FEEDING DETERRENCY AND GROWTH RETARDING ACTIVITY OF THE NAPHTHYLISOQUINOLINE ALKALOID DIONCOPHYLLINE-A AGAINST SPODOPTERA-LITTORALIS

The naphthylisoquinoline alkaloid dioncophylline A was studied for antifeedant activity against larvae of the polyphagous herbivore Spodoptera littoralis. When neonate larvae were reared on artificial diet spiked with concentrations of dioncophylline A as present in plant material of Triphyophyllum peltatum, high mortality (e.g. 86% after 20 days at 1 mg g-1 fr. wt) of the larvae and growth reduction (89% under the same conditions), as well as a pronounced increase of the larval period (50 days, controls 20 days) were observed. The deleterious effects of dioncophylline A are probably due to the strong antifeedant activity of this alkaloid since larval weight pin and amount of diet consumed were strongly reduced compared to controls when neonate larvae were kept on artificial diet spiked with 0.4 mg dioncophylline A g-1 fr. wt.