Abstract

Spodoptera frugiperda(J. E. Smith), an emerging invasive pest worldwide, has posed a serious agricultural threat to the newly invaded areas. Although somatic sex differentiation is fundamentally conserved among insects, the sex determination cascade inS. frugiperdais largely unknown. In this study, we cloned and functionally characterizedDoublesex(dsx), a “molecular switch” modulating sexual dimorphism inS. frugiperdausing male- and female-specific isoforms. Given that Lepidoptera is recalcitrant to RNAi, CRISPR/Cas9-mediated mutagenesis was employed to constructS. frugiperdamutants. Specifically, we designed target sites on exons 2, 4, and 5 to eliminate the common, female-specific, and male-specific regions ofS. frugiperda dsx(Sfdsx), respectively. As expected, abnormal development of both the external and internal genitalia was observed during the pupal and adult stages. Interestingly, knocking out sex-specificdsxvariants inS. frugiperdaled to significantly reduced fecundity and fertility in adults of corresponding sex. Our combined results not only confirm the conserved function ofdsxinS. frugiperdasex differentiation but also provide empirical evidence fordsxas a potential target for the Sterile Insect Technique (SIT) to combat this globally invasive pest in a sustainable and environmentally friendly way.Keywords:Spodoptera frugiperda;invasive species;doublesex;sex determination;CRISPR/Cas9 system;SIT