Knockout of a testis-specific gene cluster impairs male fertility in the fall armyworm, Spodoptera frugiperda

BACKGROUND: The function of some testis-specific genes (TSGs) in model insects have been studied, but their function in non-model insects remains largely unexplored. In the present study, we identified several TSGs in the fall armyworm (FAW), a significant agricultural pest, through comparative transcriptomic analysis. A testis-specific gene cluster (TSGC) comprising multiple functional genes and long non-coding RNAs was found. RESULTS: Quantitative PCR analysis validated the testis-specific expression of genes within this cluster across different developmental stages. Interspecies collinearity analysis indicated that this TSGC is conserved among lepidopterans. To elucidate the function of this TSGC, we employed the CRISPR/Cas9 gene-editing technique to generate loss-of-function mutants. Notably, the hatching rate of eggs produced by wild-type females mated with mutant males (approximately 30%) was substantially lower than that of eggs from wild-type females mated with wild-type males (approximately 80%). Additionally, a significant reduction in the size and number of sperm was observed in the testis of mutant males compared to wild-type males. CONCLUSION: Collectively, this study not only elucidates the role of the TSGC in supporting male fertility in the FAW, which provides valuable information for understanding the mechanism of male reproduction in insects, but also identifies potential target genes for the development of genetic control strategies against lepidopteran pests.