Relationships betweenDendroctonus 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. Adults and larvae ofDendroctonus 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 sites around the wound that had higher phloem moisture contents. Larvae showed higher survival and dry weights in phloem with low terpene contents. Adults oviposited in phloem with lower stilbene glucoside contents. Phloem moisture differed at sites around the wound compared with that 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 ofD. micans and the biochemistry of the host phloem are discussed in relation to preselection by adults of sites suitable for larval development.
Department of Zoology, South Parks Road, OX1 3PS, Oxford, England.
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Storer
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Speight