-The potential distribution of sirex wood wasp (Sirex noctilio) in Australia, South America and Africa (where the insect is known to occur and is spreading) and North America and China (where sirex has not established) was assessed from a study of the insect's current distribution and host range. Sirex noctilio has a wide host range, mainly in Pinus, including many important commercial species planted as exotics in the Southern Hemisphere as well as native stands in North America. Using the climate-matching program CLIMEX the potential distribution range of S. noctilio was predicted across the globe based on climatic conditions in Eurasia and northern Africa, where the insect is endemic. Sirex noctilio is predicted to establish in the majority of commercial Pinus plantations in Australia. Many countries with commercial Pinus plantations in South America (Uruguay, Brazil, Argentina, Chile and Paraguay) as well as South Africa are predicted to be colonised by S. noctilio by natural migration. Countries that are a long distance from S. noctilio-infested areas, such as Ecuador, Colombia, Venezuela, Zimbabwe, Tanzania, Uganda, Ethiopia and plantations in southern Chile, western Australia and north-western Brazil, are only likely to be colonised by S. noctilio via human-assisted transport of infested wood. Sirex noctilio was predicted to be able to persist in many areas in North America. In China, S. noctilio is predicted to be able to persist in many areas where large-scale afforestation of susceptible hosts has occurred and is planned. However, S. noctilio is endemic in neighbouring countries of China, indicating that something other than climate and host is restricting S. noctilio establishing in China, or that it has not been detected yet. The Sirex Management Strategy will help reduce the spread and impact of S. noctilio.

This study presents a model that assesses the potential impact of a new alien insect species, Sirex noctilio Fabricius, on pine timber supply and harvest activities in eastern Canada. We integrate the spread of S. noctilio with a broad-scale growth and harvest allocation model. Projections of pine mortality range between 25 Â 10 6 and 115 Â 10 6 m 3 over 20 years depending on S. noctilio spread and impact assumptions. Our model suggests Ontario could experience the highest, most immediate losses (78% of the potential losses across eastern Canada), with Quebec sustaining most of the rest of the losses over the next 20 years. Potential losses of $86 to $254 million per year are simulated after 20 years. The net present value of total harvest losses after 28 years of outbreak ranges between $0.7 to $2.1 billion. Adaptation policies decrease shortterm losses by 46%-55% and delay larger harvest failures by 9-11 years. Without harvest adaptation, failures to maintain annual allowable cut levels may occur once the total area infested exceeds 15 Â 10 6 ha. While better understanding and representing S. noctilio behaviour will involve a significant effort, there is a strong demand by policy makers for this kind of information.Résumé : Cette étude présente un modèle qui évalue l'impact potentiel d'une nouvelle espèce d'insecte exotique, Sirex noctilio Fabricius, sur les stocks de bois de pin et les activités de récolte dans l'est du Canada. Les auteurs ont intégré la propagation de S. noctilio à un modèle de croissance à grande échelle et d'allocation de la récolte. Les projections concernant la mortalité du pin varient de 25 Â 10 6 and 115 Â 10 6 sur 20 ans selon les hypothèses de propagation et d'impact de S. noctilio. Leur modèle indique que l'Ontario pourrait subir les pertes les plus élevées très tôt (78 % des pertes potentielles de tout l'est du Canada) et le Québec, presque toutes les pertes à venir au cours de la période s'étendant sur les 20 prochaines années. Les pertes annuelles pourraient atteindre 86-254 millions $ après 20 ans. La valeur actualisée nette des pertes totales de réc-olte après 28 années d'épidémie varie de 0,7 à 2,1 milliards $. Des stratégies d'adaptation diminueraient les pertes à court terme de 46-55 % et retarderaient les pires récoltes de 9-11 ans. Sans adaptation de la récolte, l'incapacité à maintenir les niveaux de possibilité annuelle de coupe pourrait survenir lorsque la superficie totale infestée dépassera 15 Â 10 6 ha. Bien que d'importants efforts restent à faire pour mieux comprendre et représenter le comportement de S. noctilio, il y a une forte demande de la part des décideurs pour ce type d'informations.[Traduit par la Rédaction]

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