First Report of the East-Asian Type of Bursaphelenchus mucronatus in Pinus sylvestris in Slovenia.

Abstract

Bursaphelenchus mucronatus Mamiya & Enda, a nematode associated with aboveground tissues of pine trees, is very similar morphologically to the pine wood nematode (PWN), B. xylophilus, a devastating pest that has caused widespread losses to pine woods in some parts of Asia since the early 1900s. During 1999, B. xylophilus was identified for the first time in Europe in Portugal (3), leading to concern that pines and other conifers all over Europe might be endangered. To protect forests from PWN and other pests, the European Union and other countries now regulate the importation of all coniferous chips, sawn wood, and logs and also have organized surveys to determine the extend of PWN infestation. Slovenia has approximately 1,227,832 ha of forest that makes up more than 60% of the surface of the country. The percentage of conifers within forests is 47.9% and comprised mainly of Picea, Pinus, Abies, and Larix species (2). During the summers of 2002-2004, approximately 100 ha of conifer forests in Slovenia were surveyed for the presence of PWN. In total, 170 wood samples from dead and dying pine (Pinus sylvestris L., P. nigra Arnold), spruce (Picea abies L.), and fir (Abies alba Miller) were analyzed. B. xylophilus (Steiner & Buhrer) Nickle was not found in the area, but a closely related nematode, B. mucronatus, previously shown to be pathogenic on conifer seedlings (4), was isolated from samples of P. sylvestris. Of 34 P. sylvestris samples analyzed, B. mucronatus was found in three samples. Samples were taken from a conifer forest located in the central part of Slovenia near the international airport of Ljubljana. The species was identified morphologically and also characterized by polymerase chain reaction restriction (PCR)-fragment length polymorphism (RFLP) analysis on the basis of ITS-rDNA fragment patterns. According to RFLP patterns (1), the analyzed species was recognized as the East-Asian type of B. mucronatus. Beside these findings, the specimens of B. homanni (Braasch) and Bursaphelenchus sp. have also been found in Slovenia. The results of the survey show that PWN was not found in Slovenia, but three different species of the Bursaphelenchus genus were present.