Despite the drastic consequences it may have on the transmission of parasites, the ability of disease vectors to learn and retain information have just begun to be characterized. The kissing-bug Rhodnius prolixus, vectors of the Chagas disease, is an excellent model, particularly because conditioning the proboscis extension response (PER) constitutes a valuable paradigm to study their cognitive abilities under carefully controlled conditions. Another characteristic of these bugs is the temporal organisation of their different activities in a bimodal endogenous daily rhythm. This offers the opportunity to address the implication of the circadian system in learning and memory. Using aversive conditioning of the PER, we have tested whether the ability of kissing-bugs to learn and remember information varies during the day. We found that bugs perform well during the night, but not during the day: their ability to acquire information -but not that to retrieve it- is modulated in time. When keeping bugs under constant conditions to analyse the origin of this rhythm, the rhythm continues to freerun, showing its endogenous and truly circadian nature. These results are the first ones to evince the implication of the circadian system in the learning abilities of disease vectors and one of the few in insects in general.
- © 2015. Published by The Company of Biologists Ltd