Variability in mosquito community composition associated with estuarine wetlands in Northern NSW, Australia

The Northern Rivers region of NSW, Australia, is well documented as being impacted by nuisance-biting mosquitoes and mosquito-borne disease. Mosquitoes of greatest concern are those associated with estuarine and brackish water habitats associated with coastal wetlands and understanding the spatial variability in abundance and diversity will assist the assessment of risk and inform surveillance and control programs. Adult mosquito populations were sampled, using carbon dioxide baited traps, at four locations within the Richmond River estuary at Ballina, NSW, Australia, during January and February 2021. Concomitant sampling of habitats for immature mosquitoes was also undertaken. A total of 16,467 mosquitoes was collected at all sites across two sampling periods with the most abundant mosquitoes, Verrallina funerea, Aedes vigilax, and Culex sitiens, those typically associated with estuarine environments. Culex annulirostris, a mosquito associated with freshwater habitats, and Aedes notoscriptus, a mosquito associated with water-holding containers, were also commonly collected. The mosquito communities differed, in relative abundance and species richness, between the four locations. The result highlighted the need for authorities to understand the variability in productivity of potential mosquito habitats, beyond those determinants associated with vegetation communities alone, when assessing suitable locations of mosquito surveillance and integrated mosquito management.

Landscape Anthropization Affects Mosquito Diversity in a Deciduous Forest in Southeastern Mexico

Mosquitoes (Diptera: Culicidae) are considered the group of insects that most impacts human health. Land use change, conversion of conserved sites into agricultural environments, urbanization, defaunation, and introduction of domestic animals can affect mosquito diversity positively or negatively, increasing the risk of transmission of zoonotic diseases. Here, we describe the diversity of adult mosquitoes in two environments (deciduous forest and anthropized zone) over 2 yr (2014–2016), using eight CDC traps at each site in three climatic seasons (rainy, cold, and dry). We captured 795 individuals belonging to 22 species. We constructed rank-abundance curves to determine spatial and temporal changes in the mosquito communities. We measured alpha diversity using the Shannon index (H′), Shannon exponential (eH) and Simpson dominance (Ds), and beta diversity using Jaccard’s coefficient of similarity (Ij). The most abundant species were Culex quinquefasciatus (40.5%), Culex coronator (18.3%), and Anopheles pseudopunctipennis (12.4%). The highest mosquito diversity was in the deciduous forest during the rainy season. Beta diversity analysis showed that species overlap varied among climatic seasons, with the sites sharing 65% species during the rainy season, but only 33% of species during the dry season. We found differences in the diversity of mosquitoes at the two sites, and the mosquito assemblage of the anthropized zone was significantly different from that of the deciduous forest.

Ecological Effects on the Dynamics of West Nile Virus and Avian Plasmodium: The Importance of Mosquito Communities and Landscape

Humans and wildlife are at risk from certain vector-borne diseases such as malaria, dengue, and West Nile and yellow fevers. Factors linked to global change, including habitat alteration, land-use intensification, the spread of alien species, and climate change, are operating on a global scale and affect both the incidence and distribution of many vector-borne diseases. Hence, understanding the drivers that regulate the transmission of pathogens in the wild is of great importance for ecological, evolutionary, health, and economic reasons. In this literature review, we discuss the ecological factors potentially affecting the transmission of two mosquito-borne pathogens circulating naturally between birds and mosquitoes, namely, West Nile virus (WNV) and the avian malaria parasites of the genus Plasmodium. Traditionally, the study of pathogen transmission has focused only on vectors or hosts and the interactions between them, while the role of landscape has largely been ignored. However, from an ecological point of view, it is essential not only to study the interaction between each of these organisms but also to understand the environmental scenarios in which these processes take place. We describe here some of the similarities and differences in the transmission of these two pathogens and how research into both systems may facilitate a greater understanding of the dynamics of vector-borne pathogens in the wild.

Buzzing Homes: Using Citizen Science Data to Explore the Effects of Urbanization on Indoor Mosquito Communities

Urbanization has been associated with a loss of overall biodiversity and a simultaneous increase in the abundance of a few species that thrive in urban habitats, such as highly adaptable mosquito vectors. To better understand how mosquito communities differ between levels of urbanization, we analyzed mosquito samples from inside private homes submitted to the citizen science project ‘Mückenatlas’. Applying two urbanization indicators based on soil sealing and human population density, we compared species composition and diversity at, and preferences towards, different urbanization levels. Species composition between groups of lowest and highest levels of urbanization differed significantly, which was presumably caused by reduced species richness and the dominance of synanthropic mosquito species in urban areas. The genus Anopheles was frequently submitted from areas with a low degree of urbanization, Aedes with a moderate degree, and Culex and Culiseta with a high degree of urbanization. Making use of citizen science data, this first study of indoor mosquito diversity in Germany demonstrated a simplification of communities with increasing urbanization. The dominance of vector-competent species in urban areas poses a potential risk of epidemics of mosquito-borne diseases that can only be contained by a permanent monitoring of mosquitoes and by acquiring a deeper knowledge about how anthropogenic activities affect vector ecology.

