Data from: Flirtation reduces males’ fecundity but not longevity

Theory predicts that due to limited resources males should strategically adjust their investment in reproduction and survival. Based on different conceptual framework, experimental designs and study species, many studies support while others contradict this general prediction. Using a moth Ephestia kuehniella whose adults do not feed and thus have fixed resources for their lifetime fitness, we investigated whether males adjusted their investment in various life activities under dynamic socio-sexual environment. We allowed focal males to perceive rivals or additional females without physical contact. We show that males do not adjust the number of sperm they transfer to mates in a given copulation at different immediate or both immediate and mean sperm competition levels. Contradictory to general predictions, our results demonstrate that cues from additional females increase males’ investment in courtship and reduce their lifetime number of copulations and sperm ejaculated, whereas cues from rivals have no effect on these parameters. Males have similar longevity in all treatments. We suggest that the sex pheromone produced by multiple females over-stimulate males, increasing males’ costly flirtations and reducing their lifetime copulation frequency and fecundity. This finding offers a novel explanation for the success of mating disruption strategy using sex pheromones in pest management.理论预测，由于资源有限，雄性应当战略性地调整其在繁殖与存活上的资源投入。基于不同的概念框架、实验设计与研究物种，诸多研究支持这一一般性预测，亦有部分研究与之相悖。本研究以成虫不取食、因此终生适合度资源固定的地中海粉螟（Ephestia kuehniella）为实验对象，探究雄性在动态社会-性环境下是否会调整其在各类生命活动中的资源投入。我们令焦点雄性在无物理接触的条件下感知竞争者或额外雌性个体。研究结果显示，在不同即时精子竞争水平，或同时结合即时与平均精子竞争水平的条件下，雄性在单次交配中转移给配偶的精子数量并未发生显著调整。与一般性预测相悖的是，额外雌性个体释放的信号线索会提升雄性的求偶投入，并降低其终生交配次数与射精精子总量；而竞争者的信号线索则对上述参数无显著影响。所有实验处理组的雄性寿命均无显著差异。我们推测，多只雌性释放的性信息素会过度刺激雄性，使其代价高昂的求偶行为增多，同时降低其终生交配频率与繁殖力。这一发现为害虫治理中利用性信息素实施交配干扰策略的成功机制提供了全新的解释。