Induced changes in the behavior of rodhnius prolixus as an indicator of sensitivity to different bitter compounds

PONTES, GINA; ASPARCH, YAMILA; MINOLI, SEBASTIAN; BARROZO, ROMINA B.

Encuentro; 32 Annual Meeting of the International Society of Chemical Ecology; 2016

Kissing bugs (Heteroptera: Reduviidae: Triatominae) are hematophagous insects responsible for the transmission of Chagas disease in Latin America. In previous experiments carried out in our laboratory we demonstrated that the presence of bitter substances as caffeine (CAF) and quinine (QUI) on the biting surface and/or in the solution to ingest can decrease the ingestion rate of R. prolixus. Although the sensorial pathways for the detection of CAF and QUI are not known yet, our group is currently working in this subject via different approaches. The aim of the present work is to study if kissing bugs are able to distinguish between CAF and QUI (i.e. two bitter substances) or if instead if they are perceived as different compounds that generate a similar gustative aversion. Over a 2-choice experimental arena we registered the aversion produced by CAF and QUI confronted to water, and both compounds confronted to each other. Then, in a second series, we applied an operant aversive conditioning to study if CAF and QUI can be discriminated by triatomines. Briefly, every time bugs visited one side of the arena loaded with either CAF or QUI, a mechanical disturbance was applied, which constituted a negative reinforcement. Our results show that both, CAF and QUI, repel these bugs in a similar manner. Moreover, no clear preferences were obtained when presented confronted or after the aversive conditioning. We conclude that triatomines are incapable of distinguishing between CAF and QUI. Additionally, the conditioning experiments changed the behavior of these insects, demonstrating that they are capable of learning about their environments. These studies have relevance at the time to develop repellents that could decrease bites of these bugs to humans.