Variabilidade genética em populações de Anopheles darlingi (Diptera: Culicidae) e relação ao comportamento da atividade de picar, analisada por RAPD

Abstract

RESUMODuas populações naturais de Anopheles darlingi foram analisadas quanto aos padrões de variabilidade genética relacionados ao comportamento hematofágico, cujas coletas foram realizadas no intra, peri e extradomicíio, em dois municípios do Estado do Amazonas: Coari e Manaus. Os resultados evidenciaram amplo número de fragmentos polimórficos, bem como elevada variabilidade genética nessas populações. Na população de Coari, a porcentagem de locos polimórficos (P) e heterozigosidade (He) variou de 77,63% -84,86% e 0,2851 -0,3069, respectivamente, sendo a maior variabilidade genética detectada nas subpopulações do intradomicílio, e a menor nas do peridomicílio. A população de Manaus mostrou variabilidade genética similar a de Coari (P= 75% -78,94% e He= 0,2732 -0,2741), onde também foi detectada maior variabilidade genética no intradomicílio. Os dados de qui-quadrado (x 2 = 695,89; GL= 304; P < 0,001) e de F ST (F ST = 0,0775 ± 0,0072) foram significativos, indicando uma estruturação micro geográfica, decorrente de alguma redução no fluxo gênico. Esses resultados podem ser interpretados como sendo em resposta à pressão de seleção face aos inseticidas, que permanecem residuais nas paredes dos domicílios. PALAVRAS-CHAVE:Anopheles darlingi, malária, variabilidade genética, RAPD.Genetic variability in populations of Anopheles darlingi (Diptera: Culicidae) and relationship to biting activity behavior as analyzed by RAPD ABSTRACT Two natural populations of Anopheles darlingi, collected in the intra, peri and extra domicile of two townships in the State of Amazonas, Coari and Manaus, were assayed as to their hematophagic behaviour-related genetic variability patterns. Findings revealed a large number of polymorphic fragments as well as high genetic variability in these populations. Polymorphic loci rate (P) and heterozygosity (He) in the Coari population varied between 77.63% -84.86% and 0.2851 -0.3069, respectively, with the highest and lowest genetic variability being detected in the intra-and peri-domicile sub-populations, respectively. The Manaus population showed genetic variability and heterozygosity similar to those in Coari (P= 75% -78.94% and He= 0.2732 -0.2741), where higher genetic variability was detected in the intra-domicile as well. Chi-square data (x 2 = 695.89; GL= 304; P < 0.001) and FST (F ST = 0.0775 ± 0.0072) were significant, indicating micro-geographic structuring resulting from some decreased gene flow. These findings point out the selective pressure response to the residual insecticide remaining on household walls after the entire neighbourhood had been sprayed with it during malaria control programs.

Adaptative processes, control measures, genetic background, and resilience of malaria vectors and environmental changes in the Amazon region

“…The population of A. darlingi of Manaus showed genetic variability similar to that of Coari (P = 75-78.94% and H E = 0.2732-0.2741), where greater genetic variability was also detected indoors ( Table 2). The Chi-square data (v 2 = 695.89, df = 304, P \ 0.001) and F ST values (F ST = 0.0775 ± 0.0072) between Coari and Manaus were significant, indicating microgeographic structuring due to a reduction in gene flow (Silva et al, 2010).…”

“…Tadei et al (2010) emphasized the importance of the occurrence of Oryza perennis (wild rice) Moench in areas of flooded forest, where the immature forms of Anopheles develop among the roots and leaves. Anopheles darlingi, the most important species involved in malaria transmission in the Amazon Basin presents high behavioral variability (Hiwat & Bretas, 2011), genetic plasticity (Scarpassa & Conn, 2007;Silva et al, 2010) and resilience, adapting very well to environmental changes, particularly those caused by anthropic activities. This vector is found in areas where it did not occur previously and returns to areas where it had already been controlled (Hiwat & Bretas, 2011), which demonstrates the great adaptability of this species.…”

“…The hematophagic behavior of A. darlingi occurs in the intra-, peri-, and extradomicile areas, relevant parameters in studies of Anopheles populations because they show the patterns of malaria transmission mechanisms (Tadei et al, 1993. A study by Silva et al (2010) that used molecular markers patterns of genetic variability to examine intra-, peri-, and extradomicile hematophagic behavior in two populations of A. darlingi of Coari and Manaus (Amazonas) revealed high genetic variability in these populations.…”

“…However, A. darlingi lacks genetic and evolutionary studies to assist in addressing unanswered basic questions about the vector-parasite and its interactions with the human host. (Ayala, 1982) b Nei's unbiased estimate (Nei,1978) (Silva et al, 2010) Several mosquito genomes have been published. Anopheles gambiae Giles, 1902 (subfamily Anophelinae), the vector of malaria in Africa, has 278, 253,050 bp, according to Holt et al (2002); Aedes aegypti Linnaeus, 1762 (subfamily Culicinae), transmitter of Dengue, Zika, and Chikungunya virus, has 1.38 Gbp (Nene et al, 2007); and Culex quinquefasciatus Say, 1823 (subfamily Culicinae), vector of arbovirus, has 579,042,118 bp (http://cquinquefascia tus.vectorbase.org/Culex_quinquefasciatus/Info/Index).…”