Efficacy of Bacillus thuringiensis Berliner var. kurstaki and var. morrisoni against Helicoverpa armigera (Hubner)

摘要

Comparative studies on the efficacy of Bacillus thuringiensis Berliner var. kurstaki (HD-1) and morrisoni (HD-12), when used alone against second instar larvae of Helicoverpa armigera (Hiibner) revealed that the strain kurstaki (HD-1) was more toxic than morrisoni (HD-12). Strain kurstaki (HD-1) could cause 79.38 per cent mortality of second instar larvae of H. armigera at 0.00963 per cent concentration, while morrisoni (HD-12) could cause 89.66 per cent mortality at 0.0576 per cent concentration. The LC_(50) value of HD-1 was 0.0055, whereas that of HD-12 was 0.02%.