Table 2: Herbivore-induced plant volatiles emitted constitutively but in increasing concentrations after herbivore attack (quantitative changes) or only after herbivore attack (qualitative changes). Compounds from both categories can have very similar structures and share a biosynthetic pathway (see Table 1). This list is non-exclusive and inter-specific variation can be expected. It is mainly based on results on potato and tobacco (Solanum tuberosum and Nicotiana tabacum) reported by Dickens [148] and Robert et al. [46] as well as several review articles [16, 20, 147].

Compound class Constitutively emitted, increasing after herbivore attack Only emitted after herbivore attack Reference

Terpenoids
Hemiterpenes
[16]
Monoterpenes [16, 46, 83, 147]
Sesquiterpenes [46, 83, 147]

Benzenoids [16, 148]
Phenylpropanoids [20, 149]

Fatty acid derivatives [20, 150]
“Green leaf volatiles” [46, 148]