## 3 Agricultural biotic Stresses: Pests and Pathogens  
Living organisms including viruses, bacteria, fungi, protists, nematodes, insects and parasitic plants, cause plant damage through their biological interactions. These pathogens and pests can affect any stage of a plant's life cycle including seedling emergence, plant maturation, or grain and fruit development [30]. Biotic stress agents extract nutrients directly from their host, thereby reducing plant vigor and, in serious instances, causing host death. As a result of co-evolution with crops, pests and pathogens (P&P) are integral components of agricultural systems. Cultivated plants tend to exhibit genetic uniformity, which facilitates the rapid proliferation of highly adapted P&P species, as they share similar phenological and physiological characteristics [31].  
Currently, it is estimated that global yield losses due to pests and diseases average at 21.5% for wheat, 30% for rice, 22.5% for maize, 17.2% for potato, and 21.4% for soybean. Overall, they account for 20-40% of total crop yield losses worldwide [31]. According to other researchers, arthropod pests alone are responsible for the destruction of 18-20% of the world's annual crop production, amounting to losses valued at over USD 470 billion [32]. P&P are widely recognized as major threats to stable and resilient food systems [33].  
Agricultural P&P species pose a significant threat to global food security, causing substantial economic and yield losses [34]. Fungal pathogens from the genus _Fusarium_ exemplify this challenge, with species such as _Fusarium graminearum_ and _Fusarium oxysporum_ ranked among the ten most significant plant pathogenic fungi [35]. Notably, _F. graminearum_ is widely regarded as the primary agent of Fusarium head blight (FHB), with estimates from natural epidemics, fungicide trials, and controlled inoculation studies indicating yield losses in small grain cereals of up to 74% [36].  
Similarly, the fall armyworm (_Spodoptera frugiperda_ [PERSON]) is a major pest in the maize-growing regions of tropical and subtropical Africa, where it is responsible for yield losses of up to 6.25% [31]. In Sub-Saharan Africa, it is estimated to cause annual maize, rice, sorghum, and sugarcane losses of USD 2.5-6.3 billion, with some estimates going up to USD 13 billion [37].  
In response to this scenario, numerous chemical and biological strategies are being developed to improve plant responses to biotic stresses. Silver and copper NPs have demonstrated potent antimicrobial activity, serving as effective nanospesticides against a wide range of phytopathogens, including _Alternaria alternata_, _F. oxysporum_, and _Sclerotinia scleroorum_[38]. Silicon is an emerging strategy against pests and diseases, as it accumulates in plant tissues [39], forming protective layers beneath the cuticle and reinforcing cell walls to hinder pathogen invasion [40]. Additionally, silicon enhances plant defense mechanisms by stimulating key enzymes (e.g., peroxidase or chitinase) and activating hormonal pathways (salicylic acid, jasmonate, and ethylene). It also limits pest feeding and reproduction by altering plant tissue composition, making it less digestible for herbivores [41]. As observed in abiotic stress management, biological approaches are gaining interest for their potential in pest and disease control. The use of endophytic microorganisms, AMF and PGPR has shown promising results, enhancing resistance against pests and diseases, as documented in various studies [30; 42]. Endophytic fungi, in particular, produce a wide range of bioactive metabolites with antifungal, antimicrobial, and insecticidal properties, reinforcing their potential for plant protection and sustainable agricultural practices [43].