Biochemical approaches have been used to enhance the potency of of Bacillus thuringiensis against Plodia interpunctella. Tests were made with different classes of chemical compounds, characterized by being safe, non-toxic to man, and cheap in price. Among the tested inorganic salts, calcium carbonate, calcium oxide and zinc sulphate were found to increase the potency of B. thuringiensis δ-endotoxin by 2.5-, 1.9- and 2.7- fold, respectively. With the nitrogenous compounds, the amino acids serine, arginine, alanine and leucine enhanced the endotoxin effect by 5.2-, 3.6-, 1.3-and 1.1-fold, respectively. Also, among the protein solubilizing agents, EDTA and sodium thioglycollate led to a 100- and 2.6-fold Increase in the potency. Formic acid was highly effective among the organic acids used in enhancing the potency, followed by malic acid, with 4.8- and 2.4-fold increase, respectively.