Genetic Differences BetweenCulex pipiensf. molestus andCulex pipiens pipiens(Diptera: Culicidae) in New York

Abstract

The definition and phylogenetic placement of the autogenous molestus form of Culex pipiens has puzzled entomologists for decades. We identified genetic differences between Cx. p. pipiens (L.) and Cx. pipiens f. molestus Forskål in the SH60 fragment described previously. Single-strand conformation polymorphism analysis, cloning, and sequencing of this fragment demonstrated high polymorphism within and among individual Cx. p. pipiens, with common SH60 variants shared among individuals from distant locations. In contrast, Cx. pipiens f. molestus from New York City each contained a single SH60 variant, which was not identified in any other Cx. p. pipiens specimens analyzed. Supporting microsatellite analysis demonstrated significant but reduced gene flow between Cx. p. pipiens and Cx. pipiens f. molestus in New York relative to Cx. p. pipiens populations in New York and California. Results are discussed in the context of two contrasting hypotheses regarding the origin of Cx. pipiens f. molestus populations. KeywordsCulex pipiens pipiens; Culex pipiens f. molestus; genetics; microsatellites; West Nile virus Culex pipiens f. molestus Forskål is a morphologically identical ecological biotype of Culex pipiens pipiens (L.) defined by a host of behavioral and physiological characteristics. In contrast to Cx. p. pipiens, Culex pipiens f. molestus has the ability to produce eggs without a vertebrate bloodmeal (autogeny); can mate in confined spaces (stenogamy); foregoes winter diapause; occupies subterranean environments with limited surface access; and feeds readily on mammals, including humans (Mattingly 1952, Vinogradova 2000. The potential public health importance of the mammal-feeding molestus biotype of Cx. p. pipiens as a human disease vector has led to a search for markers to readily identify these two forms.Despite the numerous biological differences that distinguish Cx. pipiens f. molestus from Cx. p. pipiens, reliable identification of Cx. pipiens f. molestus by using morphology and/or molecular tools and phylogenetic placement of this form within the Cx. pipiens complex NIH Public Access Polymerase Chain ReactionThe relative quality of all DNA extractions was evaluated by PCR amplification of a fragment of the mitochondrial NADH dehy-drogenase subunit four (ND4) by using arthropod-specific primers (Simon et al. 1994, Kent andNorris 2005). Molecular identification for all samples was obtained using the Crabtree et al. bromide-stained 2% agarose gels. All gels were run with GeneRuler 100-bp molecular mass marker (MBI Fermentas, Hanover, MD). p. pipiens were purified with the QIAquick PCR Purification or Gel Extraction kits (QIAGEN, Valencia, CA) and cloned using chemically competent TOP10 One Shot Escherichia coli (TOPO TA Cloning kit with pCR 2.1-TOPO vector catalog K4500-01, Invitrogen, Carlsbad, CA) to evaluate differences between SH60 variants. Transformed E. coli were grown at 37°C overnight on LB agar plates containing 50 µg/ml carbenicillin, and transformed colonies were identified by blue-white...

How often do they meet? Genetic similarity between European populations of a potential disease vectorCulex pipiens

“…We used eight primers developed for Cx. pipiens (4, 17–19) (CQ13, CQ29, CxpGT9, CxpGT20, CxpGT40, CxpGT46, CxpGT51, and CxpGT53) and followed the PCR-protocols given in the original paper. The PCR-products were run on a MegaBase using dyed primers.…”

“Bird biting” mosquitoes and human disease: A review of the role of Culex pipiens complex mosquitoes in epidemiology

“…pipiens complex are identifiable by the shape of the male genitalia (Barr, 1957; Dobrotworsky, 1967), this trait cannot be used to identify females, the primary target of surveillance efforts. Nonetheless their close evolutionary association has been repeatedly supported by genetic analyses (Kent et al, 2007; Miller et al, 1996) as well as by the relative transferability of genetic markers across species (Smith et al, 2005) . Further, Cx pipiens has two recognized subspecies, Cx.…”

Evaluation of Seasonal Feeding Patterns of West Nile Virus Vectors in Bernalillo County, New Mexico, United States: Implications for Disease Transmission

“…Specifically, an understanding of mosquito-feeding patterns can help to elucidate the roles of various mosquito species in viral amplification, maintenance of the enzootic cycle, and as bridge vectors to nonenzootic hosts. However, a clear determination of mosquito host utilization is complicated by the fact that certain mosquito species are known to alter their feeding behavior over the course of the mosquito season (Edman and Taylor 1968, Edman et al 1974, Kilpatrick et al 2006, Kent et al 2007; Molaei et al 2007). For example, certain Culex species have been found to feed primarily on birds early in the mosquito season, and as the season progresses they take an increasingly larger proportion of their bloodmeals from mammals (Turell et al 2001, Apperson et al 2002, Zinser et al 2004, Molaei et al 2006, Kent et al 2009).…”

“…All three of these species have been judged to be competent WNV vectors (Turell et al 2001, Cupp et al 2004, Kilpatrick et al 2005, Molaei and Andreadis 2006, DiMenna 2006b), and the roles of both Cx. tarsalis (Kent et al 2007) and Cx. quinquefasciatus (Samuel et al 2004, Molaei et al 2007, Garcia-Rejon et al 2010) in WNV transmission have been described elsewhere in their range.…”