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Insecticidal and growth inhibitory effects of Vitex negundo solvent extracts at different concentrations were evaluated in the laboratory and the results were presented. The different solvent extracts (methanol, hexane, acetone and water) at various concentrations (1,2,4 and 6%) were tested against third instar larvae of Spodoptera litura. Insecticidal action of V. negundo solvent extracts was determined through topical bioassay. Methanol extract of V. negundo was the most toxic and caused maximum mortality (96.3%) recording lowest LD50 of 423 ppm. Aqueous extract recorded lowest mortality of 51.7 per cent. Influence of host materials on the effect of V. negundo extract was also tested. Castor, semi-synthetic diet and banana were tested as host materials for rearing S. litura. Different solvent extracts of V. negundo were prepared at various concentrations (1,2,4 and 6%) and applied to different host materials and allowed to feed by S. litura third instar larvae. Observations on larval duration, pupal weight and extent of pupation on different hosts were taken to determine the growth inhibitory action. Among all the hosts, the highest reduction in pupal weight was on semi-synthetic diet reared S. litura. Methanol extract caused maximum reduction in pupal weight (45.15 to 72.60%) followed by acetone extract (34.52 to 70 %) and lowest reduction in pupal weight was observed in aqueous extract (52.91 to 56.51 %). Hexane, acetone and methanol extract (6%) caused the highest reduction of 96.51, 96.30 and 92.86 per cent pupation over control while, aqueous extract produced only 52 per cent reduction of pupation of S. litura reared on castor. V. negundo extracts caused the lowest reduction of pupation (26.93 to 77.78 %) of S. litura reared on semi-synthetic diet. In banana, pupation was reduced to the range of 55.56 to 85.72 per cent by aqueous and methanol extracts. A maximum larval duration of 26.33 days with the highest (102.54 %) increase in duration over control was recorded by methanol extract (6%) on semi-synthetic diet. When the larvae were fed with banana, aqueous extract of V. negundo (6%) caused longest larval duration of 19 days, when the leaves were treated with acetone extract (6%).
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