EFFECT OF , CA4LOTROPIS PROCERA AITON LEAF EXTRACT AGAINST BEAN APHID, APHIS CRACCIVORA KOCH.

Abstract

An investigation was carried out to evaluate the toxicity, repellency and residual effect of akanda leaf extract in two solvents (ethyl alcohol and chloroform) on population of bean aphid, Aphis craccivora. 0.035 mg/cm’, 0.018 mg/cm? and 0.009 mg/cm” doses were applied in the mortality experiment. The calculated LDso values were 0.074 mg/cm’ and 0.024 mg/cm’ in ethyl alcohol extract at 24 and 48 HAT, respectively and in chloroform extract the values were 2.173 mg/cm’ and 0.018 mg/cm’ at 24 and 48 HAT. Comparison of the LD. values it was observed that the akanda leaf extract showed toxicity in order of ethyl alcohol>chloroform after 24 hours exposure period while after 48 hours the order of toxicity is followed as chloroform>ethyl alcohol. The mean mortality percentage of A. craccivora in different doses was significantly different from control after 24 and 48 hours exposure for both the solvents. Mortality percentage was directly proportional to the level of doses. In repellency experiment 1.0 mg/ml, 0.5 mg/ml and 0.25 mg/ml doses were used and it showed moderate repellency against A. craccivora for both the solvents. Same trend was found in repellency class i.e. 'V, IV and III which were for both the solvents. Akanda leaf extract in chloroform and ethyl alcohol solvents had remarkable residual effect on population reduction of A. craccivora. Where 0.25 mg/ml, 0.125 mg/ml and 0.063mg/ml doses were used. After all, 56.05 and 44.95% population were reduced in chloroform extract of akanda leaf. In comparison of solvents, ethyl alcohol showed more toxicity than chloroform after 24HAT, while after 48HAT chloroform was more effective than ethyl alcohol.