Identification of the gustatory processing center in a blood-sucking insect.

CANO AGUSTINA; BERÓN DE ASTRADA MARTÍN; BARROZO ROMINA

Congreso; Congreso Argentino de Neurociencias; 2020

The gustatory sense provides animals with reliable information about the quality of a food source, contributing to discriminate nutritious from harmful food. Rhodnius prolixus is a vector of Chagas disease in Latin America. They use the gustatory sense to evaluate the quality of a potential food source or vertebrate host in order to make a feeding decision: to eat or not. Thus, when the insect takes a gorge of blood, gustatory receptor neurons (GRNs), housed inside pharyngeal structures or sensilla, provide the brain with gustatory information about the feeding source. If the ingested blood fulfills the insects´ requirements the animal will start feeding. If not, the insect will abandon the host looking for another one. To study the regions of the brain where the GRNs of the pharynx arborise, we traced their axonal projections by means of back-fills with a fluorescent dye. Our results showed that all pharyngeal GRNs arrive to the brain through the labral nerves and arborise in the suboesophageal ganglion (SOG) and that some continue to the posterior ganglion (PG). Two sort of neurons were identified: 1- a thick GRN which innervates the contralateral region of the SOG, named as H neuron; 2- a cluster of GRNs, ca. 5, that innervates the ipsilateral region of the SOG and then continues to the PG. This is the first study that shows peripheral projections to the central nervous system in R. prolixus, revealing the SOG as the primary gustatory processing center.