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.

Yellow fever virus (YFV) is an endemic arbovirus in parts of Africa and the Americas. In Brazil, following the eradication of the urban transmission cycle, YFV is maintained in a sylvatic cycle involving several species of neotropical primates and mosquitoes of the genera Haemagogus and Sabethes, which serve as primary and secondary vectors, respectively. During the 2016–2019 outbreak in São Paulo State, a total of 3731 mosquito pools were collected from sites with ongoing epizootic events in 192 municipalities. The RT-qPCR analysis detected YFV in 46 pools (1.4%) across nine mosquito species, including both primary and secondary vectors, as well as species from the genera Aedes and Psorophora. Differences in viral loads were observed among species. While Aedes aegypti was not found to be positive, the detection of natural YFV infection in other Aedes species raises concerns about potential virus reurbanization. Further studies are needed to clarify the role of additional mosquito species in YFV transmission in Brazil.

Phytotelmata are aquatic microenvironments formed by the accumulation of water and organic matter in cavities of plants. These microenvironments serve as breeding sites for various species of mosquitoes, including some of epidemiological importance. Our objective was to identify the mosquito fauna in these microenvironments and to analyze variations in mosquito fauna diversity between bromeliads, tree holes, and bamboo internodes in Cantareira State Park, São Paulo (CSP), Brazil, where there have been reports of yellow-fever epizootics in non-human primates and circulation of plasmodia. Collections were carried out monthly from February 2015 to April 2017. The bromeliads showed greater mosquito species richness and diversity than the tree holes and bamboo internodes, as well as a very different composition. Of the 11 genera collected and 49 taxa identified, Culex (Carrolia) iridescens, Cx. ocellatus, Cx. (Microculex) imitator, and Anopheles (Kerteszia) cruzii were the most abundant. The phytotelmata in the CSP showed significant differences in species richness, diversity, and composition and were found to support a diverse mosquito fauna to develop, including An. cruzii and the sylvatic yellow fever virus vector Haemagogus leucocelaenus. The finding of these epidemiologically important species highlights the key role played by phytotelma breeding sites as places of refuge and species maintenance for these vectors in green areas close to urban centers.

Yellow fever virus (YFV) is an endemic arbovirus in parts of Africa and the Americas. In Brazil, following the eradication of the urban transmission cycle, YFV is maintained in a sylvatic cycle involving several species of neotropical primates and mosquitoes of the genera Haemagogus and Sabethes, which serve as primary and secondary vectors, respectively. During the 2016–2019 outbreak in São Paulo State, a total of 3,731 mosquito pools were collected from sites with ongoing epizootic events in 192 municipalities. RT-qPCR analysis detected YFV in 46 pools (1.4%) across nine mosquito species, including both primary and secondary vectors, as well as species from the genera Aedes and Psorophora. Differences in viral loads were observed among species. While Aedes aegypti was not found to be positive, the detection of natural YFV infection in other Aedes species raises concerns about potential virus reurbanization. Further studies are needed to clarify the role of additional mosquito species in YFV transmission in Brazil.

Brazil is a great source of arbovirus diversity, mainly in the Amazon region. However, other biomes, especially the Atlantic Forest, may also be a hotspot for emerging viruses, including Bunyaviruses (Negarnaviricota: Bunyavirales). For instance, Vale do Ribeira, located in the Southeastern region, has been widely studied for virus surveillance, where Flavivirus, Alphavirus and Bunyaviruses were isolated during the last decades, including Bruconha virus (BRCV), a member of Orthobunyavirus genus Group C, in 1976. Recently, a new isolate of BRCV named Span321532 was obtained from an adult sentinel mouse placed in Iguape city in 2011, and a full-length genome was generated with nucleotide differences ranging between 1.5%, 5.3% and 5% (L, M and S segments, respectively) from the prototype isolated 35 years earlier. In addition, each segment placed BRCV into different clusters, showing the high variety within Bunyavirales. Although no evidence for reassortants was detected, this finding reiterates the need for new surveillance and genomic studies in the area considering the high mutation rates of arbovirus, and also to identify the hosts capable of supporting the continuous circulation of Orthobunyavirus.

Phytotelmata are aquatic microenvironments formed by the accumulation of water and organic matter in cavities of plants. These microenvironments serve as breeding sites for various species of mosquitoes, including some of epidemiological importance. Our objective was to identify the mosquito fauna in these microenvironments and to analyze variations in mosquito fauna diversity between bromeliads, tree holes and bamboo internodes in Cantareira State Park, São Paulo, Brazil, where there have been reports of yellow-fever epizootics in non-human primates and circulation of plasmodia. Collections were carried out monthly from February 2015 to April 2017. Bromeliads showed greater mosquito species richness and diversity than tree holes and bamboo internodes, as well as a very different composition. Of the 11 genera collected and 49 taxa identified, Culex (Carrolia) iridescens, Cx. ocellatus, Cx. (Microculex) imitator and Anopheles (Kerteszia) cruzii were the most abundant. The phytotelmata in CSP were found to allow a diverse mosquito fauna to develop, including An. cruzii and the sylvatic yellow fever virus vector Haemagogus leucocelaenus. The finding of these epidemiologically important species highlights the key role played by phytotelma breeding sites as places of refuge and species maintenance for these vectors in green areas close to urban centers.