Herbivore-induced plant volatiles

Abstract

In nature, plants are subjected to various abiotic and biotic stresses of which stress due to herbivore attack is of major concern. There are many direct and indirect mechanisms which operate within the plants to combat herbivores. The direct defence is generally of two types, i.e. physical and chemical. The physical defence includes the presence of morphological barriers such as trichomes, silica deposition and cell wall lignifications. The chemical methods involve the synthesis of many toxic compounds like terpenoids, alkaloids, phenols, etc. Indirect defence involves production of volatile compounds from the host plant which can attract natural enemies of herbivores. These compounds are known as herbivore-induced plant volatiles (HIPVs) and play an important role in communicating with the parasitoids to prey upon the attacking herbivores. HIPVs not only help the plants to attract with the natural enemies of herbivores but also warn the neighbouring plants from the upcoming danger. Thus, HIPVs provide a reliable mechanism for natural management of insect pests in plants. This chapter presents the herbivore-induced plant volatiles, types, biosyntheses, emission and their role in plant defence.