Efficiency of Thai derris extract and cypermethrin: toxicity and detoxification enzyme mechanism in the tropical armyworm, Spodoptera litura F.

This research was elucidated the toxicity and detoxification enzyme mechanism of botanical insecticide (Thai derris extract; Derris eliptica Benth) and synthetic insecticide (cypermethrin) in Tropical armyworm (Spodoptera litura F.) by larvae dipping method. Derris is extraction by Soxhlet's apparatus with ethanol solvent. Toxicity in terms of LC50 value against 1st, 2nd, 3rd, 4th and 5th instar larvae indicated that the toxicity of derris extract ca. 3.79, 9.51, 37.63, 94.49 and 158.37 and cypermethrin ca. 2.08, 2.92, 9.90, 11.16 and 18.41 ppm at 72 hours, respectively. The in vivo study revealed that both insecticides induced three enzymes activity. The cypermethrin was elevated esterase and acetylcholinesterase enzyme activities more than derris extract ca. 0.23 fold and 0.05 fold, respectively. While the crude extract tendency induced the glutathione-S-transferase enzyme activities more than cypermethrin ca. 0.04 fold. This result showed that, derris extract had efficacy like synthetic insecticide, therefore it had a possibility to be another insecticide alternative in S. litura control. Moreover, some separate experiments indicated that this extract was safe to human and environment.