Plant-associated CO₂ mediates long-distance host location and foraging behaviour of a root herbivore

Insect herbivores use different cues to locate host plants. The importance of CO₂ in this context is not well understood. We manipulated CO₂ perception in western corn rootworm (WCR) larvae through RNAi and studied how CO₂ 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 CO₂. Silencing CO₂ perception or scrubbing plant-associated CO₂ 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 CO₂. This study unravels how CO₂ can mediate plant-herbivore interactions by serving as a distance-dependent host location cue.