Effectiveness of Dead-Spore Bacillus thuringiensis Formulation Against Diamondback Moth

We developed a process of producing a dead-spore Bacillus thuringiensis Berliner var. kurstaki HD-1 formulation, Toarow CT, and studied several aspects t o improve the productivity of crystal toxin and the insecticidal potency after sterilization to kill spores. The production of cell mass or crystal toxin was highly influenced by aeration and agitation of the culture. The culture broth, within 24 hours after the release of 90% of spores from sporangia, was suitable for formulation into commercial product. We tested a live-spore (Toarow) and a dead-spore (Toarow CT) formulations, both having the similar insecticidal potency, against silkworm. Both formulations were equally effective against diamondback moth, Plutella xylostella (L.) when tested by a leaf dip method. Also no differences in mortality and control ratio were observed in a field test either. The dead-spore formulation was thus satisfactory for the control of diamondback moth.