Abstract: This study was conducted in an alfalfa field at the Luhuatai experimental site of the Institute of Plant Protection， Ningxia Academy of Agriculture and Forestry Sciences， where Beauveria bassiana and Metarhizium anisopliae were applied in alternate rows for three consecutive years. The results showed that both entomopathogenic fungi provided effective control of Odontothrips loti， with average control efficacies of 34.8% and 30.3%， respectively. Compared with the control， three years of B. bassiana application significantly improved soil physicochemical properties， with available phosphorus and soil organic carbon increasing by 67.2% and 41.7%， respectively， showing greater improvement than M. anisopliae. Soil enzyme activities were also enhanced， with increases of 36.91% in sucrase， 64.20% in alkaline phosphatase， and 31.03% in catalase. Application of M. anisopliae increased sucrase activity by 30.32% and catalase activity by 24.42% relative to the control. Compared with the soil bacterial community， soil fungal community structure was more strongly altered by the two biocontrol fungal treatments. Meanwhile， the relative abundance of beneficial taxa such as Sphingomonas increased， whereas the proportion of pathogenic fungi such as Fusarium declined. Overall， this study provides a theoretical basis and practical reference for pest biological control and the sustainable development of grassland agriculture in the Ningxia region.

Key words: Alfalfa pests, Biological translation, Soil physical and chemical properties, Rhizosphere microecology

摘要： 本研究在宁夏农林科学院植物保护研究所芦花台试验基地苜蓿田，间施3年球孢白僵菌Beauveria bassiana及金龟子绿僵菌Metarhizium anisopliae，发现两种生防菌对牛角花齿蓟马具有较高防效，防治效果平均分别为34.8%和30.3%。与对照组相比，间施3年球孢白僵菌后，土壤理化性质得到显著改善，速效磷、有机碳分别增加了67.2%，41.7%，改善效果超过金龟子绿僵菌；土壤酶活性提高，蔗糖酶、碱性磷酸酶、过氧化氢酶分别增加了36.91%，64.20%，31.03%。金龟子绿僵菌使蔗糖酶活性较对照增加了30.32%、过氧化氢酶活性增加了24.42%。与土壤细菌相比，两种生防菌处理组对土壤真菌结构改变较大，部分有益菌如鞘氨醇单胞菌丰度增加，部分病原菌如镰刀菌占比下降。本研究为害虫生物防治及宁夏地区草地农业可持续发展提供了理论依据和实践参考。

关键词: 苜蓿害虫, 生物防治, 土壤理化性质, 根际微生态