The epipharyngeal organ of the blood feeder Rhodnius prolixus

ISABEL ORTEGA-INSAURRALDE; JOSÉ MANUEL LATORRE ESTIVALES; CANO, AGUSTINA; INSAUSTI, TERESITA; ANDRE LUIS DA COSTA DA SILVA; MARTÍN BERÓN DE ASTRADA; SHEILA ONS; DEGENNARO, MATTHEW; BARROZO, ROMINA B.

Buenos Aires

Congreso; VI Congreso de la Asociación Latinoamericana de Ecología Química; 2021

ALAEQ

The detection of nutritional and toxic food by the taste sense or gustatory system is a crucial stage to ensure survival.Once a blood-sucking insect reaches the vertebrate host skin, it bites and tastes the blood. Gustatory evaluation of chemicals present in the blood occurs in putative gustatory chemoreceptors situated in the pharynx. Only if the insect’s requirements are fulfilled, they initiate feeding. Although food detection and evaluation constitute a highly relevant instance, the underlying mechanisms in blood-sucking insects remain largely unknown. In the case of the Chagas disease vector, Rhodnius prolixus, the epipharyngeal organ (EO) is a candidate to detect food components. Therefore, in this work, we characterized the EO of the kissing bug R. prolixus to identify its role in food assessment. Eight taste sensilla situated on the EO in the first portion of the food canal are the potential sensors of the food components. We hypothesized that gustatory receptor neurons (GRNs) and the cognate molecular receptors, housed within these sensilla, detect the components of the blood. The incoming information reaches ultimately specific brain regions through the GRN afferents for processing and integration. To address our hypotheses, we characterized the EO through neuroanatomical, physiological, and genetic studies. We located the cell bodies of putative GRNs underneath the epipharyngeal sensilla. We recorded neuronal responses in the EO upon stimulation with NaCl and ATP. The gene repertoire of the EO, obtained through RNA-seq, included representatives of several gene families candidate to encode sensory receptors. Finally, the GRNs of the EO reached the subesophageal ganglion in the brain through the labral nerves.This work provides the first characterization of a pharyngeal taste organ in a hematophagous insect.