Functional Characterization of Akt, a Serine/Threonine Kinase, in Tuta absoluta: A Key Regulator of Molting, Hormones, and Reproduction with Potential for RNAi Pest Control

Insect insulin signaling plays a central role in regulating development, metamorphosis, and reproduction, yet its mechanistic functions in the tomato leafminer, Tuta absoluta, a globally significant pest, remain poorly understood. This study aimed to elucidate the role of the serine/threonine kinase Akt (TaAkt) in coordinating metamorphosis and female reproductive processes. The TaAkt gene was cloned and characterized, and its spatiotemporal expression was analyzed across various developmental stages and tissues. RNA interference (RNAi) was employed to knock down TaAkt in late pupae and newly emerged females, followed by assessment of pupal-adult eclosion, chitin metabolism, 20-hydroxyecdysone (20E) titer, ovarian development, juvenile hormone (JH) levels, vitellogenin synthesis, and fecundity. Knockdown of TaAkt significantly reduced 20E titers and downregulated the expression of ecdysone biosynthesis and signaling genes, leading to pupal mortality, defective molting, and reduced chitin content. In adult females, TaAkt silencing impaired ovarian growth, decreased JH levels, suppressed vitellogenin production, and reduced egg number and hatching rates. These findings demonstrate that TaAkt exerts pleiotropic control over both metamorphic and reproductive processes in T. absoluta. The study identifies TaAkt as a promising molecular target for RNAi-based pest management strategies, offering a potential approach to simultaneously suppress survival and reproductive capacity in this economically important pest.