Abstract:To screen synergistic and optimal application concentration of inorganic compounds for Bacillus thuringiensis engineering strain WG-001 against diamondback moth, Plutella xylostella, toxicity of Bt WG-001 WP to P.xylostella containing inorganic compounds, such as MgCl2, CaCl2, NaHCO3, MgSO4, NaH2PO4, Na2CO3, Na2HPO4, KH2PO4, was evaluated. Results showed that co-toxicity factors of 0.4%MgCl2, 0.2% CaCl2, 0.4%MgSO4 and 0.2%Na2CO3 with Bt WG-001 WP were 46.75, 36.27, 41.51 and 31.03, respectively. While the other 4 kinds of inorganic compounds had no synergetic action to Bt WG-001 WP against P.xylostella. Synergistic ratios of 0.4%MgCl2, 0.2%CaCl2, 0.4%MgSO4 and 0.2%Na2CO3 with Bt WG-001 WP were 1.46, 1.33, 1.34 and 1.29 respectively. Results of field test showed that average control effect of 500 dilution of Bt WG-001 WP containing 0.4%MgSO4 against P.xylotella was 80.51% on the 7th day after spraying, and it had significantly difference from other treatments. The result indicated that 0.4% MgSO4 could significantly increase field control efficacy of Bt WG-001 WP against P.xylotella.