Reakce ptáků na ploštice ze skupiny Lygaeoidea: efektivita chemické obrany ; Behaviour of avian predators to seed bugs (Lygaeoidea): effectiveness of chemical defence

By warning signalling prey advertises its unpalatability to the predators. Typical examples are true bugs (Heteroptera) combining optical and chemical signals. The aim of this study was to find out the effectiveness of chemical defence against wild-caught adults of great tits (Parus major) and blue tits (Cyanistes caeruleus) and towards hand-reared juveniles of great tits. The tested prey were adults and larvae of two invasive species of genus Oxycarenus (Heteroptera: Oxycarenidae) (aposematic O. lavaterae, non-aposematic O. hyalinipennis), adults of Horvathiolus superbus (Heteroptera: Lygaeidae) and crickets (Gryllus assimilis) as a control prey. We were focusing on the influence of seed bugs to the initial reaction, the learning process and to the displays of discomfort behaviour in tits. Reactions affected by the tit species, age and sex were compared in adults. Juveniles were divided into two independent experimental groups, one group was offered adults of genus Oxycarenus, the second was offered sunflower (Helianthus sp.) or Digitalis sp. seed fed adults of H. superbus. The first bug offered did not elicit an initial aversive reaction in tits, but birds reacted aversively to the bugs after having further handling experience. All juveniles, contrary to the adult tits, attacked at least one bug. ; Výstražnou signalizací dává kořist predátorům najevo svou nepoživatelnost. Typickým příkladem jsou ploštice (Heteroptera), které vysílají kombinaci optických a chemických signálů. Cílem této práce bylo zjistit efektivitu chemické obrany ploštic vůči dospělým, z volné přírody odchyceným, sýkorám koňadrám (Parus major) a modřinkám (Cyanistes caeruleus) a vůči ručně odchovaným sýkorám koňadrám. Testovanou kořistí byly imága a larvy dvou invazních druhů rodu Oxycarenus (Heteroptera: Oxycarenidae) (aposematický O. lavaterae, neaposematický O. hyalinipennis), imága Horvathiolus superbus (Heteroptera: Lygaeidae) a jako kontrolní kořist cvrčci (Gryllus assimilis). Sledovali jsme vliv ploštic na prvotní reakci, na průběh ...