Abstract:In order to analyze the synergistic effect of cadherin from Tenebrio molitor to Cry3A toxin, the gene fragment of cadherin cloned from the midgut of T.molitor was expressed in Escherichia coli to evaluate the effect of cadherin on the insecticidal activity of Cry3A toxin. The expressed product of cadherin-Tm gene fragment is inclusion body, which is denatured by urea, followed by affinity chrymatography. The insecticidal activity of Cry3A toxin is enhancing corresponding to the increasing of the mass ratio of cadherin-Tm fragment to Cry3A toxin. When the ratio is about 1, there is a maximum insecticidal activity of Cry3A toxin, which is 2.5 fold higher than that of Cry3A toxin. However, cadherin-Tm fragment has no effect on the insecticidal activity of Cry3Am. This research indicated that cadherin-Tm fragment has enhancing effect just on Cry3A toxin.