Many animals utilize auditory signals to communicate with conspecific individuals. During courtship, males of the fruit fly Drosophila melanogaster and related species produce a courtship song comprised of sine and pulse songs by vibrating their wings. The pulse song increases female receptivity and male courtship activity, indicating that it functions as a sexual signal. One song parameter, interpulse interval (IPI), varies among closely related species. In D. melanogaster, a song with a conspecific IPI induces a stronger behavioral response than heterospecific songs, indicating the ability of the flies to discriminate conspecific IPI. Traditionally, the fly’s response to the song is measured under grouped conditions, in which the effect of sensory modalities other than audition cannot be excluded. Here, to quantify the individual ability to discriminate a conspecific song, we systematically analyzed the auditory response of single male flies to sound with various parameters. Moreover, we applied this method, termed SMART (Single Male Auditory Response Test), to two sister species for potential application in a comparative approach. By quantifying the locomotor activity of single D. melanogaster males during sound exposure, we detected increased locomotor activity in response to pulse songs, but not to white noise or pure tone. The conspecific song evoked stronger response than the heterospecific songs, and ablation of their antennal receivers severely suppressed the locomotor increase. A pulse song with a small IPI variation evoked a continuous response, while the response to songs with highly variable IPIs tends to be rapidly decayed. This provides the first evidence that fruit flies discriminate IPI variations, which possibly inform the age and social contexts of the singer. Sister species, D. sechellia, exhibited a locomotor response to pulse song, while D. simulans exhibited no behavioral response. This suggests that auditory and other stimuli that elicit this behavioral response are diversified among Drosophila species.

许多动物利用听觉信号与特定个体进行交流。在求爱过程中，果蝇果蝇（Drosophila melanogaster）和相关物种的雄性通过振翅而产生由正弦和脉冲歌曲组成的求爱歌曲。脉冲歌曲增加了女性的接受能力和男性的求爱活动，表明它起着性信号的作用。在紧密相关的物种之间，一个歌曲参数即脉冲间隔（IPI）有所不同。在黑腹果蝇中，具有特定IPI的歌曲比异质歌曲具有更强的行为反应，表明果蝇具有区分特定IPI的能力。传统上，苍蝇对歌曲的反应是在分组条件下测量的，在这种条件下，不能排除听觉以外的感觉方式的影响。在这里，为了量化个体区分同种歌曲的能力，我们系统地分析了单雄蝇对具有各种参数的声音的听觉响应。此外，我们将这种称为SMART（单雄性听觉反应测试）的方法应用于两个姊妹物种，以便在比较方法中潜在应用。通过量化单个D.黑腹果蝇的运动活性男性在声音暴露期间，我们检测到响应脉冲歌曲而运动的活动增加，但没有检测到白噪声或纯音。同种歌曲引起的反应比异种歌曲要强，消灭它们的触角接收器会严重抑制运动能力的增加。IPI变化小的脉冲歌曲会引起连续响应，而IPI高度可变的歌曲的响应往往会迅速衰减。这提供了第一个证据，表明果蝇可以区分IPI变异，这可能会影响歌手的年龄和社会背景。姐妹种D. sechellia表现出对脉冲歌曲的运动响应，而D. simulans没有表现出行为反应。这表明果蝇物种之间引起这种行为反应的听觉和其他刺激是多样化的。