Circadian entrainment by light and host in the Chagas disease vector, Triatoma infestans

Abstract

Triatoma infestans (Reduviidae: Triatominae, “kissing bug”) is the main insect vector of Trypanosoma cruzi, the causative agent of Chagas disease, a chronic trypanosomiasis infecting 10 million people world-wide. This hematophagous bug feeds on diurnal and nocturnal species during each host’s quiescent time. As the hosts are also its major predators, kissing bugs are subjected to dual selective pressures from a single source. Therefore, synchronization of feeding with the host’s behavior is critical to the insects’ survival. We show that nonphotic signals linked to the host eclipse the role of light and dark as the primary circadian zeitgeber for these bugs, although light still strongly inhibits locomotor behavior directly. In nature, this combination provides the insect with great flexibility in organizing physiology and behavior: anticipating a quiescent host or avoiding its potential predation while remaining directly responsive to immediate environmental conditions. Manipulation of nonphotic entrainment could be a useful chronobiotic tool in the control of Chagas disease.

• Circadian rhythms
• kissing bugs
• nonphotic synchronization
• photic synchronization
• Triatoma infestans
• triatominae

Acknowledgments

The authors wish to thank Richard Rushton of the Phillips-Respironics Company, for donation of the VitalView data acquisition system with which all the data in the manuscript was obtained. We are deeply grateful to Richard and we guaranty good and efficient use of this valuable equipment. To Dr. Claudio R. Lazzari for support and motivation as well as valuable suggestions related to the experimental setup. We are also indebted to José D. Paliza for construction and maintenance of experimental equipment as well as other technical support; to Natalia Folguera for assistance with kissing bugs maintenance; and to Gisele Oda, Danilo Flôres, Bárbara Tomotani and Patricia Tachinardi for assistance with discussion and analysis.