Learning Spatial Aversion Is Sensory-Specific in the Hematophagous Insect Rhodnius prolixus

MINOLI, SEBASTIAN; CANO, AGUSTINA; PONTES, GINA; MAGALLANES, AMORINA; ROLDÁN, NAHUEL; BARROZO, ROMINA B.

Frontiers in Psychology

Frontiers

Año: 2018 vol. 9 p. 1 - 11

Even though innate behaviors are essential for assuring quick responses to expectedstimuli, experience-dependent behavioral plasticity confers an advantage whenunexpected conditions arise. As being rigidly responsive to too many stimuli can bebiologically expensive, adapting preferences to time-dependent relevant environmentalconditions provide a cheaper and wider behavioral reactivity. According to their specificlife habits, animals prioritize different sensory modalities to maximize environmentexploitation. Besides, when mediating learning processes, the salience of a stimulususually plays a relevant role in determining the intensity of an association. Then, sensoryprioritization might reflect an heterogeneity in the cognitive abilities of an individual.Here, we analyze in the kissing bug Rhodnius prolixus if stimuli from different sensorymodalities generate different cognitive capacities under an operant aversive paradigm.In a 2-choice walking arena, by registering the spatial distribution of insects over anexperimental arena, we evaluated firstly the innate responses of bugs confronted tomechanical (rough substrate), visual (green light), thermal (32C heated plate), hygric(humidified substrate), gustatory (sodium chloride), and olfactory (isobutyric acid) stimuli.In further experimental series bugs were submitted to an aversive operant conditioningby pairing each stimulus with a negative reinforcement. Subsequent tests allowed us toanalyze if the innate behaviors were modulated by such previous aversive experience.In our experimental setup mechanical and visual stimuli were neutral, the thermal cuewas attractive, and the hygric, gustatory and olfactory ones were innately aversive.After the aversive conditioning, responses to the mechanical, the visual, the hygricand the gustatory stimuli were modulated while responses to the thermal and theolfactory stimuli remained rigid.We present evidences that the spatial learning capacitiesof R. prolixus are dependent on the sensory modality of the conditioned stimulus,regardless their innate valence (i.e., neutral, attractive, or aversive). These differencesmight be given by the biological relevance of the stimuli and/or by evolutionary aspectsof the life traits of this hematophagous insect.