Abstract: In this paper,the effects of varying concentration azadirachtin on tobacco cutworm Spodoptera litura were investigated in both laboratory and field.The results showed that azadirachtin exhibited a wide range of bioactivities, including anti-feeding,growth inhibition,larval toxicity,and oviposition deterrent.This compound could significantly reduce pupal weight and pupation and eclosion rates.After treated with 12 μl·L^-1 azadirachtin for 5 and 7 days,the third instar larvae only weighted 36.8% and 14.5% of the untreated ones,and their development took approximately 6 days longer, with a 27.79% pupation rate and a 37.23% emergence rate,significantly lower than the control by 85.66% and 82.11%,respectively.Azadirachtin was more efficient for the low instar larva than the old ones.Field experiments confirmed that after 7 days application,azadirachtin could effectively control Spodoptera litura,being more efficient than the chemistry pesticide,10% Chu-Jin SC.

Key words: Bullacta exarata, Rearing shoal, Heterotrophic bacteria, Vibrios