Abstract: The Cry1A binding region of cadherin-like protein of the Asian corn borer (ACB), Ostrinia furnacalis, MPR, as well as one of its mutants in Cry1Ac-selected strain of ACB, MPR-r2, were expressed in Escherichia coli as a soluble protein and purified on a Ni-NTA column with its His-tag. The toxicities of MPR and MPR-r2 to ACB were examined using diet incorporate bioassay. The purified MPR and MPR-r2 peptides showed low toxicity to ACB. In addition, an additive effect on the insecticidal activity against the ACB larvae was observed when MPR peptide was mixed with Cry1Ac toxin. However, ACB mortality was not significantly increased when purified MPR-r2 peptide was mixed with Cry1Ac toxin as compared with Cry1Ac used alone.