Sensory discrimination between aversive salty and bitter tastes in an haematophagous insect

MASAGUÉ, SANTIAGO; CANO, AGUSTINA; ASPARCH, YAMILA; BARROZO, ROMINA B.; MINOLI, SEBASTIAN

EUROPEAN JOURNAL OF NEUROSCIENCE

WILEY-BLACKWELL PUBLISHING, INC

Año: 2020 vol. 51 p. 1867 - 1880

0953-816X

Sensory aversion is essential for avoiding prospective dangers. We studied the chemicalperception of aversive compounds of different gustatory modalities (salty, bitter)in the haematophagous bug, Rhodnius prolixus. Over a walking arena, insectsavoided a substrate embedded with 1M NaCl or KCl if provided with water as analternative. However, no preferences were expressed when both salts were opposedto each other. A pre-exposure to amiloride interfered with the repellency of NaCland KCl equally, suggesting that amiloride-sensitive receptors are involved in thedetection of both salts. Discriminative experiments were then performed to determinewhether R. prolixus can distinguish between these salts. An aversive operantconditioning involving either NaCl or KCl modulated the repellency of the conditionedsalt, but also of the novel salt. Repellency levels of both salts were rigid to achemical pre-exposure to any of both salts. When gustatory modalities were crossedby presenting as a choice NaCl and a bitter molecule as caffeine (Caf), no innatepreferences were expressed. Aversive operant conditionings with either NaCl orCaf rendered unspecific changes in the repellency of both compounds. A chemicalpre-exposure to Caf modulated the response to Caf but not to NaCl, suggesting theexistence of two independent neural pathways for the detection of salts and bittercompounds. Overall results suggest that R. prolixus cannot discriminate molecules ofthe same gustatory modality (i.e. salty), but can distinguish between salty and bittertastes. The potential use of aversive gustatory stimuli as a complement of commerciallyavailable olfactory repellents is discussed.