THREAT ASSESSMENT OF PINE SPECIES (PINUS SP.) STANDS BY FOLIOPHAGES WINTERING IN FOREST LITTER IN THE ROGÓW ARBORETUM (POLAND)

Abstract. One effective way of evaluating the threat to pine stands by the foliophagous insects is the method of autumn exploration of primary pests. The Entomological Section of "Kolo Leśnikow" at the University of Life Sciences in Poznan in November 2012 conducted a study in the Rogow Arboretum, whose main objective was to assess the risk posed to the five species of pine stands by foliophagous insects wintering in forest litter. An additional objective of the studies was to create a list of species recognized as primary pests for each of experimental area of pine trees of different species and to develop outbreak projections of pest insects for the following year. The method used in the studies was based on the searching of litter on the surface under the tree crown [Instrukcja ochrony lasu 1999]. The final results were calculated on a surface of 5 m2. The mean area under the canopy of pine came to 9.58 m2 (SE ±1.05). The highest density was shown for insects of the Diprionidae family on an experimental plot of Scots pine amounting to 0.42 individual per 5 m2. The density of any of the reported species did not exceed the warning number. In experimental plots, the following primary pests were found: species of pine sawflies Diproninae, the pine beauty Panolis flammea (Den. et Schiff.), the pine looper moth Bupalus piniaria (L.) and the pine hawk moth Hyloicus pinastri (L.).