Field Evaluation of the Toxicity of the Biopesticide Spinosad Against Spodoptera litoralis ( Boisd. ) Larvae on Alfalfa ( Medicago sativa L. ), in Riyadh, Saudi Arabia

Abstract

Field experiments were conducted in the ARES ; Dierab Farm, to evaluate the insecticideal activity of Spinosad on alfalfa. Larvae ( 3th instar ) of a susceptible strain of Spodoptera litoralis ( Boisd. ), were used. Three rates of Spinosad were applied, in addition to the recommended rates of each of Bacillus thurengiensis ( Deflin WG ) and the pyrethroid Lambda-Cyhalothrin ( Karate ). Samples of the alfalfa were taken after several periods of times, and kept with larvae for one, two and three days respectively. Spinosad showed the heighest insecticidal activity, three days after its application, and showed toxic symptoms on the larvae, completely different to those of the tested insecticides.