Wing sexual dimorphism of pathogen-vector culicids

Abstract

BackgroundSexual dimorphism in animals has been studied from different perspectives for decades. In 1874 Darwin hypothesized that it was related to sexual selection, and even after nearly 140 years, when additional empirical data has become available and the subject has been investigated from a contemporary viewpoint, this idea is still supported. Although mosquito (Culicidae) wings are of great importance as they play a sex-specific role, little is known about wing sexual dimorphism in these pathogen-vector insects. Detection and characterization of wing sexual dimorphism in culicids may indirectly enhance our knowledge of their epidemiology or reveal sex-linked genes, aspects that have been discussed by vector control initiatives and developers of genetically modified mosquitoes.MethodsUsing geometric morphometrics, we carried out a comparative assessment of wing sexual dimorphism in ten culicid species of medical/veterinary importance from genera Culex, Aedes, Anopheles and Ochlerotatus collected in Brazil.ResultsDiscriminant analysis revealed significant sexual dimorphism in all the species studied, indicating that phenotypic expression of wing shape in mosquitoes is indeed sex-specific. A cross-validated test performed to reclassify the sexes with and without allometry yielded very similar results. Mahalanobis distances among the ten species showed that the species had different patterns of shape sexual dimorphism and that females are larger than males in some species.ConclusionWing morphology differed significantly between species. The finding of sexual dimorphism in all the species would suggest that the wing geometry of Culicidae is canalized. Although sexual dimorphism is prevalent, species-specific patterns occur. Allometry was not the main determinant of sexual dimorphism, which suggests that sexual selection or other evolutionary mechanisms underlie wing sexual dimorphism in these insects.

<b>Pupal shape and size dimorphism in <I>Aedes albopictus</I> (Skuse, 1894) (Diptera: Culicidae)</b>

“…In relation to wing shape, our results are similar to those of Devicari et al (2011) andVirginio et al (2015) who observed wing shape dimorphism in A. albopictus and other culicid species. Several studies indicate that mosquito wing conformation has a polygenic basis, being weakly influenced by heritable epigenetic factors (Jirakanjanakit et al 2007;Dujardin 2008;Morales-Vargas et al 2010).…”

“…Several studies indicate that mosquito wing conformation has a polygenic basis, being weakly influenced by heritable epigenetic factors (Jirakanjanakit et al 2007;Dujardin 2008;Morales-Vargas et al 2010). The observed sexual shape dimorphism in A. albopictus corroborates studies suggesting that wing conformation is sex-specific (Devicari et al 2011;Virginio et al 2015), and that differences can be attributed to various genes that participate in the expression of wing shape waving additive and/or differential effects on the phenotype (Carreira et al 2011).…”

“…The CS analysis indicates that female pupae are larger than males, consistent with evidence of adult sexual dimorphism in A. albopictus and other mosquitoes (Devicari et al 2011;Oliveira et al 2012;Virginio et al 2015). Lounibos (1994), however, considered adult size to be a direct effect of feed and density conditions during larval instars.…”

“…A more reliable pupal survey could be accomplished by determining the male/female ratio, which would require the ability to distinguish the sex of pupae. Geometric morphometrics is a tool for describing the phenotypic variation in organisms (Rohlf & Marcus 1993;Adams et al 2004), and it has recently has been shown useful for characterizing sexual dimorphism in mosquito wings (Devicari et al 2011;Virginio et al 2015). In this study we set out to describe shape and size dimorphism in A. albopictus pupae to facilitate dengue vector surveys.…”

Ecology and morphological variations in wings of Phlebotomus ariasi (Diptera: Psychodidae) in the region of Roquedur (Gard, France): a geometric morphometrics approach

“…Sexual dimorphism is widely observed in many insects such as Mansonia [29] and Aedes mosquitoes [30], Anopheles , Culex and Ochlerotatus mosquitoes [31], Drosophila melanogaster [32] and D. subobscura [33]. Thin-plate spline deformation analyses showed that the deformation was mostly present on the medial part of the wings.…”