THE EFFECTIVENESS OF PINE OIL AS A REPELLENT AGAINST THE STRIPED AMBROSIA BEETLE TRYPODENDRON-LINEATUM (COL, SCOLYTIDAE)

Pine oil is an effective repellent and can protect spruce logs from ambrosia beetle attack. The repellent effect was measurable 2 cm above sprayed log surface, in 50 to 80 cm it was no more detectable. Logs treated twice kept free from attack for nearly 3 weeks. Although the population was very high (mean attack density 509 borings/m2 on controls) the attack reduction was 85 % after 8 weeks flight. A single treatment with pine oil gave absolute protection for nearly 1 week during beetle flight. The attack reduction kept greater 90 % for 7 weeks if sprayed directly to the log surface and nearly 4 weeks, if applied in dispensers. After 10 weeks exposure to beetle flight both kinds of application reached about 85 % attack reduction to controls, that were heavily infested (395 borings/m2). Pine oil 65 and norpine 65, two commercial products, showed no significant differences in their effectiveness on logs. Pine oil had no negative effect on the breeding success of T. lineatum. In reverse, the lower attack density on sprayed logs gave a 3 times higher offspring per brood system.