Chapter Seven - The Behavioral and Physiological Ecology of Adult Rubyspot Damselflies (Hetaerina, Calopterygidae, Odonata)

Abstract

Abstract We review the behavioral and physiological ecology of rubyspot damselflies before, during, and after copulation. Adult rubyspots are sexually dimorphic, with males bearing a red wing spot. For reproduction, males aggregate and defend sunny river spots in a lek fashion: they mate with passing females and take them to communal vegetation sites for oviposition. Three alternative reproductive tactics (ARTs) are used: territorial (those that defend a site), nonterritorial (those that do not defend a site), and switcher (those that can switch between the former two tactics). Males using the three ARTs differ in physiological attributes related to spot size, and flight and immune ability, which are related to male quality and condition. In general, wing spot production is costly when food is scarce and therefore large spot sizes are associated with high mating success and survival. A key inducer of sexual activities is the juvenile hormone (JH). However, high JH titers in males negatively affect their immune expression and survival. In situations of immune demand, young males may skip territorial defence, while old males keep high territorial activity, supporting a scenario of terminal investment. During copulation, rubyspot males can remove sperm from the female's sperm storage organs using two mechanisms: sensory stimulation and direct physical removal. The sensory stimulation mechanism evolved through the female's sensory bias that control egg release and fertilization. The precopulatory interaction in rubyspots can be better understood using a sexual conflict scenario where, due to intense male harassment, females have reduced control of their mating rate. This may affect female survival and energetic resources.