Spatio-temporal distribution of Hylobius abietis in Scots pine stands – implications for pest monitoring

The protection of reforested areas against the large pine weevil Hylobius abietis is one of the greatest forest management challenges in many European countries. No information exists on the spatial distribution of this pest, which is necessary to assess its abundance and, consequently, to precisely estimate its threat to reforested sites. The aim of this study was to assess the spatio-temporal changes in the number of H. abietis beetles in reforested clear-cut areas (reforestations) and neighbouring Pinus sylvestris stands, from which these beetles are assumed to migrate to the reforestations. In this two-year study, baited traps were used to catch H. abietis beetles in the reforestations and neighbouring stands. The results revealed significantly more beetles in the neighbouring old stands (61–69 years) than in the young stands (5–11 years). The distribution of the beetles in both the old and young stands was inversely dependent on the distance from the stand edge. The large pine weevil migration to the reforestations was most intense in mid-May and early June. In May, most beetles were collected along the edges of the reforestations; in June, their distribution was more regular; and in July, the beetles were more abundant in the central part of the reforestations. These results allow H. abietis monitoring improvement, which is an important element of integrated forest protection.