Preliminarily Study on Activity of Crude Extracts from Nicotiana tabacum against Tetranychus cinnabarinus(Boisduva1)

The contact activities of petroleum ether,benzene,ethanol,acetone and water crude extracts of Nicotiana tabacum leaves against Tetranychus cinnabarinus(Boisduva1) were experimented in laboratory.The results showed that all the crude extracts had certain acaricidal activity,and the activity of acetone extract was the highest.The corrected mortalities of Tetranychus cinnabarinus(Boisduva1) were 80.28%,89.83% and 100% at 24,48 and 72 hrs after the contact treatment of acetone extract at a concentration of 2.5 mg/mL,the middle lethal concentration(LC50) was 0.0699 mg/mL.