Changes in Morphology of Trichostrongylus colubriformis Eggs and Juveniles Caused by Bacillus thuringiensis israelensis

Kurt P. Bottjer, Leon W. Bone


Eggs and rhabditiform juveniles of the ruminant parasite Trichostronffylus colubriformis developed normally in Caenorhabditis briggsae Maintenance Medium. A toxin from a crystal-enriched preparation of the bacterium Bacillus thuringiensis israelensis was lethal to nematode eggs and juveniles within 24 hours and to eggs and juveniles after 24 hours of development. Treated eggs had refractive granules and development was arrested, whereas nontreated eggs developed normally. Eggs treated after 24 hours of development contained juveniles that were granulated, had esophageal derangements, and were moribund or dead. The ovicidal toxin from B. t. israelensis may facilitate microbial control of parasitic nematodes. Key words: Trichostrongylus colubriformis, egg lethality, Bacillus thuringiensis israelensis, microbial toxin.

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