RESUMEN
The naturally occurring phytocidal chemical components of some Thai plant-species are responsible for controlling and repelling insects from the host plants. The aim of this study was to evaluate the insecticidal activity of Jatropha gossypifolia L. Leaf extracts and the senescent leaf Cleome viscosa L. (Capparidacae) against S. litura and detoxification enzyme activities. Laboratory no-choice bioassays showed treatment of second instars Spodoptera litura by dipping in extracts from senescent Leaves of Jatropha gossypifolia L. at 3000-10000 ppm had significant toxicity with LC50 of 6.56 mg/ml(-1) (r2=0.88) at 24 hours after exposure. The toxicity of Cleome viscosa L. extract in terms of LC50 values ca. 34 mg ml(-1) (r2=0.95) at 24 after exposure by the dipping method. ALso, S. litura Larvae surviving treatment of both extract showed a dramatic decrease in carboxylesterase and glutathione-s-transferase activities. This extract showed strong insecticidal activity and may play an alternative role as a pesticide against Spodoptera litura.