title: High genetic diversity in the Culex pipiens complex from a West Nile Virus epidemic area in Southern Europe.
abstract: BACKGROUND
  The Culex pipiens complex includes the most widespread mosquito species in the world. Cx. pipiens is the primary vector of the West Nile Virus (WNV) in Europe and North America. Cases of WNV have been recorded in Italy since 1998. In particular, wet areas along the Po River are considered some of the most WNV affected areas in Italy. Here, we analyzed the genetic structure of ten Cx. pipiens populations collected in the last part of the Po River including the Delta area.
  
  
  METHODS
  We assessed the genetic variability of two mitochondrial markers, cytochrome oxidase 1 (COI) and 2 (COII), for a total of 1200 bp, and one nuclear marker, a fragment of acetylcholinesterase-2 (ace-2), 502 bp long. The effect of the landscape features was evaluated comparing haplotype and nucleotide diversity with the landscape composition.
  
  
  RESULTS
  The analysis showed a high genetic diversity in both COI and COII gene fragments mainly shared by the populations in the Delta area. The COI-COII network showed that the set of haplotypes found was grouped into three main supported lineages with the higher genetic variability gathered in two of the three lineages. By contrast, ace-2 fragment did not show the same differentiation, displaying alleles grouped in a single clade. Finally, a positive correlation between mitochondrial diversity and natural wetland areas was found.
  
  
  CONCLUSIONS
  The high mitochondrial genetic diversity found in Cx. pipiens populations from the Po River Delta contrasts with the low variability of inland populations. The different patterns of genetic diversity found comparing mitochondrial and nuclear markers could be explained by factors such as differences in effective population size between markers, sex biased dispersal or lower fitness of dispersing females. Moreover, the correlation between genetic diversity and wetland areas is consistent with ecosystem stability and lack of insecticide pressure characteristic of this habitat. The mtDNA polymorphism found in the Po River Delta is even more interesting due to possible linkages between the mitochondrial lineages and different biting behaviors of the mosquitoes influencing their vector ability of arboviral infections.
authors.affiliation: Department of Agronomy, Food, Natural Resources, Animals, & Environment (DAFNAE), University of Padua, Viale dell'Università 16, 35020, Legnaro, PD, Italy.
authors.forename: Mauro
authors.initials: M
authors.lastname: Simonato
authors.affiliation: Department of Agronomy, Food, Natural Resources, Animals, & Environment (DAFNAE), University of Padua, Viale dell'Università 16, 35020, Legnaro, PD, Italy.
authors.forename: Isabel
authors.initials: I
authors.lastname: Martinez-Sañudo
authors.affiliation: Department of Agronomy, Food, Natural Resources, Animals, & Environment (DAFNAE), University of Padua, Viale dell'Università 16, 35020, Legnaro, PD, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Cavaletto
authors.affiliation: Department of Agronomy, Food, Natural Resources, Animals, & Environment (DAFNAE), University of Padua, Viale dell'Università 16, 35020, Legnaro, PD, Italy.
authors.forename: Giacomo
authors.initials: G
authors.lastname: Santoiemma
authors.affiliation: Istituto Tecnico Agrario "O. Munerati", Via Capello 10, 45010, Sant'Apollinare, RO, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Saltarin
authors.affiliation: Department of Agronomy, Food, Natural Resources, Animals, & Environment (DAFNAE), University of Padua, Viale dell'Università 16, 35020, Legnaro, PD, Italy. lmazzon@unipd.it.
authors.forename: Luca
authors.initials: L
authors.lastname: Mazzon
mesh_terms: D000818:Animals; D016000:Cluster Analysis; D003465:Culex / Q000145:classification* / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics; D058872:Epidemics; D014644:Genetic Variation; D006239:Haplotypes; D019476:Insect Proteins / Q000235:genetics; D007558:Italy / Q000453:epidemiology; D024101:Mitochondrial Proteins / Q000235:genetics; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D014901:West Nile Fever / Q000453:epidemiology
chemical_list: D019476:Insect Proteins; D024101:Mitochondrial Proteins; D003576:Electron Transport Complex IV
keywords: Acetylcholinesterase-2; Culex pipiens complex; Cytochrome oxidase; Genetic diversity; Mitochondrial DNA; Mosquitoes; Nuclear DNA; West Nile Virus