金龟子绿僵菌MAE921与Bt配伍对铜绿丽金龟幼虫侵染致病效应研究

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

为了明确金龟子绿僵菌与Bt可湿性粉剂配伍后对铜绿丽金龟幼虫的侵染致病的协同增效作用,为该害虫的防治提供新途径,室内生物测定了金龟子绿僵菌MAE921与Bt制剂配伍对铜绿丽金龟2龄幼虫的侵染致病效应。结果表明:绿僵菌MAE921与Bt可湿性粉剂配伍后能提高绿僵菌对铜绿丽金龟2龄幼虫的侵染致病作用,死亡率随接种浓度的升高而增加,其中绿僵菌MAE921分别与0.1、0.05和0.025 g/m L Bt可湿性粉剂配伍接种后第5、7天的LC50对数估计值分别为5.152 7、5.197 8和5.984 6,3.797 7、3.906 2和4.517 4,均明显低于绿僵菌纯菌剂第5、7天的LC50对数估计值6.472 7和4.806 3。当用1.42×10~5m L^(-1)绿僵菌分别与0.1、0.05、0.025 g/m L Bt配伍后,对铜绿丽金龟2龄幼虫的LT50分别为5.00、5.05和5.80 d,均小于纯菌剂LT50(F<0.05);高剂量1.42×108m L^(-1)绿僵菌与0.1、0.05和0.025 g/m L Bt配置接种后,LT_(50)分别为2.65、2.96和3.62 d,与纯孢子悬浮液的LT_(50)间无显著差异(F>0.05)。由此表明:绿僵菌MAE921与Bt可湿性粉剂配伍对侵染铜绿丽金龟2龄幼虫具有良好的协同增效作用,其侵染致病效应符合"时间—剂量—死亡率模型(TDM)"。

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 2^nd 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 2^nd 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 5^th day, 3. 797 7, 3. 906 2 and 4. 517 4 on the 7^th 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 LCso as that 6. 472 7 and 4. 806 3. The LTso were 5.00, 5.05 and 5.80 days after inoculating the M. anisopliae MAE921 at the concentration of 1.42 ×10^5 mL^-1 combined with Bt at 0. 1, 0. 05, and 0. 025 g/mL, respectively, they were all lower than the LTs0 from the M. anisopliae MAE921 （F 〈 0. 05 ）. The LT50 were 2. 65, 2.96 and 3.62 days after inoculating the M. anisopliae at higher con- centration of 1.42 ×10^8 mL^-11 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 ×10^8 mL^-1 M. anisopliae with Bt at 0. 1, 0. 05 and 0. 025 g/mL Bt （ F 〈 0. 05 ）. All the results showed that M. anisopliae combined with B. thuringiensis can get a good synergism against the 2^nd instar larvae of A. corpulenta, and the infec- tion effect was in accord with the time-dose-mortality model.