Summary
The pine wood nematode, Bursaphelenchus xylophilus, is a serious forest pest in
Asia and recently also in Portugal. The risk for establishments in other European
countries has been concluded to be high. An establishment in Sweden could result
in large economic losses for forestry and also influence other values (e.g. biodiversity
and recreation).The aims of the report are to: (1) evaluate and improve the
ongoing survey aimed at detecting the pine wood nematode if present in Swedish
forest and (2) develop a survey for delimiting the infested area if detected in
Swedish forest. If we assume that an establishment of the pine wood nematode in
Sweden will not cause symptoms in infested pine trees it is not possible to develop
a survey that ensures early detection. This means that if it is detected it has most
probably already been established for a long time and thus also already spread
over a too large area for eradication to be a possibility. If early detection is the
main aim of the survey one possibility could be to direct the ongoing survey more
towards industrial areas or other locations to which much material is imported. It
is also important to further increase the knowledge about commodities and trade
routes that may pose a risk for introductions of the pine wood nematode. Also the
delimitation survey (aimed at delimiting the area infested by the pine wood nematode
after an introduction) suffers from the problem of a low probability of detection
of infested substrates if the surveyed area is too large. One way of reducing
this problem is to reduce the surveyed area to an area somewhat larger than the
maximum area of eradication. This strategy requires that such a maximum area of
eradication is determined in the contingency plan for the pine wood nematode.