Response of Hylobius abietis (L.) weevils to the variation of alfa-pinene and ethanol release rates, as well as of alpha-pinen/ethanol ratio

摘要

Hylobius abietis adults use different olfactory signals for their orientation and for the identification of the suitable substrate for breeding. The signals are represented by volatile substances released by conifer stumps or slash, and contain monoterpenes, including (-)alpha-pinene (AP), and ethanol (ET). The research aimed to ascertain if the variation of AP and ET release rate, as well as the ratio of AP/ET, has any influence on the adult weevil response. The following treatments have been compared: V1 ? 0.1 ml/day AP + 0.1 ml/day ET, V2 ? 0.3 ml/ day AP + 0.3 ml/ day ET, V3 ? 0.1 ml/day AP + 0.3 ml/ day ET, V4 ? 0.3 ml/ day zi AP + 0.9 ml/ day ET, V5 ? 0.2 ml/ day AP + 0.1 ml/ day ET, V6 ? 0.6 ml/ day AP + 0.3 ml/ day ET, V7 ? control (blank), and the experiment was conducted during the summer 2007, in two Norway spruce clear cuttings of 6-8 months old. In each experimental area, ten replications of each treatment were used and the traps were set up to 4-5 m apart. Experimental results showed that ? in the presence of abundat host materials releasing natural volatiles similar with that from traps ? mature weevils of Hylobius abietis were equally attracted by the six combinations of ethanol and (-)alpha-pinene as long as the release rate of AP and ET were 0.07-0.38 mg/day and 0.08-0.57 mg/day respectively, and the ratio between the release rates was 0.33-1.55. The captures in the six treatments were significantly higher than in control traps. Key words: Hylobius abietis, alpha-pinene, ethanol, release rates, weevil response