Malaria transmission in landscapes with varying deforestation levels and timelines in the Amazon: a longitudinal spatiotemporal study

The relationship between deforestation and malaria is a spatiotemporal process of variation in Plasmodium incidence in human-dominated Amazonian rural environments. The present study aimed to assess the underlying mechanisms of malarial exposure risk at a fine scale in 5-km2 sites across the Brazilian Amazon, using field-collected data with a longitudinal spatiotemporally structured approach. Anopheline mosquitoes were sampled from 80 sites to investigate the Plasmodium infection rate in mosquito communities and to estimate the malaria exposure risk in rural landscapes. The remaining amount of forest cover (accumulated deforestation) and the deforestation timeline were estimated in each site to represent the main parameters of both the frontier malaria hypothesis and an alternate scenario, the deforestation-malaria hypothesis, proposed herein. The maximum frequency of pathogenic sites occurred at the intermediate forest cover level (50% of accumulated deforestation) at two temporal deforestation peaks, e.g., 10 and 35 years after the beginning of the organization of a settlement. The incidence density of infected anophelines in sites where the original forest cover decreased by more than 50% in the first 25 years of settlement development was at least twice as high as the incidence density calculated for the other sites studied (adjusted incidence density ratio = 2.25; 95% CI, 1.38–3.68; p = 0.001). The results of this study support the frontier malaria as a unifying hypothesis for explaining malaria emergence and for designing specific control interventions in the Brazilian Amazon.

A Systematic Review: Is Aedes albopictus an Efficient Bridge Vector for Zoonotic Arboviruses?

Mosquito-borne arboviruses are increasing due to human disturbances of natural ecosystems and globalization of trade and travel. These anthropic changes may affect mosquito communities by modulating ecological traits that influence the “spill-over” dynamics of zoonotic pathogens, especially at the interface between natural and human environments. Particularly, the global invasion of Aedes albopictus is observed not only across urban and peri-urban settings, but also in newly invaded areas in natural settings. This could foster the interaction of Ae. albopictus with wildlife, including local reservoirs of enzootic arboviruses, with implications for the potential zoonotic transfer of pathogens. To evaluate the potential of Ae. albopictus as a bridge vector of arboviruses between wildlife and humans, we performed a bibliographic search and analysis focusing on three components: (1) The capacity of Ae. albopictus to exploit natural larval breeding sites, (2) the blood-feeding behaviour of Ae. albopictus, and (3) Ae. albopictus’ vector competence for arboviruses. Our analysis confirms the potential of Ae. albopictus as a bridge vector based on its colonization of natural breeding sites in newly invaded areas, its opportunistic feeding behaviour together with the preference for human blood, and the competence to transmit 14 arboviruses.

Differences in Mosquito Communities in Six Cities in Oklahoma

Vector-borne diseases in the United States have recently increased as a result of the changing nature of vectors, hosts, reservoirs, pathogens, and the ecological and environmental conditions. Current information on vector habitats and how mosquito community composition varies across space and time is vital to successful vector-borne disease management. This study characterizes mosquito communities in urban areas of Oklahoma, United States, an ecologically diverse region in the southern Great Plains. Between May and September 2016, 11,996 female mosquitoes of 34 species were collected over 798 trap nights using three different trap types in six Oklahoma cities. The most abundant species trapped were Culex pipiens L. complex (32.4%) and Aedes albopictus (Skuse) (Diptera: Culicidae) (12.0%). Significant differences among mosquito communities were detected using analysis of similarities (ANOSIM) between the early (May–July) and late (August–September) season. Canonical correlation analysis (CCA) further highlighted the cities of Altus and Idabel as relatively unique mosquito communities, mostly due to the presence of Aedes aegypti (L.) and salt-marsh species and absence of Aedes triseriatus (Say) in Altus and an abundance of Ae. albopictus in Idabel. These data underscore the importance of assessing mosquito communities in urban environments found in multiple ecoregions of Oklahoma to allow customized vector management targeting the unique assemblage of species found in each city.