Slow-motion analysis of female refusal behaviour in dragonflies

Abstract

By means of slow-motion film analysis we found new female refusal behaviour patterns against male harassment in a variety of Odonata species. Often, females could escape simply by flying faster than males. Due to the morphological preconditions, there were differences in the two suborders. In Anisoptera, several behavioural specialities were analysed: (a) females of Aeshna cyanea, which oviposit solitarily and endophytically, clung to the substrate with great force when being pulled away by attacking males. (b) Anax imperator females showed a very fast, characteristic bending of the abdomen causing sudden U-turns for escape. (c) Solitary Libellula quadrimaculata females flew loops to escape pursuing males or to shake them off. They either used the impact of the crashing male for the turning moment or they generated it themselves by an abrupt change of the wing beat direction. In Zygoptera we investigated different Calopteryx species, which all oviposit alone. Fleeing was most common but wing clapping, not cooperating to build a tandem, tandem separation, fast diving for submerged oviposition and threatening and attacking the male were also documented. Fast water current prevented submerged oviposition by Calopteryx xanthostoma and increased refusal behaviour by females.

Keywords: Odonata, sexual conflict, coercion, communication, male harassment, dragonfly flight, flight loops, flight turns, submerged oviposition, wing clapping

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