Epsilon Open Archive

Abstract

Insects perceive their world to a large extent through olfaction. Volatile organic compounds released by the biota is therefore of utmost importance for host plant identification and selection in phytophagous insects. Plants release species-specific bouquets of volatile organic compounds which insects use as cues to guide behaviour in several life stages. For reliable localization of suitable host plants, insects need to be able to generalize and discriminate between these important cues. Several theories on the information of the odour bouquet that is used for reliable plant identification have been postulated during the last decades. Empirical studies have shown that plant identification in many species depend on ubiquitous volatile compounds, but that there are examples that insects use speciesspecific compounds or a combination of the two types of compounds. The response to plant cues can also show phenotypic plasticity and change depending on environmental conditions. For example, previous experience of particular host plants has been shown to affect the behaviour of insects through within-generation phenotypic plasticity. It is also possible that information from earlier experience could be transferred vertically from one generation to the other through transgenerational phenotypic plasticity.

This review gives an overview of host plant identification in insects. First, a brief overview of plant organic compounds and olfaction is made. Then the focus shifts to how volatile plant organic compounds are perceived by the olfactory system of insects and how they affect generalization and discrimination processes during host plant selection. Lastly, I discuss how plasticity, both within and across generations, can affect the behavioural outcome.