Distribution and diversity of mosquitoes and Oropouche-like virus infection rates in an Amazonian rural settlement

Abstract

Mosquito diversity and disease transmission are influenced by landscape modifications, i.e., vectors and pathogens previously found only in forests are now found close to human environments due to anthropic changes. This study determined the diversity and distribution of mosquitoes in forest environments in order to analyze the potential vectors of Amazonian forest arboviruses. Mosquitoes were collected by 1) vertical stratification from forest canopy and ground areas using Hooper Pugedo (HP) light traps and human attraction and 2) horizontal stratification using HP light traps in peridomicile, forest edge, and forest environments near the Rio Pardo rural settlement, Amazonas, Brazil. A total of 3,750 mosquitoes were collected, representing 46 species. 3,139 individuals representing 46 species were sampled by vertical stratification. Both the Shannon-Weaver diversity index (H’) and equitability (J’) were higher in the canopy than on the ground. 611 individuals representing 13 species were sampled by horizontal stratification. H’ decreased in the following order: forest edge > forest > peridomicile, and J’ was greater at the forest edge and smaller in the peridomicile environment. Moreover, H’ was higher for the human attraction collection method than the HP traps. A total of 671 pools were analyzed by RT-qPCR; three species were positive for Oropouche-like viruses (Ochlerotatus serratus, Psorophora cingulata, and Haemagogus tropicalis) and the minimum infection rate was 0.8%. The composition of mosquito species did not differ significantly between anthropic and forest environments in Rio Pardo. Some mosquito species, due to their abundance, dispersion in the three environments, and record of natural infection, were hypothesized to participate in the arbovirus transmission cycle in this Amazonian rural settlement.

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

“…This was also reflected in the results of the principal components analysis. Other studies 44 – 46 have shown similar changes in community composition with increasing height above the forest floor and found that species richness and mosquito abundance are generally higher at ground level than at the heights sampled in this study. We also found species richness to be greatest at 0 m, although overall abundance was similar between 0 and 9 m. The latter finding may be explained by our sampling methods which limited collections to one mosquito per minute, potentially underestimating abundance at ground level.…”

“…albigenu which were frequently caught at each height. While Psorophora species are known to be predominantly ground dwelling, they are often collected in the forest canopy 46 , 47 . In our study, the high relative abundance of both Ps.…”

Amazonian Anopheles with low numbers of oocysts transmit Plasmodium vivax sporozoites during a blood meal

“…However, at high densities, it can behave as an opportunistic species, and depending on the availability of vertebrate hosts, it can play a role in malaria transmission. In the present study, these species showed attractiveness to humans, as observed in other studies 29 , 30 . The evidence that those two species can bite humans in addition to the susceptibility to P. vivax and the capacity to develop sporozoites indicates that they must be important for maintenance of malaria transmission cycles.…”

Ecological and environmental factors affecting transmission of sylvatic yellow fever in the 2017–2019 outbreak in the Atlantic Forest, Brazil

“…Eclectic mosquitoes can serve as bridge vectors of pathogens from canopy-dwelling hosts to ground-dwelling hosts and vice versa [ 88 – 94 ] Seasonal distribution Accentuated (abrupt population peaks); moderate (no abrupt peaks) Populations increase abruptly in response to certain environmental events (e.g., rain, temperature), which increases vectorial capacity and determines the most favorable periods for transmission of pathogens [ 50 , 60 , 72 , 78 , 87 , 92 , 95 – 99 ] Environment Forest interior; forest edge; peri-urban; urban Ability to withstand different degrees of environmental impact and ecological impoverishment. Also reflects anthropophily and interspecific competition [ 46 , 60 , 83 , 94 , 98 , 100 ] Epidemiological importance YFV natural infection; YFV transmission in experimental infections; YFV primary vector; YFV secondary or local vector Indicates the accumulated evidence for vector competence and vectorial capacity of the species [ 16 , 43 , 44 , 101 – 112 ] …”