title: Population biology of the European woodwasp, Sirex noctilio, in Galicia, Spain.
abstract: Sirex noctilio Fabricius (Hymenoptera, Siricidae) is rare and rarely studied where it is native in Eurasia, but is a widespread pest of pines in the Southern Hemisphere. Here we report on the abundance, basic biology, host use patterns and natural enemies of native S. noctilio in Galicia, Spain. Most trees attacked by S. noctilio failed to produce any adult progeny: >90% of emergences came from <20% of the attacked trees. The highest reproduction was in Pinus pinaster, followed by Pinus sylvestris and Pinus radiata. The proportions of S. noctilio requiring 1, 2 or 3 years for development were 0.72: 0.24: 0.04. Delayed development could be an adaptation to avoid parasitic nematodes, which sterilized 41.5% adults with one year generation time but only 19% of adults with 2 years generation time. Hymenoptera parasitoids accounted for 20% mortality. Sex ratios were male biased at 1: 2.9. Body size and fecundity were highly variable and lower than previously reported from the Southern Hemisphere. On attacked trees, there were 5-20 attacks per standard log (18 dm2), with usually 1-3 drills per attack. Attack densities and drills per attack were higher in trees that subsequently died. The production of S. noctilio per log was positively related to total attacks, and negatively related to: (1) attack density, (2) incidence of blue stain from Ophiostoma fungi and (3) frequency of lesions in plant tissue around points of attack. A preliminary life table for S. noctilio in Galicia estimated effects on potential population growth rate from (in decreasing order of importance) host suitability, unequal sex ratio, parasitic nematodes and Hymenoptera parasitoids.
authors.affiliation: Departamento de Producción Vegetal,Universidad de Santiago de Compostela,27002 Lugo,Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Lombardero
authors.affiliation: Department of Biological Sciences,Dartmouth College,Hanover,NH 03755,USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Ayres
authors.affiliation: Department of Biological Sciences,Dartmouth College,Hanover,NH 03755,USA.
authors.forename: F E
authors.initials: FE
authors.lastname: Krivak-Tetley
authors.affiliation: Department of Genetics,Forestry and Agricultural Biotechnology Institute (FABI),University of Pretoria,Pretoria 0028,South Africa.
authors.forename: K N E
authors.initials: KN
authors.lastname: Fitza
mesh_terms: D000818:Animals; D049628:Body Size; D005260:Female; D007814:Larva / Q000254:growth & development / Q000502:physiology; D016014:Linear Models; D008297:Male; D010571:Pest Control; D028223:Pinus; D011157:Population Dynamics; D012098:Reproduction; D012744:Sex Ratio; D013030:Spain; D014863:Wasps / Q000254:growth & development / Q000469:parasitology / Q000502:physiology*
keywords: Amylostereum; Deladenus; Pinus; abundance; host suitability; invasive insect; invasive pest; population ecology; sex ratio