INDUCED RESISTANCE IN THE PHLOEM OF THE E UROPEAN LARCH LARIX-DECIDUA(MILL) AFTER ATTACK BY THE GREAT LARCH BARK BEETLE IPS-CEMBRAE (HEER)(COL, SCOLYTIDAE)

Recently caught Ips cembrae beetles were immediately transferred into cages attached to Larix decidua trees (of about 20 cm diameter) under field conditions (14.06. and 17.07.1991). After the formation of the g alleries, compounds of the phloem of unsuccessfully attacked tissue, o f tissue immediately adjacent to the galleries, and of tissue at a dis tance of 5 cm from the galleries were investigated. In comparison to u ndamaged tissue, the concentrations of soluble carbohydrates and of th e procyanidines were strongly diminished, the concentration of protein amino acids, however, had increased markedly, accompanied by qualitat ive changes in the tissue along the gallery. In unsuccessfully attacke d tissue only a small decrease in all the above-mentioned compounds wa s observed. The results are discussed with respect to induced resistan ce.