The field of morphometrics is developing quickly. Recent advances have enabled geometric techniques to be applied to many zoological problems, particularly those involving epidemiologically-relevant mosquitoes. Herein, we briefly introduce geometric morphometric (GM) techniques and then review selected groups of mosquitoes (Culicidae) to which those techniques have been applied. In most of the reviewed cases, GM was capable of satisfactorily discriminating among the tested groups primarily when the studies considered differences within and among species, sexual dimorphism, treatments and the separation of laboratory strains. Although GM approaches have developed quite rapidly, some caution must be taken during data processing for a reliable biometrical approach, such as allometry and asymmetry analyses, scale removal and wing clarification staining for landmark digitization. We also critically forecast directions in this field and discuss how the creation of image databases should enhance species identification in culicids.
Wolbachia are α-proteobacteria that were first reported in Culex pipiens mosquitoes early in the twentieth century. Since then, the effect of Wolbachia on their host's reproduction has drawn attention and has been increasingly investigated. Given the extreme complexity of this interaction, new study cases are welcomed to enhance its understanding. The present work addressed the influence of Wolbachia on Cx. quinquefasciatus, the cosmopolitan member of the Cx. pipiens complex. Samples of a Cx. quinquefasciatus colony (wPip(+)) originated from individuals naturally infected by Wolbachiapipientis B strain, were cured with tetracycline, yielding a Wolbachia-free colony (wPip(-)). Both the presence of bacteria and the efficiency of bacterial elimination were checked by PCR of the wsp gene. Total reproductive unidirectional incompatibility occurred when wPip(-) females were crossed with wPip(+) males, whereas the other three types of reciprocal crosses were viable. Reproductive aspects were also comparatively evaluated between colonies. Concerning oviposition time during the first gonotrophic cycle, wPip(+) females developed and laid eggs earlier than did wPip(-) females. Reproductive fitness was higher among wPip(-) than wPip(+) females regarding the following parameters: fertility: egg rafts/fed females; fecundity: eggs/raft, and viability: larvae/eggs. Conversely, longevity of wPip(-) females was lower. Summarising, although the infected mosquitoes have the advantage of a higher longevity, they have lower reproductive fitness. Our results are partly distinct from all other reports on Aedes and Culex mosquitoes previously published.
SUMMARYCulex quinquefasciatus is a vector of human pathogens, including filarial nematodes and several viruses. Although its epidemiological relevance is known to vary across geographical regions, an understanding of its population genetic structure is still incipient. In light of this, we evaluated the genetic diversity of Cx. quinquefasciatus and Cx. pipiens x Cx. quinquefasciatus hybrids collected from nine localities in Brazil and one site in Argentina. We used mitochondrial genes cox1 and nd4, along with the coxA and wsp genes of the maternally-inherited Wolbachia endosymbiont. The nd4 fragment was invariant between samples, whilst cox1 exhibited four haplotypes that separated two types of Cx. quinquefasciatus, one clustered in southern Brazil. Low sequence diversity was generally observed, being discussed. Both Brazilian and Argentinian mosquitoes were infected with a single Wolbachia strain. As reported in previous studies with these populations, cox1 and nd4 diversity is not congruent with the population structure revealed by nuclear markers or alar morphology. Future Cx. quinquefasciatus research should, if possible, evaluate mtDNA diversity in light of other markers.
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