A Multi-species Bait for Chagas Disease Vectors

Abstract

Background

Triatomine bugs are the insect vectors of Trypanosoma cruzi, the etiological agent of Chagas disease. These insects are known to aggregate inside shelters during daylight hours and it has been demonstrated that within shelters, the aggregation is induced by volatiles emitted from bug feces. These signals promote inter-species aggregation among most species studied, but the chemical composition is unknown.

Methodology/Principal Findings

In the present work, feces from larvae of the three species were obtained and volatile compounds were identified by solid phase microextraction-gas chromatography-mass spectrometry (SPME-GC-MS). We identified five compounds, all present in feces of all of the three species: Triatoma infestans, Panstrongylus megistus and Triatoma brasiliensis. These substances were tested for attractivity and ability to recruit insects into shelters. Behaviorally active doses of the five substances were obtained for all three triatomine species. The bugs were significantly attracted to shelters baited with blends of 160 ng or 1.6 µg of each substance.

Conclusions/Significance

Common compounds were found in the feces of vectors of Chagas disease that actively recruited insects into shelters, which suggests that this blend of compounds could be used for the development of baits for early detection of reinfestation with triatomine bugs.

Author Summary

Chagas disease is a parasitic infection affecting approximately 12 million people, and is considered to be one of the most severe burdens for public health in Latin America. Control of the disease is based on attempted elimination of domestic populations of triatomine bugs, the insects transmitting the disease to humans, by means of insecticide spraying. Currently, vigilance programs monitoring triatomine reinfestation processes in houses are performed by manual search for bugs. Effective and sustainable new methods allowing continuous monitoring of domestic triatomine populations are required. Based on the fact that the insects hide in dark refuges that are marked by volatile signals emitted in their feces, we screened the feces of three species for volatile compounds common to these prominent vectors. The potential for these odors to promote triatomine aggregation was evaluated and we present evidence that a synthetic blend of these substances is capable of recruiting bugs into shelters, mimicking the natural pheromone. This blend may be used to develop a bait to monitor triatomine reinfestation processes in a similar manner as is used commonly for the monitoring of agricultural pests.