NIBIOs employees contribute to several hundred scientific articles and research reports every year. You can browse or search in our collection which contains references and links to these publications as well as other research and dissemination activities. The collection is continously updated with new and historical material.



At a certain point in time during a bark beetle aggregation on a host tree a deadly number of attacks is reached, provided suitable swarming conditions and beetle abundance. This threshold of successful attack was studied in Norway spruce using: 1. pheromone-elicited attacks by Ips typographus, and 2. artificial inoculations of the blue-stain fungus Ceratocystis polonica. The experiments showed that 150-200 beetle attacks or fungal inoculations to trees of 20 cm DBH caused considerable blue-staining of the sapwood, leading to a high tree mortality. The results are discussed in relation to tree and stand characteristics, and to climatic conditions.