Tasting the world by a blood-sucking insect

BARROZO, R. B.; PONTES, G; CANO, A.; MINOLI, S; MASAGUE, S; GUTIÉRREZ, M. L.

Villasimius (Cerdeña)

Simposio; ESITO-European Simposium for Insect taste and Olfaction; 2015

The ability to discriminate between nutritive and harmful food is essential for animals? survival. Though olfaction contributes to find a potential food source from a distance, the taste sense works as a final control system driving food acceptance or rejection. Triatomines are lood-sucking insects, vectors of Chagas Disease in Latin America. As soon as they reach a potential vertebrate host, they walk over their skin searching for an adequate site to pierce. Then, they take a first sampling gorge to decide if food is acceptable or not. Our work shows that in triatomines, feeding can be inhibited during the gustatory assessment of both, the surface to bite or the first gorge of food. Insects can detect bitter compounds and high salt concentration and both processes can prevent them from feeding. Morphological inspections along with electrophysiological recordings confirm that the sensory organs involved in taste detection are located in the antenna and in the pharynx. These two independent sensory stages work with different thresholds of response: internal sensors are by far more sensitive to detect aversive compounds than external ones. Additionally, applying a multiapproach strategy, we study whether bugs are able to discriminate among aversive stimuli, or alternatively if they are simply ndistinguishable negative input signals that induce feeding inhibition. On the one hand we target on the putative salt receptors studying the transduction pathway possibly involved in the aversive detection. On the other hand, we use a cognitive approach to gain more insights on theability of insects to behaviorally discriminate among aversive taste modalities. We also study the effects of previous gustatory experiences on feeding. Our results highlight the relevance of taste perception of aversive compounds in modulating the feeding behavior in a bloodsuckinginsect and the importance of previous experience in the final feeding decision.