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The great European spruce bark beetle (Dendroctonus micans),which had for many years been seen as a potential threat toBritain's spruce plantations, was first discovered in Britainduring August 1982, breeding in Sitka spruce. Surveys in spruceplantations were initiated to determine the distribution ofthe beetle, a necessary background for development of controlstrategies. This paper reports the development and evolutionof survey techniques from 1982 to 1989, as well as the spreadof the D.micans populations during this time. Details of controlstrategies and legislation to contain the outbreak are alsogiven, along with conclusions concerning the natural dispersalof D.micans. Received 23 July 1990. 相似文献
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Pine wood nematode, Bursaphelenchus xylophilus (Steiner andBuhrer) Nickle, is the casual organism of pine wilt disease,a major tree killer in the Far East. This paper describes thebiology of B. xylophilus, particularly its inter-relationshipswith vector insects in the genus Monochamus (Coleoptera: Cerambycidae),tree species and environmental conditions. The principal methodof transmission, and hence of international plant health significance,is introduction of nematodes to susceptible dying or dead treesduring female oviposition. This occurs in all countries wherethe nematode occurs but is the only significant method of transmissionand survival of B. xylophilus in North America. Extensive treemortality in Japan and China is associated with presence ofhighly susceptible tree species, suitable vector species andhigh summer temperatures. Pest risk assessments have been carriedout to determine the risks to Europe; it is concluded that thenematode would undoubtedly survive in Europe but that tree mortalityis likely only in the warmer southern countries. Methods toprevent transfer of nematodes to Europe are discussed in relationto European Union legislation. 相似文献
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