Interpopulation Variability AmongPanstrongylus megistus(Hemiptera: Reduviidae) from Brazil

Abstract

Comparisons were made among Panstrongylus megistus (Burmeister) from three areas of Brazil (Bahia, Minas Gerais, and Santa Catarina), where populations differ with regard to their degree of association with human dwellings. The following characters were studied: morphology of the eggs and the male genitalia; morphometry of the head and thorax; isoenzyme profile; enzymatic activity of the alpha-glycerophosphate dehydrogenase (alpha-GPDH); and cytogenetics. In general, differences were observed in the weight, diameter, and length of the egg among Bahia, Minas Gerais, and Santa Catarina populations. Differences were not observed in the architecture of the egg exochorion. The size of the median process of the pygophore of the male genitalia of individuals from Bahia differed from the other two populations. The Minas Gerais population presented the largest number of denticles in the endosome process. The morphometry of the head and thorax differentiated Santa Catarina from the Bahia and Minas Gerais populations. Phosphoglucomutase (EC 5.4.2.2., PGM) was the only enzyme out of 11 that showed polymorphism; the population from Minas Gerais was most polymorphic, whereas the population from Santa Catarina was monomorphic. Study of the alpha-GPDH activity and cytogenetics did not reveal differences among the three populations. Analysis of all the characters studied together with information on these three populations from previous publications allowed a phenogram to be constructed. Two distinct groups were evident, one represented by Santa Catarina and the other by Bahia and Minas Gerais. Considering the greater variability of the Minas Gerais and Bahia populations, we propose the inclusion of these states within the area of origin of P. megistus.

Phenetic analysis of Panstrongylus megistus Burmeister, 1835 (Hemiptera: Reduviidae: Triatominae) in the State of Paraná-Brazil

“…Barbosa et al, (2003) analyzed three populations of P. megistus and found polymorphism for the PGM enzyme, for which no polymorphism was observed in the present study. In the 1950's, the north region of the State of Paraná received immigrant groups from various places in Brazil due to the coffee plantations expansion (LUZ -personal communication) and P. megistus could have come with the human population, and this could explain such diversity.…”

Lack of Segregation between Two Species of Chagas Disease Vectors

“…9,10 Studies on population diversity of P. megistus in different regions in Brazil reported distinct degrees of adaptation to domestic habitats. [11][12][13][14][15] In northeastern states such as Bahia, P. megistus is well adapted to domestic habitats, but its presence in sylvatic foci has not been proven. 11,12 However, in southeastern states, it can be found in sylvatic and domestic habitats.…”

Population dynamics of Triatoma vitticeps (Stål, 1859) in Itanhomi, Minas Gerais, Brazil

“…However, Chagas disease is rare in the area, a prevalence of only 0.4% has been recorded as part of a national serological survey (Camargo et al 1984). It is not known whether the low transmission of T. cruzi to man is due to characteristics of the vector (the long interval between feeding and defecation) or the strain of parasite involved.Among the available taxonomic marker techniques, morphometry of the head, random amplified polymorphism of DNA (RAPD) and isoenzyme analysis have been most used in triatomine population studies (Costa et al 1997, Dujardin et al 1998, Borges et al 2000, Soares et al 2001, Barbosa et al 2003. We used these three techniques to investigate T. vitticeps population dynamics in the Itanhomi district.…”