Wolbachia-derived small non-coding RNAs exhibit cross-kingdom regulatory effects on host reproduction of a polyphagous mite

Wolbachia is a ubiquitous endosymbiont in arthropods that produces small non-coding RNAs, which function as regulators in both the bacterium and its host. Although recent studies have shown cross-kingdom communication between Wolbachia and its host through Wolbachia-derived small non-coding RNAs (WsnRNAs), the functions of WsnRNAs have not been systematically examined. Here, we identify WsnRNAs in Wolbachia-infected Tetranychus truncatus Ehara via RNA-seq and investigate their impacts on host reproductive fitness. A total of 12 WsnRNAs were identified, along with their predicted precursors and hairpin structures. The predicted target genes of five highly expressed WsnRNAs are involved in reproductive development, as revealed by enrichment analysis. Inhibition of WsnRNA-744 and WsnRNA-3640 reduced fecundity, whereas inhibition of WsnRNA-6108 promoted it, indicating that different WsnRNAs exert opposing effects on host fecundity. These findings suggest that WsnRNAs mediate host-endosymbiont communication across species and could represent promising targets for Wolbachia-based pest control strategies.