Demography of an invading forest insect reunited with hosts and parasitoids from its native range

The Sirex woodwasp noctilio Fabricius (Hymenoptera: Siricidae), a widespread invasive pest of pines in the Southern Hemisphere, was first detected North America 2004. This study assessed impacts life history traits, host resistance and species interactions on demography S. New York, Pennsylvania Vermont, then compared key metrics to those found native range Galicia, Spain. Many trees naturally attacked by produced no adult woodwasps, with 5 38 infested (13%) sampled across six sites yielding 64% emerging insects. Reproductive success highest introduced scots pine, Pinus sylvestris , but red resinosa larger required one or sometimes two years develop sex ratios were male biased, 1:2.98 ♀:♂. Body size fecundity highly variable, generally lower than observed non-native populations Hemisphere. Hymenopteran parasitoids killed approximately 20% larvae 63% adults colonized parasitic nematode Deladenus siricidicola although nematodes entered eggs. Demographic models suggested that northeastern USA have higher potential for population growth range: estimated finite factor increase, λ, 4.17–4.52 (depending tree colonized), λ = 1.57