A parasitic wasp suppresses host pupation by microRNA-mediated transcriptional silencing of OfE93

Parasitic wasps have evolved intricate strategies to manipulate host development for the benefit of their offspring. In the lepidopteran host Ostrinia furnacalis, parasitism by Macrocentrus cingulum leads to pupation failure; however, the molecular mechanisms remain unclear. Here, we demonstrate that miR-281a-5p, upregulated in the hemolymph of parasitized host larvae, inhibits pupation by directly targeting ecdysone-induced protein 93F (OfE93), a crucial transcription factor involved in metamorphosis. A dual-luciferase assay confirmed that miR-281a-5p binds to the 3' untranslated region of OfE93. Moreover, injection of agomiR-281a-5p significantly reduced both transcript and protein levels of OfE93 in O. furnacalis larvae. RNA interference-mediated knockdown of OfE93 partially replicated the effects of parasitism, causing pupation arrest in approximately 20% of O. furnacalis larvae. These findings reveal a microRNA-based mechanism by which M. cingulum disrupts the host's endocrine-driven metamorphosis, providing new insights into the molecular interactions between parasitoids and their hosts.