The antifeedant, insecticidal and insect growth inhibitory activities of triterpenoid saponins fromClematis aethusifoliaTurcz againstPlutella xylostella(L.)

摘要

BACKGROUND The diamondback moth,Plutella xylostella(L.) (Lepidoptera: Plutellidae), is a global insect pest of crops, leading to a reduction of agricultural products in productivity and quality. Plant saponins are rich sources for the discovery of candidates to control insect pests. This study focused on discovery of triterpenoid saponins fromClematis aethusifoliaTurcz and evaluation of their antifeedant, insecticidal and insect growth inhibitory activities against the 3rd instar larvae ofP. xylostella. RESULTS Seven triterpenoid saponins (1-7) were isolated for the first time from then-BuOH extract ofC. aethusifolia. Monodesmosides1,2, and5with a free 28-COOH group showed much higher antifeedant activity (DC(50)were 733.67-844.77 mu g mL(-1)at 24 h, and 737.19-748.28 mu g mL(-1)at 48 h) than bidesmosides3-4and6-7(DC(50)were 1284.35-2053.98 mu g mL(-1)at 24 h, and 1183.72-1990.96 mu g mL(-1)at 48 h). Similarly, monodesmosides1,2, and5(LC(50)were 1462.78-1785.96 mu g mL(-1)) showed stronger insecticidal activity than bidesmosides3-4and6-7(LC(50)were 2219.22-3050.51 mu g mL(-1)) againstP. xylostellaat 72 h. These results suggest the 28-COOH group is an important functional group for their antifeedant and insecticidal activity. Besides, monodesmosides1,2, and5showed insect growth inhibitory activity againstP. xylostellathrough reduction of larval growth and percentage of pupation, associated with prolongation of larval and pupal stages. CONCLUSION The present results provide evidence that triterpenoid saponins fromC. aethusifolia, particularly those monodesmosidic saponins with a free 28-COOH group, have the potential to be developed as pesticides to controlP. xylostella.