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Granbarkborren, Ips typographus, är den mest destruktiva skadeinsekten för svensk barrskog och orsakar årligen stora ekonomiska förluster för landets skogsägare. Granbarkborren kan endast föröka sig i döda träd. För att döda ett stående friskt träd kan de med feromoner signalera till andra granbarkborrar att tillsammans inleda en massattack. Granbarkborren är även beroende av blånadssvampar för att kunna slå ut friska träd. Med dessa blånadssvampar kombinerat med en massattack kan granbarkborren döda trädet inom några veckor. Blånadssvampen ger en missfärgning i virket vilket innebär en värdeminskning av den erhållna veden. I detta examensarbete har de tillväxthämmande effekterna mellan blånadssvamparterna Ophiostoma picea, Grosmannia penicillata och Ceratocystis polonica undersökts. De tillväxthämmande effekter svamparna utövar på varandra har studerats visuellt med odlig i artificiellt såväl som naturligt medium representerad av bark. Tillväxthastigheterna hos respektive svamp har uppmätts. G. penicillata fanns ha den högsta tillväxthastigheten samt de största tillväxthämmande effekterna mot de andra svamparna. Kemiska analyser har utförts med SPME och GCMS för att se vilka ämnen svamparna och barken producerar. Resultaten tyder på att vissa ämnen som produceras av barken inte finns närvarande efter att svampen vuxit i barken. Många ämnen produceras av alla tre svampar men en del är även unika för en viss svampart. Som exempel var G. penicillata ensam om att producera seskviterpenen β-Guaiene, det aromatiska kolvätet m-Cymene och terpenen Borneol. Barken producerade ämnen, bland dessa seskviterpen-alkoholen δ-Cadinol, som sedan inte gick att finna när svamparna var närvarande. Detta tyder på att svamparna konsumerat dessa ämnen alternativt att barken inte producerar samma ämnen i svamparnas närvaro. / The spruce bark beetle, Ips typographus, is the most destructive insect pest of Swedish pine forests and causes major economic losses annually for the forest owners. The spruce bark beetle can only reproduce in dead trees. To kill a healthy tree they can, with pheromones, signal other spruce bark beetles to launch a mass attack. The spruce bark beetle is also dependent on the blue stain fungi in order to beat out healthy trees. With these blue stain fungus combined with a mass attack, the spruce bark beetles can kill the tree within a few weeks. The fungus causes a discoloration in the wood, resulting in a reduction in economic value of the obtained wood. In this thesis, the growth inhibitory effects of blue stain fungi species Ophiostoma picea, Grosmannia penicillata and Ceratocystis Polonica have been investigated. The growth inhibitory effects that the fungi have on each other have been studied visually by cultivation in an artificial as well as a natural medium represented by bark. The growth rates of the respective fungi have been measured. G. penicillata were found to have the highest growth rate and the largest growth inhibitory effects on other fungi. Chemical analyses were performed with SPME and GCMS to see what chemical substances fungi and bark produces. The results show that some substances produced by the bark are not present when the fungi are growing in the bark. Various substances are produced by all three fungi, but there are also many unique compounds from a particular fungal species. For example, G. penicillata was the only one that produced the sesquiterpene β-Guaiene, the aromatic hydrocarbon m-cymene and the terpene Borneol. The bark also produced unique substances, among these the sesquiterpenoid alcohol δ-Cadinol, which then could not be found when the fungi were present. This suggests that the fungi consume these substances or that the bark does not produce the same substances in fungi presence.

Terpenes and phenols are of importance in conifer defense against insects and pathogens. Knowledge about tree chemical defense is vital for developing practical methods to maintain healthy forests. With the aims of characterizing the defensive chemical induction in Norway spruce Picea abies and demonstrating its ecological function to spruce bark beetle Ips typographus, we measured the terpenoid and phenolic content in the bark of mature Norway spruce trees suffering windstorm, inoculated with Ceratocystis polonica, or treated with methyl jasmonate (MeJA), and investigated the colonization and pheromone emission of I. typographus. All three stressors altered the chemical profile in the bark of Norway spruce. Trees damaged by windstorm had lower proportions of (+)-3-carene and two unidentified stilbenes, and a higher taxifolin glycoside content than trees without apparent windstorm damage; C. polonica inoculation induced extremely strong quantitative terpene accumulation in the wound reaction zone, but only increased the levels of (+)-3-carene, sabinene and terpinolene in the bark near the reaction zone; MeJA treatment generally elicited quantitative terpene accumulation, but the induction differed extensively between individual trees. In addition, logs from MeJA-treated tree showed much stronger wounding response compared to control logs. The chemical profile of Norway spruce affected the colonization and pheromone emission of I. typographus. In response to fungal inoculation, terpene present in the reaction zone inhibited the colonization of I. typographus in a dose-dependent manner. Host defense elicited by MeJA treatment reduced emissions of 2-methyl-3-buten-2-ol and (S)-cis-verbenol, the two key aggregation pheromone components of I. typographus, and altered the ratio between the two components. / QC 20110503