Toxicities of some traditional insecticides; Rider® , Reldan® , Biolarve® , Speedo® , Roxy® and Grand® were examined on 2nd and 4th instars of both laboratory and field strain of Spodoptera littoralis (Boisd.) under laboratory conditions. Examined insecticides exhibited toxicities on laboratory strain greater than field strain. LC50 values on 2nd instar of laboratory strain were 0.224, 0.885, 1.033, 12.017, 24.723 and 35.171 ppm for Speedo® , Rider® , Biolarve® , Grand® , Roxy® , and Reldan® , respectively. Regarding field strain, the values were 0.391, 2.891, 7.076, 28.262, 30.675 and 45.565 ppm in the same manner. All treatments decrease activities of acetylcholine esterase (AChE) compared with control. Similarly, they exhibited a decrease in α and β-esterases (CE) of larval homogenates lower than control. Glutathione-S-transferase (GST) displayed activities in field strain and laboratory strains greater than control. In field strain, the activities were 22.50, 15.00, 16.50, 15.50, 14.00 and 20.50 nM/mg/min for Rider® , Reldan® , Biolarve® , Speedo® , Roxy® , and Grand® , respectively. In the same manner, Aspartate aminotransferase (AST) and alanine aminotransferase (ALT) of treated insects displayed activities greater than control. Esterases and GST enzymes may provide a primary investigation concern insect resistance and/or susceptibility to insecticide mixtures.

Keywords : Insecticides; Spodoptera littoralis; AChE; Esterases; GST.