Lin_2026_Pestic.Biochem.Physiol_219_107016

Spodoptera litura is a devastating polyphagous pest that has caused substantial economic losses globally. Although chemical insecticides remains the predominant control strategy, increasing insecticide resistance and environmental concerns highlight the urgent need for effective botanical alternatives. Lycorine, an Amaryllidaceae-derived alkaloid exhibiting broad-spectrum insecticidal properties, is a promising candidate; however, its effects on S. litura and its underlying mechanisms remain poorly understood. In the present study, we demonstrated that dietary lycorine (40 mg/g dry diet) significantly impaired larval survival and development, reducing the survival rate by 70.0%, body weight by 90.4%, pupal weight by 69.6%, and pupal length by 30.7% relative to the controls. Integrative transcriptomic and metabolomic analyses revealed pronounced perturbations in fatty acid metabolism, characterized by marked downregulation of secretory phospholipase A2 (sPLA2), a pivotal enzyme in phospholipid hydrolysis. Consistent with these findings, biochemical assays demonstrated significantly reduced total lipid content in lycorine-treated larvae. Molecular docking analysis revealed strong binding affinity between lycorine and sPLA2, whereas in vitro enzymatic assays confirmed that lycorine potently inhibited the activity of purified recombinant sPLA2 activity. Furthermore, CRISPR/Cas9-mediated sPLA2 knockout phenocopied the lycorine-induced developmental defects, confirming the essential role of sPLA2 in larval growth and development. This study provides the first comprehensive mechanistic evidence that lycorine targets sPLA2 to disrupting lipid homeostasis in S. litura, thereby establishing a novel molecular framework for botanical insecticide development and advancing sustainable pest management strategies.