Forest proximity and uniderstory complexity shape predation pressure on dummy caterpillars in rubber plantations

Abstract

Agriculture is a cornerstone of Brazil’s economy, but it also places the country among the world’s top four pesticide consumers. Natural enemies of pests can help reduce reliance on agrochemicals, but their presence and effectiveness depend heavily on local habitat conditions and landscape structure. In southern Bahia, rubber tree plantations—a key regional crop—face persistent threats from insect pests, including Erinnys ello, one of the most damaging to rubber production. However, the role of landscape factors and management intensity in shaping natural pest control remains poorly understood. To address this gap, we conducted predation pressure experiments in one of Bahia’s major rubber-producing regions. We investigated whether different management practices in rubber plantations influence how forest cover and proximity affect predation pressure on dummy caterpillars by natural enemies. Our findings reveal that responses varied across predator groups. Predation pressure from arthropods was sensitive to understory management, likely because of the increased habitat complexity it provides. Mammalian and overall community predation were influenced by forest distance at different scales: community-wide predation increased at 2500 m, suggesting generalist predators may benefit from less forested areas, while mammalian predation decreased at 500 m, indicating that nearby forest remnants are crucial refuges for vertebrate predators. Interestingly, overall forest cover showed no effect, implying that habitat amount alone is insufficient to explain the observed responses. Therefore, maintaining a complex understory and preserving nearby forest areas are vital strategies for enhancing natural pest control in rubber plantations.