Chemical Communication in Triatomine Bugs’ Sexual Context

GABRIEL MANRIQUE; ANA C.R. DE VITTA; GINA B. PONTES; CLAUDIA A. ZACHARIAS; MARCELO G. LORENZO

Roscoff, Brittany, France

Simposio; European Symposium for Insects Taste and Olfaction; 2007

Triatomine bugs act as vectors of Trypanosoma cruzi, a flagelate parasite that is the etiological agent of Chagas disease. This disease affects more than 16 million people in the Americas. Our work intends to clarify several aspects of the sexual behaviour of three species of relevant bugs, in order to allow the potential development of new tools for their control. For this, we have developed assays to characterize several phases of the sequence of behaviours that mediate encounters between individuals of both sexes. Furthermore, we have identified diverse chemical compounds produced by the metasternal glands (MG) of Triatoma infestans, Triatoma brasiliensis and Rhodnius prolixus and evaluated their potential role as sexual communication signals. We have demonstrated that males of R. prolixus show a directional take-off response against female odour ladden airstreams. Moreover, olfactometer experiments with the related species T. brasiliensis have shown that males are attracted by female odour ladden airstreams and that metasternal gland (MG) odours mediate this behaviour. In addition, we have performed SPME experiments that demonstrate that MG odours are emitted preferentially by R. prolixus females mostly during the dark phase. Mating pairs of T. infestans and R. prolixus, known to promote the aggregation of other males around them, also emitted some of these odours. Moreover, the occlusion of female MGs abolished male aggregation in T. infestans. Finally, experiments with T. infestans and R. prolixus showed that mating occurrence decreases drastically after the occlusion of MGs openings. For the first time, the volatile products produced by the MGs of triatomine vectors were identified. We also showed for the first time in bugs that male flight can be triggered by female odours and that MG odours mediate the attraction of males to females. We expect to perform GC-EAD studies in order to determine the capability of the different compounds to promote responses in the antennae of males and EAG experiments to detect thresholds and dose-response relationships. The active compounds produced by each species will also be analysed behaviourally to understand their role in the subsequent phases of the sexual behaviour of bugs. Finally, we intend to evaluate their potential use as baits for the detection or capture of these vector insects, to help avoiding the transmission of Chagas disease.