Two-toothed pine beetle (Pityogenes bidentatus and Pityogenes quadridens)
Kolk A. and Starzyk J. R. 1996.The Atlas of Forest Insect Pests. The Polish Forest Research Institute. Multico Warszawa. 705 pp.
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Occurrence
Europe, the northern Asia, Japan, Korea.
Host plants
Various coniferous trees, but mainly the Scots pine, occasionally the spruce, larch and fir.
Morphology
Beetles are 1.8-2.5 mm long, cylindrical, brownish-black. Elytrae are darker at the base and reddish at the end. Males of P. bidentatus have one distinct hook like tooth on each side of the upper part of elytral declivity. P. quadridens, in addition to those two teeth, has one smaller below them on each side. Females have unclear teeth.
Biology
Overwintering occurs in the larval, pupal or imaginal stage. These species have one or two generations per year that depends on the weather conditions. Adults of the first generation initiate flying in May-June, and those of the second generation in July-August. They can have also a sister generation. The male constructs nuptial chambers, where 3 up to 7 females are attracted. Females construct egg galleries of up to 10 cm in length and lay eggs singly in niches that are irregularly cut into both sides or sporadically only one side of the egg gallery. After hatching, larvae construct galleries of the different length. Oval pupal chambers are constructed in the sapwood or phloem. Newly-formed adults have maturation feeding in larval galleries.
Damage
These bark beetles attack rather young trees, but also the top and branches of old trees. They often occur with other species like: Ips acuminatus, Tomicus minor, etc. Sometimes P. bidentatus and P. quadridens infest branches on older trees attacked by Phaenops cyanea. They prefer 20-40 year old stands weakened by pollution or planted on post-agricultural lands.
Preventive measures
Removal or burning of the potential breeding material like logging residues (tops, branches). Removal of dying, weakened trees.
Control
Removal of all trees, which are infested, and burning debris like tops, branches, particularly those infested.
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