Characterisation of native Bacillus thuringiensis isolates toxicity to fall armyworm, Spodoptera frugiperda (J.E. Smith)

Abstract

Toxicity of nine indigenous Bacillus thuringiensis (Bt) isolates collected from Tamil Nadu, India were tested against fall armyworm, Spodoptera frugiperda. At 30 ?g/ml concentration, two Bt isolates viz., T350 and T532 recorded 100 per cent mortality whereas isolates T527 and T532 registered 96 per cent mortality against neonate larvae of S. frugiperda in leaf dip bioassay. SDS PAGE analysis of spore crystal mixture revealed the presence of Cry1 and Cry2 proteins with visible bands at 130 kDa and 65 kDa. PCR screening results showed the presence of cry1 (cry1A, cry1Aa, cry1Ab), cry2 (cry2Aa, cry2Ab) in four isolates and vip3A genes in three isolates but cry9 gene was not present in any of the isolates tested.