RELATIONSHIPS BETWEEN DENDROCTONUS-MICANS KUG (COLEOPTERA, SCOLYTIDAE) SURVIVAL AND DEVELOPMENT AND BIOCHEMICAL-CHANGES IN NORWAY SPRUCE, PICEA-ABIES (L) KARST, PHLOEM CAUSED BY MECHANICAL WOUNDING

The bark of Norway spruce trees, Picea abies (L.) Karst., was wounded to produce areas of bark with differing biochemical characteristics. A dults and larvae of Dendroctonus micans Kug. were inserted into these trees at points around the wounds. Larval survival was higher, larval dry weights were higher, and adults were more likely to oviposit at si tes around the wound that had higher phloem moisture contents. Larvae showed higher survival and dry weights in phloem with low terpene cont ents. Adults oviposited in phloem with lower stilbene glucoside conten ts. Phloem moisture differed at sites around the wound compared with t hat at a control site away from the wound, and the nitrogen content of entire bark cores was higher above wounds than at control sites away from the wounds. Phloem moisture correlated with the nitrogen content of entire bark. Phloem terpene contents correlated with each other, as did the stilbene contents. Associations between the host exploitation pattern of D. micans and the biochemistry of the host phloem are disc ussed in relation to preselection by adults of sites suitable for larv al development.