Abstract: In order to obtain stable and high-yield butenyl-spinosyn-producing strains and determine its lethal efficiency against agricultural pests,a high-yield mutant strain ASAGF30A11 with stable genetic traits was obtained by compound mutagenesis of a parent strain Saccharopolyspora pogona ASAGF19 screened from the previous study using ⁶⁰Co-γ-ray and nitrosoguanidine.The new strain increased yield by 61.26% compared with the parent strain,and the yield variation of 3 generations was less than 10%.The crude butenyl-spinosyn was purified from the fermentation broth of the high-yield strain,and then diluted into the mother liquor with a concentration of 1.5 g/L.The insecticidal activity against Thrips palmi Karny,aphids and Plutella xylostella was investigated and the LC₅₀ was determined to be 1.92 mg/L,1.23 mg/L and 0.27 mg/L,respectively.By comparison,butenyl-spinosyn was of a higher lethal efficiency against T.palmi than spinosyn (LC₅₀ 0.58 mg/L) and spinetoram (LC₅₀ 0.64 mg/L),a higher lethal efficiency against aphids than spinosyn (LC₅₀ 72.60 mg/L) but equal efficiency with avermectin (LC₅₀ 0.14 mg/L),and a higher lethal efficiency against P.xylostella than spinosyn (LC₅₀ 2.9 mg/L) but lower efficiency than spinetoram (LC₅₀ 0.05 mg/L).This study explored the effect of compound mutagenesis using ⁶⁰Co-γ-ray and nitrosoguanidine on S.pogona for the first time and measured the laboratory lethal efficiency of butenyl-spinosyn against three agricultural pests,which serves as part of the theoretical basis for the control of agricultural pests with new biological insecticides.

Key words: Saccharopolyspora pogona, ⁶⁰Co-γ-ray, NTG, combined mutagenesis, butenyl-spinosyns