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International audience; Plant-herbivore interactions mediated by plant-plant signalling have been documented in different species but its within-species variability has hardly been quantified. Here, we tested if herbivore foraging activity on plants was influenced by a prior contact with a damaged plant and if the effect of such plant-plant signalling was variable across 113 natural genotypes of Arabidopsis thaliana. We filmed the activity of the generalist herbivore Cornu aspersum during 1 h on two plants differing only in a prior contact with a damaged plant or not. We recorded each snails' first choice, and measured its first duration on a plant, the proportion of time spent on both plants and leaf consumption. Overall, plant-plant signalling modified the foraging activity of herbivores in A. thaliana. On average, snails spent more time and consumed more of plants that experienced a prior contact with a damaged plant. However, the effects of plant-plant signalling on snail behaviour was variable: depending on genotype identity, plant-plant signalling made undamaged plants more repellant or attractive to snails. Genome-wide associations revealed that genes related to stress coping ability and jasmonate pathway were associated to this variation. Together, our findings highlight the adaptive significance of plant-plant signalling for plant-herbivore interactions.

Plant-herbivore interactions mediated by plant-plant signaling were documented in different species. Here, we tested if herbivore foraging activity on plants was influenced by plant’s prior contact with a damaged plant and if the effect of such plant-plant signaling was variable across genotypes.We filmed snails during one hour on two plants differing only in a prior contact with a damaged plant or not. We replicated eight times the experiment on 113 natural genotypes of Arabidopsis thaliana. We recorded snails’ first choice, and measured its first duration on a plant, the proportion of time spent on both plants and leaf consumption.On average, snails spent more time on plants that experienced a prior contact with a damaged plant, and consumed them more. However, plant-plant signaling effect on snail behavior was variable across genotypes. Genome-wide association studies revealed that a small number of genetic polymorphisms related to stress coping ability and jasmonate pathway explained this variation.Plant-plant signaling modified the foraging activity of herbivores in A. thaliana. Depending on the plant genotype, plant-plant signaling made undamaged plants more repulsive or attractive to snails. This finding questions the theoretical basement of the evolution of plant-herbivore interactions mediated by plant-plant signaling.HighlightPlant-plant signaling differently affects snail foraging activity depending on genetic variations in A.thaliana. These findings question the theoretical basement of the evolution of plant-herbivore interactions mediated by plant-plant signaling.