Meisner, J., Div. of Toxicology, ARO, The Volcani Center, Bet Dagan, Israel
Ascher, K.R.S., Div. of Toxicology, ARO, The Volcani Center, Bet Dagan, Israel
Aly, R., Div. of Toxicology, ARO, The Volcani Center, Bet Dagan, Israel
Warthen, J.D., Biologically Active Natural Products Laboratory, Agricultural Environmental Quality Institute, Agricultural Research Center, U.S.D.A., Beltsville, 20705, MD, United States

The effect of azadirachtin and salannin, two triterpenoids isolated from seeds of neem (Azadirachta indica A. Juss), on the feeding response of Spodoptera littoralis (Boisd.) and Earias insulana (Boisd.) larvae, was investigated. Styropor (foamed polystyrene) lamellae were painted on both sides with a mixture of 5% sucrose with different concentrations of either azadirachtin or salannin dissoled in methanol-water (3:7). Azadirachtin strongly suppressed feeding in S. littoralis larvae even at 0.001%, whereas salannin showed some antifeedant activity at 0.005% and above. Larvae of E. insulana were deterred from feeding on azadirachtin-treated lamellae even at 0.005%, whereas salannin was effective only at 0.01% and above. Azadirachtin applied on cotton leaves deterred larvae of S. littoralis from feeding at all concentrations ranging between 0.001 and 0.02%. © 1981 Springer Science + Business Media B.V.