Facilitative Interactions among Extrafloral Nectary-bearing Plants, Ants, and Neighboring Vegetation in the Brazilian Cerrado

Herbivory is a key plant–insect interaction that can have a negative impact on plant development. Some plants have evolved indirect defenses by attracting protective ants through extrafloral nectaries (EFNs). These mutualistic ants may extend their protective behavior to neighboring plants, generating facilitative interactions. This study investigated whether two Malpighiaceae species − one with EFNs (Peixotoa tomentosa) and one without (Byrsonima intermedia − benefit from proximity to EFN-bearing neighbors. We assessed herbivory, leaf loss, growth rate, and the number of young leaves in focal plants near EFN and non-EFN neighbors. B. intermedia produced more young leaves when close to EFN-bearing plants but fewer when near non-EFN plants; similarly, P. tomentosa experienced greater leaf loss when in proximity to non-EFN plants. Specifically, in B. intermedia, increasing the distance to EFN plants from 1 to 2 meters led to a reduction of approximately 1.57 young leaves (-27.2%), whereas increasing the distance to non-EFN plants resulted in a gain of 3.47 young leaves (+83.5%). In P. tomentosa, the same increase in distance to non-EFN neighbors reduced leaf loss by 4.84 leaves (-64.5%). These results highlight the ecological importance of neighboring plant identity at realistic spatial scales. Prior research suggests that EFN-bearing plants may promote anthill formation and enhance soil quality, potentially explaining the observed facilitation. Our findings underscore the role of ant-mediated facilitative interactions in shaping plant community dynamics and guiding ecosystem management.