Canadian Forest Service Publications

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Abstract

In a laboratory essay in which synthetic media were used, several variets of Bacilus thuringiensis have been tested for pathogenicity for larvae of the spruce budworm, Choristoneura fumiferana. The toxicity of nearly pure parasporal inclusions (crystals) and precipitated parasporal inclusion protein was also investigated. the varieties alesti, berliner, entomocidus, sotto, and galleriae were highly to moderately pathogenic; the varieties Kenyae and dendrolimus were less so, and the variety )finitimus_ was only slightl pathogenic. Although ingestion of crystals and precpitated crysta protein led to inhibition of eeding by larvae, the most pathogenic preparations were those that contained both spores and crystals.