Thermo-tolerance, climatic variability and geographical distribution of Chagas disease vectors

DE LA VEGA, GJ; MEDONE, P; CECCARELLI, S; RABINOVICH, J; SCHILMAN, P.E.

Portland

Congreso; LXII Annual Meeting of the Entomological Society of America (ESA); 2014

An understanding of the relationship between physiological traits and geographic range limits of vector species is increasingly urgent to predict the potential effect of global warming not only on the geographic distribution of vector species but also on disease transmission risk. Like in many other insect species, the geographical distributions of Chagas´ disease vectors, is affected by temperature. This work examines experimentally for the first time the range of thermo-tolerance in two of the most important vectors of Chagas disease, Triatoma infestans in the Southern South America and Rhodnius prolixus in the Northern South America and Central America, and test the climatic variability hypothesis. We measured and compared for those two species: the critical thermal maxima (CTmax) and the upper lethal temperature (ULT) (measured by thermo-limit respirometry), chilled coma recovery (i.e., the time to recovery from a 4 hours 0°C), and the critical thermal minima (CTmin).We also identified macroclimatic variables that could potentially limit the distribution of both species, and analyzed their variation across the geographical range of both species. We found a significant wider range of thermo-tolerance for T. infestans as compared with R. prolixus. Ecological niche modeling corroborated the links between macroclimatic variables and suitable areas for their distribution, with the minimum temperature of the coldest month as the most important abiotic factor for the distribution of both species. Combining correlative and mechanistic approaches it is possible to explain the southern limit distribution for both species in terms of physiological constraints. The greater temperature tolerance of T. infestans compared to R. prolixus supports the climatic variability hypothesis that explains Rapoport´s rule in physiological terms.