Comparative efficacy of native isolates of Bacillus thuringiensis Berliner against Cnaphalocrocis medinalis (Guenee) on rice

Twenty two native and one standard check BtkHD-1 isolates were compared at different concentration levels to evaluate their efficacy for the control of rice leaffolder. Among these isolates, three native isolates, namely BtK4, BtC5 and BtJ showed more than 55% larval mortality of C. medinalis at 10% concentration level of spore crystal mixture within 96 hrs of treatment. The maximum larval mortality (61.88%) was achieved due to BtK4 isolate. The per cent larval mortality was dose dependent of spore crystal mixture and it increased with increase in the post treatment period.