Finnerty, Patrick B.Banks, Peter B.Shrader, A.M. (Adrian)McArthur, Clare2025-10-242025-10-242025-08Finnerty, P.B., Banks, P B., Shrader, A.M. & McArthur, C. (2025) Fine-scale associational effects: Single plant neighbours can alter susceptibility of focal plants to herbivores. PLoS One 20(8): e0330572. https://doi.org/10.1371/journal.pone.0330572.1932-6203 (online)10.1371/journal.pone.0330572http://hdl.handle.net/2263/104990DATA AVAILABILITY : The datasets generated during and/or analysed during the current study are available on figshare (https://doi.org/10.6084/m9.figshare.29525723).The neighbourhood of plants in a patch can shape vulnerability of focal plants to herbivores, known as an associational effect. Associational effects of plant neighbourhoods are widely recognised. But whether a single neighbouring plant can exert an associational effect is unknown. Here, we tested if single neighbours indeed do influence the likelihood that a focal plant is visited and eaten by a mammalian herbivore. We then tested whether any refuge effect is strengthened by having more neighbours in direct proximity to a focal plant. We used native plant species and a browser/mixed feeder mammalian herbivore (swamp wallabies (Wallabia bicolor)) free-ranging in natural vegetation. We found that a single neighbouring plant did elicit associational effects. Specifically, plant pairs consisting of one high-quality seedling next to a single low-quality plant were visited and browsed by wallabies later and less than pairs of two high-quality seedlings. Having more neighbours did not strengthen these associational effects. Compared with no neighbours, one or five low-quality neighbours had the same effect in delaying time taken for wallabies to first visit a plot and browse on a high-quality focal seedling. While traditionally a ‘patch’ refers to a broad sphere-of-influence neighbouring plants have on a focal plant, our findings suggest the influence of plant neighbours can range from the nearest individual neighbour to the entire plant neighbourhood. Such fine-scale associational effects are fundamentally important for understanding intricate plant-herbivore interactions, and ecologically important by potentially having knock-on effects on plant survival, in turn influencing plant community structure.en© 2025 Finnerty et al. This is an open access article distributed under the terms of the Creative Commons Attribution License.Focal plantsVulnerabilityHerbivoresAssociational effectArticle