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Beat Wermelinger

Forschungsanstalt WSL

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Forest Entomology
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Article

Author(s): Dagmar Nierhaus-Wunderwald
Editorial office: WSL, Switzerland
Comments: Article has 0 comments
Rating:: To my favourites Print preview 64.3364.3364.3364.3364.33 (43)

The Natural Enemies of Bark Beetles

Fact sheet for the practitioner

The biology and the environmental needs of bark beetles are already well known. The knowledge about their antagonistic agents however is limited. The fact sheet describes in detail the natural enemies (antagonists) of the spruce bark beetles (Ips typographus und Ips amitinus) and other bark beetles in Central Europe. The enemies of bark beetles may be classified in three superordinate groups: pathogens, predators, and parasites.

Pathogens

Dreizehenspecht
Fig. 1 - Three-toed woodpecker
Photo: A. Aichhorn
 
  • Bacteria are taken up by the beetle with food. The body content turns into a bad smelling-decayed pulp.
  • Under humid, warm conditions, fungi have a significant influence on the mass reproduction of numerous bark beetle species.
  • Protozoa mainly attack the larvae stages of the hosts. However, there is little known about the effect of protozoa on bark beetles.
  • Nematode worms can usually be found in the breeding system of the bark beetles. There is, however, still too little known about their effects.
  • According to the newest state of art, viruses also occur but play a secondary role as pathogens of bark beetles.

Predators

  • Mites can be found in almost all bark beetle breeding systems. The suck on the eggs, larvae, and cocoons of the bark beetles. However, there is still little known about their effect.
  • Among the beetles, there are numerous species which are as larvae and/or in the adult stage important predators for bark beetles. The most conspicuous one is the checkered-beetle (see photo).
  • The snakeflies also play a role with the natural regulation of the population density of various bark beetles. However, it is only the larvae which are feeding on bark beetles.
  • The true flies play an important role as predators of bark beetles. The larvae of the long legged flies (Dolichopodidae) and lance flies (Lonchaeidae) are particularly important predators.
  • Birds can intervene in a regulatory manner in bark beetle populations, as long as these are not too large. The black woodpecker, the lesser spotted woodpecker and, in particular, the three-toed woodpecker are important enemies.

Parasites

  • Various parasitic wasps among the Hymenoptera, contribute as parasititoids of bark beetles significantly to the maintenance and the reestablishment of the natural balance.
     
Ameisenbuntkäfer Schlupfwespe  
Fig. 2 - European checkered-beetle (Thanasimus formicarius) eats a bark beetle.
Photo: Beat Fecker (WSL)
Fig. 3 - Parasitic wasp laying eggs onto a bark beetle.
Photo: Beat Wermelinger (WSL)
 
     

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  • This fact sheet, issued by the Swiss Federal Institute for Forest, Snow and Landscape Research WSL, is not available in English language.

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