Zika virus (ZIKV) was first discovered in 1947 in Uganda but was not considered a public health threat until 2007 when it found to be the source of epidemic activity in Asia. Epidemic activity spread to Brazil in 2014 and continued to spread throughout the tropical and subtropical regions of the Americas. Despite ZIKV being zoonotic in origin, information about transmission, or even exposure of non-human vertebrates and mosquitoes to ZIKV in the Americas, is lacking. Accordingly, from February 2017 to March 2018, we sought evidence of sylvatic ZIKV transmission by sampling whole blood from approximately 2000 domestic and wild vertebrates of over 100 species in West-Central Brazil within the active human ZIKV transmission area. In addition, we collected over 24,300 mosquitoes of at least 17 genera and 62 species. We screened whole blood samples and mosquito pools for ZIKV RNA using pan-flavivirus primers in a real-time reverse-transcription polymerase chain reaction (RT-PCR) in a SYBR Green platform. Positives were confirmed using ZIKV-specific envelope gene real-time RT-PCR and nucleotide sequencing. Of the 2068 vertebrates tested, none were ZIKV positive. Of the 23,315 non-engorged mosquitoes consolidated into 1503 pools tested, 22 (1.5%) with full data available showed some degree of homology to insect-specific flaviviruses. To identify previous exposure to ZIKV, 1498 plasma samples representing 62 species of domestic and sylvatic vertebrates were tested for ZIKV-neutralizing antibodies by plaque reduction neutralization test (PRNT₉₀). From these, 23 (1.5%) of seven species were seropositive for ZIKV and negative for dengue virus serotype 2, yellow fever virus, and West Nile virus, suggesting potential monotypic reaction for ZIKV. Results presented here suggest no active transmission of ZIKV in non-human vertebrate populations or in alternative vector candidates, but suggest that vertebrates around human populations have indeed been exposed to ZIKV in West-Central Brazil.

Feeding patterns of mosquitoes in six Brazilian environmental preservation areas were analyzed by the precipitin technique. The mosquito populations were captured using Shannon traps during different time periods. Bird, cow, dog, horse, opossum, human, and rodent antisera diagnostic tests were employed and results were analyzed by calculating the Sørensen similarity index and using the null-model test. Of the 647 analyzed specimens, 443 reacted to the utilized antisera, of which 331 reacted to one blood source, with the most frequent being birds (49.4%); and 112 specimens reacted to two blood sources, with the most frequent combination from birds + rodents (14.3%). The feed profiles demonstrated that Anopheles albitarsis, An. evansae, Aedes fulvus, Psorophora albigenu, Ps. albipes, Ps. ferox, and Mansonia titillans fed predominantly on birds. The similarity index showed that in some localities An. cruzii, Chagasia fajardi, Ae. scapularis, Ae. serratus, Haemagogus leucocelaenus, Ps. albigenu, and Ps. ferox presented similar dietary habits. The null-models test indicated that species from SMSP, INP, CGNP, and THP demonstrated an aggregate pattern, while species from SONP and SBNP showed a random pattern. The mosquitoes fed predominantly on birds, but from an epidemiological standpoint, the eclectic feeding habits were found to be constant among the mosquitoes analyzed.

The influence of climatic factors on the seasonal frequency of mosquitoes (Diptera: Culicidae) at the Peixe Angical hydroelectric scheme (Tocantins, Brazil) was evaluated in the present paper. Mosquito surveys were conducted in the municipality of Peixe and in areas surrounding the reservoir in the municipalities of Paranã and São Salvador do Tocantins during two daytime periods (10 am-12 noon and 2 pm-4 pm) and two night-time periods (6 pm-8 pm and 6 pm-10 am) over 14 months. In total, 10,840 specimens from 42 species were captured, 84.5% of which belonged to the Culcinae. The most common species were Anopheles darlingi, Psorophora albipes and Sabethes chloropterus. The number of Culicidae specimens was higher in months with higher rainfall and air humidity than during the drier months. The large population of Ps. albipes and the presence of both An. darlingi (primary vector for human malaria parasites) and Haemagogus janthinomys (primary vector for yellow fever virus) are highlighted.

