Biology and status of Tranosema rostrale rostrale (Hymenoptera: Ichneumonidae), a parasitoid of the eastern spruce budworm (Lepidoptera: Tortricidae)

Tranosema rostrale rostrale (Brishke) (subfamily Campopleginae) is a parasitoid of the eastern spruce budworm, Choristoneura fumiferana (Clemens),in Canada and the United States. T. r. rostrale has often been confused with the closely related Euyius montanus (Ashmead), another parasitoid of C. fumiferana. These 2 species are defined and characters distin guishing them are compared and illustrated. A survey across southern Quebec indicates that >99% of all T. r. rostrale/E. montanus-like parasitoids recovered from spruce budworm larvae implanted in fr stands over a period of 1 wk belong to the former species. T. r. rostrale oviposits in all postdiapause instars of C. fumiferana, as well as in several alternative hosts, starting in late May in the Quebec City region. At 20 degrees C, development inside the host takes approximate to 14 d and the parasitoid goes through 3 stadia. T. r. rostrale is believed to complete 2 or 3 additional generations on alternate hosts.