Roles of and in the Development of (Coleoptera: Scolytinae).

In insects, metamorphosis is controlled by juvenile hormone (JH) and 20-hydroxyecdysone (20E). (), a key JH-early inducible gene, is responsible for the suppression of metamorphosis and the regulation of the () gene, which is induced by 20E and functions as a "pupal specifier". In this study, we identified and characterized the expression patterns and tissue distribution of and at various developmental stages of . The expression of the two genes was induced by JH analog (JHA) methoprene and 20E, and their functions were investigated by RNA interference. and were predominantly expressed in the heads of larvae and were significantly downregulated during the molting stage. In contrast, the transcript level was highest in the adult anterior midgut. was mainly expressed in female adults, with the highest transcript levels in the ovaries. In the larval and pupal stages, both JHA and 20E significantly induced , but only 20E significantly induced , indicating the importance of hormones in metamorphosis. knockdown in larvae upregulated expression, resulting in precocious metamorphosis from larvae to pupae and the formation of miniature pupae. knockdown in pupae suppressed expression, increased emergence, caused abnormal morphology, and caused the formation of small-winged adults. These results suggest that is required for the metamorphosis of . Our findings provide insight into the roles of and in JH-induced transcriptional repression and highlight as a potential target for metamorphosis suppression in .