Food recognition: the organization of the pharyngeal gustatory organ of a disease vector.

BARROZO, RB

Workshop; Behaviour of Arthropods Disease Vectors: A source for biorational pest control in a ?One Health? context.; 2022

Taste is the ultimate sensory modality involvedin resource quality assessment, resulting in acceptance or rejection. Located in the pharynx, gustatory sensilla evaluate thesuitability of the ingested food helping the insect to make a crucial decision:to eat or not to eat. Through multiple approaches, we have characterized theepipharyngeal organ (EO) of the kissing bug Rhodnius prolixus to uncoverits role in food assessment. The EO, located anterodorsally in the pharynx, holds8 gustatory sensilla, which are bathed with the incoming blood immediatelyafter the first sip enters the food canal. Gustatory receptor neurons (EO-GRNs)are housed in these sensilla and project their axons through the labral nerves tothe subesophageal zone in the brain. These EO-GRNs are activated by gustatory appetitiveand aversive stimuli such as ATP, NaCl and caffeine. Several gene families areexpressed in the EO-GRNs, including gustatory receptors, ionotropic receptors,transient receptor potential channels, pickpocket channels, opsins, takeouts,neuropeptide receptors and neurotransmitter receptors, many of them have been previouslyrelated with feeding. Particularly, the pickpocket channel receptor RproPPK014276shows to be crucial in modulating the appetitive salt response of bugs, demonstratingthe role of the EO in food assessment. This work provides the first completecharacterization of a pharyngeal gustatory organ in a hematophagous insect.