Leucas lavandulifolia Smith (Labiatae), a Botanical for Tea Red Spider Mite, Oligonychus coffeae Nietner (Acarina: Tetranychidae) Management

Bioefficacy of the solvent extracts of Leucas lavandulifolia Smith (Labiatae) leaves and their fractions against red spider mite (RSM), Oligonychus coffeae Nietner (Acarina: Tetranychidae) infecting tea is reported. The ethyl alcoholic extract caused 46.0 to 97.0% adult mortality at 72 hours after treatment with LC₅₀ 74.402 ppm. This extract when eluted with toluene followed by chloroform and methyl alcohol revealed that toluene fraction at 500 ppm concentration was most active causing 100.0% mortality of the mite followed by the chloroform and methyl alcohol fractions which revealed 88.0 and 71.0% mortality respectively at 72 hours after treatment. The respective LC₅₀ values were 6.624, 38.827 and 42.887 ppm. In terms of ovicidal property, chloroform extract was the most toxic (6.67% hatching) followed by toluene (8.1% hatching) and methyl alcohol (31.67% hatching). The LC₅₀ values were 2.648, 10.814 and 1627.191 ppm, respectively.