Biphasic Dose-Response of Components From on Feeding and Detoxification Enzymes of Larvae.

Due to long-term coevolution, secondary metabolites present in plants apparently function as chemical defense against insect feeding, while various detoxification enzymes in insects are adaptively induced as a prosurvival mechanism. , a medicinal plant used in traditional Chinese medicine for a thousand years, was found to be less prey to insects in our earlier field observations. Herein, 4 crude extracts obtained from sequential partition of aqueous extract of with petroleum ether, ethyl acetate, and n-butanol exhibited antifeedant activity against (Fabricius) larvae at high doses and inducing activity at low doses. Furthermore, a similar biphasic dose-response of the antifeedant activity against larvae was also observed for jateorhizine, palmatine, and obakunone in . Notably, the enzyme activities of glutathione-S-transferase and carboxyl esterase in larvae affected by the different components (jateorhizine, palmatine, obakunone, berberine, and coptisine) of also showed a biphasic dose-response with an increasing trend at low doses and a decreasing trend at high doses. Together, our study suggests that the components of may play a chemical defensive role against larvae in a hormetic manner.