Agricultural Science Digest

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.