The vertical stratification of potential bridge vectors of mosquito-borne viruses in a central Amazonian forest bordering Manaus, Brazil

Abstract

The emergence of Zika virus (ZIKV) in Latin America brought to the fore longstanding concerns that forests bordering urban areas may provide a gateway for arbovirus spillback from humans to wildlife. To bridge urban and sylvatic transmission cycles, mosquitoes must co-occur with both humans and potential wildlife hosts, such as monkeys, in space and time. We deployed BG-Sentinel traps at heights of 0, 5, 10, and 15 m in trees in a rainforest reserve bordering Manaus, Brazil, to characterize the vertical stratification of mosquitoes and their associations with microclimate and to identify potential bridge vectors. Haemagogus janthinomys and Sabethes chloropterus, two known flavivirus vectors, showed significant stratification, occurring most frequently above the ground. Psorophora amazonica, a poorly studied anthropophilic species of unknown vector status, showed no stratification and was the most abundant species at all heights sampled. High temperatures and low humidity are common features of forest edges and microclimate analyses revealed negative associations between minimum relative humidity, which was inversely correlated with maximum temperature, and the occurrence of Haemagogus and Sabethes mosquitoes. In this reserve, human habitations border the forest while tamarin and capuchin monkeys are also common to edge habitats, creating opportunities for the spillback of mosquito-borne viruses.

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

“…Some species from the Haemagogus genus are responsible for the transmission of YFV in forested and rural areas in Brazil [52], and in several locations in the country, species in this genus are considered important vectors of YFV [53]. Haemagogus leucocelanus has been found inhabiting different types of environments, such as urban parks, forested areas close to urban areas [54], and forested areas close to dwellings [55,56].…”

Zoonotic spillover: Understanding basic aspects for better prevention

“…Usually, spillover refers to the cross-species transmission of pathogens from wildlife (vertebrate animals) to humans Wells and Clark, 2019). The transmission of a pathogen from humans to wildlife (reverse zoonosis), by direct contact between species or mediated by vectors, can be called "spillback" (Weaver, 2013;Hendy et al, 2020;Olival et al, 2020). Finally, "horizontal virus transfer" is a term that can be used to describe the transmission (regardless of direction) of viruses between different species, including viral transmission between organisms of different biological kingdoms (Dolja and Koonin, 2018).…”

Microclimate and the vertical stratification of potential bridge vectors of mosquito‑borne viruses captured by nets and ovitraps in a central Amazonian forest bordering Manaus, Brazil

“…Which mosquito species effectively bridge urban and sylvatic cycles is determined in part by their vertical stratification relative to humans living at ground level and sylvatic hosts which may prefer different heights within the forest canopy. We recently identified Haemagogus janthinomys , Sabethes chloropterus , and Psorophora amazonica as potential bridge vectors of mosquito-borne arboviruses in a rainforest reserve bordering the city of Manaus, Brazil 15 . The two former species are major sylvatic vectors of YFV in Latin America and are commonly active in forest canopies 16 , a behavior termed acrodendrophily 17 .…”

“…The two former species are major sylvatic vectors of YFV in Latin America and are commonly active in forest canopies 16 , a behavior termed acrodendrophily 17 . The latter is a poorly studied species of unknown vector status 15 . All three species opportunistically feed on humans and are primarily active during the daytime 15 , 16 .…”