A Defensive Kicking Behavior in Response to Mechanical Stimuli Mediated by Drosophila Wing Margin Bristles.
Mechanosensation, one of the fastest sensory modalities, mediates diverse behaviors including those pertinent for survival. It is important to understand how mechanical stimuli trigger defensive behaviors. Here, we report that Drosophila melanogaster adult flies exhibit a kicking response against invading parasitic mites over their wing margin with ultrafast speed and high spatial precision. Mechanical stimuli that mimic the mites' movement evoke a similar kicking behavior. Further, we identified a TRPV channel, Nanchung, and a specific Nanchung-expressing neuron under each recurved bristle that forms an array along the wing margin as being essential sensory components for this behavior. Our electrophysiological recordings demonstrated that the mechanosensitivity of recurved bristles requires Nanchung and Nanchung-expressing neurons. Together, our results reveal a novel neural mechanism for innate defensive behavior through mechanosensation.



We discovered a previously unknown function for recurved bristles on the Drosophila melanogaster wing. We found that when a mite (a parasitic pest for Drosophila) touches the wing margin, the fly initiates a swift and accurate kick to remove the mite. The fly head is dispensable for this behavior. Furthermore, we found that a TRPV channel, Nanchung, and a specific Nanchung-expressing neuron under each recurved bristle are essential for its mechanosensitivity and the kicking behavior. In addition, touching different regions of the wing margin elicits kicking directed precisely at the stimulated region. Our experiments suggest that recurved bristles allow the fly to sense the presence of objects by touch to initiate a defensive behavior (perhaps analogous to touch-evoked scratching; Akiyama et al., 2012).
Departments of Physiology, Biochemistry, and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, California 94158.
Jiefu
J
Li
Departments of Physiology, Biochemistry, and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, California 94158.
Wei
W
Zhang
Departments of Physiology, Biochemistry, and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, California 94158.
Zhenhao
Z
Guo
Departments of Physiology, Biochemistry, and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, California 94158.
Sophia
S
Wu
Departments of Physiology, Biochemistry, and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, California 94158.
Lily Yeh
0000-0003-3938-8498
LY
Jan
Departments of Physiology, Biochemistry, and Biophysics, Howard Hughes Medical Institute, University of California, San Francisco, California 94158 yuhnung.jan@ucsf.edu.
Yuh-Nung
0000-0003-1367-6299
YN
Jan
D000818:Animals; D001362:Avoidance Learning / Q000502:physiology*; D003674:Defense Mechanisms; D004330:Drosophila / Q000502:physiology*; D029721:Drosophila Proteins / Q000502:physiology; D005121:Extremities / Q000294:innervation / Q000502:physiology; D008465:Mechanoreceptors / Q000502:physiology; D040542:Mechanotransduction, Cellular / Q000502:physiology*; D010812:Physical Stimulation / Q000379:methods; D012018:Reflex / Q000502:physiology*; D012679:Sense Organs / Q000502:physiology*; D011984:Sensory Receptor Cells / Q000502:physiology; D014110:Touch / Q000502:physiology; D050051:Transient Receptor Potential Channels / Q000502:physiology; D014921:Wings, Animal / Q000294:innervation / Q000502:physiology*
D029721:Drosophila Proteins; C476010:Nan protein, Drosophila; D050051:Transient Receptor Potential Channels
Drosophila; defensive behavior; touch; trp channel