Efficacy of plant extracts against Tetranychus urticae under in-vitro conditions

The acaricidal activity of aqueous extracts of 20 plant species at 10 per cent concentration was evaluated against red spider mite, Tetranychus urticae Koch under laboratory condition by the leaf disc method. Among the plants, the extract of solanum virginianum and Eucalyuptus deglupta caused the highest mortality of 93.33 and 85.57 43 percent of T. urticae respectively at 72 hours after treatment (HAT) followed by strychonas nux-vomica (82.23%), Colacasia esculenta (81.10%) and Cympogan schaenanthus (81.10%). Next in the order of efficacy were Curcuma longa, Dodonia viscosa, Melia azedarach, Piper nigrum, Phylanthus niruri, Cyprus rotantus, Azadirachta indica, Cynodon dactylon and Andropogan murigatus which caused statistically similar acaricidal activity ranging from 72.23 to 64.43 percent Moderate acaricidal action was noticed in Cardiospermum halicabum (56.67%) and Antigonon leptopus (51.10%). The least effective plants were spathodea campanulata (45.57%), Murraya koenigii (42.23%)> Lantana camera (30.00%), Pedalium murex (30.00%) and Ocimum tenuiflorum (27.77%).