Heterogeneous distribution of Culex pipiens, Culex quinquefasciatus and their hybrids along the urbanisation gradient

Abstract

The mosquitoes of the Culex pipiens complex, hereafter referred to as the Pipiens Assemblage, are vectors of arbovirus of worldwide concern including West Nile and St. Louis encephalitis. Given their distinct eco-physiology and vectorial capacity, accurate specimen identification and insight in the environmental drivers of their distribution are essential for the understanding of disease transmission patterns. Using a PCR-based identification protocol, we characterized the spatial distribution of Cx. pipiens, Cx. quinquefasciatus and their hybrids developing in used tyres located within the overlapping region in South America as a function of different estimators of the urbanisation gradient. Out of 84 samples collected from tyre piles of 20 sites, we identified 369 larvae which corresponded predominantly to Cx. quinquefasciatus (76.4% of immatures) all along the gradient but more frequent at the urban end. Cx. pipiens (21.4%) was more conspicuous at the low urbanised end but was also present in highly urbanised sites, whereas hybrids were collected in very low numbers (2.2%). The urbanisation estimator best associated with the heterogeneous occurrence of the Pipiens Assemblage members was the proportion of impervious surface 1km around each tyre pile, which explained 41.7% of the variability in the data, followed closely by the distance to the Capital City (38.3%). Cumulative annual precipitation, population number in a 1km radius around each pile and distance to the de la Plata River were significantly associated with the distribution of the Pipiens Assemblage at lower explanation percentages (20-23%). A thorough understanding of the ecological basis and environmental associations of the distribution of Pipiens Assemblage members will enable forecasting population trends in changing environments to develop effective control measures for mosquitoes and the diseases they transmit.

Improved spatial ecological sampling using open data and standardization: an example from malaria mosquito surveillance

“…The consequence of which could be an over- or under-estimate of the true abundance, even when the population phenology is correctly delineated [56]. In some cases, however, a quantitatively determined sampling design may not be necessary, especially if the study intends to survey the entire area under study (as for example in [57,58]), or if it is a consequence of interventions recommended by national or international authorities [58,59] (i.e. WHO guidelines [60]).…”

A rural–urban latitudinal study of the distributions of Culex quinquefasciatus and Culex pipiens bioforms in their southernmost sympatric fringe

“…quinquefasciatus were frequently collected in coexistence at the same cemetery and, on two occasions, even the same container, indicating that there is no ecological barrier in terms of habitat usage, no hybrid specimens in flower vases along Buenos Aires Province were identified. Within this area, hybrids were previously reported in very low abundances (2%; eight out of 369 specimens) in discarded vehicle tires (Cardo et al ., ) but abundantly in artificial drainage ditches with organically polluted water (Micieli et al ., ). Hybrids are fertile, at least in laboratory conditions (Almirón et al ., ), and could therefore select aquatic habitats of certain characteristics for oviposition.…”

“…pipiens , Cx. quinquefasciatus and their hybrids have been reported in discarded tyres (Cardo et al ., ) and drainage ditches (Micieli et al ., ) from the Buenos Aires metropolitan area (approximately 35° S); the latter included the first and only identification of Cx. pipiens bioforms in the region as form molestus .…”

The impact of industrial activities on vector-borne disease transmission

“…Consistent with this, mosquitoes collected from tyres along an urbanisation gradient in South America revealed Cx. quinquefasciatus to be more frequent at the urban end (Cardo et al, 2018). In this context, it is clear how anthropogenic alterations that affect the availability of breeding sites and other features of local ecology can have impacts on communities of insects of medical importance (Abella-Medrano et al, 2015).…”