Abstract: 【Aim】 This study aims to explore the negative influence of Beauveria bassiana on female adults of a cryptoparasitoid Scleroderma guani， so as to more effectively prevent and control the pine longicorm beetle， Monochamus alternatus. 【Methods】 The pathogenicity of B. bassiana to S. guani was tested with different concentrations of spore suspension (1.0×10⁴-1.0×10⁸ conidia/mL) and spore powder (1.0×10⁷ conidia/female) with sterile water as the control. 【Results】 The female adults of S. guani were infected by both spore suspension and spore powder of B. bassiana. After inoculation with different concentrations of spore suspension， both the infection rate and mortality rate of female adults of S. guani showed a positive correlation with spore concentration. At 2 and 4 d after inoculation， only the highest concentration of spore suspension caused the death and infection in female adults of S. guani. At 5 d after inoculation， the infection rates of female adults of S. guani by 1.0×10⁸， 1.0×10⁶ and 1.0×10⁴ conidia/mL spore suspension were 56.0%， 8.0% and 4.0%， respectively， and the mortality rates were 88.0%， 44.0% and 16.0%， respectively. At 6 d after inoculation， the mortality rate of female adults of S. guani caused by 1.0×10⁸ conidia/mL spore suspension reached 100%. The spore suspension had stronger capability causing death of female adults of S. guani than the spore powder. At 7 d after inoculation， the mortality rate of female adults of S. guani inoculated with 1.0×10⁷ conidia/mL spore suspension was 100%. This was likely to be related to the behavior of female adults of S. guani.【Conclusion】 Spore suspension of B. bassiana should preferably be applied in the comprehensive prevention and control of stem borers using pathogeninfected S. guani. And the release time of S. guani parasitoids after pathogen infection should be controlled so as to facilitate to spread the fungal conidia and to infect larvae and pupae of stem borers within its latent period (4-5 d) infected by B. bassiana.

Key words: Scleroderma guani, stem borer, Beauveria bassiana, infection rate, pathogenicity, mortality rate