球孢白僵菌与杀螨剂混配对二斑叶螨的毒力测定及其田间防治效果

为探究球孢白僵菌Beauveria bassiana与杀螨剂混配对二斑叶螨Tetranychus urticae的防控作用，采用Munger cell法测定球孢白僵菌ZJU435与联苯肼酯、乙唑螨腈按照不同有效成分比混配后对二斑叶螨的室内毒力及其增效作用，并测定不同药剂组合对二斑叶螨的田间防治效果。结果表明，不同杀螨剂对二斑叶螨的室内毒力大小排序为乙唑螨腈>联苯肼酯>球孢白僵菌ZJU435,LC50分别为2.68、9.31和29.37 mg/L；球孢白僵菌ZJU435与联苯肼酯、乙唑螨腈分别以1∶9、3∶7、5∶5、7∶3、9∶1的有效成分比混配后均有显著的增效作用，其中球孢白僵菌ZJU435与联苯肼酯、乙唑螨腈均以9∶1有效成分比混配时的共毒系数最高，分别为324.61和391.80，增效作用最显著。以9∶1有效成分比混配时，12.50、9.50和8.00 mg/L球孢白僵菌+联苯肼酯混配处理后第10天的防治效果分别为84.13%、81.94%和77.96%,8.60、3.60和2.40 mg/L球孢白僵菌+乙唑螨腈混配处理后第10天对二斑叶螨的防治效果分别为89.38%...

Determination of the virulence of Beauveria bassiana mixed with acaricides against two-spotted spider mite Tetranychus urticae and its field control efficiency

To explore the control efficacy of Beauveria bassiana and acaricide on two-spotted spider mite Tetranychus urticae, we used the Munger cell method to determine the toxicity and synergism indoors with B. bassiana ZJU435, bifenazate, and cyetpyrafen. Additionally, we determined the field efficacy of different combinations among B. bassiana and acaricides. Indoor results revealed the following toxicity order to T. urticae: cyetpyrafen>bifenazate>B. bassiana ZJU435, with LC₅₀ values of 2.68, 9.31, and 29.37 mg/L, respectively. B. bassiana ZJU435 combined with bifenazate and cyetpyrafen showed significant synergistic effects at the ratios of 1∶9, 3∶7, 5∶5, 7∶3 and 9∶1. The highest co-toxicity coefficients of B. bassiana ZJU435 mixed with bifenazate and cyetpyrafen at a ratio of 9∶1 were 324.61 and 391.80, respectively, indicating moresignificant synergistic effects. Field experiments showed that the control efficacy of B. bassiana ZJU435 mixed with bifenazate at concentrations of 12.50, 9.50, and 8.00 mg/L for ten days were 84.13%, 81.94% and 77.96%, respectively. Similarly, the control effects of B. bassiana ZJU435 mixed with cyetpyrafen at concentrations of 8.60, 3.60, and 2.40 mg/L for 10 days were 89.38%, 83.08% and 79.95%, respectively. These results suggest that combining B. bassiana ZJU435 with low doses of bifenazate and cyetpyrafen could enhance the control efficacy while reducing the amount of chemical acaricides required.