Abstract：To investigate the synergism of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) chitinase with insect pathogens for pest control, the chitinase A (chiA) gene was amplified from the AcMNPV genome by PCR and expressed in E. coli BL21 and Spodoptera frugiperda cell line Sf-9 respectively. The results of SDS-PAGE showed that chiA gene could be expressed as a 60 kDa protein in both E. coli and Sf-9 successfully. When the fifth instar larvae of Helicoverpa armigera were fed with the expressed product of chiA gene, the perforations on the peritrophic membrane (PM) were observed by the scanning electron microscope (SEM). When the expressed product of chiA gene was mixed with Bt and with Mamestra brassica nuclear polyhedrosis virus (MbNPV) fed to larvae of Helicoverpa armigera respectively. Then bioassay indicated that when compared with their corresponding controls, the LT50 of Helicoverpa armigera larvae fed by a mixture of Bt Cry2Ac protein and expressed product of chiA gene in E. coli and in Sf-9 cells were shortened 17.8 and 20.6 hours, with rates of enhancement were 33.4% and 54.5%, respectively. Another LT50 of Helicoverpa armigera larvae fed with MbNPV and expressed product of chiA gene in E. coli and in Sf-9 cells were shortened 16.6 and 22.4 hours, respectively. These results suggested that AcMNPV Chitinase may enhance insecticidal activity of Bt and NPV for pest control.
