EFFECT OF NEW CHEMISTRY INSECTICIDES ON THE ESTERASE ACTIVITY OF BREVICORYNE BRASSICAEA (HOMOPTERA: APHIDIDAE)

Insecticides are widely used to control cabbage aphids attacking on the various agricultural crops. Esterase is one of the enzymes which cause the detoxification of the insecticides leading to the resistance against the insecticides. In the present study four new chemistry insecticides and a plant extract were used against adult of wingless cabbage aphid (Brevicoryne brassicae). Three different concentrations, LC , LC and LC of each 40 50 60 insecticide were used. Esterase activity in insects against each insecticide was determinedafter the 1 hour and 24 hours. Application of LC of diafentiuron after I hr and 24 hrs, esterase 50, activity was 222.3 μmol/min/mg and 313.33 μmol/min/mg respectively and at LC after I hr 60 and 24 hrs, the esterase enzymatic activity was 173.66 μmol/min/mg and 293.33 μmol/min/mg respectively. Esterase specific activity of LC of bifenthrin was 322.5 50 μmol/min/mg after 1 hr and decreased down to 158.033 μmol/min/mg and at LC activity 60 was 303.1 μmol/min/mg after 1 hr and decreased down to 185.07 μmol/min/mg after 24 hrs. Higher esterase activity shows higher resistance of insect against insecticide and its fewer efficacies. The results showed that pymetrozine is less effective while bifenthrin is more effective insecticide due to lower esterase activity.