Plasticity of host finding behaviour of herbivorous insects in dependence of environmental factors

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Most phytophagous insects within Europe are feeding specialists. They necessarily need to find their specific host plants which are acceptable for feeding and oviposition. From the distance, volatile and visual cues are used, whereas after contact also chemotactile cues play a role in the host finding and acceptance behaviour. Different plant species contain each their characteristic chemical metabolite profile, which can vary highly in its composition even within a species from organ to organ and due to age. Furthermore, environmental factors such as ultraviolet radiation and nitrogen availability can induce changes in the quality and quantity of plant metabolites as well as the visual appearance of the plant. Thus, an herbivorous insect must possess a pronounced behavioural plasticity to respond to such variation and to be able to recognise a suitable host. Also, it might prefer plants that increase its fitness. The main aims of the project are to evaluate, how the oligophagous mustard leaf beetle, Phaedon cochleariae (Coleoptera: Chrysomelidae), can detect chemical differences between plants with regard to olfactory, chemotactile and/or visual cues, how the host finding behaviour of the beetles is affected by environmentally influenced changes of plant quality, and whether the host finding behaviour is modified by the experience of the individual.