[Anatomical Characteristics of Norway Spruce Bark (picea-abies-karst) and the Intensity of Ips-typographus L Attacks (col, Scolytidae)]

This study, which is part of a research on resistance factors of spruce against Ips typographus, analyses relationships between the intensity of the bark beetle's attacks and anatomical characteristics of the bark. Bags of synthetic pheromones were hung on 10 healthy trees in each of the two stands of 50 and 70 years old spruce trees. Two months later, these variables and the intensity of the insects attacks were quantified. In the 70 years old stand, the intensity of attacks was hardly related to the anatomical characteristics of the bark. However, for the other stand, 59 % and 83 % of the variability of the attacks at 3 and 6 meters respectively are explained by the anatomical characteristics, mainly due to the thickness of dead parenchyma and phloem of the outer bark. This may be partly due to chemical substances impregnating these tissues. Moreover, it would seem that the resiniferous system is not a major resistance factor of the tree against the bark beetle. Lastly, the intracellular starch content decreases the most on heavily infested trees.