Assessment of wing geometric morphometrics of urban Culex quinquefasciatus (Diptera: Culicidae) populations.

Culex quinquefasciatus is a cosmopolitan species distributed throughout tropical and subtropical areas of the world. The species is of great epidemiological importance as it is responsible for vectoring the causative agent of lymphatic filariasis and several arboviruses, including West Nile virus. Wing geometric morphometrics has been widely used to assess phenotypic variations in mosquito species. Here, we hypothesize that Cx. quinquefasciatus populations in urban parks in the city of São Paulo, Brazil, have been subjected to anthropogenic selective pressures that are responsible for driving their ecology and behavior. Mosquitoes were collected by CDC traps in five municipal parks in the city of São Paulo. Eighteen anatomical landmark coordinates on each female right wing were digitized. Canonical variate analysis, wireframe graphs, cross-validated reclassification tests and the neighbor-joining method were used to assess phenotypical dissimilarity in wing shape between populations. Centroid size was calculated to assess differences in wing size between populations, which can result from different environmental conditions during immature mosquito development. Moderately heterogeneous wing shape and wing size patterns were found in the populations analyzed, indicating that selective pressures in the urban environment are affecting the wing patterns of Cx. quinquefasciatus populations in the city of São Paulo, Brazil.

Using machine learning to understand microgeographic determinants of the Zika vector, Aedes aegypti.

There are limited data on why the 2016 Zika outbreak in Miami-Dade County, Florida was confined to certain neighborhoods. In this research, Aedes aegypti, the primary vector of Zika virus, are studied to examine neighborhood-level differences in their population dynamics and underlying processes. Weekly mosquito data were acquired from the Miami-Dade County Mosquito Control Division from 2016 to 2020 from 172 traps deployed around Miami-Dade County. Using random forest, a machine learning method, predictive models of spatiotemporal dynamics of Ae. aegypti in response to meteorological conditions and neighborhood-specific socio-demographic and physical characteristics, such as land-use and land-cover type and income level, were created. The study area was divided into two groups: areas affected by local transmission of Zika during the 2016 outbreak and unaffected areas. Ae. aegypti populations in areas affected by Zika were more strongly influenced by 14- and 21-day lagged weather conditions. In the unaffected areas, mosquito populations were more strongly influenced by land-use and day-of-collection weather conditions. There are neighborhood-scale differences in Ae. aegypti population dynamics. These differences in turn influence vector-borne disease diffusion in a region. These results have implications for vector control experts to lead neighborhood-specific vector control strategies and for epidemiologists to guide vector-borne disease risk preparations, especially for containing the spread of vector-borne disease in response to ongoing climate change.

Diel activity patterns of two distinct populations of Aedes aegypti in Miami, FL and Brownsville, TX.

The diel biting activity of Aedes (Stegomyia) aegypti (L) populations was extensively investigated in the early 1900s to gain more information on the biology of Ae. aegypti, and this information was used to devise effective approaches to controlling populations of this species and protect the human population from widespread arbovirus outbreaks. However, few contemporary studies are available regarding the diel activity patterns of Ae. aegypti. To assess the diel activity patterns of Ae. aegypti in southern Florida and Texas, we conducted 96-h uninterrupted mosquito collections once each month from May through November 2019 in Miami, Florida, and Brownsville, Texas, using BG-Sentinel 2 Traps. The overall diel activity pattern in both cities was bimodal with morning and evening peak activity between 7:00 and 8:00 and between 19:00 and 20:00. There were significant daily, monthly, seasonal, and site-specific differences in activity patterns, but these differences did not affect the overall peak activity times. These differences suggest daily, monthly, seasonal, and site-specific variations in human exposure to Ae. aegypti. Our observations can be used in planning and executing Ae. aegypti vector control activities in southern Florida and southern Texas, specifically those targeting the adult mosquito populations.

The Influence of the pH and Salinity of Water in Breeding Sites on the Occurrence and Community Composition of Immature Mosquitoes in the Green Belt of the City of São Paulo, Brazil.

