Toxicity and field control efficacy of the new acaricide bifenazate to the two-spotted mite Tetranychus urticae Koch

The paper aims to assess the control efficacy of the bifenazate and to select effective pesticides to the two-spotted mite Tetranychus urticae.[Methods] The toxicity and field control efficacy of the bifenazate and other pesticides to the two-spotted mite were studied using the slide-dip method.[Results] The bioassay results showed that bifenazate had high control efficacy to all stages of the two-spotted mite with LC50 value of 221.243?0 mg/L to the eggs,10.927?7,5.151?4 and 3.389?4 mg/L to the nymphs at 24,48 and 72 hours after dip,10.389?1,10.051?6 and 3.881?8 mg/L to the adults at 24,48 and 72 hours after dip.Among the other five pesticides,abamectin showed the highest activity with LC50 of 3.1143,2.259?0 and 2.058?6 mg/L to the adults at 24,48 and 72 hours after dip,followed by emamectin benzoate.The hexythiazox showed the lowest activity to the adults of the two-spotted mite.The field test indicated that the 43% bifenazate SC had good control efficacy to the two-spotted mite,with 99.71,100 and 96.66% control after application for 2,7 and 14 days,significantly higher than that of the other five pesticides.[Conclusions] Our study suggested that the abamectin,emamectin benzoate,pyridaben,propargite and hexythiazox could not efficiently control the two-spotted mite,while the bifenazate showed very high toxicity.