The joint toxicity of bifenazate and propargite mixture against Tetranychus urticae Koch

ABSTRACTBifenazate is a new type of hydrazine derivative acaricide which has been registered in China since 2008. In order to prolong the service life of bifenazate, the joint toxicity of bifenazate and propargite against Tetranychus urticae was evaluated in this study. The results showed that, with the mass ratio of 5:1 for bifenazate and propargite, the cotoxicity coefficient was 137.5, which showed synergistic toxicity to T. urticae. Moreover, when T. urticae was treated by the mixture of bifenazate and propargite (5:1) at the serial concentrations of 20.00 mg/L, 14.29 mg/L, 11.11 mg/L, 9.09 mg/L, and 7.69 mg/L for 24 h, the activities of glutathione s-transferase (GST) in T. urticae were 3.37, 3.64, 3.93, 4.04, and 4.08 mmol/min/mgPro, which were significantly (P < 0.05) lower than those in T. urticae being treated by bifenazate (7.25, 6.82, 6.71, 6.44, and 5.81 mmol/min/mgPro) and propargite (10.13, 9.79, 9.14, 8.93, and 8.44 mmol/min/mgPro) individually at the same concentration, indicating that the...