Abstract: In order to ascertain the effect of bifenazate on spider mites oviposition and mite eggs. The acaricidal activities, oviposition changes and egg hatch under different concentration of bifenazate against Tetranychus cinnabarinus and T. urticae were compared by leaf disc method in indoor condition. The results indicated that 1.25-100.00 mg·L^-1 bifenazate showed significantly acaricidal activities against T. cinnabarinus and T. urticae female adults with LC₅₀ of 7.52 and 12.42 mg·L^-1, respectively, and their oviposition were significantly inhibited with the oviposition inhibitory rate between 27% to 81% and 10% to 80%, and the median oviposition inhibitory concentration were 4.16 and 6.86 mg·L^-1, respectively. Moreover, hatchability significantly decreased with increasing bifenazate concentration, and the LC₅₀ were 24.26 and 15.28 mg·L^-1, respectively. Therefore, bifenazate not only killed adult mites, but also had a significant effect on oviposition inhibitory, and the hatching of sprayed mite eggs was also significantly affected.

Key words: bifenazate, acaricidal activity, Tetranychus cinnabarinus, Tetranychus urticae, oviposition inhibitory