In vitro evaluation of microencapsulated Bacillus thuringiensis (Berliner) formulation against Helicoverpa armigera (Hubner)

An experiment was conducted to evaluate microencapsulated formulation of lyophilized spore crystal aggregate of native isolate BGC-1 and reference isolate HD-1 against second instar larvae of Helicoverpa armigera. The results revealed that the microcapsule diameter was ranged from 3.2 to 8.3 µm. Median lethal concentrations of the BGC-1 and Bt-HD1 were 0.66 g/l and 0.50 g/l respectively. UV protectants viz., melanin and para-amino benzoic acid were evaluated by exposing microencapsulated Bacillus thuringiensis to UV A light at 365nm. Among four microencapsulated formulations, BGC-1 with melanin recorded significantly highest mortality of 95.00 per cent at 0h exposure, as time increased, the mortality decreased and HD-1 was on par with BGC-1.