Circadian system responses to nocturnal and diurnal hosts in the kissing bug, Triatoma infestans

ABSTRACT

Insects express diverse behavioral rhythms synchronized to environmental cycles. While circadian entrainment to light–dark cycles is ubiquitous in living organisms, synchronization to non-photic cycles may be critical for hematophagous bugs that depend on rhythmic hosts. The purpose was to determine whether Triatoma infestans are capable of synchronizing to the circadian rhythms of potential hosts with temporally distinct activity patterns; and, if so, if this synchronization occurs through masking or entrainment. Precise synchronization with the food source may be critical for the insects’ survival due to the specific predatory or defensive nature of each host. Kissing bugs were housed in a compartment in constant dark, air-flow-connected to another compartment with a nocturnal or a diurnal host; both hosts were synchronized to a light–dark cycle. The activity rhythms of kissing bugs were modulated by the daily activity rhythms of the vertebrates. Effects were a decrease in the endogenous circadian period, independent of the host being nocturnal or diurnal; in some cases relative coordination occurred and in others synchronization was clearly achieved. Moreover, splitting and bimodality arose, phenomena that were also affected by the host presence. The results indicate that T. infestans were able to detect the non-photic cycle of their potential hosts, an ability that surely facilitates feeding and hinders predation risk. Understanding triatomines behavior is of fundamental importance to the design of population control methods.

KEYWORDS:

• Circadian rhythms
• non-photic synchronization
• Triatominae
• hematophagous vectors
• Chagas disease
• masking
• entrainment

Acknowledgments

The authors thank D. Gorla for the initial support and discussion in planning. The authors also thank I. Amelotti, ML Hernandez, MJ Cavallo, and C. Nieto for kissing bug field captures and laboratory analysis of T. cruzi. Centro Regional de Vectores, Córdoba, for facilitating some insects. A word of thanks also goes to C. Nieto for assistance with animal maintenance and J. Barros for experimental support; and G. Oda, M. Gomes, G. Improta, and T. Yamamoto for collaboration with data analysis.

Declaration of interest

The authors declare that there is no conflict of interest.

Additional information

Funding

This work was supported by the Agencia Nacional de Promoción Científica y Tecnológica [grant number PICT 2013/2753], Consejo Nacional de Investigaciones Científicas y Técnicas [grant number PIP-11220120100415CO], and Natural Sciences and Engineering Research Council of Canada [grant number 170040].