Feeding deterrents from Zanthoxylum schinifolium against two stored-product insects.

Screening for insecticidal principles from several Chinese medicinal herbs showed that the fruit pericarp of Zanthoxylum schinifolium possessed significant feeding deterrence against two stored-product insects (Tribolium castaneum and Sitophilus zeamais). From the methanol extract, two feeding deterrents were isolated by bioassay-guided fractionation. The compounds were identified as schinifoline and skimmianine from their spectroscopic data. Schinifoline has feeding deterrent activity against T. castaneum and S. zeamais adults with EC(50) values of 47.8 and 85.6 ppm respectively. Skimmianine possess feeding deterrent activity against T. castaneum and S. zeamais adults with EC(50) values of 75.7 and 129.7 ppm respectively.