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.

Influence of water's physical and chemical parameters on mosquito (Diptera: Culicidae) assemblages in larval habitats in urban parks of São Paulo, Brazil.

Water's physical and chemical characteristics are important constraints in aquatic ecosystems, acting on the development, survival, and adaptation of different organisms. Immature forms of mosquitoes develop in widely diverse aquatic environments and are mainly found in permanent or temporary freshwater bodies with little or no movement. The current study aimed to investigate whether variations in larval habitats' pH, salinity, dissolved oxygen, and water temperature influence the composition of Culicidae assemblages and the presence and abundance of Aedes albopictus and Ae. aegypti. From August 2012 to July 2013, captures of immature forms and measurement of water's physical and chemical profiles were performed monthly in natural and artificial breeding sites in four urban parks in the city of São Paulo, Brazil. Changes in species composition related to the parameters' variation were assessed by multivariate analysis. Regression trees were performed to evaluate the effect of breeding sites' physical and chemical variations on the presence and abundance of Ae. albopictus and Ae. aegypti. The observations suggest ranges of conditions for the measured variables in which most species tend to be found more frequently, and pH and salinity are the variables most closely associated with variations in mosquito composition. Ae. aegypti and Ae. albopictus were present in both natural and artificial breeding sites and were observed under significantly varying conditions of pH, salinity, dissolved oxygen, and temperature. For Ae. albopictus, larval habitat type and pH were the best predictors of incidence and abundance. For Ae. aegypti, pH and salinity were the best predictors of abundance, while dissolved oxygen and larval habitat type were better predictors of presence. This information broadens our understanding of the ecology and interaction of the investigated species with abiotic factors in the aquatic environments, providing useful data for studies that seek to elucidate the underlying mechanisms of selection and colonization of breeding sites by these mosquitoes. This study also reinforces previous observations indicating that Ae. albopictus and Ae. aegypti can colonize diverse types of larval habitats with widely varying physical and chemical conditions.

Comparison between albino and pigmented rabbit ERGs.

BACKGROUND: Pigmented and albino rabbits are commonly used in visual research; however, the lack of pigment in the eyes may affect retinal responses. Here, we compare and describe the differences of retinal function between pigmented (English Butterfly) and albino (New Zealand) rabbits. METHODS: Electroretinograms were recorded in pigmented and albino rabbits in the dark-adapted eye, in the light-adapted eye and for four temporal frequencies in the light-adapted eye. The implicit time and amplitude of the a- and b-waves were analyzed, as well as the amplitude and phase of the first harmonic component of the photopic flicker response. RESULTS: Albino rabbits presented significantly larger amplitudes for both a- and b-waves at all intensities and frequencies. The intensity-response function of the scotopic b-wave also showed that the albino retina is more sensitive than the pigmented retina and the larger flicker amplitudes found in the albino group also revealed post-receptoral changes specifically related to cone pathways. CONCLUSIONS: The larger amplitude of albino receptoral and post-receptoral activities might be attributed to greater availability of light due to scatter and reflection at the retinal layer, and as the differences in response amplitudes between the groups increase with flicker frequency, we suggest that ON bipolar cells recover faster in the albino group, suggesting that this might be a mechanism to explain the higher temporal resolution for albinos compared to the pigmented group.

Estudo da resposta de mosquitos (Diptera: Culicidae) a diferentes tipos de criadouros e condições de fatores físico-químicos da água / Study of mosquito response (Diptera: Culicidae) to different breeding types and conditions of physical and chemical factors of water

