Abstract: 【Aim】 Emamectin benzoate, a novel highly effective semi-synthetic antibiotic insecticide, is widely used for chemical control of Monochamus alternatus. This study aims to explore the sublethal effects of emamectin benzoate on the natural enemy insect, Sclerodermus alternatusi. 【Methods】The toxicity of emamectin benzoate to S. alternatusi adults was determined using the topical application method. Two sublethal doses, i.e. LD₁₀(0.813×10^－3 μg/individual) and LD₃₀(3.427×10^－3 μg/individual) of emamectin benzoate were applied to the female adults of S. alternatusi to observe the changes in the number of eggs laid per female adult of the F₀ generation, and the developmental duration, fecundity, survival rate, female and male adult longevity and other parameters of the F₁ generation. An age-stage, two-sex life table was constructed, and the Timing-MSChart software was utilized to predict the 60-d population dynamics of the F₁ generation after exposure of adults to LD₁₀ and LD₃₀ of emamectin benzoate.【Results】Compared with the blank control, both LD₁₀ and LD₃₀ of emamectin benzoate stress significantly inhibited the number of eggs laid per female of the F₀ generation and significantly reduced the survival rate of the F₁ generation of S. alternatusi. Exposure of S. alternatusi adults to LD₃₀ of emamectin benzoate significantly prolonged the egg duration of the F₁ generation and significantly shortened larval duration of the F₁ generation, and significantly prolonged the male adult longevity of the F₁ generation. Population parameters of the F₁ generation showed that exposure of S. alternatusi adults to LD₁₀ and LD₃₀ of emamectin benzoate significantly decreased the intrinsic rate of increase (r), net reproductive rate (R₀), and finite rate of increase (λ) of the F₁ generation, and the treatment with LD₃₀ of emamectin benzoate significantly prolonged the mean generation time (T), compared with the blank control. Population dynamic predictions over 60 d revealed significant suppression of offspring populations of S. alternatusi by LD₁₀ and LD₃₀ of emamectin benzoate.【Conclusion】 Sublethal doses of emamectin benzoate markedly inhibited the survival rate and population growth of S. alternatusi offspring. Additionally, high-dose sublethal exposure to emamectin benzoate had no significant impact on the fecundity of female adult offspring, whereas low-dose sublethal exposure to emamectin benzoate significantly reduced the fecundity of female adult offspring. These findings provide a theoretical basis for the scientific application of emamectin benzoate in integrated pest management strategies in agriculture and forestry.

Key words: Sclerodermus alternatusi, emamectin benzoate, biological control, fecundity, age-stage, two-sex life table