The physicochemical parameters of water, such as pH, salinity, conductivity, and total dissolved solids, can influence mosquito larval development, survival, and abundance. Therefore, it is important to elucidate how these factors influence mosquito occurrence. We hypothesized that the occurrence and community composition of immature mosquito species are driven not only by the availability of suitable aquatic habitats, but also by the physicochemical factors of these habitats. The primary objective of this study was therefore to investigate the influence of the physicochemical parameters of water in different types of aquatic habitats on the occurrence of mosquito species in two remnants of Atlantic Forest in the city of São Paulo, Brazil. Collections of immature mosquitoes and assessment of the physicochemical characteristics of the water in the collection sites were carried out for twelve months. The variation in species composition and occurrence with the measured physicochemical parameters and the type of breeding site was assessed using constrained ordination methods. The results indicate that there was a statistically significant difference in species composition as a function of the different types of aquatic habitats, and that pH had an influence on species occurrence even when the variance explained by the type of aquatic habitat was removed from the analysis. There was a statistically significant association between mosquito species occurrence and pH and salinity, and the former had a significant influence on the mosquito species collected regardless of the type of aquatic habitat, showing that the pH of the breeding site water is an important factor in driving mosquito population dynamics and species distribution.

Different Domains of Dengue Research in Malaysia: A Systematic Review and Meta-Analysis of Questionnaire-Based Studies.

This review provided a systematic overview of the questionnaire-related dengue studies conducted in Malaysia and evaluated their reliability and validity used in the questionnaires. An extensive literature search was conducted using various electronic databases, including PubMed, EMBASE, Medline, and ScienceDirect. Systematic reviews and meta-analysis (PRISMA) were selected as the preferred item reporting method. Out of 88 identified dengue-related, 57 published from 2000 to April 2020 met the inclusion criteria and were included. Based on the meta-analysis, a poor mean score was obtained for knowledge (49%), attitude (44%), and preventive practice (55%). The study showed that the level of knowledge on cardinal signs and modes of transmission for dengue virus were highest among health care workers, followed by students (international and local) and lastly community residents. In treatment-seeking behaviours, only half of the respondents (50.8%) would send their child to the nearest health clinics or hospitals when a child became restless or lethargic. The acceptance rate for dengue vaccine, bacteria (Wolbachia), as a vector for dengue control and self-test diagnostic kit for dengue showed considerably high (88.4%, 70%, and 44.8%, respectively). Health belief model (HBM) constructs, such as perceived barriers, perceived severity, perceived susceptibility, self-efficacy, and perceived benefit influence prevention practices. Lastly, only 23 articles (40.3%) had piloted or pretested the questionnaire before surveying, in which three reported Cronbach's alpha coefficient (0.70-0.90). A need for active participation of communities and healthcare personnel, promotion of awareness, and safe complementary medicines, as well as assessment of psychometric properties of questionnaire use in dengue surveys in Malaysia, in order for assessing dengue reliably and valid.

Microgeographic Wing-Shape Variation in Aedes albopictus and Aedes scapularis (Diptera: Culicidae) Populations.

Aedes albopictus and Aedes scapularis are vectors of several arboviruses, including the dengue, chikungunya, and Rocio virus infection. While Ae. albopictus is a highly invasive species native to Asia and has been dispersed by humans to most parts of the world, Ae. scapularis is native to Brazil and is widely distributed in the southeast of the country. Both species are highly anthropophilic and are often abundant in places with high human population densities. Because of the great epidemiological importance of these two mosquitoes and the paucity of knowledge on how they have adapted to different urban built environments, we investigated the microgeographic population structure of these vector species in the city of São Paulo, Brazil, using wing geometric morphometrics. Females of Ae. albopictus and Ae. scapularis were collected in seven urban parks in the city. The right wings of the specimens were removed and digitized, and eighteen landmarks based on vein intersections in the wing venation patterns were used to assess cross-sectional variation in wing shape and size. The analyses revealed distinct results for Ae. albopictus and Ae. scapularis populations. While the former had less wing shape variation, the latter had more heterogeneity, indicating a higher degree of intraspecific variation. Our results indicate that microgeographic selective pressures exerted by different urban built environments have a distinct effect on wing shape patterns in the populations of these two mosquito species studied here.

The influence of anthropogenic habitat fragmentation on the genetic structure and diversity of the malaria vector Anopheles cruzii (Diptera: Culicidae).

