Genome Editing of the Fall Armyworm: A Critical Appraisal of CRISPR/Cas9 Evidence on Gene Function, Resistance Mechanisms and Genetic Control Prospects

The fall armyworm, Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae), has moved within a decade from a hemispheric pest of maize (Zea mays L.) to a pest of near-global distribution, and its capacity to erode the efficacy of synthetic insecticides and transgenic Bacillus thuringiensis (Bt) crops has made functional genomics a practical rather than purely academic priority. Clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) editing has become the principal tool through which gene function is now established in this species, yet the resulting literature has expanded faster than its methodological foundations have been examined. This review evaluates the evidence generated by CRISPR/Cas9 and related editing platforms in S. frugiperda, covering platform development, Bt receptor identification, insecticide resistance genetics, reproductive and chemosensory targets for genetic control, and developmental gene function. Peer-reviewed literature was identified through structured searching of open scholarly databases and indexes, supplemented by citation tracking and verification of bibliographic records. The synthesis indicates that editing has delivered one robust and independently replicated conclusion, namely that the adenosine triphosphate-binding cassette transporter SfABCC2 is the principal functional receptor for Cry1F and Cry1Ab, and has simultaneously overturned several receptor assignments derived from in vitro work. Evidence on resistance to the vegetative insecticidal protein Vip3Aa is advancing rapidly but remains mechanistically unresolved, with at least three non-allelic loci implicated. Reproductive and pheromone-pathway knockouts have produced a substantial catalogue of sterility phenotypes, although almost none has progressed beyond laboratory cage experiments. Recurrent methodological weaknesses include reliance on a small number of laboratory strains, limited reporting of off-target assessment, scarce independent replication and an absence of fitness measurement under field-relevant conditions. Confidence in mechanistic conclusions is therefore considerably higher than confidence in their translational implications, and the priority now lies in replication across genetic backgrounds, quantitative phenotyping and realistic evaluation of candidate genetic control systems.