With the objective of providing knowledge about the natural habitat of mosquito larvae, we conducted a study on the culicid fauna and identified larval habitat types at 3 different locations in the Serra do Mar State Park, Brazil, over the 12 months of 1991. We collected 1,425 larvae belonging to 23 species, of which the most frequent were Culex iridescens, Culex spp., Limatus durhami, and Trichoprosopon pallidiventer. The mosquito larval habitats presenting the greatest densities of specimens were bamboo, bromeliads, rubber boots, and streams. We observed that the culicids used a variety of containers as larval habitats and bred under a diversity of ecological conditions. Most of the habitats were natural, formed by bamboo, bromeliads, streams, and depressions in the ground and in rocks, along with artificial habitats consisting of rubber boots and abandoned metal cans. Seven species occurred preferentially in the internodes of closed bamboo stems, 6 in internodes of open stems, and 4 in bromeliads.

This study registers the diversity of Culicidae in the Bom Retiro Private Natural Heritage Reserve (RPPNBR), Rio de Janeiro state, Brazil, based on the collection of the immature stages in natural and artificial larval habitats. Larvae and pupae were collected monthly at two sites of the RPPNBR from May 2014 to July 2015 using dippers and aquatic pipettes. The diversity of the mosquito community was described using the Shannon–Wiener Diversity Index (H′), as well as diversity, richness, and dominance of species found in different larval habitats (lake, bamboos, bromeliads, and artificial vessels). The Mann–Whitney test was used to calculate differences between the two natural and artificial habitats. Overall, 15,659 specimens belonging to 25 species, ten genera, and two subfamilies were collected. The most abundant species collected at sites that were reforested recently were Culex pleuristriatus Theobald, 1903, Limatus durhamii (Theobald, 1901), Aedes albopictus (Skuse, 1895), Culex neglectus (Lutz, 1904), and Culex retrosus (Lane & Whitman, 1951). In a forest preserved site, the most abundant species were Cx. neglectus, Culex iridescens (Lutz, 1905), Sabethes identicus (Dyar & Knab, 1907), Wyeomyia arthrostigma (Lutz, 1905), and Li. durhamii. With respect to larval habitats, 0.1% of the specimens were collected along the edge of a lake, 5.5% in bamboos, 35.9% in bromeliads, and 58.4% in artificial containers. Only 5.5% of the specimens were collected in the forest preserved site, with the remaining samples from the site with altered vegetation. A greater species richness and diversity were found in forest-altered sites compared to the forest preserved site. Several species were collected in the water accumulated in the nylon lids of plastic water tanks. Such vessels can promote an increase in mosquito population density in the environment surrounding the study area.

In 2017–2019, Brazil recorded its most severe outbreak of yellow fever due to the spread of the virus (YFV) in the country’s southeast. Here, we investigated mosquito fauna and the spatial distribution of species in a primatology center in the Atlantic Forest bioregion in Rio de Janeiro state to evaluate the risk of YFV transmission in distinct environments. Fortnightly mosquito collections were performed from December 2018 to December 2019 at 12 sites along a disturbance gradient from a modified environment to 400 m inside the forest. We used ovitraps, BG-Sentinel, and protected human attraction (PHA). A total of 9349 mosquitoes of 21 species were collected. The collection method strongly influenced the captured fauna, with species such as Anopheles cruzii, Psorophora ferox, Runchomyia cerqueirai, Wyeomyia incaudata, Wy. theobaldi, Sabethes chloropterus, and Sa. albiprivus only collected via PHA. Collections with ovitraps resulted in low diversity and richness, with Haemagogus leucocelaenus and Hg. janthinomys/capricornii predominating. The diverse local fauna and the abundance and ubiquity of the latter species, which are the primary vectors of YFV, indicated that this area was highly vulnerable to arbovirus transmission, especially yellow fever, highlighting the need for improved surveillance and vaccination coverage in human and captive endangered non-human primates.