| Plants that are infested with herbivorous arthropods emit complex odour blends that can comprise up to 200 different components. Carnivorous arthropods exploit odours to locate their herbivorous prey. Chemical characterisation of herbivore-induced plant volatiles and the response of carnivorous arthropods have been extensively studied. This has led to the establishment that plant volatile blends can be specific and that carnivorous arthropods can discriminate among belnds. However, very little knowledge is available on the blend components that are important in evoking a and that enable carnivores to discriminate among blends. Qualitative vs. quantitative differneces and major vs. minor components of the blend may be important. This project will fill this gap in our knowledge. Experimentally manipulated odour sources will be used to investigate the role of quantitative and qualitative variation in odour blends on the behavioural responses of the predatory mite , Phytoseiulus persimilis. This will be done by (1) composing synthetic blends and (2) adding components to a natural odour blend emitted from lima bean leaves infested with spider mites. This natural odour blend has been well charcterised. Through manipulation of the odour blend we can experimentally define odour sources that differ quantitatively and/or qualitatively and in major and/or minor components. The response of predatory mites will be investigated in a Y-tube olfactometer. Natural odour blends will be offered vs natural odour blends artificially manipulated by increasing the contribution of compounds already present or by adding new compounds. These manipulations will be based on knowledge on (1) variation in odour blend composition among different plant species infested with the same herbivore, he two-spotted spider mite T. urticae and (2) variation among Lima bean plants infested with different herbivore species. Keyword(s): PREDATORY MITES / HOST PARASITE RELATIONSHIPS / PLANTS / VOLATILE COMPOUNDS / TROPHIC LEVELS / PLANT PESTS / INSECT PESTS |
