Isozyme Evidence of Lack of Speciation Between Wild and Domestic Triatoma Infestans (Heteroptera: Reduviidae) in Bolivia1

Abstract

UÏld and domestic Triatoma b+stans from the Cochabamba region of Bolivia were virtually identical at 19 gene loci coding for enzymes. ìio allele \,.as distinctive of either the wild or the domestic populations. Hence, there is no evidence that the 2 populations are different species. Domestic populations separated by 20 km shoL%.ed statistically significant ' differences in allelic frequencies: this is compatible' with the hypothesis of other authors that migrations of T. iq'2stans are limited Ghen feeding conditions are satisfactory. Fifteen trypanosomatid stocks isolated from wild T. i?zJ>:taiis \,.ere shown by isozyme analysis to be Tr$anosonia rruri. This provides evidence that wild T. i+staizs are involved in the Chagas' disease cycle. The T. crui isozymic strains from wild T. infpjtans were genetically similar to those isolated from domestic T. i+vtans in the same region. Thissupports the hypothesis that there is no speciation between wild and domestic T. injjtai::. and that wild and domestic T. crud cycles may overlap in this region.

Mitochondrial DNA variation of Triatoma infestans populations and its implication on the specific status of T. melanosoma

“…Our results show that the silvatic and domestic T. infestans from Jamach'Uma, Bolivia, share the same haplotype, therefore giving support to similar observations based on allozyme (Dujardin et al 1987) and cytogenetic markers (F Panzera, pers. comm.).…”

“…It has been suggested that silvatic and domestic T. infestans populations may be undergoing a process of isolation. The fact that these two populations presented not only the same gene frequencies at two polymorphic loci but were also infected by the same strain of T. cruzi, prompted the idea that the silvatic populations could be, in fact, feral derivatives of the domestic colonies (Dujardin et al 1987. On the other hand, metric and genetic (based on RAPD profiles) differences between the same silvatic and domestic T. infestans populations have been interpreted as indication of their incipient separation not detected by the allozyme analysis .…”

“…As a consequence it has also been the main target of the Southern Cone Initiative, a triatomine vector control campaign that relies largely on residual insecticides to eradicate domestic and peri-domestic insect populations from infested areas. The success of this control campaign is based on the fact that true natural silvatic T. infestans colonies are very rare and found exclusively in the Cochabamba Valley in Bolivia (Dujardin et al 1987), therefore largely precluding the recolonization of treated areas by insects coming from silvatic foci.…”

“…Although silvatic and domestic T. infestans populations from Bolivia are virtually identical based on allozyme markers (Dujardin et al 1987), morphometric differences between them have been interpreted as an indication of incipient separation . The trend of silvatic T. infestans populations living in rockpiles (associated with guinea-pigs) towards domesticity (and association with humans) is the first step in Schofield's (1988) historical reconstruction hypothesis to explain the current distribution of the species.…”

Wild Triatoma infestans, a potential threat that needs to be monitored

“…Recent reports provide evidence that wild populations of T. infes-Wild T. infestans populations were first reported more than 60 years ago on a rocky hill situated in the immediate outskirts of Cochabamba, an important Bolivian Andean city 2,600 m above sea level (asl) (Torrico 1946). During the 1980s, wild T. infestans were also documented at other sites in the Cochabamba and nearby valleys (Dujardin et al 1987, Bermudez et al 1993. From the late 1990s to the present, new foci have been detected in the Andean departments of Cochabamba, La Paz, Chuquisaca and Potosi (Noireau et al 2005).…”