Abstract:In order to value the bioactivity and the effect of environment on the efficacies of butene-fipronil against Plutella xylostella L. by the numbers, the laboratorial egg-dipping, leaf-dipping, topical application bioassay and field trails were used in present paper. Meanwhile, susceptible toxicity baseline of Plutella xylostella to butene-fipronil was established with topical application method as well. Butene-fipronil displayed the better contact toxic to the larvae of diamondback mouth and the LD50 was 0.45μg/larva after treated 48h by the topical method. The hatching rate of eggs and the survival rate of larvae were reduced, the control rate of hatching to Plutella xylostella was 46.24% with 64mg/L concentration. The toxicity of butene-fipronil to Plutella xylostella deduced with the increase instar. 1st or 2nd instar larvae were the most sensitive stage by leaf dipping method. Temperature tests showed that the toxicity become greater as temperature ranged from 15℃ to 32℃, at 15-32℃, the toxicity of butene-fipronil to the larvae of Plutella xylostella increased by 15.49-folds. In addition, the mortality was 84%-95% and residual activity was over 15d at concentration of 64mg/L treatment. The result of field trial demonstrated that the compound butene-fipronil was a predominant insecticide with rapider toxicity and keep a longer effectiveness than others against diamondback mouth.