Salt Sensing in a Blood-Feeding Insect: Genes, Neurons, and Sensory Organs

ORTEGA INSAURRALDE, ISABEL; JOSÉ MANUEL LATORRE ESTIVALIS; ANDRE LUIS DA COSTA DA SILVA; GINA PONTES; DEGENNARO, MATTHEW; BARROZO, ROMINA B.

Ciudad Autónoma de Buenos Aires

Congreso; VII Congress of the Latin American association of Chemical Ecology; 2023

Blood-sucking arthropods possess adapted gustatory organs to efficiently detect and obtain blood as their nutritional source. In the Chagas disease vector Rhodnius prolixus, gustatory detection of blood components occurs in chemoreceptors situated in the pharyngeal organ (PO). As a result, they only initiate feeding when they detect adenosine triphosphate (ATP) and salt (NaCl) in the first sip of blood. Salt concentration is a critical factor, and R. prolixus' decision to accept or reject the blood depends on it. In this study, we investigated the presence of gustatory receptor neurons (GRNs) in the PO associated with salt sensing. Furthermore, we explored genes that might be involved in detecting NaCl within the PO and hypothesized that two pickpocket channels, RproPPK014276 and RproPPK28, could play a role in salt detection by PO-GRNs.We conducted electrophysiological studies on PO-GRNs of R. prolixus, subjecting them to different concentrations of NaCl. We also tested their response to ATP and caffeine as positive controls. To investigate the functional role of the genes RproPPK014276 and RproPPK28, we performed RNAi experiments to suppress their expression and examined their impact on the feeding response of insects. Our findings indicate that PO-GRNs are involved in gustatorily sensing NaCl, ATP, and caffeine. Moreover, the suppression of RproPPK014276 expression disrupts feeding acceptance. This work represents the first characterization of internal salt sensing by a pharyngeal taste organ in a hematophagous insect.