Ant management with cover crops in Citrus agroecosystems

Abstract: Up to 40 % of global agricultural harvests are lost to pests, representing more than € 240 billion in annual damage. Reducing reliance on chemical control remains a major challenge for sustainable agriculture, especially in perennial systems such as Citrus. Landscape management strategies that incorporate semi-natural vegetation and diversified ground covers are increasingly recognized as key drivers of functional biodiversity and natural pest regulation. Ants are among the most abundant arthropods in Mediterranean agroecosystems and play a central role in pest management. While they provide valuable ecosystem services such as pest predation, they can also disrupt biological control by tending honeydew-producing hemipterans. Understanding how habitat diversification practices shape ant communities and ant-mediated processes is therefore crucial for designing effective biodiversity-based pest management at field and landscape scales. In this study, we assessed how two cover-crop types, implemented in Citrus orchard alleyways, influence ant communities and ant-driven ecosystem services. We compared a standard grass cover (Poaceae) with a diverse mix of seven wildflower species differing in phenology, a design intended to enhance resource continuity across the season. We evaluated effects on: i) ant community composition; ii) ant activity in the tree canopy; iii) ant – hemipteran mutualisms; and iv) ant-driven predation of pest pupae. Trees embedded within the floral-mix cover crop supported higher ant activity, stronger tending behavior toward hemipteran pests, and higher predation rates compared to the grass-covered plots. These results indicate that local ground-cover diversification can influence ant-mediated interactions with both pests and natural enemies. Our findings highlight that strategic design of herbaceous vegetation within managed landscapes can modulate arthropod functional groups and their contribution to ecosystem services. Integrating functionally diverse cover crops into orchard landscapes may represent a promising pathway to enhance functional biodiversity and promote more resilient pest control in Mediterranean perennial crops.