Abstracts - Deutsche Zoologische Gesellschaft

134 Evolutionary Biology PostersP EB.20 - ENA protective shell? – The effect of cocoons on pupal infections in antsSimon Tragust, Line V. Ugelvig, Sylvia CremerEvolution, Genetics and Behaviour, University of RegensburgColonies of social insects contain a high number of developing larvae and pupae, which can face arisk of infection by parasites. The workers of social insects therefore perform intensive brood care,including hygienic behaviours and physiological protection of the brood. As some ant subfamilieshave their pupae enclosed in cocoons whereas others do not, we studied the effect of pupal cocoonsas barriers against infection in four unrelated and ecologically different ant species, two of whichwith and two without cocoons. A group of five workers of each species was confronted with threesets of larval and pupal brood items, which were either treated with live spores of the pathogenicfungus Metarhizium anisopliae, with dead (UV-irradiated) spores of this fungus or with a controlsolution. Immediately upon treatment and for the next five days the intake of the brood into thenest chamber and the hygienic actions towards the brood and between the workers were observed.Thereafter the status of the brood, their location and the status of the workers on signs of infectionwas scanned for another seven days.P EB.21 - ENSexual selection and male head secretions in the tropical spider Argyrodes elevatus:behaviour, morphology and biochemistryGabriele Uhl 1 , Peter Michalik 2 , Stefan Schulz 31Institut für Zoologie, Universität Bonn; 2 Institut für Zoologie, Universität Greifswald; 3 Institutfür Organische Chemie, TU BraunschweigThe kleptoparasitic tropical spiders of the genus Argyrodes are widely known for their peculiarforaging behaviour: they live in webs of large orb-web spiders where they glean trapped insects andsteal large food bundles and even feed on the host´s web. Apart from their interesting ecology, Argyodesspecies are markedly sexually dimorphic: Males possess two large protrusions on the prosomathat involve the ocular region. We tackled the potential functions of the male head structures on themorphological, behavioural, and biochemical level. Morphological investigations demonstrate thatthe protrusions consist of massive glandular tissue. The head structures play a role during mating,since a bite by the female in between the two protrusions of the male is a prerequisite for successfulcopulation. Females were observed to release saliva onto the male structures. Experimentally coveredhead structures resulted in similar copulation probabilities compared to control matings. However,only brief copulations occurred in covered males since the females ended these copulationsprematurely. Our studies suggest that the male head structures do not emit a pheromone for mateattraction but a gustatorial product that functions as a mating effort through prolonged copulationduration. These findings are in accordance with results from chemical analysis.