The Infection Effect of Metarhizium anisopliae MAE921 with Bt against 2nd instar Larvae of the Anomala corpulenta Motschulsky

To confirm the synergism effect,and get a new method for the control of the larvae of Anomala corpulenta, the entomopathogenic fungi Metarhizium anisopliae combined with Bacillus thuringiensis agent, bioassay test against the 2nd instar larvae of A. corpulenta was conducted in the laboratory using the conidia suspension of M. anisopliae MAE921 combined with Bt at the dosage of 0.1,0.05 and 0.025g/mL. Results showed that the combination of M. anisopliae MAE921 with Bt showed a higher synergism against the 2nd instar larvae of A. corpulenta, the mortality increased with the increase of the inoculation concentration,the logarithm value of LC50 were 5.152 7,5.197 8 and 5.984 6 on the 5th day,3.797 7,3.906 2 and 4.517 4 on the 7th day after the inoculation of MAE921 with Bt at 0.1, 0.05 and 0.025 g/mL, respectively, they were all lower than the logarithm value of LC50 as that 6.472 7 and 4.806 3. The LT50 were 5.00,5.05 and 5.80 days after inoculating the M. anisopliae MAE921 at the concentration of 1.42×105 mL-1 combined with Bt at 0.1,0.05, and 0.025 g/mL, respectively,they were all lower than the LT50 from the M. anisopliae MAE921(F50 were 2.65,2.96 and 3.62 days after inoculating the M. anisopliae at higher concentration of 1.42×108 mL-1 with 0.1,0.05 and 0.025 g/mL Bt, but no significant difference was found between them and those LT50 from the combination of 1.42×108 mL-1 M. anisopliae with Bt at 0.1,0.05 and 0.025 g/mL Bt(FM. anisopliae combined with B. thuringiensis can get a good synergism against the 2nd instar larvae of A. corpulenta, and the infection effect was in accord with the time-dose-mortality model.