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联苯肼酯是用于农作物害螨防治的一种新型选择性叶面喷雾杀螨剂.以43％联苯肼酯悬浮剂(SC)供试,采用叶碟喷雾法测定药剂对朱砂叶螨和二斑叶螨的室内毒性,采用食下毒叶法测定药剂对家蚕的急性毒性和桑园施药后的残留毒性.43％联苯肼酯SC对2种害螨的成螨、若螨和螨卵均具有较高的杀灭活性,48 h LC50值分别为4.93和3.38 mg/L、0.75和1.90mg/L、18.61和11.85 mg/L,其中对朱砂叶螨成螨和若螨的毒力分别为其对螨卵毒力的3.78和24.81倍,对二斑叶螨成螨和若螨的毒力则分别是对螨卵毒力的3.51和6.24倍.43％联苯肼酯SC对家蚕3龄起蚕48 h的LC50和LC90值分别为1 063.36和3 523.77 mg/L,属于低毒级农药(LC50＞200mg/L);桑树喷施143.33～573.33 mg/L药液后14d采摘桑叶养蚕,对家蚕的龄期经过、眠蚕体质量、全茧量、茧层量、茧层率等均无明显影响.依据试验结果确定,43％联苯肼酯SC可以用于桑园内朱砂叶螨和二斑叶螨的防治,建议田间施用联苯肼酯143.33 mg/L药液对家蚕的安全间隔期定为10 d,286.67～573.33 mg/L药液对家蚕的安全间隔期定为14 d.“,”Bifenazate is a new type of selective foliar spray acaricide for mite control in crops.In this study,leaf disc spray method was employed to determine the in-door acaricidal activity of 43％ bifenazate suspension concentrate (SC)against Tetranychus cinnabarinus and Tetranychus urticae,and toxic leaf feeding method was used to detect the acute toxicity to silkworm (Bombyx mori),and the residual toxicity to silkworm after drug application in mulberry field.The results showed that 43％ bifenazate SC had high acaricidal activity to adults,nymphs and eggs of both mites.The LCso values to adults,nymphs and eggs of the two mites were 4.93 and 3.38 mg/L,0.75 and 1.90 mg/L,18.61 and 11.85 mg/L at 48 h of treatment,respectively.The acaricidal activity to 7.cinnabarinus adults and nymphs was 3.78 and 24.81 times to that to T.cinnabarinus eggs respectively,and the acaricidal activity to T.urticae adults and nymphs was 3.51 and 6.24 times to that of T.urticae eggs respectively.LC50 and LC90 of 43％ bifenazate SC to the 3rd instar newly exuviated silkworm larvae were 1 063.36 and 3 523.77 mg/L at 48 h of treatment,being of low toxicity grade to Bombyx mori (LC50＞200 mg/L).The developmental duration,body weight of molting larvae,cocoon weight,cocoon shell weight,and cocoon shell rate of silkworm were not obviously changed after silkworm larvae were fed with leaves harvested at 14 d after spraying 143.33-573.33 mg/L bifenazate SC in mulberry field.Therefore,43％bifenazate SC can be used to control T.cinnabarinus and T.urticae in mulberry field.The safety interval of 143.33 mg/L and 286.67-573.33 mg/L bifenazate SC to silkworm larvae are 10 days and 14 days,respectively.