Essential oil of sweetflag, Acorus calamus L. was fed (in artificial diet) to the variegated cutworm, Peridromo soucia Hubner, to assess its antifeedant and growth inhibitory effects. The oil decreased food consumption and larval growth in a dose-dependent manner in both neonate (first instar) and second instar larvae. Calamus oil applied to cabbage leaf discs significantly inhibited feeding by fourth and fifth instar larvae in a choice test. Nutritional experiments with fourth instar larvae using topical application or dietary exposure confirmed that sweetflag oil induces both antifeedant and growth inhibitory effects in Peridroma saucia, the latter possibly being independent of feeding behaviour.
