Bio-efficacy and field test of Chromolaena odorata extract alone and with Beauveria bassiana against Rice hispa, Dicladispa armigera

Bioassay of solvent extracts of Chromolaena odorata leaves at 1.0% concentration against Dicladispa armigera adults revealed activity in the order of methyl alcohol (77.5%) > acetone (70.7%) > petroleum ether (66.9%) > chloroform (40.1%) > water (31.4%) after 5 days of treatment. When the plant extract at 0.5% concentration was combined with Beauveria bassiana at 3.0 x 10⁷ spores/ml caused 89.6% reduction of D. armigera population over pre treatment count under field situation and was at par with chlorpyriphos. This combination may replace use of synthetic insecticides and is a strategy of biointensive crop production.