statistical Office: Logging Statistics 2018; Retrieved on May 4, 2020 at https://www.destatis.de/GPStatistik/servlets/MCRFileNodeServlet/DEHeft_derivate_00042999/2030331187005_aktualisiert.xlsx
- ^ Forest condition report 2019. Report on the ecological condition of the forest in North Rhine-Westphalia. published by the Ministry for the Environment, Agriculture, Nature and Consumer Protection of the State of North Rhine-Westphalia, Düsseldorf, in November 2019. PDF
- ↑ Bavarian Forest National Park (publisher): Forest development in the mountain forest after windthrow and bark beetle infestation ( Memento of the original from August 12, 2014 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 9.6 MB), p. 35.
- ↑ Helmut Klein: Threat Bark Beetle , p. 12.
