Biocontrol Reimagined: Microbial Allies for Resilient and Sustainable Crop Protection

Microbial biocontrol is being reimagined from the application of single antagonists toward the deliberate management of plant-associated microbiomes as adaptive, multi-functional “living infrastructure” for crop protection. This shift is driven by persistent yield losses to pathogens, erosion of pesticide efficacy through resistance, heightened regulatory and market pressure to reduce chemical inputs, and climate volatility that destabilises plant health and disease dynamics. This review synthesises contemporary understanding of microbial mechanisms that directly inhibit pathogens and indirectly fortify plant defences, while emphasising why reliability in the field depends on formulation, delivery, colonisation traits, and compatibility with resident microbiota and agronomic practices. Literature was identified using Web of Science, Scopus, PubMed, and Google Scholar, covering January 2000-December 2025, with searches combining terms like "biological control", "biocontrol", "microbial biopesticide", and other relevant keywords. Peer-reviewed articles and reviews with mechanistic insight, in planta validation, or translational relevance were prioritized, excluding non-peer-reviewed sources and studies lacking plant validation or methodological detail. Over the last two decades, research has clarified that successful biocontrol is rarely a simple one-microbe–one-pathogen interaction; instead, it emerges from ecological processes such as priority effects, niche pre-emption, metabolite-mediated interference, immune priming, and community-level buffering that collectively suppress disease and stabilise host performance. The study highlights suppressive soils as natural blueprints for resilient protection, discusses design principles for synthetic communities and microbiome engineering, and examines bacteriophages as precision tools that can be integrated into broader plant protection strategies. Finally, the review outlined emerging directions—multi-omics-guided strain selection, genome-informed metabolite discovery, and predictive community assembly—that can enable robust, sustainable crop protection without relying on chemical-intensive paradigms.