Evaluation of olfactory plasticity in laboratory populations of Spodoptera frugiperda based on odorant receptors

The fall armyworm Spodoptera frugiperda is a globally significant migratory agricultural pest, whose key behaviors such as host location and mating reproduction are highly dependent on the olfactory system, with odorant receptors (ORs) serving as key molecules in the olfactory signaling pathway. This study aimed to investigate the olfactory plasticity reflected by the transcriptional and expression profiles of OR genes in a laboratory-reared S. frugiperda population.

Using an integrated approach combining bioinformatics and molecular experiments, we systematically annotated the OR gene family and evaluated olfactory plasticity across different sexes and tissues. Four expressed OR genes (SfruOR13, SfruOR19, SfruORco, and SfruOR42) were selected, cloned, and their expression patterns in antennae, proboscis, and labial palps of male and female adults were examined using qRT-PCR.

A total of 48 full-length OR genes were identified from genomic data, and their phylogenetic relationships, motif compositions, domain architectures, and gene structures were analyzed to infer their evolutionary divergence and functional conservation. qRT-PCR revealed significant differences in the expression of the four OR genes between sexes, with generally higher expression levels in females.

These findings demonstrate notable sexual dimorphism and olfactory plasticity at the odorant receptor level in the laboratory population. This study not only enhances the understanding of olfactory molecular mechanisms in S. frugiperda under laboratory conditions but also provides potential targets and a theoretical foundation for developing OR-based green control strategies, such as the design of effective attractants and repellents.