The second instars S. littoralis larvae were exposed to the LC 50 of Teflubenzuron, Bacillus thuringiensis Var. kurstaki. , and the concentration (MC 50) of Serratia marcescens causes 50% malformation for pupae, separately and in sequential combined of both B. thuringiensis/ S.marcescens (Bt/Sm) and Teflubenzuron/S.marcescens to compare the effect of the tested pesticides on the aspartate aminotransferase (AST) activity and alanine aminotransferase (ALT) activity during pupal stage of Spodoptera littoralis Boisd. Treatment with B. thuringiensis or S. marcescens alone revealed generally significant decreases to AST through pupal stage relative to control. The highest levels of (AST) aspartate aminotransferase activities were clearly found in individual treatment with Teflubenzuron. On the other hand , when the sequential combined effect treatment B. thuringiensis/ S. marcescens (Bt/Sm) was used , there were more reduction in the AST activity at 2 nd , 4 th and 10 th days than that of S. marcescens and generally ,during the pupal stage, the sequential Bt/Sm had less effect than individual B. thuringiensis. The effect of Teflubenzuron / S. marcescens ((Teflu/Sm) commonly was higher than individual S. marcescens but less effective than Teflubenzuron alone. Also, Teflubenzuron had an effect on alanine aminotransferase (ALT) activity higher than B. thuringiensis which was effective than S.marcescence. In contrast, in the sequential combined effect treatments, Bt/Sm exhibited more decreasing effect at 2 nd , 12 th and 14 th day of pupation (-72.93% ,-82.86% and-89.56% , respectively) than treatment with B. thuringiensis alone. Teflu/Sm caused significant reduction in alanine aminotransferase activity except at 4 th and 6 th days, where there is significant increase. The increase at 6 th day (203.56%) was higher than that of Teflubenzuron alone (126.18%) or S. marcescens (47.60%). But overall, Teflubenzuron alone had the highest effect.