Plant-associated CO(2) mediates long-distance host location and foraging behaviour of a root herbivore

Insect herbivores use different cues to locate host plants. The importance of CO(2) in this context is not well understood. We manipulated CO(2) perception in western corn rootworm (WCR) larvae through RNAi and studied how CO(2) perception impacts their interaction with their host plant. The expression of a carbon dioxide receptor, DvvGr2, is specifically required for dose-dependent larval responses to CO(2). Silencing CO(2) perception or scrubbing plant-associated CO(2) has no effect on the ability of WCR larvae to locate host plants at short distances (<9 cm), but impairs host location at greater distances. WCR larvae preferentially orient and prefer plants that grow in well-fertilized soils compared to plants that grow in nutrient-poor soils, a behaviour that has direct consequences for larval growth and depends on the ability of the larvae to perceive root-emitted CO(2). This study unravels how CO(2) can mediate plant–herbivore interactions by serving as a distance-dependent host location cue.