Natural Pesticides in Crop Protection: Comparative Advantages, Ecological Risks, and Future Directions

Although synthetic pesticides have long been used to protect crops, their widespread use has led to significant health and environmental problems, including ecological contamination, resistant pest populations, and hazardous residues in food. These restrictions have sparked interest in natural pesticides (NPs), particularly the secondary metabolites of plants, which can offer less persistent and biodegradable alternatives. However, each compound must be assessed for bioactivity, selectivity, and ecological impact; natural origin does not guarantee environmental safety or pesticidal appropriateness. This review highlights the pesticidal potential of five major classes of natural products: alkaloids, flavonoids, terpenoids, steroids, and phenolic compounds. Alkaloids such as berberine and matrine exhibit strong antifungal and insecticidal activities, while flavonoids such as quercetin derivatives suppress bacterial pathogens, including Xanthomonas spp. Terpenoids such as thymol inhibit fungal pathogens, including Rhizoctonia solani and Fusarium oxysporum , and phenolics such as resveratrol contribute to resistance against Botrytis cinerea . Natural steroids provide additional antifungal and insecticidal efficacy. All these cases show that NPs are interesting instruments for sustainably protecting crops, although there are still issues with formulation optimization, toxicity assessment, and economic viability. To close these gaps and make it possible to include natural insecticides in standard agricultural practices, more studies are necessary.