Isolation, Identification, Bioassay and Field Evaluation of Native Bacillus thuringiensis Strains against Spodoptera litura (Fabricius) in Groundnut (Arachis Hypogaea)

A field experiment in a randomized block design was conducted to evaluate 28 Bacillus thuringiensis isolates along with a reference strain HD1 and untreated control against Spodoptera litura in groundnut. Larval population of S. litura per meter row at 3 days after spray (DAS) was lowest (9.0) in plot treated with Bt strain 341. Mean per cent reduction of larval population over pretreatment was maximum (56.83%) in HD1 reference strain and it was followed by the Bt strain 375 (51.45%). Minimum larval population of S. litura (7.0) was observed at 5DAS in HD1 and 375 Bt strains. Mean per cent reduction of larvae over pretreatment was maximum (68.32%) in HD1 reference strain followed by Bt strain 21 (57.27%). Minimum larval population of S. litura (5.0) was recorded at 7DAS in plot treated with Bt strains HD1, 375 and 416. Mean per cent reduction of larvae over pretreatment was highest (77.02%) in HD1 reference strain followed by Bt strain 375 (74.47%). Per cent leaf damage due to S. litura was minimum (12.83%) in plots treated with HD1 reference strain followed by strain 375 (14.06%). Maximum pod yield (3900 kg/ha) was recorded in the plots treated with HD1 reference strain followed by Bt strain 375 (3870.0kg/ha).