Abstracts - Deutsche Zoologische Gesellschaft

28 Behavioral Biology SymposiumO BB.11 (Mo) - ENMemory formation in Nasonia vitripennis: ecology and behaviourDaria Schurmann, Johannes L.M. SteidleInstitut für Zoologie, Fg. Tierökologie, Universität HohenheimThroughout the animal kingdom, the formation of memory after learning involves different phases,which can be roughly characterized as short-term memory (STM), medium-term memory (MTM)and long-lasting, protein-synthesis dependent long-term memory (LTM). According to Menzel,these memory phases represent an adaptation to the specific ecology of a species. This hypothesiswas studied in the pteromalid Nasonia vitripennis, a parasitoid of fly pupae. Bioassays revealed thatone host encounter with drilling in the presence of an odour induces an intermediate-term memoryfor that odour in N. vitripennis. Interestingly, the trained wasps avoided odours that were not presentduring the host encounter, although naive wasps did not react to these odours. This unique behaviourprobably causes wasps to focus during host searching on those chemical cues they have experiencedin the host environment. In support of the studied hypothesis, these findings seem to fit the ecologyof the wasp. The host patches of N. vitripennis range from one to some hundred hosts and might differwith respect to their olfactory environment. Under these conditions, the induction of a transient,intermediate form of memory after one learning event is adaptive to avoid costs involved with formationand maintenance of memory for misleading cues. Currently, the formation of other memoryphases are investigated under laboratory and field conditions to get more information about theirsignificance in an ecological context.O BB.12 (Mo) - ENSpectral sensitivity in the Archerfish Toxotes chatareusLieselotte Jäger 1 , Almut Kelber 2 , Meik Landsberger 1 , Gerhard von der Emde 11Institut of Zoology, University of Bonn; 2 Department for Cell and Organism Biology, Lund University,SwedenAll species of archerfish use a special technique to hunt their prey: they spit with shots of water oninsects and other arthropods, located close above the water surface. Due to the interface betweenwater and air, this technique leads to difficulties in faming the prey correctly. To minimise this problemcolour vision might be useful because it can enhance the contrast between prey and background.We therefore tested whether archerfish can discriminate colours. In behavioural experiments, threeToxotes chatareus were trained to spit on a light-emitting diode (LEDs) of a defined wavelength.They were conditioned to distinguish between this rewarded and an unrewarded colour. By usingrandomised intensities of both stimuli we could show that the fish choose the correct stimulus onlyby discriminating between the wavelengths and not because of the intensities. Therefore the fishmust be able to see colours. Our results show, that archerfish can distinguish between 655nm (red)and 600nm (orange) as well as between 525nm (green) and 470nm (blue). The wavelength-discriminationthresholds (Δλ) are approximately 55 nm. In addition, we tested intensity-thresholds ofdifferent wavelengths in order to determine their visible spectral range and to get an estimate of thenumber of cone types they possess.