Identification of six species of lepidopteran adults by using cuticular hydrocarbons

Chemotaxonomy based on cuticular hydrocarbons (CHCs) serves as a critical supplementary tool for insect taxonomic identification. The composition and relative abundance of CHCs in male and female adults of six common lepidopteran species, including Spodoptera frugiperda (J.E.Smith), S. litura (Fabricius), S. exigua (Hübner), Mythimna separata (Walker), Helicoverpa armigera (Hübner), and Ostrinia furnacalis (Guenée), were analyzed by Thermal Separation Probe (TSP) and Gas Chromatography-Mass Spectrometry (GC-MS). Principal component analysis (PCA), discriminant analysis (DA), and cluster analysis (CA) were applied to the CHC profiles. The results revealed that a total of 79 distinct CHCs were detected across the six lepidopteran species, including 11 n-alkanes, 42 monomethyl alkanes, 17 dimethyl alkanes, and 9 unidentified hydrocarbons. Discriminant analysis accurately distinguished all six lepidopteran species and highlighted significant sexual dimorphism in their CHC profiles. Cluster analysis results showed agreement with morphological and molecular phylogenetic relationships at the subfamily level, but exhibited incomplete consistency in interspecific clustering relationships below their taxonomic level. These findings demonstrate that CHC composition provides a robust method for species-specific identification of lepidopteran adults, particularly for damaged specimens, with potential applications in pest monitoring and forecasting, as well as rapid quarantine screening of invasive alien species at ports.