Pine weevil abundance on clear-cuttings of different ages: A 6-year study using pitfall traps

Patterns of seasonal and yearly variation in the abundance of the pine weevil, Hylobius abietis (L.) (Coleoptera: Curculionidae), were determined on clear-cuttings of various age in southern Sweden. New clear-cuttings were established during each of five consecutive years, and the numbers of weevils caught in pitfall traps baited with alpha-pinene and ethanol were recorded weekly during the season for up to 6 yrs on these areas. In total, 74 281 weevils were trapped. On fresh clear-cuttings, the catches increased drastically once migrating weevils had arrived in spring. Catches peaked in May and July but were lower in June, when oviposition underground is most intense. The catches declined suddenly in the middle of August, coincident with the weevils becoming post-reproductive. On older clear-cuttings, most weevils were caught before migration in spring; thereafter the catches gradually decreased from June to September. Pine weevils were even abundant on 5-yr-old clear-cuttings. Relationships between trap catch and weevil-induced seedling mortality were examined on fresh clear-cuttings and on the same areas over the following 3 yrs. A significant relationship between these two variables existed only for the 2-yr-old clear-cuttings. Therefore, trapping data alone appear to be insufficient in forecasting seedling damage.