TSWV modulates sex ratio in the western flower thrips, Frankliniella occidentalis, by down-regulating a FSCB-like gene

Abstract Plant viruses can facilitate their transmission by modulating sex ratios of their insect vectors. Previously, we found that exposure to tomato spotted wilt orthotospovirus (TSWV) in the western flower thrips, Frankliniella occidentalis, led to a male-biased sex ratio in the offspring. TSWV, a generalist pathogen with a broad host range, is transmitted primarily by F. occidentalis in a circulative-propagative manner. Here, we integrated proteomic tools with nanoparticle-mediated RNAi to comprehensively investigate the genetic basis underlying the shift in vector’s sex ratio induced by virus. Proteomic analysis showed 104 differentially expressed proteins between F. occidentalis adult males with and without TSWV. The expression level of the fiber sheath CABYR-binding-like (FSCB) protein, namely FoFSCB-like, a sperm-specific protein associated with sperm capacitation and motility was decreased by 46%. The predicted FoFSCB-like protein include 10 classic Pro-X-X-Pro motifs and 42 phosphorylation sites, which are key features for sperm capacitation. The relative expression of FoFSCB-like was gradually increased alongside the developmental stages and peaked at the pupal stage. After exposed to TSWV, FoFSCB-like expression was substantially down-regulated. RNAi substantially suppressed FoFSCB-like expression and led to a significant male bias in the offspring. This study not only advances our understanding of virus-vector interactions, but also identifies a potential target for the genetic management of F. occidentalis, the primary vector of TSWV, by manipulating male fertility.