Seedling Mortality Caused by Hylastes cunicularius Er. (Coleoptera, Scolytidae) in Picea abies Plantations in Northern Sweden

Mortality of Picea abies seedlings caused by Hylastes cunicularius was studied by analysing damage reports and by repeatedly inspecting 12 000 individually marked seedlings in 59 plantations. The findings indicated that H. cunicularius caused more damage in the northern parts of Sweden than in the more southern parts. Feeding by H. cunicularius was the most frequent cause of spruce seedling death in plantations during 4 to 6 years after cutting of the previous stand. Although accumulated seedling losses sometimes exceeded 30%, yearly loss rates were generally moderate. The long period over which damage can occur is one of the reasons why H. cunicularius has rarely been identified as an important cause of seedling mortality in spruce plantations.