Knockout of the SfVipR1 gene confers high-level resistance to Bacillus thuringiensis Vip3Aa toxin in Spodoptera frugiperda.

Background: Bacillus thuringiensis (Bt) insecticidal proteins, including crystalline (Cry) proteins and vegetative insecticidal proteins (Vips), are extensively used in transgenic crops due to their efficacy, low environmental impact, and safety. The fall armyworm, Spodoptera frugiperda, has evolved practical resistance to Cry1Fa, yet no practical resistance to Vip3Aa has been documented. However, both laboratory selection and field screen studies indicate a high potential for this pest to evolve resistance to Vip3Aa, making it crucial to evaluate potential resistance genes. HaVipR1 has recently been identified as a key determinant of Vip3Aa resistance in the cotton bollworm, Helicoverpa armigera. This study investigated whether the HaVipR1-homologous gene in S. frugiperda (SfVipR1) is similarly involved in Vip3Aa resistance.

Results: We employed CRISPR/Cas9 technology to generate a homozygous knockout strain of SfVipR1. In comparison with the parent susceptible YJ-19 strain, the knockout strain (Sfru-KO) exhibited high-level resistance to Vip3Aa (>1850-fold) but showed no cross resistance to Cry1Fa. Resistance to Vip3Aa in Sfru-KO is autosomal, recessive, and genetically linked with SfVipR1.

Conclusion: Disruption of SfVipR1 results in high-level resistance to Vip3Aa, highlighting SfVipR1 has a critical role in Vip3Aa toxicity in S. frugiperda, despite the exact mechanism remaining unclear. Early detection of SfVipR1 mutant alleles in the field is essential for developing adaptive resistance management strategies against S. frugiperda. © 2025 Society of Chemical Industry.