Chemical insecticides remain the main strategy to combat mosquito-borne diseases, but the growing threat of insecticide resistance prompts the urgent need to develop alternative, ecofriendly, and sustainable vector control tools. Entomopathogenic fungi can overcome insecticide resistance and represent promising biocontrol tools for the control of mosquitoes. However, insects have evolved robust defense mechanisms against infection. Better understanding of mosquito defenses against fungal infection is critical for improvement of fungal efficacy. Here, we show that as the pathogenic fungus Beauveria bassiana penetrates into the host hemocoel, mosquitoes increase expression of the let-7 and miR-100 microRNAs (miRNAs). Both miRNAs translocate into fungal hyphae to specifically silence the virulence-related genes sec2p and C6TF, encoding a Rab guanine nucleotide exchange factor and a Zn(II)₂Cys₆ transcription factor, respectively. Inversely, expression of a let-7 sponge (anti–let-7) or a miR-100 sponge (anti–miR-100) in the fungus efficiently sequesters the corresponding translocated host miRNA. Notably, B. bassiana strains expressing anti–let-7 and anti–miR-100 are markedly more virulent to mosquitoes. Our findings reveal an insect defense strategy that employs miRNAs to induce cross-kingdom silencing of pathogen virulence-related genes, conferring resistance to infection.

化学杀虫剂仍然是对抗蚊媒疾病的主要策略，但杀虫剂耐药性的威胁日益严重，迫切需要开发替代的、生态友好的和可持续的病媒控制工具。昆虫病原真菌可以克服杀虫剂耐药性，是控制蚊子的有前途的生物防治工具。然而，昆虫已经进化出强大的防御机制来抵御感染。更好地了解蚊子对真菌感染的防御对于提高真菌功效至关重要。在这里，我们展示了当病原真菌球孢白僵菌渗透到宿主血腔中时，蚊子会增加 let-7 和 miR-100 微 RNA (miRNA) 的表达。两种 miRNA 均转移到真菌菌丝中以特异性沉默毒力相关基因sec2p和C6TF，分别编码 Rab 鸟嘌呤核苷酸交换因子和 Zn(II) ₂ Cys ₆转录因子。相反，真菌中 let-7 海绵（anti-let-7）或 miR-100 海绵（anti-miR-100）的表达有效地隔离了相应的易位宿主 miRNA。值得注意的是，表达抗-let -7 和抗-miR-100 的球孢杆菌菌株对蚊子的毒性明显更强。我们的研究结果揭示了一种昆虫防御策略，该策略利用 miRNA 诱导病原体毒力相关基因的跨界沉默，赋予对感染的抵抗力。