Effectiveness of commercialformulations of Bacillus thuringiensisvarKurstaki (Bt) "Agerin, Dipel 2X and Dipel DF" on total protein and lipid contents as well as the activities of detoxification enzymes and metabolic enzymes were measured in treated and control larvae of Spodopteralittoralis. Collected samples from treated larvae at intervals of 48 and 120 hours post treatment were analyzed to assess the total protein and lipid contents as well as the enzymes activities. Significant reductions were observed in total protein content at 120 hours larvae in all treatments than the control. In all larvae treated with Agerin and Dipel DF the lipid content was significantly elevated after 48 and 120 hours of treatment while Dipel 2X showed no significant difference in lipid content. However fluctuated changes in the enzymes activity of treated larvae were found. We conclude that there are differences in biochemical effects between various commercial formulations of Btkurstaki. In most cases Agerin was found more effective to S. littoralis than others.