Antifeedant and Insecticidal Activity of Quassinoids against the Diamondback Moth<i>(Plutella xylostella)</i>and Structure—Activity Relationships

Abstract

Four semi-synthetic and fourteen quassinoids were tested for their antifeedant and insecticidal activity against 3rd instar larvae of the diamondback moth (Plutella xylostella). In this quassinoid series, isobrucein-B was the most potent compound in both assays. Chemical conversion of the methoxy and/or methylenedioxy groups in the A and C rings to hydroxy groups among these quassinoids resulted in decreased activity.