A review on silicon: the hidden defender of fruit crops against insect pests

Silicon (Si) has emerged as an important beneficial element in horticultural production, particularly in fruit crops, where it enhances tolerance against multiple biotic and abiotic stresses. This review is focused on the multifunctional role of Si in improving fruit crop performance. The application of Si has been found to reduce insect pest infestations through mechanical barriers formed by Si deposition and biochemical defense pathways. In addition, Si enhances photosynthesis rate, nutrient uptake, water-use efficiency, and structural integrity of plant tissues, thereby improving fruit yield and quality. Silicon promotes growth and development, resulting in stronger root systems and erect leaves, and improves resource utilization. The mechanisms of Si-mediated resistance were analyzed in depth, including physical protection, induced defense responses, antioxidant activity, and modulation of plant hormones. The review also shows the positive effects of Si on natural enemies of insect pests, its synergistic effects with fertilizers and pesticides, and its role in shaping tritrophic relationships among plants, herbivores, and natural enemies. Overall, Si is a promising eco-friendly input for sustainable fruit crop production.