Behavioral changes during early development provide useful insights into the internal mechanisms that generate complex behavior expressed by mature individuals. At the same time, social conditions during early adult phase can influence behavior in later stages of development even in holometabolous insects. In this study, age-dependent changes in courtship behavior and the effect of social conditions were examined in a fruit fly, Drosophila prolongata. Younger males showed lower mating activity and simpler courtship behavior. Mating activity reached a maximum level by 5 days after eclosion, whereas expression of complex courtship behavior was not yet fully developed at that time, suggesting that they are controlled by different mechanisms. When two males were maintained in the same vial, not only mating activity but also courtship complexity was reduced, demonstrating for the first time that preceding social experience, not current social conditions, influenced the complexity of male courtship. The effect of social experience was completely erased by 1 day of isolation, however, showing that social experience did not suppress or promote behavioral development itself. Rather, these results suggest that the observed effect of social experience was a plastic response of males that reduced investment in courtship effort by anticipating increased male–male competition.

中文翻译：

---

社会条件对延长果蝇成年早期行为发育的影响

早期发育过程中的行为变化为了解成熟个体表达复杂行为的内部机制提供了有用的见解。同时，成年早期的社会条件会影响发育后期的行为，即使是全代谢昆虫。在这项研究中，在果蝇中检查了求偶行为的年龄依赖性变化和社会条件的影响。年轻的雄性表现出较低的交配活动和更简单的求偶行为。交配活动在羽化后 5 天达到最高水平，而此时复杂求偶行为的表达尚未完全发展，表明它们受不同机制的控制。当两只雄性被保存在同一个小瓶中时，不仅交配活动减少了，求偶的复杂性也降低了，这首次表明，以前的社会经验，而不是当前的社会条件，影响了雄性求爱的复杂性。然而，社交体验的影响在隔离 1 天后完全消失，这表明社交体验本身并没有抑制或促进行为发展。相反，这些结果表明，观察到的社会经验的影响是雄性的可塑性反应，通过预期雄性竞争的增加来减少对求爱努力的投资。表明社会经验并没有抑制或促进行为发展本身。相反，这些结果表明，观察到的社会经验的影响是雄性的可塑性反应，通过预期雄性竞争的增加来减少对求爱努力的投资。表明社会经验并没有抑制或促进行为发展本身。相反，这些结果表明，观察到的社会经验的影响是雄性的可塑性反应，通过预期雄性竞争的增加来减少对求爱努力的投资。