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Memorias del Instituto de Investigaciones en Ciencias de la Salud

On-line version ISSN 1812-9528


LOPEZ, E et al. Morphometric differences in Triatoma infestans populations from the fastern and western regions of Paraguay. Mem. Inst. Investig. Cienc. Salud [online]. 2002, vol.1, n.1, pp.51-57. ISSN 1812-9528.

ABSTRACT In order to compare Triatoma infestans populations from different geographical origin and to study morphometric variations of male and female triatomines, populations from 4 departments endemic for Chagas disease were studies within the National Program of Chagas Control. Morphometric characters, 7 in the head and 4 in each wing, of 150 specimens were measured. T test was used to measure the differences bettween means and the uni and multi-variate analysis were used to evaluate size and conformations variables. The sexual dimorphism in size, with females being significantly bigger than males, is a general rule for triatomines which was confirmed by this study. Metric differences were also found, when comparing male (P< 0.01) and female (P<0.05) insects from Easterm and Western regions, being smaller those from the former region. In the uni-variate non-parametric analysis, significant differences were observed in eye conformation and size (P< 0.05) as well as in total length and head conformation(P<0.01). In specimens from the Departament of Paraguari, both variables were smaller. In the analysis of the main components, no significant differences were observed. However, in the discriminating analysis the populations of the Western region (Boqueron and Presidente Hayes) showed a trend of conforming only one group while the populations of the Eastern region (Paraguari and Cordillera) tended to be different from the former and between them (P < 0.0001). These results support the hypothesis stating that differences between populations could be attributed to environmental factors. The evaluation of the shape or the persistence of these differences in successive generations maintained in laboratory could corroborate the existence of genetic variations between populations.

Keywords : Morphometric; triatoma infestans; geografic differentiation.

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