OLFACTORY RESPONSE OF THE LARGE PINE WEEVIL, HYLOBIUS-ABIETIS L (COLEOPTERA, CURCULIONIDAE), TO PLANT-EXTRACTS

Initial investigations were made to test the attractiveness of extracts from primary needles, old needles, bark and roots of spruce (Picea abies (L.) Karst.), Scots pine (Pinus silvestris L.), Douglas fir (Pseudotsuga menziesii Fr.) and European larch (Larix decidua Mill.) for the large pine weevil (Hylobius abietis L.). In a ring test, extracts from the bark of Pinus silvestris and Pinus abies and from old needles of Pinus silvestris and Pseudotsuga menziesii turned out to be most attractive for H. abietis. Contrary to the extract from roots of P. silvestris, the attractiveness to H. abietis of all the other extracts under review declined in the course of the year. This may be due to the different behaviour of the imagines, i.e. the transition from the main feeding period in spring to the period of less intensive feeding and increased oviposition in summer. It can be concluded from the preliminary results that all the parts of conifers that were tested contain certain substances attracting H. abietis. However, old needles are most important to the orientation of the weevils.