Abstract:In order to value the bioactivity and impact on the biology of spirotetramat against Bemisia tabaci biotype B, the toxicity of spirotetramat and imidacloprid (control agent) to different instar nymphs of B.tabaci biotype B and the effects of the longevity, fecundity and eggs hatchability were measured in the laboratory by using egg-dipping and leaf-dipping. The toxicity of the 2nd instar nymph is high after treatment by spirotetramat, the LC50 was 4.07 mg/L, it was 2.73 times to the toxicity of imidacloprid, toxicity was low to the eggs and adults, and lower than that of imidacloprid. Longevity of the B.tabaci biotype B was 17.3 days after treatment with 12.5 mg/L spirotetramat, it was significantly shorted compared with the contrast experiment (treatment without pesticides), while imidacloprid was insignificant. The fecundity was 5 and the eggs hatching rate was 3.23% after treatment with 12.5 mg/L spirotetramat, which has significantly inhibition to the fecundity and the eggs hatching, and it was significantly lower than those treated with imidacloprid and the contrast experiment. It was no significant differences between imidacloprid and the contrast experiment. The repellent action was 52% to the adults of spirotetramat after 24 h treated with 100 mg/L spirotetramat, and the repellent action was not very good.