A male-derived volatile sex pheromone in Caenorhabditis nematodes identified through its mimicry by a predator

Recent studies demonstrated that the predacious fungi Arthrobotrys oligospora emits a mixture of volatile chemical cues that function to attract nematode prey. The strong attraction elicited by one of the mixture components, methyl 3-methyl-2-butenoate (MMB), was highly female- and hermaphrodite-specific within several Caenorhabditis species, including C. remanei and C. elegans, suggesting that MMB might function as a mimic of an endogenous, male-produced, volatile sex pheromone (VSP) within these species. Here, we report evidence that MMB is produced by C. remanei males at levels that are attractive to C. remanei females and C. elegans hermaphrodites. Notably, MMB production was not detected for C. elegans males; a finding which correlates with behavioral assays for which worm-conditioned media (WCM) prepared from C. remanei, but not from C. elegans adult males is strongly attractive to both C. remanei females and C. elegans hermaphrodites. Our findings establish MMB as the first chemically identified VSP in nematodes and show that A. oligospora exploits a dual strategy of chemical deception-mimicry and eavesdropping-to enhance prey capture.