Antifeedant Diterpenoids against Tribolium castaneum from the Stems and Twigs of Ceriops tagal (Rhizophoraceae)

The screening of several Chinese mangrove plants for insecticidal principles showed that ethanol extract of Ceriops tagal stems and twigs possessed significant feeding deterrent activity against the red flour beetle, Tribolium castaneum (Family: Rhizophoraceae). From the ethanol extract, three feeding deterrent diterpenoids were isolated by bioassay-guided fractionation. The compounds were identified as tagalsin A, B, and H on the basis of their phytochemical and spectral data. Tagalsin A, B, and H exhibited strong feeding deterrent activity against T. castaneum adults with EC 50 values of 375.3 ppm, 277.3 ppm, and 285.45 ppm, respectively. Keywords: feeding deterrents; Ceriops tagal ; Tribolium castaneum ; tagalsin 1. Introduction The red flour beetle [ Tribolium castaneum (Herbst)] is one of the most widespread and destructive primary insect pests of stored cereals [1]. Infestations not only cause significant losses due to the consumption of grains; they also result in elevated temperature and moisture conditions that lead to an accelerated growth of molds, including toxigenic species [2]. Botanical pesticides have the advantage of providing novel modes of action against insects that can reduce the risk of cross-resistance as well