SENSITIVITY OF MARITIME PINE (PINUS-PINAS TER-AIT) TO ATTACK BY THE PINE MOTH, DIORYCTRIA-SYLVESTRELLA RATZ (LEPIDOPTERA, PYRALIDAE) IN A RANGE OF SITE CONDITIONS - RELATIONSHIPS TO CERTAIN GROWTH-CHARACTERISTICS

In order to evaluate the differential susceptibility of Pinus pinaster Ait growing in 13-21-yr-old stands where the soil conditions and wate r content vary gradually with the attacks of the Pine moth Dioryctria sylvestrella (Ratz), several types of measurement were made (basal are a, height of the 100 largest trees/ha, etc) and correlated with the in tensity of attacks. It appears that the highest productivity stands ar e the most infected. In a given stand, the trees with the best radial growth are attacked first. It is suggested that the larval penetration in the inner bark is aided by any naked surface of the tree (linked w ounds or cut branches) as well as the presence of thin bark; the quali ty and quantity of the inner bark facilitates larval growth.