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Environmental variables and the distribution of other Triatominae

Costa et al.78 described the geographic distribution of T. brasiliensis in the northeast of Brazil. These authors used 22 environmental variables, including climate data (temperature, precipitation, vapor pressure, etc.), terrain elevation, and land cover data, which were analyzed with the genetic algorithm for rule-set production (GARP) tool. The results showed the allopatric and parapatric distribution of four

T. brasiliensis populations. T. b. brasiliensis occupies regions at 16.5—22.5°C that experienced 10—35 mm of precipitation. T. b. juazeirensis was similar but had a narrower ecologic altitude. T. b. macromelasoma was found at the highest altitude, occupying two potentially disjunct ecological zones where annual mean temperature ranges from 11.0°C to 23.5°C and annual mean precipitation of 10—45 mm. T. b. melanica appears restricted to a narrow ecological zone with annual temperatures between 18°C and 19°C and precipitation of 20—35 mm.

Studying T. brasiliensis and T. melanica, two species occupying the northern and southern extremes of the geographic distribution of the brasiliensis species complex, Souza et al.77 analyzed the ecological niche overlap between them. They compared the geographic distribution of the species using generalized linear models fitted to elevation and current data on land surface temperature, vegetation cover, and rainfall recorded by Earth observation satellites for northeastern Brazil. The ecological niche models show that the environmental spaces currently occupied by T. brasiliensis and T. melanica are similar although not equivalent, and associated with the caatinga ecosystem.

Carbajal de la Fuente et al.101 showed that the sylvatic triatomine species of eastern Brazil, T. pseudomaculata and T. wygodsinskyi, have allopatric but not partially sympatric populations as previously accepted. This was discovered after studying their geographic distributions characterized by temperature, VPD, vegetation, and altitude estimated from information provided by the satellite remote sensors AVHRR and moderate-resolution imaging spectroradiometer (MODIS). In this study, the 8 X 8 km spatial resolution of the AVHRR imagery more accurately described the species distributions compared to the MODIS imagery. Both satellites were able to produce a >85.7% correct classification for presence and absence from point data.

Peterson et al.102 studied the joint distribution of Triatoma species of the Protracta complex with packrat species (Neotoma species) using terrain elevation, hydrological, and climate data, which were analyzed with the ecological niche modeling GARP tool. This study showed a close association between the distribution of T. barberi (one of the main vector species for T. cruzi transmission in Mexico) and N. mexicana, a finding that led these authors to suggest a specific interaction between the species.

Gurgel-Goncalves and Cuba103 studied the distribution of R. neglectus in Central Brazil, using data on biophysical variables (altitude, temperature, vegetation, and rainfall) obtained from the Worldclim database with information about the distribution of palm tree and bird species. This study showed that this Rhodnius species is closely associated with dry areas of the Cerrado-Caatinga corridor and partially overlaps with the considered palm tree and birds species. In a more recent article and using a similar methodology, Gurgel-Goncalves et al.104 later reported the distribution of 16 triatomine species among the most frequent and synanthopic in Brazil and showed a strong association between species distribution and the biome in which they are distributed.

Arboleda et al.36 studied the geographic distribution of R. pallescens using the 1982—2000 monthly time series of AVHRR imagery at the 8 X 8 km spatial resolution mentioned above. The analysis showed that the minimum VPD is the most important variable for determining the geographic distribution of the species, along with its stenohydric status. The study also showed the potential distribution of most species of Rhodnius, except R. domesticus, R. neglectus, and R. nasutus, a result probably derived from the evolution of common ancestors among the species groups. Using correlation analysis and logistic regression, the distribution of domestic Triatominae species in Guatemala was studied.105 Results of this study showed that the distribution of T. nitida is positively associated with places of lower average minimum temperature, whereas the past distribution of R. prolixus corresponded with areas of maximum absolute temperature and relative humidity.

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