A single male auditory response test to quantify auditory behavioral responses in Drosophila melanogaster

Abstract

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.

Keywords:

• Word
• courtship song
• auditory behavior
• audition
• fruit fly

Acknowledgments

We thank Dr. Ralf Heinrich for providing a recorded pulse song of D. melanogaster, Dr. Joerg Albert and Dr. Matthew Paul Su for providing a recorded pulse song of D. simulans, Yumi Maki and Miki Kuno for technical support, Dr. Yoichi Oda, Dr. Tsunehiko Kohashi, Dr. Eriko Matsuo, Dr. Nao Morimoto and Dr. Hitoshi Ishimoto for helpful discussion. We also thank Bloomington Stock Center and KYORIN-Fly for fly strains.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by MEXT KAKENHI Grants-in-Aid for Scientific Research (B) (16H04655 to AK and 18H02488 to YI), Scientific Research on Innovate Areas ‘Evolinguistics’ [18H05069 to AK], ‘Evolutionary theory for con- strained and directional diversities’ [18H04819 to YI], ‘Systems science of bio-navigation’ [19H04933 to AK], Challenging Research (Exploratory) [17K19450 to AK and 17K19425 to YI], and Young Scientists (B) 26870264 to YI and Narishige Zoological Science Award to YI, JAPAN.