Predicting the potential distribution of Sirex noctilio (Hymenoptera: Siricidae), a significant exotic pest of Pinus plantations

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.