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Reactions of spider and insect predators to aposematic prey
Koláčná, Klára ; Exnerová, Alice (advisor) ; Sentenská, Lenka (referee)
Aposematic prey advertises its unprofitability to predators by means of warning signals, which can be visual, chemical, acoustic or combined with each other as multimodal signals. Most experimental studies dealing with responses of predators to aposematic prey focus on vertebrates, especially birds. This thesis focuses on the most frequently tested groups of terrestrial arthropod predators - spiders, dragonflies, and mantises - supplemented by less tested insect predators. Most of the tested arthropod predators are able to learn to avoid noxious aposematic prey based on either visual, olfactory or acoustic signals depending on their perception. Some can remember this aversion for several days. Only in case of jumping spiders, ability to generalise previous experience with a particular prey to similar prey has been confirmed. Prey chemical defenses most often consist of cardenolides or aldehydes, which proved to be aversive for tested arthropod predators.
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Antipredatory function of flash display in Heteroptera (case of Coreus marginatus)
Pipek, Pavel ; Exnerová, Alice (advisor) ; Kleisner, Karel (referee)
1 Abstract Aim of the present study was to test antipredatory function of fulguration (or flash display), which means sudden exposition of conspicous body part on otherwise cryptic animal during escape. Adult squash bugs (Coreus marginatus; Heteroptera) were used as model prey, while as model predator served two species of passerine birds - blue tit (Cyanistes caerulus) and great tit (Parus major). Three approaches were undertaken. Test of palatability should have assessed the efficiency of squash bug chemical defence against bird predators. Experiment was carried out in experimental cage without interference of experimenter and without occurrence of fulguration. The results show that chemical defense of squash bug is less efficient than defense of other species of true bugs (Pyrrhocoris apterus, Graphosoma lineatum) and that the efficiency differs between two generations of squash bugs. In the test of efficiency of fulguration, the prey was forced by experimenter to fly in response to bird attack. Blue tits attacked the immobile prey more often than the flying and fulgurating one, but the same relation wasn't significant with great tits. The latencies of birds' returns to the bugs that landed after fulguration wasn't influenced by colour of the bugs' abdomen. Third experiment consisted of computer...
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