Bitter taste recognition in the blowfly: Electrophysiological and behavioral evidence

Blowflies respond to sugars, salts, and water through the activation of specific chemoreceptor neurons in the labellar taste chemosensilla. These insects also detect deterrent stimuli, but identification of a specific deterrent chemoreceptor within their sensilla has been elusive. Here electrophysiological evidence is provided that the so-called fifth cell in taste chemosensilla of blowflies responds to deterrent compounds, such as quinine, amiloride, nicotine, and caffeine, which are also known to be bitter tasting for vertebrates. Therefore, comparison of behavioral and electrophysiological data, including crossadaptation analysis, suggests that the blowfly can detect bitter stimuli by activation of the fifth cell. A possible chemoreception mechanism is discussed. (C) 2000 Elsevier Science Inc. All rights reserved.