Fragmentation of natural environments as a result of human interference has been associated with a decrease in species richness and increase in abundance of a few species that have adapted to these environments. The Brazilian Atlantic Forest, which has been undergoing an intense process of fragmentation and deforestation caused by human-made changes to the environment, is an important hotspot for malaria transmission. The main vector of simian and human malaria in this biome is the mosquito Anopheles cruzii. Anthropogenic processes reduce the availability of natural resources at the tree canopies, An. cruzii primary habitat. As a consequence, An. cruzii moves to the border of the Atlantic Forest nearing urban areas seeking resources, increasing their contact with humans in the process. We hypothesized that different levels of anthropogenic changes to the environment can be an important factor in driving the genetic structure and diversity in An. cruzii populations. Five different hypotheses using a cross-sectional and a longitudinal design were tested to assess genetic structure in sympatric An. cruzii populations and microevolutionary processes driving these populations. Single nucleotide polymorphisms were used to assess microgeographic genetic structure in An. cruzii populations in a low-endemicity area in the city of São Paulo, Brazil. Our results show an overall weak genetic structure among the populations, indicating a high gene flow system. However, our results also pointed to the presence of significant genetic structure between sympatric An. cruzii populations collected at ground and tree-canopy habitats in the urban environment and higher genetic variation in the ground-level population. This indicates that anthropogenic modifications leading to habitat fragmentation and a higher genetic diversity and structure in ground-level populations could be driving the behavior of An. cruzii, ultimately increasing its contact with humans. Understanding how anthropogenic changes in natural areas affect An. cruzii is essential for the development of more effective mosquito control strategies and, on a broader scale, for malaria-elimination efforts in the Brazilian Atlantic Forest.

Wing Geometric Morphometrics as a Tool for the Identification of Culex Subgenus Mosquitoes of Culex (Diptera: Culicidae).

Culex is the largest subgenus within the genus Culex that includes important vectors of diseases. The correct identification of mosquitoes is critical for effective control strategies. Wing geometric morphometrics (WGM) has been used to identify mosquito species alongside traditional identification methods. Here, WGM was used for eleven Culex species from São Paulo, Brazil, and one from Esquel, Argentina. Adult mosquitoes were collected using CDC (Centers for Disease Control) traps, morphologically identified and analyzed by WGM. The canonical variate analysis (CVA) was performed and a Neighbor-joining (NJ) tree was constructed to illustrate the patterns of species segregation. A cross-validated reclassification test was also carried out. From 110 comparisons in the cross-validated reclassification test, 87 yielded values higher than 70%, with 13 comparisons yielding 100% reclassification scores. Culexquinquefasciatus yielded the highest reclassification scores among the analyzed species, corroborating with the results obtained by the CVA, in which Cx. quinquefasciatus was the most distinct species. The high values obtained at the cross-validated reclassification test and in the NJ analysis as well as the segregation observed at the CVA made it possible to distinguish among Culex species with high degrees of confidence, suggesting that WGM is a reliable tool to identify Culex species of the subgenus Culex.

Proliferation of Aedes aegypti in urban environments mediated by the availability of key aquatic habitats.

Aedes aegypti is the main vector of dengue, Zika, chikungunya, and yellow fever viruses. Controlling populations of vector mosquito species in urban environments is a major challenge and being able to determine what aquatic habitats should be prioritized for controlling Ae. aegypti populations is key to the development of more effective mosquito control strategies. Therefore, our objective was to leverage on the Miami-Dade County, Florida immature mosquito surveillance system based on requested by citizen complaints through 311 calls to determine what are the most important aquatic habitats in the proliferation of Ae. aegypti in Miami. We used a tobit model for Ae. aegypti larvae and pupae count data, type and count of aquatic habitats, and daily rainfall. Our results revealed that storm drains had 45% lower percentage of Ae. aegypti larvae over the total of larvae and pupae adjusted for daily rainfall when compared to tires, followed by bromeliads with 33% and garbage cans with 17%. These results are indicating that storm drains, bromeliads and garbage cans had significantly more pupae in relation to larvae when compared to tires, traditionally know as productive aquatic habitats for Ae. aegypti. Ultimately, the methodology and results from this study can be used by mosquito control agencies to identify habitats that should be prioritized in mosquito management and control actions, as well as to guide and improve policies and increase community awareness and engagement. Moreover, by targeting the most productive aquatic habitats this approach will allow the development of critical emergency outbreak responses by directing the control response efforts to the most productive aquatic habitats.

