RNAi mediated knockdown of RpL11, RpS2, and tra-2 led to reduced reproduction of Phytoseiulus persimilis.

Phytoseiulus persimilis is one of the most important biological control agents of spider mites. Multiple studies have been conducted on factors affecting its reproduction, but limited research on related molecular mechanisms has been carried out. In this study, RNA interference of three genes, ribosomal protein L11 (RpL11), ribosomal protein S2 (RpS2), and transformer-2 (tra-2), to newly emerged females were performed through oral delivery of double-stranded RNA, and knockdown of target genes was verified using qRT-PCR analysis. When RpL11 or RpS2 was interfered, 42 and 30% P. persimilis individuals either laid no egg or had no egg hatched, whereas the remaining females had their oviposition duration reduced by 31.8 and 49.9%, fecundity reduced by 48.1 and 67.8%, and egg hatching rate reduced by 20.4 and 22.4%, respectively. In addition, offspring sex ratios were significantly male biased especially at low fecundities. When tra-2 was interfered, no significant difference in fecundity was detected, but egg hatching rate reduced by 30.6%. This study verified the possibility of RNA interference in Phytoseiidae through oral delivery, and indicated that RpL11 and RpS2 are involved in egg formation, whereas tra-2 is involved in embryo development in P. persimilis. Phytoseiid mites have different sex determination pathways compared to insects. The present study provides data and evidence at molecular biological level for future research on reproduction and sex determination of phytoseiid mites.