The role of carbon dioxide in nematode behaviour and physiology

Carbon dioxide (CO(2)) is an important sensory cue for many animals, including both parasitic and free-living nematodes. Many nematodes show context-dependent, experience-dependent and/or life-stage-dependent behavioural responses to CO(2), suggesting that CO(2) plays crucial roles throughout the nematode life cycle in multiple ethological contexts. Nematodes also show a wide range of physiological responses to CO(2). Here, we review the diverse responses of parasitic and free-living nematodes to CO(2). We also discuss the molecular, cellular and neural circuit mechanisms that mediate CO(2) detection in nematodes, and that drive context-dependent and experience-dependent responses of nematodes to CO(2).