Genetic-morphometric variation in Culex quinquefasciatus from Brazil and La Plata, Argentina

Abstract

Variation among natural populations of Culex (Culex) Key words: Culex pipiens complex -Culex quinquefasciatus -clines -molecular identification -wing morphologyThe Culex (Culex) pipiens complex in the Americas is composed of two main species, Culex (Culex) quinquefasciatus Say, which is adapted to tropical zones and Cx. pipiens L., which is found in temperate zones. In intermediate areas, these two members can mate yielding hybrids and intermediate forms (Barr 1957), through the processes of gene flow and introgression (Humeres et al. 1998, McAbee et al. 2008, Kothera et al. 2009). Mosquitoes of the Cx. pipiens complex are potential vectors of filarid worms in tropical and subtropical areas (Bockarie et al. 2009) and diverse arboviruses, including West Nile virus (Apperson et al. 2004, Cook et al. 2006.Adult females and immature stages of the Cx. pipiens complex are morphologically similar. The differentiation of adult males can be made by analysis of genitalia, which includes measuring the DV/D ratio of the dorsal arms of the aedeagus in the phallosome, as reported by Sundararaman (1949). Because members of the Cx. pipiens complex have a broad geographical distribution, other phenotypical differences beyond those of the male genitalia can be found. For example, some wing characters can also been used for morphologic identification of mosquito species.Financial support: FAPESP (05/50225-2, 06/02622-5) SAM and CM contributed equally to this work (FAPESP 06/57272-9 and 07/1665-5, respectively The taxonomic keys compiled by Forattini (2002) compared wing morphology of adult females. In that report, the subcosta vein (Sc) was reported to bind with the costa vein (C) before the bifurcation of the radial 2+3 vein (R 2+3 ) in Cx. quinquefasciatus, whereas in Cx. pipiens, the Sc vein binds to vein C at the same point or beyond the R 2+3 bifurcation. To our knowledge, these findings have not been investigated in other geographically distant populations. Linam and Nielsen (1962) reported that Bekku (1956), in Northern Japan, also attempted to use wing characteristics [the length of radial cell R 2 (second marginal cell) divided by the length of vein R 3 ] to distinguish adults of the pipiens group. The results of Bekku (1956) were inconclusive, which was later explained when Kamura (1958) found that these particular wing measurements varied with the temperature of the environment. Nielsen and Rees (1961) and Linam and Nielsen (1962) reported that the most reliable method of separating females of Cx. pipiens and Cx. quinquefasciatus was by a wing measurement value obtained by dividing the length of the cell R 2 by the length of the vein R 2+3 (R 2 /R 2+3 ratio). These authors reported the value of this ratio to be about 5.0 in Cx. pipiens and 3.0 or less in Cx. quinquefasciatus, with intermediate values present in the hybrids. However, these studies did not evaluate morphometric data among mosquito populations and climatic/geographic gradients.In insects, the phenotypic variations among members of species complexes have...

Low genetic diversity in Wolbachia-Infected Culex quinquefasciatus (Diptera: Culicidae) from Brazil and Argentina

“…quinquefasciatus cox1 haplotypes is incongruent with the results from the ace2 intron and for mosquitoes of hybrid origin (with Cx. pipiens) found by MORAIS et al 30 , potentially because ace2 mutates slower than cox1 20 . This suggests that mitochondrial DNA does not distinguish taxa within the pipiens subgroup.…”

“…The low frequency of H2 in Chapecó suggests that this city may represent the limits of haplotype's northern distribution. However, the La Plata population, which is genetically confirmed as a hybrid 30 , contains individuals sharing nd4 and cox1 genes with pure Cx. quinquefasciatus elsewhere.…”

“…Hybrids of quinquefasciatus/pipiens occur in Uruguay and central Argentina, whilst Cx. pipiens occupies regions southward into Argentina 4,30 .…”

Comparison of Biological Attributes ofCulex quinquefasciatus(Diptera: Culicidae) Populations from India

“…quinquefasciatus biology and insecticide susceptibility [15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Recently, Suman et al [25,28] reported significant variations in morphology among eggs and life table attributes from the four strains of Cx.…”

Caracterização populacional de Aedes scapularis (Diptera; Culicidae): aspectos moleculares, morfofuncionais e morfológicos.

“…A partir dos dados posicionais desses marcos, pode-se estimar a variação morfométrica intra e interpopulacional, comparar a magnitude das variações (Dujardin, 2008). Um recente estudo de nosso grupo exemplificou essa aplicação teórica no complexo Culex pipiens (Morais et al, 2010). …”