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Insight into the biology and ecology of Triatominae in the silvatic environment

In many areas of Latin America, the domestic intrusion of species until now considered as strictly silvatic has led to more interest in their study. The observation of a species in its natural environment supplies a basic pattern which may help to understand its process of adaptation to a new environment (for instance, when populations are displaying synanthropic behavior). However, the studies carried out in the silvatic environment are often fragmentary, principally because the field observations and collections of specimens are laborious and time-consuming.

Interest of a trapping device

Searching for domestic Triatominae bugs in rural houses of Latin America is an important activity carried out by Health Services in every country affected by Chagas disease. In general, infestation by Triatominae in the domestic and perido- mestic structures is recorded by active search by means of timed manual collection using a dislodging spray and a normal light torch. However, as demonstrated by Abad-Franch et al.,69 standard vector searches used by Control Programs, had low sensitivity except in certain singular circumstances. They suggest that many infestation foci may go undetected during routine surveys, especially when vector density is low. Undetected foci can cause control failures and induce bias in entomological indices; this may confound disease risk assessment and mislead program managers into flawed decision making. A pheromone-containing infective box, was recently presented as a promising new tool to detect (and even control) indoor populations of T. infestans.70 On the other hand, a new method for finding intradomestic bugs was proposed, based on the unexplored property of Triatominae feces to fluoresce when exposed to UV light.71 Normally, a torch light is used to search for triatomines within the houses. Replacing the regular light bulb by an UV bulb could substantially improve the early detection of residual or emergent populations of domestic triatomine bugs and contribute to a successful evaluation and awareness of Chagas disease vectors.

The detection and collecting of sylvatic Triatominae in their natural environment, a necessary precondition to biological and ecological observations, would greatly benefit from the use of trapping devices.2 In many cases, it provides the only way to detect and collect bugs in less accessible ecotopes, such as rock piles, hollow trees, or palm trees, and avoids ecological damages caused, e.g., by tree dissection or logging. Because starved bugs are preferentially attracted, the device does not allow an estimating of the accurate density of insects and population structure. Nevertheless, it allowed some interesting observations: thus, for instance, wild populations of T. infestans, T. brasiliensis, or T. pseudomaculata may exhibit high motivation for food search during the daylight hours (Noireau, unpublished data) whereas they are supposed to leave their refuges and make for food source during

the night.72

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