THE EFFECT OF MARGOSAN-O ON THE DEVELOPMENT OF THE EGYPTIAN COTTON LEAFWORM, SPODOPTERA-LITTORALIS (BOISD) (LEP, NOCTUIDAE)

The effect of Margosan-O (a commercial biochemical insecticide containing azadirachtin) on the development of larvae of Spodoptera littoralis (Boisd.) was investigated by feeding them treated cotton leaves or by topical application, followed by recording mortality until the adult stage. Seedlings of cotton were sprayed in the laboratory with varying concentrations of Margosan-O and offered for 2 days to larvae weighing 30-50 mg. Margosan-O exhibited high activity down to a concentration of 2 x 10(-3) % a.i. azadirachtin in the spraying liquid. Topical application of Margosan-O showed that at 5 x 10(-3) % (0.1-mu-g) to 2 x 10(-1) % a.i. (4-mu-g) azadirachtin caused mortality of larvae up to pupation ranging from zero to approximately 70 %. The ED50 (effective dose) was 2.0-mu-g/larva.