Wing geometric morphometrics for identification of mosquito species (Diptera: Culicidae) of neglected epidemiological importance.

Culicidae comprises more than 3500 species, some of which are responsible for the spread of various human diseases, causing millions of deaths worldwide. Correct identification of these species is essential for the development of surveillance and control strategies. The most common method of mosquito identification is based on specific traits of the external morphology of species. However, identification of mosquitoes by morphological characters can be inaccurate or even unfeasible if the specimen is damaged or there is a lack of distinguishing features, as in the case of cryptic species complexes. Wing geometric morphometrics is a reliable, affordable tool for the identification of mosquito species, including sibling species. More importantly, it can be used in addition to both traditional morphologic identification methods as well as genetic approaches. Here, wing geometric morphometrics was used to identify sixteen mosquito species from eight genera: Aedes, Coquillettidia, Culex, Limatus, Mansonia, Psorophora, Runchomyia, and Wyeomyia. The 390 specimens used here were collected in São Paulo, Brazil using CDC traps, aspiration, and Shannon traps. Allometry was assessed by multivariate regression of the Procrustes coordinates on centroid size followed by canonical variate analysis and a pairwise cross-validated reclassification test. A Neighbor-Joining tree based on Mahalanobis distances was constructed with 1,000 bootstrap replicates using MorphoJ 1.02 and Past 2.17c. The canonical variate analysis of genera resulted in distinct clusters for Culex, Limatus, and Psorophora and partial overlapping between Aedes, Coquilettidia, and Mansonia, and between Runchomyia and Wyeomyia. Pairwise cross-validated reclassification tests indicated that genera were identified with an accuracy of at least 99% and subgenera with a mean accuracy of 96% and that in 160 of the 240 possible comparisons species were identified with an accuracy of 100%. Our results show that the eight genera in the study were correctly distinguished by wing shape, as were subgenera and most species, demonstrating that wing geometric morphometrics can be used for the identification of the mosquito species studied here.

Neotropical Anopheles (Kerteszia) mosquitoes associated with bromeliad-malaria transmission in a changing world.

Kerteszia is a neotropical subgenus of Anopheles composed of 12 species. The species in this subgenus are strongly associated with humid forests rich in epiphytic bromeliads. Forest fragmentation and anthropogenic changes can therefore have a negative impact on the abundance and survival of these mosquito species. Within this subgenus, four species are considered primary vectors of malaria: An. cruzii, An. bellator, An. homunculus and An. neivai. Malaria cases associated with Kerteszia species are often referred to as bromeliad malaria, a type of malaria reported to be endemic in the coastal rainforest of the neotropical region since the end of the nineteenth century. Although the incidence of bromeliad-malaria cases has decreased since the middle of the last century, autochthonous malaria cases continue to be registered every year. The complexity of the epidemiology of bromeliad malaria appears to be increasing as asymptomatic plasmodial infections and transmission of simian Plasmodium to humans have recently been reported. Kerteszia vector species have a great affinity for human beings and can be found in human-modified areas close to forest fragments such as in the Extra-Amazonian region of Brazil, Colombian pacific coast, and the Caribbean coast. Deforestation and forest fragmentation have been occurring continuously in the biomes of the neotropical region, and findings of Kerteszia species in dwellings are frequent in this region. Controlling the species in the Kerteszia subgenus is particularly difficult because they move frequently from natural to rural and peri-urban areas in search of blood sources, posing a challenge for the development of control strategies based on integrated vector management. Furthermore, as it has been shown that some Kerteszia species share similar morphological and genetic characteristics, the existence of a species complex formed by cryptic, sibling species within the Kerteszia group in different areas in the South and Southeast of Brazil cannot be ruled out. The existence of such a complex could represent an obstacle to the control of Kerteszia species and consequently to the elimination of bromeliad-malaria transmission in these regions. Here, we review publications that focus on the biology and ecology of Kerteszia malaria vectors and their association with human-modified areas and bromeliad-malaria transmission.

