Modelling pine wilt disease (PWD) for current and future climate scenarios as part of a pest risk analysis for pine wood nematode Bursaphelenchus xylophilus (Steiner and Buhrer) Nickle in Germany

Pine wood nematode (PWN), Bursaphelenchus xylophilus, causes pine wilt disease (PWD) in Pinus species given suitable climatic conditions. A model was run for Germany to assess the potential that Pinus sylvestris trees succumb to pine wilt once B. xylophilus has been introduced. The following climate scenarios have been modelled: current climatic conditions, an exceptional hot year (2003) and two future climatic conditions with target year 2050 for low (B1) and middle (A1B) emission scenarios based on the IPCC classification. Additional parameters included in the model were nematode inoculum, time of infestation and tree physiological conditions (healthy ors stressed). Under the current climatic conditions, P. sylvestris would not develop PWD assuming that trees are healthy. However, water-stressed trees in the river Rhine area south-west of Germany may succumb to PWD in the current climate. Climatic conditions like those experienced in 2003 would support the expression of PWD in healthy trees in the south of Germany and in almost the whole of Germany if the trees are stressed. Predicted future temperature increases up to 2050 under both emission scenarios will lead to more stress, placing extensive areas of Germany at risk of PWD, including the north-eastern part where Pinus sylvestris is the dominant tree species.