Structural Defences in Plants against Herbivores- A Review

Plants have developed various defence mechanisms to protect themselves against herbivores, a topic that has fascinated researchers for decades. These mechanisms enable plants to thrive even in environments with intense herbivore pressure. The threats to plants are diverse, including insects, mammals, reptiles and microorganisms. Despite this, plants possess robust defence, both constitutive and inducible. Constitutive defences viz., physical and chemical barriers, exist before herbivore attacks, while inducible defence are activated upon attack. Direct plant defence includes anti-nutritional strategies and toxicity, limiting food supply or reducing nutrient value. Physical defences viz., waxes, trichomes, spines, and sclerophyllous leaves hinder herbivores physically, while chemical defence viz., toxic metabolites, disrupt herbivore physiology. Indirect defence involves attracting natural enemies of herbivores. Understanding these complex interactions is crucial for optimizing crop protection strategies. Future research should adopt a holistic approach, integrating environmental factors and utilizing advanced biological methodologies to further elucidate plant-herbivore dynamics.