Mitochondrial codon usage bias and evolutionary constraints in noctuidae moths

Codon usage bias (CUB), evolved through mutation, natural selection, and genetic drift closely linked to protein expression, translational efficiency, and overall functional performance of the species. Analyzing codon patterns in genomes provides valuable insights into the evolutionary relationships between species, molecular evolution of genes and detect specific forces that drive their evolution. While some studies have examined codon usage in different insects, a systematic investigation towards the codon usage on the mitochondrial protein‑coding genes of the family Noctuidae (a diverse group of Lepidopteran pests) has not been reported yet. In this study, we explored the effects of mutation pressure and selective constraints on mitochondrial codon usage in the selected pest species belongs to the Noctuidae moths. Our results demonstrate that their mitochondrial genomes are strongly AT‑rich, with effective number of codons (ENC) values indicating a moderate level of bias. Further analyses suggest that mutation pressure and structural constraints significantly shape the evolution of the synonymous codons, with structural constraints emerging as the primary determinant of mitochondrial codon usage in the species of the Noctuidae moths. This work addresses a key question in mitochondrial molecular evolution and provides a foundation for future research on phylogenetic relationships and genome evolution in Lepidoptera.