The epipharyngeal organ of the blood feeder Rhodnius prolixus.

ORTEGA INSAURRALDE, I; INSAUSTI, T; ONS, S; CANO, A; BERON DE ASTRADA, M; BARROZO, RB; LATORRE-ESTIVALIS, JM; DA COSTA DA SILVA, A; DEGENNARO, M

Congreso; VI Congress of the Latin American Association of Chemical Ecology; 2021

The detection of nutritional and toxic food by thetaste sense or gustatory system is a crucial stage to ensure survival.Once a blood-sucking insect reaches thevertebrate host skin, it bites and tastes the blood. Gustatory evaluation ofchemicals present in the blood occurs in putative gustatory chemoreceptorssituated in the pharynx. Only if the insect’srequirements are fulfilled, they initiate feeding.  Although fooddetection and evaluation constitutes a highly relevant instance, the underlyingmechanisms in blood-sucking insects remain largely unknown. In the caseof the Chagas disease vector Rhodniusprolixus, the epipharyngeal organ (EO) is a candidate to detect foodcomponents. Therefore, in this work, we characterizedthe EO of the kissing bug R. prolixus to identify its role in foodassessment. Eight taste sensilla situated onthe EO inthe first portion of the food canal are the potentialsensors 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 incoming blood. The incoming information reachesultimately specific brain regions through the GRN afferents for processing andintegration. To address our hypotheses, we characterized the EO throughneuroanatomical, physiological, and genetic studies. We located the cellbodies of putative GRNs underneath the epipharyngeal sensilla. We recorded neuronalresponses in the EO upon stimulation with NaCl and ATP. The gene repertoire ofthe EO, obtained through RNA-seq, included representatives of several genefamilies candidate to encode sensory receptors. Finally, the GRNs of theEO reached the subesophageal ganglion in the brain through the labral nervesThiswork provides the first characterization of a pharyngeal taste organ in ahematophagous insect.