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 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.