Response of Spruce Budworm (Lepidoptera: Tortricidae) Infected with Nosema fumiferanae (Microsporida) to Bacillus thuringiensis Treatments
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Environmental Entomology. Vol. 18. no. 5.:p. 816-821.
Diease in spruce budworm, Choristoneura fumiferana (Clemens), caused by the microsporidian Nosema fumiferanae (Thomson), increase larval susceptibility to mortality by bacillus thuringlensis (Berliner) treatments compared with larvae free of N. fumiferanae disease. The median lethal concentration (LC50) of B. thuringiensis as determined by the diet incorporation bioassy method, was significantly lower for larvae infected transoverially with N. fumiferanae, but the similar slope obtained for intitially healthy larvae indicated an independent and additive interaction. The median lethal time (LT50) for B. thuringiensis was shortest for the group diseased with N. fumiferanae. Results from seperate and sequential oral treatments (horizontal transmission) of both microorganisms at fixed physiological stages support the finding from the transovarial studies. It also was determined that N. fumiferanae-free larvae surviving B. thuringiensis treatment were more susceptible to mortality from subsequent inoculations with N. fumiferanae than were larvae not previously exposed to B. thuringiensis.
KeywordsInsecta; Choriistoneura fumiferana; Nosema fumiferanae; Bacillus thuringiensis
Bauer, Leah S.; Nordin, Gerald L. 1989. Response of Spruce Budworm (Lepidoptera: Tortricidae) Infected with Nosema fumiferanae (Microsporida) to Bacillus thuringiensis Treatments. Environmental Entomology. Vol. 18. no. 5.:p. 816-821.