Cyclohexyl acetate functions like a volatile sex pheromone mimic in Caenorhabditis nematodes

Abstract

Nematodes communicate via diverse sex pheromones, including long-range volatile signals, short-range chemical cues, and contact-dependent molecules. While the ascaroside family of small molecules that mediate short-range attraction is well characterized, the identities and roles of volatile sex pheromones (VSPs) that act over longer ranges remain unknown. Using GC-MS analysis of crude VSP extracts, we identified cyclohexyl acetate (CA) as a candidate mimic, sharing retention time and mass spectral features with natural VSPs. Behavioral assays demonstrated that CA acts as a concentration-dependent, male-specific attractant in Caenorhabditis. Pre-exposure to VSPs induced cross-adaptation to CA, suggesting shared sensory processing. Surprisingly, genetic and calcium imaging analyses revealed that CA perception is mediated primarily by AWCon (str-2-expressing) neurons and involves VSPs chemoreceptor srd-1-independent pathways, which are distinct from the neural pathways involved in natural VSPs perception. These findings establish that CA is not a major component of VSPs but a structural and functional mimic of nematode VSPs, operating through a parallel sensory circuit. Although the endogenous source of CA remains unknown, its structural and behavioral mimicry provides new insights into the complexity of chemosensory signaling and the potential for interspecies chemical eavesdropping in nematode ecology.