Expression profiling of juvenile hormone and ecdysteroid biosynthesis genes during the development and reproduction of Phytoseiulus persimilis

Abstract Juvenile hormone (JH) and ecdysteroids play a vital role in arthropods growth and development. Significant progress has been made in recent years regarding the roles and molecular mechanisms of juvenile hormones and molting steroids in regulating insect metamorphosis and developmental. However, the related genes and regulatory mechanisms in Acari remain unclear. In this study, we conducted a comprehensive analysis by screening genomic and transcriptomic data to identify three genes associated with the biosynthesis of juvenile hormone and five genes related to ecdysteroid biosynthesis in the predatory mite, Phytoseiulus persimilis. We analyzed the spatial-temporal expression patterns of each gene at different developmental stages by Real-time quantitative PCR (qRT-PCR). The expression levels of juvenile hormone signaling factors PpJHAMT and PpKr-h1 and ecdysteroid biosynthesis signaling factors PpSad and PpShd were the highest during the larval stage. In addition, the ecdysteroid biosynthesis related Halloween gene PpSpo exhibited a serrated expression pattern in the immature stages. Similarly, PpDib was expressed throughout each immature developemental stage, with early expression always higher than the late one. The expression of the ecdysone receptor gene PpEcR was found to be consistently low during the immature stage. However, after fertilization of female adults, the expression of PpEcR increased significantly, reaching a level approximately 4.28 times higher than the average expression level. Upon verification of the gene function through RNAi (RNA interference), it was observed that the total egg production of pre-mating and post-mating female adults treated with dsKr-h1 (double-stranded RNA targeting Kr-h1) decrease by 8.73% and 13.30%, respectively. In the case of nymphs treated with dsEcR (double-stranded RNA targeting EcR), molting failure was observed, accompanied by severe dorsum crumpling and death. The expression pattern and RNAi functional verification of two hormone biosynthesis-related genes in P. persimilis offer a preliminary understanding in regulating the growth and development of predatory mites.