Genetic variability among Anopheles species belonging to the Nyssorhynchus and Anopheles subgenera in the Amazon region / Variabilidade genética entre espécies de Anopheles dos subgêneros Nyssorhynchus e Anopheles da região Amazônica

INTRODUCTION: Isoenzymatic analyses were performed involving species of the Nyssorhynchus and Anopheles subgenera in order to estimate the intra and interspecies genetic variability. METHODS: Mosquitoes were caught at different localities in the Amazon region. The collection and rearing of mosquitoes in the laboratory followed specific protocols. For the genetic variability analyses, the technique of horizontal electrophoresis on starch and starch-agarose gel with appropriate buffer systems was used. The alloenzyme variation was estimated using the Biosys-1 software. RESULTS: Out of the 13 loci, eight were polymorphic. Anopheles nuneztovari presented the largest number of alleles per locus, while the smallest number was detected in Anopheles marajoara from Macapá. The largest number of polymorphic loci was found for Anopheles marajoara from Maruanum and the smallest for Anopheles benarrochi (Guayará Mirim). Anopheles darlingi (Macapá) presented the greatest heterozygosity (Ho = 0.167 ± 0.071), while the lowest heterozygosity (Ho = 0.045 ± 0.019) was observed in Anopheles intermedius (Pacoval) of the subgenus Anopheles. Wright's F coefficient revealed considerable genetic structuring between the populations of Anopheles darlingi (Fst = 0.110) and between the populations of Anopheles marajoara (Fst = 0.082). CONCLUSIONS: Considering all the species studied, the genetic distance ranged from 0.008 to 1.114. The greatest distance was between Anopheles mattogrossensis and Anopheles oswaldoi, while the smallest was between the Anopheles benarrochi populations.

INTRODUÇÃO: Análises isoenzimáticas foram realizadas envolvendo espécies dos subgêneros Nyssorhynchus e Anopheles para estimar a variabilidade genética intra e interespecífica. MÉTODOS: Os mosquitos foram capturados em diferentes localidades da região Amazônica. A coleta e a criação dos mosquitos em laboratório foram conforme protocolos específicos. Na análise da variabilidade genética empregou-se a técnica de eletroforese horizontal em géis de amido e amido-agarose com sistemas tampões apropriados. A variação alozímica foi estimada pelo Programa Biosys-1. RESULTADOS: Dos 13 loci, oito foram polimórficos. Anopheles nuneztovari apresentou o maior número de alelos por loco, sendo o menor detectado para Anopheles albitarsis (Macapá). O maior número de loci polimórficos foi detectado em Anopheles marajoara (Maruanum) e o menor, em Anopheles benarrochi (Guayará Mirim). Anopheles darlingi (Macapá) apresentou a maior heterozigosidade (Ho = 0,167 ± 0.071) e a menor (Ho = 0,045 ± 0.019) foi observada em Anopheles intermedius (Pacoval) do subgênero Anopheles. O coeficiente F de Wright evidenciou considerável estruturação genética entre populações de Anopheles darlingi (Fst= 0,110) e entre as populações de Anopheles marajoara (Fst= 0,082). CONCLUSÕES: Considerando todas as espécies estudadas, a distância genética variou de 0,008 a 1,144, onde a maior distância foi entre Anopheles mattogrossensis e Anopheles oswaldoi e a menor, entre as populações de Anopheles benarrochi.

Variability and genetic differentiation among Anopheles Ano. intermedius Chagas, 1908 and Anopheles (Ano.) mattogrossensis Lutz & Neiva, 1911 (Diptera: Culicidae) from the Brazilian Amazon

Anopheles (Anopheles) intermedius and Anopheles (Ano.) mattogrossensis are Brazilian anopheline species belonging to the scarcely studied Anopheles subgenus. Few studies have been done on the genetic differentiation of these species. Both species have been found infected by Plasmodium and are sympatric with other anopheline species from the Nyssorhynchus subgenus. Eighteen enzymatic loci were analyzed in larval specimens of An. intermedius and An. mattogrossensis aiming to estimate the variability and genetic differentiation between these species. An. mattogrossensis population showed higher genetic variability (P = 44.4 and Ho = 0.081 ± 0.031) than that of An. intermedius (P = 33.3 and Ho = 0.048 ± 0.021). Most analyzed loci showed genotypic frequencies according to Hardy-Weinberg equilibrium, except for LAP1 and LAP2 in An. intermedius, and EST1 and PGM loci in An. mattogrossensis. The genetic distance between these species (D = 0.683) was consistent with the inter-specific values reported for Anopheles subgenus. We verified that the polymorphism and heterozygosity percentile values found in both species and compared to those in the literature, showed no relation between the level of isozyme variability and geographical distribution. The low variability found in these two species is probably more related to the niche they occupy than to their geographic distribution.

Isoenzymatic variability among five Anopheles species belonging to the Nyssorhynchus and Anopheles subgenera of the Amazon region, Brazil

An isoenzymatic comparative analysis of the variability and genetics differentiation among Anopheles species was done in populations of An. (Nys.) intermedius and An. (Ano.) mattogrossensis of the Anopheles subgenus, and of An. darlingi, An. albitarsis and An. triannulatus of the Nyssorhynchus subgenus, with the aim of detecting differences between both subgenera and of estimating the degree of genetic intere specific divergence. Samples from Macapá, State of Amapá and Janauari Lake, near Manaus, State of Amazonas, were analyzed for eight isoenzymatic loci. Analysis revealed differences in the average number of alleles per locus (1.6-2.3) and heterozygosity (0.060-0.284). However, the proportion of polymorphic loci was the same for An. (Nys.) darlingi, An. (Nys.) triannulatus and An. (Ano.) mattogrossensis (50 percent), but differed for An. (Nys.) albitarsis (62.5 percent) and An. (Ano.) intermedius (25 percent). Only the IDH1 (P > 0.5) locus in all species studied was in Hardy-Weinberg equilibrium. The fixation index demonstrated elevated genetic structuring among species, based on values of Fst = 0.644 and genetic distance (0.344-0.989). Genetic difference was higher between An. (Nys.) triannulatus and An. (Ano.) intermedius (0.989) and smaller between An. (Nys.) albitarsis sensu lato and An. (Nys.) darlingi (0.344). The data show interspecific genetic divergence which differs from the phylogenetic hypothesis based on morphological characters

Enzymatic variability in Aedes aegypti (Diptera: Culicidae) populations from Manaus-AM, Brazil

Eighteen enzymatic loci were analysed in Aedes aegypti populations from four neighbourhoods in the city of Manaus. The analyses showed that the Downtown population was the most polymorphic (p = 55.6 percent) with higher observed and expected mean heterozygosities (Ho = 0.152 ± 0.052; He = 0.174 ± 0.052, respectively). The least variability was detected in the Coroado and Cidade Nova populations, both with polymorphism of 44.4 percent. The latter population presented the least observed heterozygosity (Ho = 0.109 ± 0.037). Wright's F statistics showed that the mean value of Fis was higher than that of Fst (Fis = 0.164 > Fst = 0.048), and from analysis of molecular variance (AMOVA) it was found that 95.12 percent of the variability is found within populations indicating a certain intra-population differentiation possibly of the microgeographic structure resulting from some barrier in the random coupling. Although the four populations were similar genetically (D = 0.003 to 0.016), the 4.88 percent differentiation was significant