--- - |2- Abstract Sterol regulatory element‐binding protein‐1c (SREBP‐1c) is a basic helix‐loop‐helix type transcription factor that regulates the fatty acid and cholesterol biosynthesis. Lepidoptera sex pheromone is a product of fatty acid biosynthesis followed by carbon chain modifications. However, the role of SREBP‐1c on sex pheromone biosynthesis remains elusive. In the present study, Helicoverpa armigera was used as a model to investigate the role of SREBP‐1c on sex pheromone biosynthesis (HaSREBP‐1c). Sequence analysis demonstrated that the open reading frame of HaSREBP‐1c consists of 3201 bp nucleotides that encode 1066 amino acid residues. Blast searches based on amino acid sequences demonstrated that HaSREBP‐1c shares higher amino acid identity with lepidopteran homologues. Development expression profiles demonstrated that HaSREBP‐1c transcript could be detected at 72 hr before adult emergence, then gradually increased, and finally reached its peak at 24 hr after adult emergence. The spatial expression pattern demonstrated that HaSREBP‐1c was ubiquitously expressed in all examined tissues. The decrease of HaSREBP‐1c messenger RNA (mRNA) levels as shown by RNA interference caused significant decreases in acetyl‐coA carboxylase (ACC) mRNA levels and subsequent sex pheromone production. Behavior analysis demonstrated that the decrease of HaSREBP‐1c mRNA level caused a significant decrease in the female’s ability to attract males. Altogether our results demonstrated that HaSREBP‐1c acts as a transcription factor to regulate ACC mRNA expression and, therefore, to influence female sex pheromone biosynthesis. - Archives of Insect Biochemistry and Physiology, EarlyView.