Wing geometric morphometrics as a tool for the Identification of culex subgenus mosquitoes of culex (Diptera: Culicidae)

Culex is the largest subgenus within the genus Culex that includes important vectors of diseases. The correct identification of mosquitoes is critical for effective control strategies. Wing geometric morphometrics (WGM) has been used to identify mosquito species alongside traditional identification methods. Here, WGM was used for eleven Culex species from São Paulo, Brazil, and one from Esquel, Argentina. Adult mosquitoes were collected using CDC (Centers for Disease Control) traps, morphologically identified and analyzed by WGM. The canonical variate analysis (CVA) was performed and a Neighbor-joining (NJ) tree was constructed to illustrate the patterns of species segregation. A cross-validated reclassification test was also carried out. From 110 comparisons in the cross-validated reclassification test, 87 yielded values higher than 70%, with 13 comparisons yielding 100% reclassification scores. Culexquinquefasciatus yielded the highest reclassification scores among the analyzed species, corroborating with the results obtained by the CVA, in which Cx. quinquefasciatus was the most distinct species. The high values obtained at the cross-validated reclassification test and in the NJ analysis as well as the segregation observed at the CVA made it possible to distinguish among Culex species with high degrees of confidence, suggesting that WGM is a reliable tool to identify Culex species of the subgenus Culex.

Population structuring of the invasive mosquito Aedes albopictus (Diptera: Culicidae) on a microgeographic scale.

Aedes albopictus is an invasive mosquito species that has spread globally and can transmit several arboviruses, including dengue, chikungunya and yellow fever. The species was first reported in Brazil in 1986 and since then has been found in 24 of the 27 Brazilian states, often in peri-urban environments close to highly urbanized areas. To date, population genetics of this important mosquito in areas in the city of São Paulo has not been investigated. In this study, we used 12 microsatellite loci to investigate the microgeographic population genetics of Ae. albopictus, which is present throughout the city of São Paulo. All the analyses revealed structuring of the populations studied, divided into two groups with restricted gene flow between them and without evidence of isolation by distance. We propose two hypotheses to explain the results: (i) low dispersal capability-limited gene flow between populations is due to the low dispersal capability inherent to Ae. albopictus; and (ii) multiple introductions-the structure identified here results from multiple introductions, which led to different dispersal patterns within the city and more genetic heterogeneity. The ability of Ae. albopictus to invade new areas and expand may explain why these mosquito populations appear to be well established and thriving in the city of São Paulo.

Urbanization as a driver for temporal wing-shape variation in Anopheles cruzii (Diptera: Culicidae).

Anopheles cruzii is the main vector of human and simian malaria in the Brazilian Atlantic Forest. This biome, which is an important hotspot of malaria transmission, has suffered fragmentation and deforestation as a result of urban expansion. Fragmentation and deforestation occur continually in the south of the city of São Paulo, Brazil, and findings of An. cruzii in the peridomicile have consequently become more frequent in this part of the city. Although An. cruzii is of considerable epidemiological importance, the impact of urbanization on the microevolution of this species in this malaria-endemic region has not been investigated to date. In this study, we investigated temporal variation in wing shape and size in An. cruzii populations collected in sylvatic, peri-urban and urban areas over a three-year period. Our results show a slight but significant phenotypic variation in all three populations over the study period. Time was a more powerful driver for wing variation than geographic distance. Temporal wing-shape variation appears to be positively associated with urbanization, suggesting that anthropogenic changes in the environment may be a strong driver for wing-shape variation in An. cruzii. Further studies using genetic markers are needed to assess genetic differentiation in these populations.

Wing morphometric variability in Aedes aegypti (Diptera: Culicidae) from different urban built environments.

