Salts controls feeding decisions in kissing bugs: linking peripheral detection to behavior.

BARROZO, RB

Orlando

Congreso; XXV International Congress of Entomology; 2016

Introduction. Salts are vital for physiologicalprocesses to occur. Deficientor excessive salt levelscan result in adverse effects. Salt homeostasis is controlled by foodingestion, for which taste plays a main role in this balance. Rhodnius prolixus uses its taste system toexamine a potential biting site first, and then, to assess the quality ofingested food. Here, we studied the role of salts on the whole feeding processof Rhodnius, from site recognition toingestion.Methods. Salts solutions were addedover bitten substrates or in the diet, and registered the ingested volume,electromiograms of the cibarial pump and electrophysiological recordings oftaste sensilla. The effect of amiloride (a specific sodium channel blocker) in saltperception was studied. Lastly, by using bioinformatic tools ppk genes (coding forENaC receptors in other animals) were characterized and their expressionevaluated in antennae.Results. Rhodnius avoided feeding on an appetitive diet when substrates wereimpregnated with high-salt levels. When treated with amiloride, this inhibitiondisappeared. Antiappetitive responses also occurred when diets contained no-saltor high-salt levels. Electromiograms revealed different inhibitory mechanisms forboth feeding conditions. Electrophysiological recordings evinced that thetargets of amiloride are antennal taste receptors, and probably epipharyngeal receptors. Additionally, three R. prolixus ppks showed a characteristic amiloride-binding-sitedomain.Discussion. Our results show thecrucial role that salt detection plays in the feeding decisions of Rhodnius. Moreover, we described theexistence of amiloride-sensitive salt receptors involved in salt recognition inRhodnius, likely ENaC receptors.