The role of lignin as a defence against the spruce bark beetle Dendroctonus micans: effect on larvae and adults.

The role of lignin as a physical defence against Dendroctonus micans was investigated in laboratory feeding experiments. The effect of lignin is dose-dependent, reducing larval survival, growth rate, and weight, as well as affecting gallery construction. Adults lay fewer eggs in lignified bark and also tend to construct abnormal galleries. The distribution of lignin in trees suggests a role in defence against bark beetles that feed in the thicker bark on the lower bole.