The large pine weevil Hylobius abietis (L.) as a potential vector of the pathogenic fungus Diplodia sapinea (Fr.) Fuckel

Diplodia sapinea, an important pathogen of various conifer species, was recently recorded in the northern Baltic region. The pathogen can disperse over short distances via rain or wind, whereas long range dispersal occurs via movement of contaminated plant material and seeds by humans, as well as by insects. Hylobius abietis is one of the most important forest pests over large areas of Europe. Adult weevils feed on the bark of seedlings of young conifers, causing injury and often death. Weevils were collected from fresh clear-cut areas and near the symptomatic conifer stands to analyze the presence of D. sapinea. Entire weevils collected from natural environments were crushed without surface washing. The identity of D. sapinea and the fungal DNA extraction from the insects was confirmed by species-specific polymerase chain reaction priming. Eight H. abietis individuals were determined to be infected with D. sapinea. In a laboratory experiment, pine branches were infected with D. sapinea and were fed to adult H. abietis. The results show that the pathogen survived in the digestive tract of H. abietis in the laboratory experiment, and also that the isolation of fungus from the faeces was successful. In addition, the results demonstrate that the large pine weevil may be a potential vector of pathogenic fungus D. sapinea.