The modified fall armyworm contains two gene cassettes: a synthetic Discosoma sp. DsRed2 selectable marker and self-limiting, synthetic tetracycline-controlled transactivator (tTAV).

The Dsred2 coding sequence is under control of an Autographa californica multiple nucleopolyhedrovirus (AcMNPV) immediate-early 1 promoter and a Macaca mulatta polyomavirus 1 SV40 terminator. An AcMNPV homologous region 5 enhancer was also included to promote high levels of transcription. At the 5' end of the transcript, a Drosophila melanogaster scraps intron has also been included to further enhance the transcription of DsRed2. Additionally,  nuclear localization signals (N- and C- terminal peptides) have been included at both the 5' and 3' ends surrounding the DsRed2 coding sequence to direct the the protein to the nucleus after translation. The accumulation in the nucleus improves visualization of the red fluorescence.

The tTAV sequence is under control of a D. melanogaster heat shock protein 70 minimal promoter, AcMNPV P10 terminator and synthetic tetracycline operator. Initially after transcription, the pre-mRNA contains the following genetic elements (from 5' to 3'): Spodotera frugiperda doublesex (dsx) splicing module, D. melanogaster ubiquitin and finally tTAV. Next, the pre-mRNA undergoes sex-specific alternative splicing wihtin the dsx module to produce the mature mRNA. In females, two isofroms are produced either containing exons 2, 3, 4, 5 or exons 2, 3, 3a, 4 and 5 from dsx (in addition to ubiquitin and tTAV sequences downstream). Post-translation, ubiquitin stimulates the cleavage of tTAV from DSX-Ubiquitin from the N-terminal end. In males, alternative splicing produces a mature mRNA with exons 2 and 5 from the dsx splicing module. In addition, the splicing causes a frameshift, which aligns the reading frame with a stop codon in exon 5 and causes the start codon of tTAV to be out of frame. Thus, male transcripts are likely degraded by nonsense-mediated decay (no proteins are produced).

It is important to note that transcriptional expression of tTAV is also influenced by the presence of tetracycline. Adjacent to the tTAV cassette is a tetracycline operator, which acts as a repressible switch. In the presence of tetracycline, tTAV preferentially binds tetracycline rather than the operator sequences. Thus, transcription remains repressed, only occurring at a basal level. In the absence of tetracycline, tTAV binds the operator sequences and stimulates transcription (positive feedback loop), resulting in elevated levels of the tTAV mRNA and subsequently protein.

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