Insecticidal activity of Piper retrofractum fruit extracts and isolated compounds against Spodoptera litura

Abstract

Secondary metabolites found in plants have been recognized as potent botanical insecticides that are safer than synthetic insecticides. The potential of Piper retrofractum Vahl. fruit extracts and their isolated compounds was investigated against the second instar of Spodoptera litura Fab. using topical application. The results showed that the hexane extract was the most potent with a median lethal dose (LD₅₀) value of 0.87 μg/larva at 24 hr and 48 hr posttreatment. Among seven isolated compounds from the hexane extract, methyl piperate had the highest toxicity to S. litura with LD₅₀ values of 2.00 and 1.60 μg/larva at 24 hr and 48 hr posttreatment, respectively, followed by pipernonaline, piperanine and retrofractamide D, respectively. The fruits of P. retrofractum could have potential for the development of novel insecticides to control S. litura for use in an integrated pest management program.