Contrasting Ecological Strategies, Herbicide Resistance, and Management of Eleusine indica and Digitaria insularis in Tropical Agroecosystems: An Integrative Review

Understanding the contrasting ecological strategies, resistance mechanisms, and management challenges associated with major tropical grass weeds is essential for the sustainability of agricultural systems. This integrative review combines a structured scientometric analysis of the Web of Science Core Collection (403 unique publications: 316 on Eleusine indica, 100 on Digitaria insularis) with a narrative synthesis of their botanical, ecological, physiological, and management dimensions. Research on E. indica is older and broader, progressing from classical weed science and turfgrass studies toward a strongly developed molecular resistance literature, whereas research on D. insularis expanded more recently and has a smaller molecular-scale component. The two species differ fundamentally in persistence strategy: E. indica is annual and seed-driven, relying on rapid tillering and prolific seed production, whereas D. insularis is perennial, combining seed recruitment with rhizome-mediated regeneration and clump formation. Herbicide-resistance evidence is likewise unevenly resolved, with target-site mechanisms more extensively documented in E. indica than in D. insularis, where population heterogeneity and candidate non-target-site pathways remain less understood. Physiology and ecophysiology emerge as a persistently underrepresented research axis for both species. These contrasting biological trajectories require species-specific Integrated Weed Management, combining prevention, cultural and mechanical tactics, locally validated herbicide programs, and monitoring, rather than a single universal control strategy. This synthesis provides an evidence-based framework linking ecological strategy, resistance biology, and sustainable management for two of the most relevant tropical grass weeds in world agriculture.