Abstract

Orthaga exvinacea is one of the major pests of mango crop and the caterpillars defoliate the leaves and thereby reduce the crop yield. Use of synthetic insecticide is the quick method for the control this pest but its uncontrolled usage has resulted in serious lethal effects on non-target organisms and environmental pollution. Botanical insecticides are very effective, safe and ecologically acceptable. In the present study, the impact of methanolic leaf extracts of Clerodendrum infortunatum and Chromolaena odorata on carbohydrate concentration in the haemolymph of sixth instar larvae of O. exvinacea was studied under laboratory conditions. The different concentrations (1% to 5%) of each botanical treated mango leaves were fed to the sixth instar. After 48 hours, larvae were sacrificed to collect haemolymph and the quantitative estimation of carbohydrate has been done. The results showed that there was some noticeable decrease in the amount of carbohydrate in the treated larvae when compared to control. The decrease in level of carbohydrate concentration was correlated with the increase in concentration of botanicals. Among the botanicals tested C. odorata possessed more efficacy than that of C. infortunatum and this experiment reveals the potency of both botanicals to be used as natural biopesticides against this pest.

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