BACKGROUND: Aedes aegypti is the main vector of the dengue, Zika and several other arboviruses. It is highly adapted to urbanized environments and can be found worldwide. Mosquito population control is considered the best strategy for fighting mosquito-borne diseases, making an understanding of their population dynamics vital for the development of more effective vector control programs. This study therefore sought to investigate how different levels of urbanization affect Aedes aegypti populations and modulate population structure in this species with the aid of wing geometric morphometrics. METHODS: Specimens were collected from eleven locations in three areas with distinct levels of urbanization in the city of São Paulo, Brazil: conserved, intermediate and urbanized. The right wings of female mosquitoes collected were removed, and photographed and digitized. Canonical variate analysis and Mahalanobis distance were used to investigate the degree of wing-shape dissimilarity among populations. Thin-plate splines were calculated by regression analysis of Canonical Variation Analysis scores against wing-shape variation, and a cross-validated reclassification was performed for each individual; a neighbor-joining tree was then constructed. RESULTS: Metapopulation and individual population analysis showed a clear segregation pattern in the Canonical Variation Analysis. Pairwise cross-validated reclassification yielded relatively high scores considering the microgeographical scale of the study and the fact that the study populations belong to the same species. The neighbor-joining tree showed that mosquitoes in the intermediate urban area segregated in the metapopulation and individual population analyses. Our findings show significant population structuring in Aedes aegypti mosquitoes in the areas studied. This is related to the different degrees of urbanization in the areas where the specimens were collected along with their geographical location. CONCLUSIONS: Urbanization processes in the study areas appear to play an important role in microevolutionary processes triggered by man-made modifications in the environment, resulting in a previously unknown population structuring pattern of major epidemiological importance.

Retention of ancestral polymorphism in Culex nigripalpus (Diptera: Culicidae) from São Paulo, Brazil.

Culex nigripalpus Theobald (Diptera: Culicidae) is a native species of Brazil that is well adapted to urban environments and found extensively in the city of São Paulo, Brazil. As a native species, it has been present in this region since long before the foundation of the city, but over time Cx. nigripalpus populations have been affected by man-made changes to the environment. We hypothesize that the populations analyzed in this study constituted a large Cx. nigripalpus population that separated into smaller populations as a result of increased levels of urbanization in the city, and that such high levels of urbanization would result in a genetic homogenization effect. We therefore investigated the microgeographic genetic structure and microevolutionary processes in Cx. nigripalpus populations from seven different locations in the city of São Paulo using a set of six microsatellite primers originally developed for Culex quinquefasciatus and Culex pipiens. Our results indicate that Cx. nigripalpus did not benefit from urbanization and is currently under selective pressures caused by anthropogenic changes and that populations from areas with higher levels of urbanization exhibited similar genetic patterns and low levels of polymorphism, contrasting with the more sylvatic SHA population. These findings are likely to contribute to a better understanding of how anthropogenic selective pressures are driving population genetics and, to some extent, the dynamics of Cx. nigripalpus populations. They should also help elucidate the effects that urbanization processes have on the ecology and behavior of these mosquito populations.

Microsatellite Markers Transferability in Culex nigripalpus (Diptera: Culicidae).

Microsatellite loci specifically designed and optimized for secondary vectors and neglected species of mosquitoes are lacking. Cross-species transferability of microsatellite loci between close taxa has been used as a reliable option, being successfully done for Aedes taeniorhynchus Wiedemann (Diptera: Culicidae), Triatoma sordida Stål (Hemiptera: Reduviidae), and Aedes fluviatilis Lutz (Diptera: Culicidae). Nonetheless, prior to the utilization of transferred microsatellites, they must be assessed for their performance and reliability on the target species. Therefore, the goal of this study was to transfer and validate SSR primers previously developed for the Culex pipiens complex to Culex (Culex) nigripalpus Theobald (Diptera: Culicidae). Culex nigripalpus were collected in seven different locations throughout the city of São Paulo using CDC traps baited with dry ice between 2011 and 2013, yielding a total of 223 specimens. Six SSR primers were successfully transferred to Cx. nigripalpus yielding satisfactory results for allele richness, ranging from 5 to 12 alleles per locus. The expected heterozygosity values were higher than the observed heterozygosity (P < 0.05) for the loci CxqCTG10, CxqGT51, and Cxpq59. Linkage disequilibrium results were statistically significant only for the comparison between the loci CxqCA115 and CxqCTG10, and the estimation for the probability of null alleles was also low, ranging from 0 to 0.052. These results substantially validate the SSRs transference to Cx. nigripalpus as well as their subsequent use in microevolution studies comprising this species.

