Genetic control of a multifunctional trait: The central role of a fatty acid synthase gene in regulating survival and sexual communication

The genetic basis of multifunctional traits shaped by both natural and sexual selection remains poorly understood. In insects, cuticular hydrocarbons (CHCs) are an excellent example of such traits, providing protection against different micro-climatic conditions while simultaneously encoding cues predominantly used in sexual signaling. The fatty acid synthase (fas) gene family has been implied as an important cornerstone in initiating and maintaining CHC functionality, whereas their exact biosynthetic and regulatory mechanisms have remained largely elusive. Here, we characterize a single fatty acid synthase gene (fas3) impacting the main CHC functions in the parasitoid wasp Nasonia vitripennis. Knockdown of fas3 significantly decreases wasp survival under desiccation stress while also completely depleting sexual attractiveness of female wasps, where this trait naturally functions as sex pheromone. Further transcriptomic analyses reveal that fas3 is co-expressed with other fas and CHC-associated genes, as well as key biosynthetic pathway hubs. We also identify striking sex-specific expression differences in fas3 across different developmental stages, suggesting divergent functional roles of this gene in males and females. These findings largely advance our knowledge on the multifunctionality of fas genes in governing survival and sexual signaling mechanisms and underscore their relevance for future studies on metabolomics, adaptation, and sexual communication.