Pine Wilt Disease A Worldwide Threat to Forest Ecosystems

About this book

The pinewood nematode (PWN), Bursaphelenchus xylophilus, the causal agent of pine wilt disease (PWD), is a serious pest and pathogen of forest tree species, in particular among the genus Pinus. It was first reported from Japan in the beginning of the XXth century, where it became the major ecological catastrophe of pine forests, with losses reaching over 2 million m3/ year in the 1980s. It has since then spread to other Asian countries such as China, Taiwan and Korea, causing serious losses and economic damage. In 1999, the PWN was first detected in the European Union (EU), in Portugal, and immmediately prompted several government (national and EU) actions to assess the extent of the nematode's presence, and to contain B. xylophilus and its insect vector (Monochamus galloprovincialis) to an area with a 30km radius in the Setbal Peninsula, 20 km south of Lisbon.

International wood trade, with its political as well as economic ramifications, has been seriously jeopardized. The origin of the population of PWN found in Portugal remains elusive. Several hypotheses may be considered regarding pathway analysis, basically from two general origins: North America or the Far East (Japan or China). World trade of wood products such as timber, wooden crates, palettes, etc. play an important role in the potential dissemination of the pinewood nematode. In fact, human activities involving the movement of wood products may be considered the single most important factor in spreading of the PWN. Despite the dedicated and concerted actions of government agencies, this disease continues to spread. Very recently (2006), in Portugal, forestry and phytosanitary authorities (DGRF and DGPC) have announced a new strategy for the control and ultimately the erradication of the nematode, under the coordination of the national program for the control of the pinewood nematode (PROLUNP).

Research regarding the bioecology of the nematode and insect as well as new detection methods, e.g., involving real-time PCR, has progressed since 1999. International agreements (GATT, WTO) and sharing of scientific information is of paramount importance to effectively control the nematode and its vector, and thus protect our forest ecosystems and forest economy.

Contents

I: Pine wilt disease: global issues, surveys, trade and economic impact. Session Summary. I.1. Eradication program for the pinewood nematode in Portugal. I.2. Incursion management in the face of multiple uncertainties: a case study of an unidentified nematode associated with dying pines near Melbourne, Australia. I.3. The risk of pine wilt disease to Australia and New Zealand.I.4. Potential threat and present status of survey of pine wood nematode in Turkey. I.5. Investigations on wood-inhabiting nematodes of the genus Bursaphelenchus in pine forests in the province Brandenburg, Germany. I.6. Official survey for Bursaphelenchus xylophilus carried out on the territory of the Republic of Poland. I.7. Bursaphelenchus spp. in wood packaging intercepted in China. II: Pine wood nematode: biology and microbial inter-relationships. Session Summary. II.1. Developmental biology and cytogenetics of B. xylophilus. II.2. The relationship between PWN and fungi cohabiting in pine trees inoculated with thee PWN. II.3. Influence of fungi on multiplication and distribution of the pinewood nematode. III: PWN taxonomy and detection methods. Session Summary. III.1. Taxonomic databases for Bursaphelenchus and other aphelenchoid nematodes. III.2. The enlargement of the xylophilus group in the genus Bursaphelenchus. III.3. Interspecific variation in ITS rDNA of Bursaphelenchus species of different groups. III.4. Molecular characterization of isolates of the Bursaphelenchus sexdentati group using ITS-RFLP and ribosomal DNA sequences. III.5. Analysis of Bursaphelenchus xylophilus provenances using ISSR and RAPD fingerprints. III.6. Satellite DNA as a versatile genetic marker for Bursaphelenchus xylophilus. III.7. An effective PCR-based diagnostic method for the detection of PWN in wood samples. IV: The insect vectors: biology, ecology and interaction with PWN. Session Summary IV.1. Biological studies relevant to the vector role of Monochamus species for pinewood nematode. IV.2. Potential insect vectors of Bursaphelenchus spp. in Spanish pine forests. IV.3. Genetic structure of Monochamus alternatus in Japan. IV.4. Distribution of nematodes (Bursaphelenchus xylophilus) in the beetle of Monochamus alternatus and its exiting transmission way. V: Ecology and modelling. Session Summary. V.1. Modelling PWN-induced wilt expression: a mechanistic approach. V.2. Field diagnosis of the asymptomatic carrier of pinewood nematode. VI: The tree: physiology, resistance and histopathology as a result of pine wilt disease. Session Summary.VI.1. Inoculation of pine trees with avirulent pinewood nematode under experimental conditions: risk-benefit analysis.VI.2. Rapidity of disease development seems to result in high mortality -- insight from an inoculation test using hybridized populations between a virulent and an avirulent isolates of Bursaphelenchus xylophilus.VI.3. Defense systems of Pinus densiflora cultivars selected as resistant to pine wilt disease.VI.4. Histological observations of Bursaphelenchus xylophilus in symptomatic tissues of pinewood. VI.5. Development of external and internal symptoms in pine seedlings (Pinus sylvestris) due to inoculation with Bursaphelenchus vallesianus.VII: PWN and insect vector control methods. Session Summary. VII.1. Screening and isolation of antinematodal metabolites against Bursaphelenchus xylophilus produced by fungi and plant. VII.2. Microbial control of Bursaphelenchus xylophilus by fungi. VII.3. Attraction trap for monitoring Monochamus alternatus adults -- its usefulness and limitations. VII.4. Studies on Scleroderma guani to control the pine sawyer, Monochamus alternatus. VII.5. Effect of aerial spraying insecticide as a control measure of pine wilt disease. VII. 6. Control program of pine wilt disease for landscape conservation - the case of Amanohashidate in Kyoto, Japan.

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