School of Life Science, Shanxi University, 92 Wucheng Rd, Taiyuan, 030006, Shanxi, China.
Sci Rep. 2021 Jul 6;11(1):13915. doi: 10.1038/s41598-021-92694-y.
Beauveria bassiana is one of the most widely studied and used entomopathogenic fungus as biopesticide. In the biological control of pests, B. bassiana will persist in the soil after application, and will inevitably contact with earthworms, especially the epigeic earthworm species. So, what are the effects of earthworm and its epidermal mucus on the activity of B. bassiana? We employed the epigeic earthworm Eisenia fetida, B. bassiana TST05 strain, and the insect Atrijuglans hetaohei mature larvae to study the impact of earthworm epidermal mucus on the vitality and pathogenicity of B. bassiana to insect. Methods included scanning electron microscope observation, detection of spore germination, fungal extracellular enzyme activity, and infection testing to A. hetaohei. The results showed that the B. bassiana spores may attach to the cuticle of E. fetida but they could be covered by the epidermal mucus and became rough and shrunken. After treatment with the epidermal mucus, the spore germination and extracellular enzymes of B. bassiana was significantly inhibited. Inoculation of A. hetaohei larvae with a mixture of B. bassiana and mucus showed that the mucus could reduce the pathogenicity of B. bassiana to the insect, resulting in a slower disease course and lower mortality. It was concluded that the epidermal mucus of the earthworm E. fetida can inhibit the activity of B. bassiana, as well as the infectivity and pathogenicity of fungus to target insects. However, after treatment with epidermal mucus the surviving B. bassiana still had certain infectivity to insects. This is of great significance for the application of B. bassiana in biological control of pests.
球孢白僵菌是研究和应用最广泛的昆虫病原真菌之一，作为生物农药。在害虫的生物防治中，白僵菌施用于田间后会在土壤中持续存在，不可避免地会与蚯蚓接触，特别是表栖性蚯蚓种类。那么，蚯蚓及其表皮黏液对球孢白僵菌的活性有什么影响呢？我们采用表栖性蚯蚓赤子爱胜蚓、球孢白僵菌 TST05 菌株和昆虫金龟子绿僵菌成熟幼虫来研究蚯蚓表皮黏液对球孢白僵菌活力和对昆虫致病性的影响。方法包括扫描电子显微镜观察、孢子萌发检测、真菌胞外酶活性和对金龟子绿僵菌的感染试验。结果表明，球孢白僵菌孢子可能附着在赤子爱胜蚓的表皮上，但会被表皮黏液覆盖，变得粗糙和皱缩。用表皮黏液处理后，球孢白僵菌的孢子萌发和胞外酶活性显著受到抑制。将球孢白僵菌和黏液混合物接种到金龟子绿僵菌幼虫上，表明黏液可以降低球孢白僵菌对昆虫的致病性，导致病程较慢，死亡率较低。结论是，赤子爱胜蚓的表皮黏液可以抑制球孢白僵菌的活性，以及真菌对靶标昆虫的感染力和致病性。然而，经表皮黏液处理后存活的球孢白僵菌对昆虫仍具有一定的感染力。这对于球孢白僵菌在害虫的生物防治中的应用具有重要意义。
