الفهرس 
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Abstract
The insecticidal, biological and morphogenetic effects of flufenoxuron Bacillus thuringiensis (Agrien) and cyanophos, as well as the effect of the two most active compounds ( flufenoxuron, Bacillus Thuringiensis) on the histology of the mid gut and integument of 6th instar larvae of Spodoptera littoralis treated as 4th instar larvae with LC50 of the previous compound. The insect growth inhibitor flufenoxuron was the most toxic compound against the larvae of 2nd and 4th instar larvae of S. littorali. Both compounds of flufenoxuron and Bacillus thuringiensis tested significantly increased (P< 0.05) the mean larval and pupal durations. On the other hand both compounds decreased the percentage of pupation, adult emergence, the mean pupal weight, adult longevity, fecundity and fertility. However the preoviposition, oviposition and postoviposition periods differed according to the compound used. Both compounds of flufenoxuron, and Bacillus thuringiensis (Agerin) exhibited larval, pupal and adult deformities as well as pupaladult intermediates. Treatment of 4th instar larvae of S. littoralis with flufenoxuron and Bacillus thuringiensis resulted in sever histological changes in the integument and midgut of surviving late 6th instar larvae. Flufenoxuron disrupted formation of endocuticle whereas Bacillus thuringiensis (Agerin) effected only the hypodermis. The most prominent changes induced by these two compound for the midgut was the vacuolation of epithelial cells and disruption of peritrophic membrane.