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Publication - Dr Erica Morley

    Directional cues in Drosophila melanogaster audition: structure of acoustic flow and inter-antennal velocity differences

    Citation

    Morley, EL, Steinmann, T, Casas, J & Robert, D, 2012, ‘Directional cues in Drosophila melanogaster audition: structure of acoustic flow and inter-antennal velocity differences’. Journal of Experimental Biology, vol 215., pp. 2405-2413

    Abstract

    Drosophila melanogaster have bilateral antisymmetric antennae that receive the particle velocity component of an acoustic
    stimulus. Acoustic communication is important in their courtship, which takes place in the acoustic near-field. Here, the small size
    of the dipole sound source (the male wing) and the rapid attenuation rate of particle velocity produce a spatially divergent sound
    field with highly variable magnitude. Also, male and female D. melanogaster are not usually stationary during courtship, resulting
    in a variable directionality of the acoustic stimulus. Using both particle image velocimetry and laser Doppler vibrometry, we
    examined the stimulus flow around the head of D. melanogaster to identify the actual geometry of the acoustic input to the
    antennae and its directional response. We reveal that the stimulus changes in both magnitude and direction as a function of its
    angle of incidence. Remarkably, directionality is substantial, with inter-antennal velocity differences of 25dB at 140Hz. For an
    organism whose auditory receivers are separated by only 660±51m (mean ± s.d.), this inter-antennal velocity difference is far
    greater than differences in intensity observed between tympanal ears for organisms of similar scale. Further, the mechanical
    sensitivity of the antennae changes as a function of the angle of incidence of the acoustic stimulus, with peak responses along
    axes at 45 and 315deg relative to the longitudinal body axis. This work indicates not only that the flies are able to detect
    differential cues in signal direction, but also that the male song structure may not be the sole determinant of mating success; his
    spatial positioning is also crucial to female sound reception and therefore also perhaps to her decision making.

    Full details in the University publications repository