The present study is to through light on role of some insecticides (chemical insecticides (a.i.chlorphyrifos) Dursban® 48% EC, spinosyns group (a.i.spinosad) Tracer® 24% SC and insect growth regulator (a.i.lufenuron) Match® 5% EC) against insect attacking cotton cultivation Spodoptera littoralis under Egyptian conditions. The toxicological effects and biochemical analysis carried out against laboratory strain of target insects after 24 and 72 hours. Toxicity of the three insecticides chlorphyrifos, spinosad and lufenuron were tested against the 2nd instar larvae of the cotton leafworm, spodoptera littoralis. The results showed that lufenuron was more effective on the 2nd instar larvae than chlorphyrifos and spinosad. The LC25 values for lufenuron, chlorphyrifos and spinosad were 0.0005, 2.21 and 8.1 ppm, respectively. The biochemical study used for tested insecticides at LC25 on some biocomponents namely acetylcholinesterase (AchE), glutathione-s-transferase (GST), chitinase, phenoloxidase, aspartate (AST) and alanine (ALT) aminotransferases, α-esterase (α-EST), total protein and protein gel electrophoresis for laboratory strain were investigated. The tested chlorphyrifos and lufenuron were significantly increased (AchE). Spinosad was significantly decreased (GST) and phenoloxidase. Spinosad and lufenuron significantly increased (α-EST) and (chitinase) (ALT). Chlorphyrifos caused significantly decreased on α-esterase and total protein and (AST). Lufenuron significantly decreased total protein and phenoloxidase. Spinosad showed insignificant increase in (AchE) and total protein (levels).
Chlorphyrifos decreased both of phenoloxidase and (ALT) levels insignificantly and increased the levels of (GST) and chitinase, while lufenuron, recorded insignificant decrease in GST levels. The total body proteins of 2nd instar larval of S. littoralis treated with LC25 of insecticides performed by SDS-PAGE. Control and different treatments were separated into 56 different bands according to their relative frequencies (Rf values), and molecular weights (MW). Samples of electrophoresis were carried out for three different insecticides namely chlorphyrifos, spinosad and lufenuron which used to treat insects. The treatment with insecticides on protein gel electrophoresis led to detection of new bands, and disappeared some bands in comparison to control. It is concluded that treatment with insecticides have strong efficacy on the soluble protein in the body of insects.