Third instar larvae of Spodopfera iiitoralis (Boisd.) of susceptible. Behera. Gharbia and spinosad resistant strains, were tested in the laboratory. Treatments were done in the laboratory with profenofos, sumi-gold and spinosad insecticides. before and after spraying programs in the fields of these areas. In general data indicated that the LCso values of these insecticides after spraying programs were higher than those before spraying. The results also indicated that no-cross resistance. between spinosad. profenofos and sumigold insecticides. With regard to the activity of a, (3 esterases acid and alkaline phosphatases in 4-1"1 instar larvae of S. liltoralis for each governorates and spinosad resistant strains at giMinilarvae. it was clear that the enzyme activity increased gradually with increasing the levels of resistance. On the other hand. a positive correlation was recorded between resistance values and esterases activity. Also a good correlation between phosphatases activity and resistance to insecticides. As for the spinosad resistant -strain. there are a good correlation between the activity of a. B esterases and alkaline phosphatase, while a negative correlation between acid-phosphatase and a resistant to spinosad.