PDK1 ‐mediated PI3K /Akt signaling regulates metabolic and developmental programs in a cosmopolitan pest

BACKGROUND: 3-Phosphoinositide-dependent protein kinase 1 (PDK1) is a central kinase in the phosphatidylinositol 3-kinase/serine-threonine kinase (PI3K/Akt) pathway that integrates growth and nutrient signals to regulate metabolism and development across diverse animal taxa. However, its functions in insects remain ambiguous. RESULTS: Here, we identify and characterize PxPDK1 in the diamondback moth, Plutella xylostella, a major agricultural pest. PxPDK1 encodes a conserved kinase containing serine/threonine kinase and pleckstrin homology domains, and is highly expressed during embryonic, pupal and adult stages. CRISPR/Cas9-mediated knockout of PxPDK1 resulted in developmental delay, failure of pupal-adult eclosion, impaired ovarian development, and sharply reduced fecundity and egg hatchability. Loss of PxPDK1 attenuated Akt phosphorylation and disrupted genes involved in metabolism, reproduction and cuticle formation, accompanied by decreased adult glycogen content. Conversely, PxPDK1 expression promoted Sf9 cell proliferation. CONCLUSION: These findings establish PxPDK1 as an essential regulator of insect development and metabolism, highlighting PDK1 as a promising molecular target for pest control.