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J Exp Biol. 2014 Oct 15;217(Pt 20):3708-17. doi: 10.1242/jeb.107722. Epub 2014 Sep 4.

Bitter stimuli modulate the feeding decision of a blood-sucking insect via two sensory inputs.

Author information

1
Laboratory of Insect Physiology, Department of Biodiversity and Experimental Biology, FCEyN, University of Buenos Aires, Buenos Aires C1428EHA, Argentina IBBEA, CONICET-UBA, Ciudad Universitaria, Buenos Aires C1428EHA, Argentina.
2
Laboratory of Insect Physiology, Department of Biodiversity and Experimental Biology, FCEyN, University of Buenos Aires, Buenos Aires C1428EHA, Argentina.
3
Centre de Recherches sur la Cognition Animale, CNRS - Univ. Paul Sabatier (UMR 5169), Narbonne F-31062, Toulouse, France.
4
Laboratory of Insect Physiology, Department of Biodiversity and Experimental Biology, FCEyN, University of Buenos Aires, Buenos Aires C1428EHA, Argentina IBBEA, CONICET-UBA, Ciudad Universitaria, Buenos Aires C1428EHA, Argentina rbarrozo@bg.fcen.uba.ar.

Abstract

The gustatory system of animals is involved in food quality assessment and controls the feeding decision of an individual confronted with a potential alimentary source. Triatomines are haematophagous insects that feed on vertebrate blood. Once they reach a potential host, they walk over the host skin searching for an adequate site to pierce. Then, they insert their stylets and take a first sampling gorge to decide whether food is acceptable. Our work reveals that the presence of bitter compounds inhibits the feeding behavior of these bugs. Firstly, triatomines decreased their feeding behavior if substrates spread with quinine or caffeine were detected by external receptors localized exclusively in the antennae. Morphological inspections along with electrophysiological recordings revealed the existence of four gustatory sensilla located in the tip of the antenna that respond to both bitter tastants. The absence of these bitter detectors by antennal ablation reversed the observed feeding inhibition evoked by bitter compounds. Secondly, once triatomines pumped the first volume of food with bitter compounds (quinine, caffeine, berberine, salicin), a decrease in their feeding behavior was observed. Morphological inspections revealed the existence of eight gustatory sensilla located in the pharynx that might be responsible for the internal bitter detection. Finally, we found that a brief pre-exposure to bitter compounds negatively modulates the motivation of bugs to feed on an appetitive solution. Results presented here highlight the relevance of bitter taste perception in the modulation of the feeding behavior of a blood-sucking insect.

KEYWORDS:

Bitter; Blood-sucking; Feeding behavior; Plasticity; Taste sensilla

PMID:
25189371
DOI:
10.1242/jeb.107722
[Indexed for MEDLINE]
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