Abstract: Penicillium raistrickii is a strain with biological control effect, which was isolated from the body of the infected Bactericera gobica by our research group. Enhancing the growth performance of P. raistrickii has a great significance to improve its control effect. In this study, a single-factor experiment was conducted to select and optimize different medium components and their concentrations for culturing P. raistrickii using spore production as an indicator. We determined the virulence of P. raistrickii culturing broth against the third instar of B. gobica. The results showed that the optimized medium was composed of 40 g·L^-1 soluble starch, 1 g·L^-1 yeast powder, 1 g·L^-1 K₂HPO₄, 1.5 g·L^-1 MgSO₄·7H₂O, 0.5 g·L^-1 KCl and 0.01 g·L^-1 FeSO₄, which increased spore production by 9.84 times compared to the basic medium. The results of the toxicity assay showed that the corrected mortality rate of the third instar of B. gobica treated by the P. raistrickii culturing broth with the optimized medium at 7 d increased by 25.56% compared to the basal medium. Based on the spore production and virulence results, the optimized medium is more effective than the basic medium in culturing P. raistrickii and controlling B. gobica, which provides a foundation for improving the biological control effect of P. raistrickii against B. gobica.

Key words: Penicillium raistrickii, medium optimization, toxicity, Bactericera gobica, biological control