A família dos culicídeos é diversa e possui muitas espécies com alta relevância epidemiológica e que transmitem os patógenos causadores de doenças como dengue, febre amarela e malária. Os imaturos se criam exclusivamente na água e nos mais diversos tipos de criadouros, podendo ser influenciados por fatores biológicos e fatores físico-químicos, que incluem pH, salinidade, condutividade, sólidos totais dissolvidos, entre outros. Entender as variações das condições dos criadouros é importante para entender e esclarecer como esses fatores agem no desenvolvimento dos imaturos, na sua fisiologia e nas relações interespecíficas, que influenciam o desenvolvimento larval e a sobrevivência dos mosquitos. Portanto, o objetivo principal desse trabalho foi investigar a influência de fatores físico-químicos e do tipo de criadouro sobre a ocorrência das espécies de culicídeos em dois remanescentes de Mata Atlântica no município de São Paulo. As coletas dos imaturos ocorreram em três diferentes pontos no Parque Estadual da Cantareira e quatro diferentes pontos na Área de Proteção Ambiental Capivari-Monos, remanescentes de Mata Atlântica inseridos na Grande São Paulo, durante vinte e sete meses para as coletas de diversidade geral e doze meses para as coletas de diversidade juntamente com fatores físico químicos da água. Os imaturos foram coletados em bromélias epífitas e de solo, bambus, poças d\'água no solo e em pedras, ocos de árvore, lagos e recipientes artificiais. As análises dos dados foram feitas através do cálculo do coeficiente de variação das variáveis para os tipos de criadouros, Análise Restrita de Proximidade (CAP), Análise de Correspondência Canônica (CCA) e boxplots sem outliers. Os resultados indicaram que há uma diferença estatisticamente significante na composição de espécies em função dos diferentes tipos de criadouros e que o pH possui influência sobre a ocorrência das espécies, tanto para a variável tipo de criadouro quanto para situações em que se retira essa variável. As espécies com importância epidemiológica coletadas foram: Aedes aegypti, Aedes albopictus, Anopheles cruzii, Haemagogus leucocelaenus, Psorophora ferox e Sabethes purpureus, com ocorrência das duas espécies de Aedes e Haemagogus no mesmo criadouro. Esses resultados são importantes para reforçar a necessidade do monitoramento de criadouros das espécies vetoras de patógenos e para um melhor entendimento da ecologia das espécies

The Culicidae family is diverse and has many species of high epidemiological relevance that transmit the pathogens that cause diseases such as dengue fever, yellow fever and malaria. The immatures are created exclusively in the water and in the most diverse types of breeding places, being able to be influenced by biological factors and physicochemical factors, that include pH, salinity, conductivity, total solids dissolved, among others. Understanding variations in breeding conditions is important in understanding and clarifying how these factors affect the development of immatures, their physiology, and interspecific relationships that influence larval development and mosquito survival. Therefore, the main objective of this work was to investigate the influence of physical-chemical factors and breeding type on the occurrence of Culicidae species in two remnants of Atlantic Forest in the city of São Paulo. Immature collections occurred at three different points in the Cantareira State Park and four different points in the Capivari-Monos Environmental Protection Area, remnants of the Mata Atlântica, located in Greater São Paulo, during twenty-seven months for collections of general diversity and twelve months for collections of diversity along with physical chemical factors of water. The immatures were collected in epiphytic and soil bromeliads, bamboos, pools of water in the soil and stones, tree hollows, lakes and artificial containers. Data analysis was done by calculating the coefficient of variation of the variables for breeding types, Restricted Proximity Analysis (CAP), Canonical Correspondence Analysis (CCA) and boxplots without outliers. The results indicated that there is a statistically significant difference in species composition as a function of the diverse types of breeding sites and that pH has an influence on the occurrence of species, both for the type of breeder variable and for situations in which this variable is removed. The species with epidemiological importance were: Aedes aegypti, Aedes albopictus, Anopheles cruzii, Haemagogus leucocelaenus, Psorophora ferox and Sabethes purpureus, with occurrence of both Aedes and Haemagogus species in the same breeding ground. These results are important to reinforce the need to monitor breeding sites of pathogen vector species and to better understand species ecology

Composition and diversity of mosquitoes (Diptera: Culicidae) in urban parks in the South region of the city of São Paulo, Brazil / Composição e diversidade de mosquitos (Diptera: Culicidae) em parques urbanos localizados na região Sul do município de São Paulo, Brasil

Abstract Many parks in the city of São Paulo contain remnants of Atlantic Forest. Of the 30 municipal parks in the South of the city, we investigated two in this study (Santo Dias Park and Shangrilá Park) in order to survey their mosquito fauna and investigate the presence of potential bioindicators of environmental conditions and vectors of human pathogens. Mosquitoes were collected monthly between March 2011 and February 2012 using aspirators, Shannon and CDC traps for adult mosquitoes and larval dippers and suction samplers for immature forms. Sampling effort was evaluated by plotting a species accumulation curve, and total richness was estimated using the first-order jackknife. To compare the diversity between the two parks Shannon and Simpson diversity indexes were calculated. Species similarity was compared by the Sorensen similarity index. In all, 8,850 specimens were sampled in both parks. Collections in Santo Dias Park yielded 1,577 adult mosquitoes and 658 immature individuals distributed in seven genera (Aedes, Anopheles, Culex, Limatus, Mansonia, Toxorhynchites and Wyeomyia) and 27 taxonomic units. Among the adult mosquitoes collected, Culex nigripalpus .and Aedes fluviatilis were the most abundant, while the most abundant immature forms were Cx. imitator, Wy. davisi, Wy. galvaoi and Ae. albopictus. Collections in Shangrilá Park yielded 4,952 adult specimens and 1,663 immature forms distributed in eight genera (Aedes, Anopheles, Culex, Limatus, Mansonia, Toxorhynchites, Uranotaenia and Wyeomyia) and 36 taxonomic units. Species accumulation curves in both parks were close to the asymptote, and the total richness estimate was close to the observed richness. Although the observed species richness was higher in the Shangrilá Park, there was no statistically significant difference between the diversity indexes measured. Regarding species composition, the two sites shared 16 species, including those of epidemiological importance such as Culex nigripalpus, Cx. quinquefasciatus, Aedes albopictus and Ae. aegypti. As some of the mosquito taxa found are bioindicators of environmental conditions and have epidemiological potential to carry pathogens, we recommend that urban parks should be included in official mosquito surveillance programs, and regular surveys carried out to detect circulating arboviruses.

