《环境昆虫学报》

为了解球孢白僵菌Beauveria bassiana对驴豆根瘤象Sitona callosus的致病机制，利用扫描电镜与透射电镜观察了球孢白僵菌菌株B1对驴豆根瘤象成虫体壁的侵染过程。接种白僵菌后，其分生孢子选择性地在驴豆根瘤象体表粗糙部位和凹陷区域附着；接种后12 h在两小眼凹陷处观察到了白僵菌萌发产生芽管，在机械压力和酶的作用下开始侵入根瘤象体壁；接种48 h在足跗节处观察到了白僵菌完全侵入，正式建立了寄生关系；接种后72 h，表皮层变形，与皮细胞层开始分离，脂肪体和肌肉组织被破坏。菌丝遍布鞘翅，深入刚毛窝；接种96 h后，菌丝体继续在虫体内向其他组织渗透扩张，虫体内充满菌丝和孢子，寄主开始死亡；120 h菌丝生长出虫体外，包裹虫尸；144 h，体外的菌丝出现凋亡。球孢白僵菌分生孢子的附着受根瘤象体表物理结构的影响，其在接种后96 h左右完成了对驴豆根瘤象的寄生并导致虫体发病死亡，B1菌株具有较强的致病力。

英文摘要:

The infection process of Beauveria bassiana strain B1 on the body wall of adult Sitona callosus were observed using SEM and TEM to elucidate the pathogenic mechanism. Following inoculation, B. bassiana conidia adhered to the rough areas and concave regions of S. callosus. Germination occurred between two ommatidium depressions 12 hours post-inoculation, initiating invasion into the body wall through mechanical pressure and enzymatic action. Infiltration of B. bassiana was observed in the digitus 48 hours after inoculation, establishing a parasitic relationship with the host organism. At 72 hours post-inoculation, the epidermal layer undergoes deformation, while the endothelium layer initiates separation. The adipose tissue and muscular fibers undergo destruction. Mycelium spread throughout elytron and penetrated setal alveolus. By 96 hours post-inoculation, mycelial growth continued to invade other tissues until complete colonization occurred along with spore formation resulting in host mortality. At 120 hours, mycelium emerged from the host's body enveloping its corpse while the apoptosis of mycelium was observed at 144 h in vitro. The attachment of B. bassiana was influenced by the physical structure of S. callosus. The conidia parasitize S. callosus 96 hours post-inoculation, leading to the onset of disease and subsequent mortality in the host, demonstrating a high degree of pathogenicity.

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