Interactive Effect of Metarhizium anisopliae and Bifenthrin on the Mortalities of Oedaleus asiaticusin Laboratory Bioassays

The synergistic effect between low concentration bifenthrin and Metarhizium anisopliae on the mortality of grasshopper,Oedaleus asiaticus was tested in laboratory biassays. The results showed that a significantly increased efficacy of M. anisopliae against grasshopper when combined with low concentration bifenthrin was achieved. The LT50 estimates of mixed-use decreased by about 70.62,24.88,10.85 d compared to those in the treatments of bifenthrin alone. The LT50 estimates of mixed-use decreased by about 3.44,3.1 and 1.83 d compared to those in the treatments with M. anisopliae alone. The study showed that the concentration of mixed application for more satisfactory control was bifenthrin 5 mg/L + M. anisopliae 107 spores/mL.