Resumo Parques urbanos do município de São Paulo contêm remanescentes de Mata Atlântica. No sul da cidade há 30 parques municipais, sendo os parques Santo Dias e Shangrila alvos deste estudo. Este estudo teve a proposta de levantamento da fauna de culicídeos desses dois parques no sul da cidade de São Paulo e avaliar a presença de potenciais bioindicadores e espécies vetoras de patógenos aos seres humanos. Os mosquitos foram coletados mensalmente entre março de 2011 e fevereiro de 2012, com aspiradores, armadilhas de Shannon e CDCs para mosquitos adultos e conchas entomológicas e bombas manuais de sucção para os imaturos. O esforço amostral foi avaliado por traçar uma curva de acumulação de espécies, e a riqueza total foi estimada pelo método jackknife de primeira ordem. Para comparar a diversidade entre os dois parques, foram calculados os índices de diversidade de Shannon e de Simpson. A similaridade na composição de espécies foi comparada pelo índice de similaridade de Sorensen. Foram coletados um total de 8.850 espécimes de culicídeos em ambos os parques. Coletas no parque Santo Dias renderam 1.577 mosquitos adultos e 658 imaturos, distribuídos em sete gêneros (Aedes, Anopheles, Culex, Limatus, Mansonia, Toxorhynchites e Wyeomyia) e 27 unidades taxonômicas: Culex nigripalpus, e Aedes fluviatilis foram as mais abundantes unidades taxonômicas coletadas como adultos, enquanto em formas imaturas, as espécies mais abundantes coletadas foram Cx. imitator, Wy. davisi, Wy. galvaoi e Ae. albopictus. Coletas no parque Shangrilá renderam 4.952 espécimes como adultos e 1.663 formas imaturas, distribuídas em oito gêneros (Aedes, Anopheles, Culex, Limatus, Mansonia, Toxorhynchites, Uranotaenia e Wyeomyia) e 36 unidades taxonômicas.. As curvas de acúmulo de espécies em ambos os parques ficaram perto da assíntota, e as estimativas de riqueza total foram próximas às riquezas observadas. Apesar da riqueza observada ter sido maior no parque Shangrilá, não houve diferença estatisticamente significante entre os índices de diversidade mensurados. Em relação à composição de espécies os dois locais compartilharam 16 espécies, incluindo as de maior importância epidemiológica como Culex nigripalpus, Cx. quinquefasciatus, Aedes albopictus e Ae. aegypti. Alguns táxons de culicídeos são bioindicadores de condições ambientais nas áreas ou possuem potencial para veicular patógenos. Atenção deve ser dada a parques urbanos, com inclusão destes locais nos programas oficiais de vigilância entomológica e investigações periódicas na circulação de arbovírus.

Haemagogus leucocelaenus and Other Mosquitoes Potentially Associated With Sylvatic Yellow Fever In Cantareira State Park In the São Paulo Metropolitan Area, Brazil.

The aim of this work was to investigate whether Haemagogus leucocelaenus and other mosquito species associated with sylvatic transmission of yellow fever virus are present in Cantareira State Park (CSP) in the São Paulo Metropolitan Area (SPMA). From October 2015 to March 2016, adult mosquitoes were captured with the Centers for Disease Control and Prevention traps, manual battery-powered aspirators, and Shannon traps; larvae and pupae were collected in natural and artificial breeding sites. A total of 109 adult mosquito specimens and 30 immature forms belonging to 11 taxonomic categories in 4 genera (Aedes, Psorophora, Sabethes, and Haemagogus) were collected, including Hg. leucocelaenus, the main vector of yellow fever. The entomological findings of the present study indicate that the area is of strategic importance for yellow fever surveillance not only because of the significant numbers of humans and nonhuman primates circulating in CSP and its vicinity but also because it represents a potential route for the disease to be introduced to the SPMA.