الفهرس 
Toxicity of certain insecticides to spodoptera littoralis (Boisd.) in relation to genetic structure
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Abstract
DNA (RAPD), efficacy of certain insecticides against S. littoralis and their effect on total protein, protein SDS-PAGE and the persistence of cypermethrin and chlorpyrifos in and on cotton leaves were investigated. On the basis of LC₅₀ and LC₉₀ levels, cypermethrin was the most potent compound against S. littoralis after 2 days of treatment, followed by esfenvalerate, chlorpyrifos and then B. thuringiensis. The potential of random amplified polymorphic DNA (RAPD) detected genetic polymorphism among the control and treated S. littoralis larvae by tested compounds at LC₅₀ levels. Five primers revealed differences among control and (dead and alive) treated samples with visible changes in DNA fragments number and size. Primer C1 was the most powerful in detecting polymorphism frequency as 63.6%. Total protein of S. littoralis alive larvae increased at the 2nd,the 4th, the 6th, and the 9th day posttreatment as 4th instar in most treatments by LC50 of the tested compounds. The electrophoretic analysis of proteins by SDS-PAGE was carried out for untreated normal strain at different days posttreatment with LC₅₀ of the above mentioned compounds. 119 bands were separated and their molecular weights ranged between 3.06 and 128.09 KDa. Cypermethrin was the most effective compound caused thickening of outer cuticle fibrous layer in the integument of S. littoralis larvae after 6 days of treatment as 4th instar