Predation by nematode-trapping fungus triggers mechanosensory-dependent quiescence in C. elegans

Abstract

Predation can induce behavioral changes in prey, yet the molecular and neuronal mechanisms underlying prey responses remain poorly understood. Here, we investigated how the nematode Caenorhabditis elegans responds to predation by the nematode-trapping fungus, Arthrobotrys oligospora. We found that A. oligospora predation induced quiescence in C. elegans showing rapid cessation of pharyngeal pumping and movement. Calcium imaging revealed that this quiescence was regulated by the activation of sleep-promoting neurons, ALA and RIS. Genetic analyses demonstrated that ALA were essential for pharyngeal pumping inhibition, whereas both ALA and RIS contributed to movement cessation. Transcriptomic analysis in C. elegans showed the upregulation of immune defense genes in response to A. oligospora predation. We demonstrated that mechanosensation was required for pumping inhibition and transcriptomic regulation upon A. oligospora trapping. These findings suggest that physical constraints imposed by fungal traps trigger a stress-induced quiescence and the upregulation of defense genes in C. elegans. We suggest that trapping-induced quiescence might be a predation strategy used by sessile predators to prevail in the evolutionary arms race.