Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Introduction. Surveys regarding accumulated amounts of spruce branches, which provided breeding material for the spruce wood engraver (Pityogenes chalcographus L.) were conducted in four forests divisions: Zdrojowisko, Ścinawka, Bożków and Wojbórz of the Jugów Forest District. Material and methods. In January 2019 branches left after the fall/winter sanitation cutting were collected. The branches originated from a Norway spruce (Picea abies (L.) Karst.) forest and were sampled during the mass gradationof Pityogenes chalcographus. Overall 4 samples of branches of 1–6 cm in diameter and length up to 40 cm were collected for analyses. Branches were placed in 4 separate, specially designed cardboard photo-eclectors of 450×350×250 mm (length/width/height) and equipped with a 53-mm outlet. Collected insects were described by family, type, species and in the case of spruce wood engravers also determined their sex. Results. The conducted experiment resulted in collecting of 3459 specimens of P. chalcographus with the highest number of 1422 insects collected in the case of branches originating from the Wojbórz Forest Division, while the lowest number (335) originated from the Zdrojowisko Forest Division. Pityogenes chalcographus was the most frequent pest insect overwintering in the form of larvae, pupae and imagoes. The sex ratio of the species ranged from 50.38% to 61.74% in favour of females. In the case of separate branches the share of females was the highest in the Wojbórz (61.74%), Zdrojowisko (59.10%), Ścinawka (57.08%) and Bożków Forest Division (50.38%), respectively. The frequency of other pest insects was also determined. The second ranking insect in terms of its frequency was Pityophthorus pityographus, reported mostly in two forest divisions: Bożków (29.26%) and Zdrojowisko (21.53%). The other collected insect species were not found on spruce branch residue in significant numbers. During the surveys overwintering single predatory and parasitic insects were also collected. Conclusion. It has been concluded that the most frequent insect on the analysed material was the spruce wood engraver, which played a significant role in colonisation of spruce branches and is considered as a major factor of the tree top weakening. The use of photo-eclectors facilitates identification of the entomofauna originating from individual tree stands and in the case of potential danger provides data for the selection of an appropriate method to control pest insects before the onset of their reproduction. The numerous presence of pest insects on analysed branches suggests that logging residue needs to be disposed of. The developed method should be introduced to monitor the presence of harmful entomofauna, especially in weakened Norway spruce stands. Both Pityogenes chalcographus and Pityophthorus pityographus appeared on the analysed material in very large numbers, therefore they may contribute to considerable economic losses in forests. The sex ratio of P. chalcographus slightly favoured females, which is in contrast to the biology of species, suggesting the need of additional research to confirm the obtained results.