Information on the mating system of an insect species is necessary to gain insight into sexual selection and population structure. Male territoriality of the common evening brown butterfly Melanitis leda has been studied in the wild, but other aspects of its mating system remain largely unknown. For a population of M. leda in South India, we observed male-male and male-female interactions in captivity, measured mating duration and spermatophore mass, and also determined the degree of polyandry in the wild. We found that mating behavior takes place for short periods of time around dawn and dusk. Our observations corroborate that males compete in aerial combats (twirling) and interfere with mating pairs. In the morning, they may use shivering to warm up. Females can twirl with males and refuse mating by pointing their abdomens upwards or by flying away. Males court females by fluttering their wings while perched behind females, and then initiate copulation by curling their abdomens ca. 180 degrees sideways to make genital contact. While in the morning, matings lasted on average one hour and twenty-three minutes and never exceeded three hours, in the evening, matings could be of similar duration, but 42% of butterflies only separated when dawn was approaching. However, such long nocturnal matings did not result in heavier spermatophores. The first spermatophore of a male tended to be larger than subsequent spermatophores. Together with previous studies on this species, our findings suggest that males compete mainly through territorial defense (as reported before), courtship performance, and interference, and to a lesser extent by providing spermatophores, while females exert some control over the mating system by the timing of their receptivity and mate choice.

中文翻译：

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蝴蝶黑斑蝶在黎明和黄昏的短暂交配行为和长时间的夜间交配

有关昆虫物种交配系统的信息对于深入了解性选择和种群结构是必要的。已经在野外研究了常见的晚褐色蝴蝶 Melanitis leda 的雄性领土，但其交配系统的其他方面仍然未知。对于印度南部的 M. leda 种群，我们观察了人工饲养的雄性-雄性和雄性-雌性相互作用，测量了交配时间和精囊质量，还确定了野外一妻多夫的程度。我们发现交配行为发生在黎明和黄昏前后的短时间内。我们的观察证实，雄性在空战（旋转）中竞争并干扰交配对。早上，他们可能会通过颤抖来暖身。雌性可以与雄性旋转并通过将腹部朝上或飞走来拒绝交配。雄性栖息在雌性身后，通过扇动翅膀向雌性求爱，然后通过卷曲腹部开始交配。侧身 180 度以进行生殖器接触。早上的交配时间平均为1小时23分钟，从未超过3小时，晚上的交配时间可能相似，但42%的蝴蝶只在天亮时才分开。然而，如此长的夜间交配并没有导致更重的精囊。雄性的第一个精囊往往比随后的精囊大。结合之前对该物种的研究，我们的研究结果表明，雄性主要通过领土防御（如前所述）、求偶表现、