The Role of Volatile Oil Composition for Trunk Pest Resistance in Coniferous Plants. Experiments on Lumber

Abstract

It has been found that the damage caused by Callidium violaceum L. in unbarked coniferous lumber stored within a year is in the average: in spruce 95%, in pine 60% and in fir 30% of its length. Some of fir lumber was not damaged at all. The amount of volatile oil (VO) in fir phloem was 7–8 times as much as in spruce. In laboratory tests the composition of VO (by gas-liquid chromatography method) and its toxicity (lethal concentration 50 by probit method) as well as the toxicity of terpenes obtained from the investigated species were determined. The VO toxicity in undamaged fir was 3.2 times as high as in spruce, and it was 1.5 times as high as in little damaged fir. Larval toxicity of substances present in the wood decreases in the following order: bornil acetate, Δ3-carene, alpha-pinene, VO of undamaged fir, VO of little damaged fir, beta-pinene, limonene, VO of spruce. The toxicity of VO in undamaged fir (per 1 mg of insect’s weight) for young larvae was 34–39 times as high as for 4th—5th instar larvae.