Younes Rezaee Danesh, José Mulet, Rosa Porcel
The increasing prevalence of pests and diseases in agriculture necessitates innovative strategies for crop protection that mitigate environmental impacts. This review paper investigates the synergistic potential of combining microbial biocontrol agents and phytochemical biopesticides as sustainable alternatives to chemical pesticides. Through a comprehensive review of recent literature, we analyze the mechanisms by which beneficial microbes (e.g., Trichoderma, Bacillus, and Pseudomonas) enhance plant resilience and suppress pathogens, and how plant-derived phytochemicals such as essential oils, alkaloids, and flavonoids contribute to pest deterrence and disease resistance. The integration of these bio-based resources forms an actionable framework for sustainable crop protection—enabling reduced chemical dependence, improved soil health, and enhanced biodiversity. Examples of synergistic success, such as the combined use of Bacillus thuringiensis with neem extract and Trichoderma with lemongrass oil, illustrate their field potential. Future research should prioritize the formulation of stable microbial–phytochemical consortia, field validation of synergistic efficacy, and optimization of delivery systems to support commercial-scale adoption. Ultimately, this study promotes a paradigm shift toward eco-efficient pest management, bridging fundamental research and applied innovation for resilient agroecosystems.