Inducible Defenses in Herbivore-plant Interactions: Functions Mechanisms and Manipulations

In the ecological context of insect-plant interactions, the interdependence of each other is important for their survival in complex ecosystem. Insect herbivores locate suitable host plants that can provide better resources for food and reproduction. In nocturnal herbivores, especially Lepidopterans, olfaction plays a major role during the selection of suitable host plants. Generally, Lepidopteran herbivores orient towards host plants using sensory cues such as volatile chemicals. Search for a host plant suitable for feeding, mating and oviposition is pertinent to the females while males are more conscious in mate and food findings. In addition, the chances of encountership between males and females increase in the presence of healthy host plants. Female moths prefer to lay eggs on healthy plants in order to provide better food resources for their offsprings. On the other hand, plants defend themselves from herbivore feeding by producing chemical volatiles as well as non-volatiles. The specific blend of volatile compounds in response to feeding damage by herbivores is commonly called as herbivore-induced plant volatiles (HIPVs). HIPVs are ecologically important because the plant species that release these compounds can improve their performance against attacking herbivores by several means e.g., by attracting the natural enemies of the herbivores or by repelling herbivores at a distance. Here, I review induced defenses in plants based on their classification along with perception and signaling in response to herbivory. In addition, the ecological significance of HIPVs at different levels will be described. Furthermore, I will highlight the ease of screening HIPVs on olfactory basis, by using different approaches within the laboratory, for their future implications in plant protection program.