Microgeographic Population Structuring of Culex quinquefasciatus (Diptera: Culicidae) From São Paulo, Brazil.

The continuing worldwide increase in urbanization can potentially have a major impact on the epidemiology of vector-borne diseases, as anthropogenic changes to the environment are known to favor a few species of mosquitoes that can thrive in urban environments. Culex quinquefasciatus Say (Diptera: Culicidae) is found extensively in urban habitats, where it lives in degraded, polluted areas and is often the only species of mosquito capable to surviving under such conditions. Traditional mosquito control strategies no longer have the desired effect due to the several factors such as insecticide resistance, abundance of breeding sites, lack of proper sewage and sanitation, and absence of natural predator, leading Cx. quinquefasciatus populations to increase its numbers in cities. In this study, five Cx. quinquefasciatus populations were analyzed using 12 microsatellite markers to investigate whether the dynamics of these populations are being modulated by urbanization and how they are structured in the city of São Paulo, Brazil. Our results indicate that only one of the study populations (the population from Anhanguera Park) exhibited evidence of expansion. The populations from Ibirapuera Park and Piqueri Park, the most urbanized regions of the areas studied, did not show signs of expansion. A better understanding of the mechanisms involved in the dispersal of Cx. quinquefasciatus and its colonization of new areas, as well as the species' demographic patterns and how these are associated with urbanization, particularly in areas undergoing a rural-to-urban transformation, such as Anhanguera Park, is of great importance for mosquito control.

Microgeographic population structuring of Aedes aegypti (Diptera: Culicidae).

Aedes aegypti is one of the species most favored by changes in the environment caused by urbanization. Its abundance increases rapidly in the face of such changes, increasing the risk of disease transmission. Previous studies have shown that mosquito species that have adapted to anthropogenic environmental changes benefit from urbanization and undergo population expansion. In light of this, we used microsatellite markers to explore how urbanization processes may be modulating Ae. aegypti populations collected from three areas with different levels of urbanization in the city of São Paulo, Brazil. Specimens were collected at eleven sites in three areas with different degrees of urbanization in the city of São Paulo: conserved, intermediate and urbanized. Ten microsatellite loci were used to characterize the populations from these areas genetically. Our findings suggest that as urbanized areas grow and the human population density in these areas increases, Ae. aegypti populations undergo a major population expansion, which can probably be attributed to the species' adaptability to anthropogenic environmental changes. Our findings reveal a robust association between, on the one hand, urbanization processes and densification of the human population and, on the other, Ae. aegypti population structure patterns and population expansion. This indicates that this species benefits from anthropogenic effects, which are intensified by migration of the human population from rural to urban areas, increasing the risk of epidemics and disease transmission to an ever-increasing number of people.

Wing variation in Culex nigripalpus (Diptera: Culicidae) in urban parks.

BACKGROUND: Culex nigripalpus has a wide geographical distribution and is found in North and South America. Females are considered primary vectors for several arboviruses, including Saint Louis encephalitis virus, Venezuelan equine encephalitis virus and Eastern equine encephalitis virus, as well as a potential vector of West Nile virus. In view of the epidemiological importance of this mosquito and its high abundance, this study sought to investigate wing variation in Cx. nigripalpus populations from urban parks in the city of São Paulo, Brazil. METHODS: Female mosquitoes were collected in seven urban parks in the city of São Paulo between 2011 and 2013. Eighteen landmark coordinates from the right wing of each female mosquito were digitized, and the dissimilarities between populations were assessed by canonical variate analysis and cross-validated reclassification and by constructing a Neighbor-Joining (NJ) tree based on Mahalanobis distances. The centroid size was calculated to determine mean wing size in each population. RESULTS: Canonical variate analysis based on fixed landmarks of the wing revealed a pattern of segregation between urban and sylvatic Cx. nigripalpus, a similar result to that revealed by the NJ tree topology, in which the population from Shangrilá Park segregated into a distinct branch separate from the other more urban populations. CONCLUSION: Environmental heterogeneity may be affecting the wing shape variation of Cx. nigripalpus populations.