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.

Relationship between vertical stratification and feeding habits of mosquito (Diptera: Culicidae) assemblages collected in conservation units in the green belt of the city of São Paulo, Brazil.

São Paulo is one of the largest cities in the world and has several characteristics that favor a diversity of urban and wild mosquitoes. Little is known about how variations in mosquito diversity and feeding preferences for different hosts in different vegetation strata can influence the risk of pathogen transmission to humans. We investigated vertical stratification of mosquitoes and its relationship with vertebrate hosts in environments with different degrees of conservation in two conservation units in the city of São Paulo. Adult mosquitoes were collected using CDC traps, aspiration and Shannon traps. After morphological identification, host blood in engorged females was analyzed by PCR with a vertebrate-specific primer set based on mitochondrial cytochrome b DNA of vertebrates commonly found in the two conservation units. Although a higher abundance of the species Anopheles cruzii and Culex nigripalpus was found in the canopy, blood not only from birds but also from humans and rodents was identified in these mosquitoes. In one of the units, Wyeomyia confusa and Limatus durhamii were found occupying mainly niches at ground level while Culex vaxus was frequently found in the canopy. Haemagogus leucocelaenus, the main vector of yellow fever, was found in low abundance at all collection points, particularly in the canopy. Species richness and composition tended to vary little between canopy and ground level in the same environment, but the abundance between canopy and ground level varied more depending on the species analyzed, the most abundant and frequent species exhibiting a predilection for the canopy. Even those mosquito species observed more frequently in the canopy did not show an association with hosts found in this stratum as most of the blood identified in these species was from humans, suggesting opportunist feeding behavior, i.e., feeding on the most readily available host in the environment. The two most common species in the study, An. cruzii and Cx. nigripalpus, may be able to act as bridge vectors for pathogens to circulate between the forest canopy and ground level.

Complexity of malaria transmission dynamics in the Brazilian Atlantic Forest.

Plasmodium malariae and Plasmodium vivax are protozoan parasites that can cause malaria in humans. They are genetically indistinguishable from, respectively, Plasmodium brasilianum and Plasmodium simium, i.e. parasites infecting New World non-human primates in South America. In the tropical rainforests of the Brazilian Atlantic coast, it has long been hypothesized that P. brasilianum and P. simium in platyrrhine primates originated from P. malariae and P. vivax in humans. A recent hypothesis proposed the inclusion of Plasmodium falciparum into the transmission dynamics between humans and non-human primates in the Brazilian Atlantic tropical rainforest. Herein, we assess the occurrence of human malaria in simians and sylvatic anophelines using field-collected samples in the Capivari-Monos Environmental Protection Area from 2015 to 2017. We first tested simian blood and anopheline samples. Two simian (Aloutta) blood samples (18%, n = 11) showed Plasmodium cytb DNA sequences, one for P. vivax and another for P. malariae. From a total of 9,416 anopheline females, we found 17 pools positive for Plasmodium species with a 18S qPCR assay. Only three showed P. cytb DNA sequence, one for P. vivax and the others for rodent malaria species (similar to Plasmodium chabaudi and Plasmodium berghei). Based on these results, we tested 25 rodent liver samples for the presence of Plasmodium and obtained P. falciparum cytb DNA sequence in a rodent (Oligoryzomys sp.) liver. The findings of this study indicate complex malaria transmission dynamics composed by parallel spillover-spillback of human malaria parasites, i.e. P. malariae, P. vivax, and P. falciparum, in the Brazilian Atlantic forest.

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.