关键词: 松墨天牛, 环链虫草, 响应面优化, 液体发酵, 生物防治

Abstract:

 This study used the larval immersion method to determine the pathogenicity of eight Cordyceps cateniannulata strains against the 4th instar larvae of Monochamus alternatus. Single-factor experiments were conducted to investigate the effects of liquid fermentation parameters on mycelial dry weight. Plackett-Burman experiments, the steepest ascent experiment, and Box-Behnken response surface methodology were combined to explore the optimal fermentation interval. The aim was to screen C. cateniannulata strains with high pathogenicity against M. alternatus and to optimize liquid fermentation conditions, thus providing a basis for the subsequent large-scale production and application of biocontrol formulations. Strain H-81655 caused 100% mortality of the 4th instar larvae of M. alternatus within 14 days, with a median lethal time (LT₅₀) of 4.412 d. Response surface optimization determined the optimal liquid fermentation conditions as follows: N content 13 g/L, medium volume 66 mL in a 250 mL flask, rotational speed 219 r/min, and incubation time 4 d. Under these fermentation conditions, the maximum mycelial dry weight reached 26.95 g/L, a 46.9% increase compared with 18.35 g/L before optimization. The C. cateniannulata strain H-81655 showed strong pathogenicity against the 4^th instar larvae of M. alternatus, with cumulative corrected mortality reaching 100% by the 14^th day. After optimization of its liquid fermentation process, the mycelial dry weight was significantly increased, which can provide high-quality strain resources for the large-scale solid-state fermentation production of this strain.

Key words:

Monochamus alternatus, Cordyceps cateniannulata, response surface optimization, liquid fermentation, biocontrol