Abstract :
This study aimed mainly to estimate the resistance of the cotton leafworm Spodoptera littoralis to several bioinsecticides (Spnitor, Protecto, Dipel DF, Dipel 2X, Agrine and Radical) throughout determining the resistance ratio values. Among all the tested bioinsecticides, Radical had the highest resistance ratio in the four Governorates, while, Spnitor had the lowest resistance ratio in all these Governorates. The relative toxicity of these bioinsecticides to S. littoralis was also determined. The results clearly indicated that Radical was the most toxic bioinsecticides in all four field strains followed by Spnitor, while the other bioinsecticides were the least toxic action.
