Optische Reize im Wirtsfindungsverhalten von Blattläusen

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The general aim of the project is to elucidate the visual mechanisms in the host finding behaviour of aphids. For selected species, the following questions of colour perception will be investigated: (1) Neurophysiological level: How many classes of photo receptors with different spectral sensitivity functions do aphids have? In which wavelengths are they sensitive? Are different species and morphs also different in their receptor sensitivities? This will be investigated by electroretinogram and intracellular recordings. (2) Ethological level: Is true colour vision involved in the host finding and landing behaviour? How are the inputs from the photoreceptors used to produce a behavioural response? This question will be addressed by behavioural tests in the laboratory (flight chamber and arena) and in the field. (3) Why do aphid species differ in their behavioural response to colour stimuli? (a) cause: Are interspecific behavioural differences due to different receptor sensitivities? (b) function: Can interspecific differences regarding behaviour or receptor sensitivity be related to food specialization or zoological systematics? Which role plays the spectral characteristic of the host plant for the host selection? These aspects will be investigated by combining the obtained physiological and ethological data with a spectral screening of host and non-host plants. We regard the proposed project as the first systematic approach to the evolution and adaptive value of colour vision in herbivorous insects.