Mosquitoes are well known for their epidemiological importance as vectors of a wide range of human pathogens. Despite the many studies on medically important species, little is known about the diversity patterns of these insects in urban green spaces, which serve as shelter and refuge for many native and invasive species. Here, we investigate drivers of mosquito richness and composition in nine urban parks in the city of São Paulo, Brazil. Using the equilibrium theory of island biogeography, we tested predictive models for species richness and composition and performed nestedness analysis. We also investigated whether species loss tends to benefit vector mosquitoes. In the period 2011 to 2013, a total of 37,972 mosquitoes belonging to 73 species and 14 genera were collected. Our results suggest there is a species-area relationship, an increase in species similarity as richness is lost and a nested species composition pattern. Seven of the eight most commonly found species are considered vectors of human pathogens, suggesting a possible link between species loss and increased risk of pathogen transmission. Our data highlight the need for studies that seek to understand how species loss may affect the risk of infectious diseases in urban areas.
Background
The mosquito
Anopheles
(
Kerteszia
)
cruzii
is the main vector of human and simian malaria in the Atlantic Forest. This species is usually abundant in the forests where it occurs, preferring to live and feed on canopies, behaviour known as acrodendrophily. However, in several studies and locations this species has been observed in high density near the ground in the forest. In this study, it was hypothesized that factors associated with anthropogenic landscape changes may be responsible for the variation in abundance and acrodendrophily observed in
An. cruzii
.
Methods
The study was conducted in a conservation unit in the city of São Paulo, Brazil. Monthly entomological collections were performed from March 2015 to April 2017, and the resulting data were used with data from another study conducted in the same area between May 2009 and June 2010. Mosquitoes were collected from five sites using CDC and Shannon traps. Landscape composition and configuration metrics were measured, and generalized linear mixed-effect models were used to investigate the relationship between these metrics and variations in the abundance and acrodendrophily of
An. cruzii
.
Results
The model that showed the best fit for the relationship between landscape metrics and
An. cruzii
abundance suggests that an increase in the proportion of forest cover leads to an increase in the abundance of this mosquito, while the model that best explained variations in
An. cruzii
acrodendrophily suggests that an increase in total forest-edge length leads to greater activity by this species at ground level.
Conclusion
While the data indicate that changes in landscape due to human activities lead to a reduction in
An. cruzii
abundance, such changes may increase the contact rate between this species and humans living on the edges of forest fragments where
An. cruzii
is found. Future studies should, therefore, seek to elucidate the effect of these landscape changes on the dynamics of
Plasmodium
transmission in the Atlantic Forest, which according to some studies includes the participation of simian hosts.
Electronic supplementary material
The online version of this article (10.1186/s12936-019-2744-8) contains supplementary material, which is available to authorized users.
A mosquito faunal survey was conducted from October 2010 to February 2011 in the municipal parks of São Paulo City, Brazil. A total of 7,015 specimens of 53 taxonomic categories grouped into 12 genera (Aedes, Anopheles, Coquilletidia, Culex, Limatus, Lutzia, Mansonia, Psorophora, Toxorhynchites, Trichoprosopon, Uranotaenia, and Wyeomyia) were collected. The largest and most peripheral parks showed greater species richness compared to smaller and more centralized parks.
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