Chemical Signatures in Plant-Insect Interactions

Chemical signals are important cues throughout the life of an insect especially for mate location and for prey and host finding. The chemical signal, whether pheromone or plant volatile organic compound (VOC), remains specific because of the mixture, of the ratio of the components in mixture and of the release quantity. The plasticity of pheromone emissions is now studied in several insect species in relation to geographic variation, host plant specialization and chemical and light environment. The actual vision is that the pheromone composition is likely to be more plastic than previously assumed. The perception of the environmental odorscape produced by living plants and animals together addressed the question on the specific detection of the pheromone signal in the atmospheric blend of molecules. In agrobiocoenosis, the cultivated plants produce a specific odorscape. The insects rely on plant VOCs to locate the crop or the host plant, after which specific mixtures act as oviposition stimulants. The insect responses to host plants and their odours vary with the physiological status of both actors: the plant and the insect. Chemical signals released by plants vary with plant physiology, diel periodicity, climatic factors and pollution, and these signals can be species or even variety specific. Many of plants signalling compounds detected by insects have important roles as warning signals, which can also function in plant–plant communication.