Enzyme polymorphism among Triatoma infestans (Hemiptera: Reduviidae) colonies.

Allozyme variability in populations of the Chagas's disease vector Triatoma infestans (Klug) was investigated by means of starch gel electrophoresis. Samples were taken from nine laboratory colonies established with individuals collected at different localities across the range of this insect in South America. Zymograms for proteins coded by a total of 17 loci were obtained. Allele frequencies, proportion of polymorphic loci (P), mean heterozygosity per locus (H), similarity (S), and identity (I) indices, genetic distance (D), and gene flow among populations were estimated. Mean values for P = 58.53% and for H = 0.095, indicating an important level of genetic variability. There was remarkable similarity among the colonies (mean I = 0.9946). Estimated gene flow among populations was high. However, on the basis of the known natural history of T. infestans, the uniformity of allele frequencies among populations may be interpreted as the result of the recent and rapid dispersal of the species from the site of origin in the Cochabamba Valley, Bolivia.