ANTIFEEDANT AND GROWTH INHIBITORY EFFECTS OF TALL OIL AND DERIVATIVES AGAINST THE VARIEGATED CUTWORM, PERIDROMA SAUCIA HÜBNER (LEPIDOPTERA: NOCTUIDAE)

Abstract

AbstractCrude tall oil and two of its derivatives were assessed for antifeedant and growth inhibitory effects, via incorporation into an artificial diet, in the variegated cutworm (Peridroma saucia Hübner). The substances tested are both toxic to neonate P. saucia and inhibitory to larval growth. The dietary LC50 (lethal concentration for 50% mortality) values are 4.3, 4.7, and 5.3% fresh weight for depitched tall oil (DTO), crude tall oil (CTO), and tall oil pitch (TOP), respectively. These materials significantly reduced growth, feeding, and dietary utilization by first-, second-, third-, and fourth-instar larvae in chronic larval growth bioassays, choice and no-choice feeding tests, and nutritional experiments. The EC50s (effective concentration to inhibit growth by 50% relative to controls) of DTO, CTO, and TOP were 1.4, 2.0, and ≥2.4%, respectively, when first-instar larvae fed on treated diets for 10 days. DTO significantly reduced both growth and consumption rates with corresponding reduction in the efficiency of conversion of food (i.e. nutritional efficiency), suggesting that both antifeedant and toxic effects are involved in larval growth inhibition. DTO and CTO are consistently more biologically active than TOP. Our results suggest that an environmentally sound, low cost natural pest control agent may be developed based on tall oil.