Azusa Kamikouchi, PhD
Principal Investigator, Institute of Transformative Bio-Molecules (WPI-ITbM);
Professor, Graduate School of Science, Nagoya University
Lecture Title
Acoustic communication in fruit flies and mosquitoes
Abstract
Many animals, from humans to birds to insects, produce sounds to communicate with other members of the same species, particularly during mating behaviors. One such example is acoustic communication in flies (including the fruit fly Drosophila melanogaster and mosquitoes) prior to mating, with this courtship communication mediated by wing movements. Male fruit flies produce courtship songs, while mosquito males detect the faint flight tones emitted by nearby females, triggering a phonotactic attraction towards them. However, the mechanisms by which flies detect and evaluate the sounds emitted by potential mating partners are not well understood. Through the study of their ears and brains, our aim is to comprehend the molecular and neural mechanisms that underlie their acoustic communication.
Female fruit flies assess species-specific song rhythms during courtship. We have identified an inhibitory feed-forward circuit in the brain that uses GABA to modulate the fly's preference for the conspecific song rhythm, which serves as a key component of the song-evaluation pathway (Yamada et al., 2018). Furthermore, our behavioral analyses identified experience-dependent plasticity in song preference, mediated by GABAergic inhibition (Li et al., 2018). These findings together suggest a significant role of GABAergic systems in fine-tuning the properties of the fruit fly’s auditory system in both innate and experience-dependent manners.
In contrast to fruit flies, mosquito males do not produce specific songs but instead rely on female flight sounds. Mosquito ears are the largest among insects and possess an auditory efferent system that regulates ear function. Our study focused on yellow fever mosquitoes (Aedes aegypti) suggests that serotonin is involved in this efferent control (Xu et al., 2022). Manipulating the serotoninergic system affects the frequency tuning of male ears and phonotactic behaviors. These findings reveal serotonin's key role in fine-tuning the male mosquitoes' hearing system, making it a potential target for vector control.
References:
- X. Li, H. Ishimoto, A. Kamikouchi (2018). Auditory experience controls the maturation of song discrimination and sexual response in Drosophila. eLife 7(e34348).
- D. Yamada, H. Ishimoto, X. Li, T. Kohashi, Y. Ishikawa, A. Kamikouchi (2018). GABAergic local interneurons shape female fruit fly response to mating songs. The Journal of Neuroscience 38(18) 4329-4347.
- Y.Y.J Xu, Y-M. Loh, T-T Lee, T. S. Ohashi, M. P. Su, A. Kamikouchi (2022). Serotonin modulation in the male Aedes aegypti ear influences hearing. Frontiers in Physiology 13(931567).