Ginsenosides from the stems and leaves of Panax ginseng show antifeedant activity against Plutella xylostella (Linnaeus)

摘要

The diamondback moth, Plutella xylosteila, is one of the most serious insect pests of cruciferous crops all over the world. Although chemical insecticides are used to control this pest, it develops resistance to almost all kinds of insecticides. In recent, triterpenoid saponins have been reported to show potent antifeedant or synergize insecticidal activity on several pests. Therefore, to assess the antifeedant activity of ginsenosides against P. xytostella is benefit to biological control of this pests. Total ginsenosides were extracted from ginseng leaves and stems, and the total content of 9 ginsenosides was 72.91 mg/mL measured by high-performance liquid chromatography (HPLC) method. Total ginsenosides extracted from ginseng leaves and sterns showed significant antifeedant activity on P. xylostella larvae in both non-choice and choice assays. The concentration of median antifeedant (AFC(50)) of total ginsenosides for the second instar larval of P. xytostella were 4.98 and 5.03 mg/mL at 24 h and 48 h respectively in non-choice assay, and they were 2.74 and 4.14 mg/mL respectively in choice assay. The residue rate of 9 ginsenosides in the pest became gradually higher as applied concentration increased. Feeding with ginsenosides generally resulted in decrease of glutathione S-transferase (GST), acetylcholine esterase (AChE), and carboxylesterase (CarE) activities, but increase of mixed-functional oxidase (MFO) activity in P. xylostella. These results indicate that ginsenosides are suitable for developing it into a botanical pesticide.