THE NUISANCE OF THE ROCKY PINE FORESTS – THE SHARP-DENTATED BARK BEETLE
The sharp-dentated bark beetle (Ips acuminatus) (approx. 2.2-3.5 mm) is a pine bark beetle that breeds in timber, logging residues and in the crowns of trees. The sharp-dentated bark beetle has previously appeared in Finland mainly in northern and eastern Finland, but in recent years, damage caused by it has been observed especially in southwestern Finland in dry and rocky habitats. The species benefits from the drought stress of pine trees caused by climate change.
The sharp-dentated bark beetle swarms in May and June. The new adults hatch in late July and overwinter either under the bark or on the ground. The species can also reproduce parthenogenetically, i.e. virginally. The sharp-dentated bark beetle carries a blue-stain fungus to the tree for feeding purposes. The blue-stain fungus migrates into the wood and because of that the tree or part of the tree starts to dry out.
Dead pines in the archipelago of Turku. Galleries of Ips acuminatus were found in the pines.
Detecting the sharp-dentated bark beetle in pine can be difficult, but the species make ventilation holes to the bark, which is causing peeling of the bark.
Detecting the sharp-dentated bark beetle in pine can be difficult, but the species make ventilation holes to the bark, which is causing peeling of the bark. These ventilation holes in the bark can be the first noticeable symptom of the beetle reproduction in the pine. The mother galleries of the beetle are filled with fine dense sawdust. Thus, detecting the sharp-dentated bark beetle from the tree is more difficult, unlike, for example, European spruce bark beetle, which is causing sawdust below the tree trunk. The mother galleries can be up to twenty centimeters long. The larval galleries are short and eventually sink into the wood.
Along with the sharp-dentated bark beetle, it has also been observed that Diplodia tip blight caused by the Sphaeropsis sapinea fungus often occurs in pines. The relationship between the sharp-dentated bark beetle and the fungus is still not very well known, but these have often been found in the same pine individuals.
The mother and larval galleries of the sharp-dentated bark beetle.
Siitonen J. (2014). Ips acuminatus kills pines in southern Finland. Silva Fennica vol. 48 no. 4 article id 1145.
Terhonen, E. & Melin, M. (toim.) 2023. Metsätuhot vuonna 2022. Luonnonvara- ja biotalouden tutkimus 48/2023. Luonnonvarakeskus. Helsinki. 98 s. [In Finnish].
Tuhonaiheuttajat, Metsäinfo, Luonnonvarakeskus. Viitattu 10.11.2023. https://metsainfo.luke.fi/cms/opas/tuhonaiheuttajaluettelo [In Finnish].