The Role of Herbivore-Induced Plant Volatiles in Tri-trophic Interactions and Pest Management

In agricultural ecosystems, the tri trophic interactions between plants, herbivores and their natural enemies are crucial for maintaining ecological balance and crop health. Natural enemies of pests predominantly regulate herbivore populations, emphasizing the importance of these interactions. Plants exhibit both induced and constitutive defences, Plants use herbivore-induced plant volatiles (HIPVs) as a key mechanism to attract natural enemies that defend them against the herbivores. HIPVs are chemical signals emitted in response to herbivore damage and can attract predators and parasitoids, indirectly they protect the plants. This review explores the role of HIPVs in plant defense, focusing on their evolutionary, chemical and practical aspects. with HIPVs acting as indirect defenses by recruiting natural enemies. The interaction between physical traits, chemical signals and semiochemicals, including volatile organic compounds (VOCs), significantly influences these interactions. Olfactometers, such as the Y-tube and four-arm designs, have been proven to be pivotal in studying insect responses to these volatile compounds, providing insights into their behavior and effectiveness in pest management. Despite advances in understanding HIPVs, research indicates variability in volatile emissions and their effectiveness across different herbivore species and developmental stages. Further studies are needed to improve the specificity of HIPV research, incorporating field-based analyses to capture natural environmental complexities. Future research should focus on optimizing HIPV applications in pest management, understanding spatial and temporal scales of HIPV interactions, and addressing the influence of environmental factors on HIPV efficacy.