Recent Trends in the Olfactory Responses of Insect Natural Enemies to Plant Volatiles

Abstract

The area of plant volatile signaling in multitrophic interactions has developed one of the fascinating and fastest growing fields of research. It has been reported that plant leaves generally release minor quantities of volatile compounds, but when a plant is damaged by insects, several more volatiles are released. Numerous studies have demonstrated the dynamic role of herbivore-damaged plants in the attraction of natural enemies (predators and parasitoids). Volatile plant compounds released in response to insect feeding serve as a chemical signal for herbivore natural enemies. Volatiles released by insect-damaged plants function as attractants and affect the behavior of the natural enemies of herbivorous insects. They also display diverse effects on insect behaviors and are also used as foraging cues by parasitoids and predators. After damaged by phytophagous insects, some host plants could attract parasitoids and predators as an indirect defense. They can also induce defense responses in adjacent plants. Trees of some species are reported to produce volatile signals that affect the behavior of natural enemies. A summary on the recent trends published since 2000 to date on the plant volatiles in relation to insect natural enemies was specified. The use of plant volatiles in integrated pest management programs was also discussed.