Herbivorous insects utilize plant volatile organic compounds (PVOC) to locate food, oviposition substrate and to find mating rendezvous sites where conspecifics are present. The environment surrounding the insect can be described as a complex ‘soup’ of PVOC emitted from a wide range of plants. To make this even more complex, the release of PVOC differs between plant species, varieties and even different parts of the plants. In the case of specialist insects, detection of a few PVOC released from their host plant could work as a ‘fingerprint’ and facilitate host plant selection. For generalist herbivores, host plant selection can be somewhat more complex since they have a wider array of hosts. My project focuses on how generalist insect herbivores utilize PVOC to identify host plants. Which compounds are important to the insect in order to tell plant A from plant B? Do they use ubiquitously occurring compounds or species-specific compounds for host-plant identification? How does the composition and ratios between the compounds in the headspace of the plant affect the insect? How does previous experience to a particular plant influence host-plant identification?
To find an answer to these questions, I use the model moth, Spodoptera littoralis. This moth has a well-defined preference hierarchy among its host plants that can be modified through previous experience.