Local canopy cover, shade tree identity and landscape tree cover shape leaf‐cutter ant nest density and herbivory in cacao agroforestry systems

Crop herbivory by arthropods poses a major threat to food production, particularly in tropical regions. Leaf‐cutter ants are key herbivores in the Neotropics and can threaten major crops like cacao. High tree diversity in agroforestry systems can mitigate their impact. As ecosystem engineers, leaf‐cutter ants modify soil conditions through nest construction and the accumulation of organic matter. It is essential to understand the trade‐offs between services and disservices generated by leaf‐cutter ants in agroforestry and to identify biodiversity‐friendly strategies to manage the damage they cause. We assessed leaf‐cutter ant nest occurrence and herbivory on cacao trees in 13 cacao agroforests in the northern Peruvian Amazon in relation to local canopy structure and landscape tree cover. Specifically, we evaluated whether potential soil fertility benefits could offset herbivory damage and conducted a leaf‐preference experiment to identify alternative resource trees within these agroforests. Our results show that agroforests with higher canopy cover host more leaf‐cutter ant nests. However, herbivory in cacao agroforests is generally low and can be managed effectively. Herbivory concentrated on trees near the nest, reaching up to 89% of affected leaves, but dropped below 10% at a 15 m distance. Agroforests with higher landscape tree cover (~80%) showed reduced herbivory rates, underscoring the importance of conserving and enhancing landscape tree cover. Moreover, the leaf‐preference experiment showed that common agroforest trees, like papaya or orange, are preferred by leaf‐cutter ants over cacao. This suggests that intercropping these alternative trees can help dilute herbivory pressure on cacao while providing additional food and income for farmers. Finally, soil nutrient concentrations near the nests were unexpectedly low, suggesting that soil enrichment from ant nests occurs at greater soil depths and highlighting the need for vertical soil profiling. Synthesis and applications . Our findings provide practical guidance for agroforestry management by demonstrating that intercropping with selected species can mitigate damage from leaf‐cutter ants in cacao agroforests. At the landscape scale, high tree cover was associated with low herbivory rates, emphasising the need to maintain or restore forested habitats. Integrating local and landscape management can support more resilient and productive cacao agroforestry systems.