CHANGES IN SPRUCE BUDWORM,CHORISTONEURA FUMIFERANA(LEPIDOPTERA: TORTRICIDAE), BIOMASS IN STANDS TREATED WITH COMMERCIALBACILLUS THURINGIENSISVAR.KURSTAKI

Abstract

Larval biomass of the spruce bud worm, Choristoneura fumiferana (Clem.), in balsam fir, Abies balsamea L., stands was significantly reduced following aerial applications of commercial Bacillus thuringiensis (B.t.) (Thuricide 16B®, 24B and 32BX and Dipel 85®). Treatment with Dipel vehicle (Dipel 88® without B.t.) did not affect larval biomass. Biomass reduction following the Thuricide treatment was directly related to feeding activity. These findings support published observations on the long-term effect of B.t. on budworm populations.