The testis-specific gene SfGSTe11 regulates eupyrene sperm morphogenesis and is indispensable for male reproduction in a global pest, Spodoptera frugiperda

BACKGROUND: The fall armyworm, Spodoptera frugiperda, is a devastating agricultural pest whose rapid population expansion and increasing crop damage are driven by its exceptional reproductive capacity. While glutathione S-transferases (GSTs) are well known for their roles in insecticide detoxification, their functions in male reproduction remain largely unexplored. RESULTS: Here, we identified a testis-expressed GST gene, SfGSTe11 (LOC118265997) in S. frugiperda through transcriptome sequencing and confirmed its testis-specific expression pattern via real-time quantitative polymerase chain reaction (RT-qPCR). CRISPR/Cas9-mediated knockout of SfGSTe11 resulted in a significant reduction in egg hatching rates when mutant males were crossed with wild-type females. Phenotype analysis revealed markedly reduced testis size and a substantial decrease in total sperm bundle counts in mutant males. Fluorescence microscopy further demonstrated the loss of SfGSTe11 specifically disrupts the head morphology of eupyrene (nucleated) sperm, while apyrene (anucleated) sperm development remains unaffected. Transcriptomic profiling of mutant testes uncovered significant down-regulation of genes associated with endoplasmic reticulum protein processing, longevity regulating pathways, and glycerolipid metabolism. CONCLUSION: Collectively, these findings establish a novel and essential role for a testis-specific GST in male reproduction in S. frugiperda, expanding our understanding of insect GST functional diversity and identifying SfGSTe11 as a promising molecular target for genetic pest management strategies.