Flat bark beetle
| Flat bark beetle | ||||||||||||
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| Scientific name | ||||||||||||
| Rhizophagus grandis | ||||||||||||
| ( Gyllenhaal , 1827) |
The flat bark beetle ( Rhizophagus grandis ) is a beetle from the family of Monotomidae (in older literature mostly listed under the synonym Rhizophagidae). As the most important predator of the giant bast beetle ( Dendroctonus micans ), it plays an outstanding role in biological forest protection .
features
The beetles are about 4.5 to 5.5 millimeters long. They are built very flat - hence the name -, maroon colored and shiny. The pronotum is a little longer than it is wide. An important species feature is a row of dots between the second and third secondary stripes of the wing . There are several very similar-looking species that the flat bark beetle can be confused with.
Similar species
- Flat root beetle ( Rhizophagus depressus ) - pronotum longer than wide
Way of life
The beetles and their larvae live under the bark of conifers , where they hunt down the giant bast beetle and its brood. The bark beetle larvae in particular are very voracious and literally suck their prey. They detect giant beetle larvae using certain odorous substances that they leave behind in the drill dust . Even small amounts of these chemical signal substances are sufficient for this. The adult beetles recognize infested trees and the holes in the giant bast beetles by their smell and visual characteristics.
To pupate, the bark beetle larvae leave the bark and look for suitable places in the ground. About 45 days later, the then slip imagines .
Importance in forest protection
Wherever giant bark beetles cause considerable damage to the common spruce ( Picea abies ), the flat bark beetle is used with good success for the biological control of these bark beetles . It is even bred en masse in Georgia , France , Belgium and Great Britain . While the foresters in Georgia have had experience with this since 1963, comparable programs only started in France and Great Britain in 1983 and in 1984 in Turkey .
The giant bast beetle did not appear in Great Britain until the early 1970s and had no natural predators there. For a control program, the foresters therefore imported the flat bark beetle from Belgium, which began in 1984 on a large scale. It was the first such project in which a non-native antagonist of a pest was used. In the meantime, the flat bark beetles are also released in forests in which no giant bark beetle infestation has yet been detected. Since the bark beetles, due to their strict host specialization, cannot survive long without a sufficient Giant Beetle population, attractant traps can be used to determine after about a year whether they are still present in the area concerned. If so, this also proves the infestation by giant bast beetles. However, the flat bark beetles never deprive themselves of their livelihood by exterminating the giant bark beetles. But they can reduce the population of their prey by up to 80 to 90 percent, which means for forestry that only about 0.25 to 1 percent of spruce trees die after bast beetle infestation. Scientific studies in the forests of Great Britain, including Wales , which were first infested by the giant bark beetle, showed that this state was achieved within five to seven years after the flat bark beetle had been brought out.
literature
- Uwe Depping: Predator-prey relationships in forests of temperate latitudes using the example of Rhizophagus grandis Gyll. and Dendroctonus micans Kug. Possibilities and methods of biological pest control . (Diploma thesis). Göttingen 1997, 76 pp.
- NJ Fielding, HF Evans: Biological control of Dendroctonus micans (Scolytidae) in Great Britain . In: Biocontrol News and Information , Volume 18, Issue 2/1997, pp. 51–60
Web links
Individual evidence
- ↑ a b Bohumil Starý, Pavel Bezdecka, Miroslav Capek, Petr Starý, Georg Benz, et al .: Atlas of useful forest insects . Ferdinand Enke, Stuttgart 1990, ISBN 3-432-97121-4 , p. 77
- ^ A b c d Hugh Evans, David Wainhouse, Nick Fielding: Biological cruise missile . The Royal Society's Summer Science Exhibition 2004 (accessed June 10, 2007) ( Memento November 12, 2007 in the Internet Archive )
- ↑ a b Hazan Alkan, Akinci, Gonca Ece Özcan, Mahmut Eroğlu: Damage Status of Dendroctonus micans (Kugelann) (Coleoptera: Scolytidae) and Effectiveness of Rhizophagus grandis Gyllenhal (Coleoptera: Rhizophagidae) On It In The Field , accessed June 10 2007