Parasitoid complex of Zeiraphera canadensis (Lepidoptera : Tortricidae) and evaluation of Tycherus osculator (Hymenoptera : Ichneumonidae) as a biological control agent

A survey of larval and pupal populations of the spruce bud moth, Zeiraphera canadensis Mutuura and Freeman (Lepidoptera: Tortricidae), conducted from 1994 to 1996 in eastern Newfoundland, disclosed that the incidence of endem ic parasitism by Hymenoptera was up to 50% for Tycherus osculator (Thunberg ) (Ichneumonidae), up to 15% for Earinus zeirapherae (Walley), under 3% for Ascogaster (Wesmael 1835) sp. and Clinocentrus (Haliday 1833) sp. (Braconi dae), and under 1% for Lamachus (Foerster 1868) sp. and Triclistus (Foerste r 1868) sp. (Ichneumonidae). Tycherus oscillator, E. zeirapherae, Ascogaste r sp., and Clinocentrus sp. represent new distributional range extensions t o Newfoundland, and to the nearctic region in the case of T. osculator. The biology of European populations of T. osculator was studied on a natural h ost, Zeiraphera diniana (Guenee). Only females overwintered and ovarian mat uration did not occur until after several months of exposure to near-freezi ng temperatures. Tycherus osculator successfully parasitized prepupae and p upae of Z. diniana of all ages but, in the laboratory, appeared to prefer p upae. Host feeding by T. osculator was common but not necessary for ovarian maturation. Tycherus osculator imported from Europe attacked and successfu lly developed within the spruce bud moth host in laboratory screenings. Mor phological comparisons indicated that T. oscillator reared from Z. canadens is were smaller than those reared from Z. diniana. Tycherus osculator obtai ned from either Newfoundland or Europe may have potential as a biological c ontrol of Z. canadensis in mainland Canada, where it is presently absent.