In the present investigation, the effect of chemical induced defense in host colonization process of the spruce bark beetle Ips typographus (L.) in mature Norway spruce were studied. We used methyl jasmonate (MJ), a wellknown inducer of plant defense responses, to manipulate the biochemistry and anatomy of mature Picea abies trees and test their resistance to attack by Ips typographus. Stem sections of P. abies treated with MJ had a significantly higher concentration of mono-, sesqui- and diterpenes than untreated sections. Bark sections of P. abies treated with MJ had significantly less I. typographus colonization than bark sections in the controls and exhibited shorter parental galleries and fewer eggs deposited. The increased amount of terpenoid resin presentin MJ-treated bark could be directly responsible for the observed decrease in I. typographus colonization and reproduction.
