| 刘雨生1, 李 栋1, 王建宇1, 苏长平1, 张 玉2, 肖海军1*.草地螟幼虫致病白僵菌的分离鉴定及其致病机制研究[J].植物保护,2025,51(3):31-40. |
| 草地螟幼虫致病白僵菌的分离鉴定及其致病机制研究 |
| Isolation and identification of pathogenic Beauveria from Loxostege sticticalis larvae and its pathogenic mechanism |
| 投稿时间：2024-02-08 修订日期：2024-03-22 |
| DOI：10.16688/j.zwbh.2025057 |
| 中文关键词: 草地螟 生物防治 白僵菌 致病力 组织病理学 |
| 英文关键词:Loxostege sticticalis biological control Beauveria pathogenicity histopathology |
| 基金项目:国家重点研发计划(2022YFD1400600) |
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| 中文摘要: |
| 草地螟Loxostege sticticalis是我国“三北”地区重要的农牧业害虫。球孢白僵菌Beauveria bassiana的推广与应用是草地螟绿色防控技术之一。本研究通过组织分离法从自然罹病的草地螟幼虫中分离出4株病原真菌, 通过ITS序列分子鉴定确定4个菌株与球孢白僵菌的相似性均在99%以上。通过浸虫法测试其对草地螟3龄幼虫的致病力，结果表明:菌株Bb2和Bb1对草地螟幼虫的致死率较高，处理后7 d, 幼虫死亡率分别为92.96%和89.26%。孢子悬浮液浓度与幼虫死亡率呈正相关，较高浓度的孢子悬浮液能提高幼虫死亡率。Bb2孢子悬浮液浓度为1.0×108 个/mL和5×108 个/mL时, 处理后7 d草地螟3龄幼虫的校正死亡率为82.05%和92.31%, 测试幼虫的半致死时间(LT50)分别为3.48 d和3.02 d。用菌株Bb2侵染草地螟幼虫, 对其进行组织病理学研究, 发现侵染后40 h, 球孢白僵菌孢子附着在幼虫体表, 侵染后72 h, 幼虫表皮开始出现褶皱断裂。随着处理时间的延长, 幼虫体壁出现融溃, 脂肪体和肌肉断裂。侵染后108 h, 幼虫中肠局部破裂, 内容物流出, 幼虫死亡。本研究为利用白僵菌防治草地螟提供了理论依据, 并为草地螟生物农药研究和非化学绿色防控提供参考资料。 |
| 英文摘要: |
| The beet webworm, Loxostege sticticalis, is a major agricultural and pastoral pest in the “Three-North” regions of China. The promotion and application of Beauveria bassiana is considered one of the green control technologies for managing beet webworm populations. In this study, four pathogenic fungal strains were isolated from naturally infected beet webworm larvae using the tissue separation method. The internal transcribed spacer (ITS) sequence analysis revealed that all four isolates showed over 99% similarity with B. bassiana. The pathogenicity of these fungal pathogens against the third-instar beet webworm larvae was tested using immersion infection method. The results showed that strains Bb2 and Bb1 had higher pathogenicity against beet webworm larvae. The corrected mortalities of beet webworm were 92.96% and 89.26%, respectively, seven days after treated with Bb2 ad Bb1 strains, with positive correlation between spore concentration and larval mortality. The corrected mortality rate of the third-instar L. sticticalis larvae was 82.05% seven days after treated with 1.0×108 spores/mL Bb2 strain, and the median lethal time (LT50) was 3.48 days. Increasing the spore concentration to 5.0×108 spores/mL resulted in the corrected mortality of 92.31% and LT50 of 3.02 days. Histopathological studies revealed that 40 hours post-infection, B. bassiana spores attached to the larval surface and gradually invaded the internal tissues. 72 hours post-infection, the larval epidermal tissue wrinkled and ruptured. As infection progressed, the larval cuticle collapsed, and the fat body and muscles ruptured. 108 hours post-infection, the midgut ruptured locally, leading to leakage of contents and larval death. This study provides a theoretical basis for the development and utilization of B. bassiana for beet webworm control. It also offers valuable reference materials for biological pesticide research and non-chemical green control strategies for L. sticticalis. |
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