Mitochondrial genome evolution in Noctuidae: codon usage bias, nucleotide composition, and phylogenetic relationships among major agricultural pests

The family Noctuidae includes agricultural pests that vary in geographic distribution and host range. This study analyzed 30 mitogenomes representing 14 noctuid species; Ostrinia nubilalis (Crambidae) served as the phylogenetic outgroup. The genomes contained the typical complement of 37 mitochondrial genes and exhibited conserved gene order, pronounced A + T enrichment, and a preference for A/T-ending synonymous codons. A neutrality regression based on species means revealed a modest positive association between GC3 and GC12 (R2 = 0.3201; p = 0.03494), although it could not distinguish the respective contributions of mutation and selection. Maximum-likelihood and Bayesian analyses of 13 protein-coding genes (11,229 bp) agreed on 26 of the 28 internal groupings in the maximum-likelihood tree, including a strongly supported Spodoptera clade. Differences in deeper relationships occurred at nodes with limited support. All 13 genes had dN/dS estimates below one (0.00306–0.01691), consistent with purifying selection. Codon usage varied among gene categories, and gene-wise codon bias was not significantly associated with dN/dS. Five crop-associated species with multiple larval host plants and documented long-distance migration—Helicoverpa armigera, Athetis lepigone, Spodoptera litura, S. frugiperda, and Mamestra brassicae—fell below the fitted neutrality regression line. Whether their ecological traits relate to this pattern remains requires broader taxonomic sampling and ecological data in future investigations.