Microsclerotia (MS) are considered one of the most promising propagules for use as active ingredients in biopesticides due to their tolerance to abiotic factors and ability to produce infective conidia for the control of pests. Therefore, the objective of this research was to establish the conditions required to induce the formation of microsclerotia in Mt004 and to study its development process, tolerance to abiotic factors and insecticidal activity of MS-derived conidia. started to form hyphal aggregates after 2 days and looked more compact after 8 days. MS were mature and pigmented after 20 days. The final yield was 2.0 × 10 MS/mL and MS size varied between 356.9 and 1348.4 μm. Ultrastructure analysis revealed that mature MS contained only a few live cells embedded in an extracellular matrix. Mature MS were more tolerance to UV-B radiation, heat and storage trials than conidia from Solid State Fermentation. MS-derived conidia were as virulent as conidia against larvae. These results showed that MS are promising propagules for the development of more persistent and efficient biopesticides for harsh environmental conditions. Our findings provide a baseline for production and a better understanding of microsclerotia development in strains.

中文翻译：

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罗伯茨绿僵菌的微菌核：生产、超微结构分析、稳健性和杀虫活性

微菌核 (MS) 被认为是最有希望用作生物农药活性成分的繁殖体之一，因为它们对非生物因素具有耐受性，并且能够产生感染性分生孢子来控制害虫。因此，本研究的目的是建立诱导Mt004微菌核形成所需的条件，并研究其发育过程、对非生物因素的耐受性以及MS衍生分生孢子的杀虫活性。 2天后开始形成菌丝聚集体，8天后看起来更加紧凑。 20天后MS成熟并着色。最终产量为 2.0 × 10 MS/mL，MS 大小在 356.9 至 1348.4 μm 之间变化。超微结构分析表明，成熟的 MS 仅含有少量嵌入细胞外基质的活细胞。与固态发酵的分生孢子相比，成熟的 MS 对 UV-B 辐射、热和储存试验的耐受性更强。 MS 衍生的分生孢子与分生孢子对幼虫的毒性一样。这些结果表明，MS 是开发适用于恶劣环境条件的更持久、更有效的生物农药的有前途的繁殖体。我们的研究结果为生产提供了基线，并更好地了解菌株中微菌核的发育。