Leafcutter bees and their leaf resources: ecology, behavior, and conservation

As insect pollinators continue to decline across much of the world, understanding the factors that support them in the wild has become increasingly critical. Leafcutter bees, which are widespread and represent the first successfully managed solitary bees, require detailed knowledge of their nutrient sources, nesting materials, and nesting opportunities for effective conservation. While 'bee hotels' have been developed to provide nesting sites and nutrient resources are relatively well understood, our knowledge of the leaf sources that underpin nesting remains limited. Recent studies - though largely concentrated in North America and India - offer valuable insights into the plant species used by leafcutter bees and the ecological and biological factors influencing leaf selection. These emerging findings may prove transformative, illuminating the chemical, molecular, microbial, and biochemical mechanisms that shape leaf-foraging decisions. Such knowledge could also inform agricultural practices, enabling farmers to enhance habitats by provisioning suitable leaf sources. In this review, we examine the drivers of nesting and leaf-foraging behavior, the diversity of leaf resources, and patterns of brood mortality. We highlight research priorities that should be pursued in an integrative manner to advance the management and conservation of leafcutter bees, with particular emphasis on deepening our understanding of their sensory ecology.