CONIFER STUMP CONDITION AND PINE WEEVIL (HYLOBIUS-ABIETIS) REPRODUCTION

Reproduction of the pine weevil (Hylabius abietis (L.)) in stumps of S cots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Ka rst.) was studied in relation to stump condition. Cut surfaces of stum ps were treated to promote or retard microbial colonization. During th e 4 months following cutting, chemical and physiological properties of the stumps were monitored. The number of emerging weevils and the est imated proportion of root area utilized by the weevil larvae and other organisms were used to evaluate the influence of the stump treatments on pine weevil reproduction. Stump treatments had no clear effect on pine weevil reproduction. However, fewer pine weevils emerged from stu mps treated to retard microbial colonization than from other stumps. M oisture content increased with time and decreased with distance from t he cut surface. Pine stumps died faster (content of living cells estim ated by dehydrogenase activity) and supported higher levels of pine we evil reproduction compared with spruce stumps. Ethanol contents of bot h pine and spruce stumps were lower in August than in the preceding mo nths. This lower ethanol content coincided with a lower content of liv ing cells.