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Limitation of sampling methods to estimate the geographic distribution of Triatominae

Data on the distribution of triatomine species are usually obtained from the detection of peridomestic/domestic colonies, focal sampling of sylvatic populations, and information on the domestic intrusion of wild adult forms. Consequently, the more the synanthropic process of a Chagas disease vector is advanced, the more its geographic range may be precisely known. Thus, the past and recent changes in the geographic range of the most efficient vectors of T. cruzi to humans (T. infestans and R. prolixus) are well known. However, an incomplete knowledge of species distribution exists when these organisms are restricted to sylvatic environments. It is unfeasible to systematically sample over wide areas (wild populations are usually focally sampled) because it is difficult to access certain types of ecotopes, thus making it difficult to investigate these areas. Moreover, in the case of exclusively sylvatic species, the sampling is generally random and, consequently, often unproductive. The sampled subsets are considered isolated species when they may represent components of an unknown continuous population.12 With regard to triatomine species that exhibit a certain level of domestic incursion, their easy detection will depend on some behavioral traits, such as flight ability and attraction to light. The live-baited trap and light trap are the tools currently available to collect wild Triatominae. Unfortunately, both trapping systems only catch starved triatomines and, in the case of the light trap, only adult forms. Thus, the number of bugs a trap would be able to capture in a defined area would be inversely correlated to the nutritional status of the population.16

The decrease of the relative importance of the main domestic triatomine species, accompanied by the demographic transition of populations from rural areas to large urban centers that frequently results in a disordered occupation of forest remnants and the expansion of agricultural lands (led by soy fields) and cattle ranching, increased the relative importance of the once called “secondary” species. The increased attention of these secondary species is reflected by an increasing number of articles studying the process of house invasion by wild species of Triatominae.17-22

 
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