Can. Ent. 109: 1409Ent. 109: -1415Ent. 109: (1977 Parasitoid studies were conducted concurrently with a pilot control project to test the efficacy of DipeF WP, a formulation of Bacillus thuringiensis Berliner, in reducing western spruce budworm, Choristoneura occidentalis Freeman, populations. Twenty-one species of parasitoids were recovered in rearings of the budworm and an associated defoliator, the spruce coneworm, Dioryctria reniculelloides Mutuura and Munroe. Parasitoid population alterations occurred following application. Parasitism by Apanteles fumiferanae Vier. and Glypta fumiferanae (Vier.), which attack prediapausing first-instar budworm, was significantly higher in treatment blocks following B.t. application. Parasitism by Phaeogenes hariolus (Cr.), Cermoasia auricaudata Tns., and Madremyia saundersii (Will.), parasitoids of late instars and pupae, was significantly lower following treatment. Comparisons of parasitoid populations were made between pre-and post-spray sampling periods and between treatment and check blocks. THE CANADIAN ENTOMOLOGISTNovember 1977 Materials and MethodsThe pilot control project was conducted on the Gallatin Ranger District, Gallatin National Forest, Montana. The most recent budworm outbreak on the Forest was detected in 1971 (Ciesla et al. 1972). Host trees occurring in the area include Douglas-fir, Pseudotsuga menziesii var. glauca (Biessen.) Franco, Engelmann spruce, Picea engelmannii Parry, and subalpine fir, Abies lasiocarpa (Hook.) Nutt. A 1974 egg mass survey indicated an average of 24.6 new egg masses per 6452 sq. cm of foliage in the area proposed for testing (Tunnock et al. 1975). Prespray sampling in 1975 indicated an average of 42 budworm larvae per 100 buds.

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Can. Ent. 109: 10.57-1062Ent. 109: 10.57- (1977. The effect of density on host-parasite interactions between Hypera postica (Gyllenhal) and Bathyplectes anurus (Thomson) was studied in a caged system in the laboratory. There was no significant relationship between proportion of hosts parasitized and host density. The frequency distribution of the parasite's eggs approximated the Poisson distribution in 83% of the cases. There was a quadratic relationship between number of superparasitized hosts and parasite density. However, no significant correlation between proportion superparasitized and host density was detected. The Nicholsonian area of discovery was inversely related to parasite density with a strong mutual interference constant of -,467.