Land use patterns and the risk of West Nile virus transmission in central Illinois

Seasonal Bird Migration Could Explain Regional Synchronicity and Amplification in Human West Nile Virus Case Numbers

West Nile virus (WNV) is a zoonotic virus with a mosquito-avian transmission cycle having occasional spillover to mammals. A network analysis of annual log-transformed WNV case numbers (2003-2022) generated four spatially and temporally coherent clusters among 48 U.S. states and six Canadian provinces. Cluster 1 and Cluster 3 were the largest groups corresponding to the Central Flyway and the closely associated Eastern Flyway (with an east-coast subset). Cluster 2 and Cluster 4 corresponded with less-well defined segments of a distinctly different Western Flyway. Thus, clustering can be explained by migratory pathways of terrestrial birds. We investigated avian involvement in the spread of WNV from potential sources in the southern U.S. Analyses revealed consistent patterns in log-transformed case numbers of human WNV. This study highlights the significant role of migratory birds in shaping the spatiotemporal patterns of WNV incidence across North America. However, the observed variability in incidence also likely reflects the interplay of other factors including local environmental conditions, mosquito populations, and regional variations in both migratory and non-migratory bird populations.

Spatial and temporal analysis of West Nile virus infection in mosquito and human populations based on arboviral detection testing data

West Nile virus (WNV) is a mosquito-borne zoonotic flavivirus which often causes asymptomatic infection in humans but may develop into a deadly neuroinvasive disease. In this study, we aimed to investigate variables potentially associated with human WNV infection using human and mosquito WNV surveillance and monitoring datasets, established over 20 years, from 2003 to 2022, across the province of Ontario, Canada. We combined climatic and geographic data, mosquito surveillance data (n = 3010 sites), blood donation arboviral detection testing data in the human population, and demographic and socio-economic data from Canadian population censuses. We hypothesized that spatio-temporal indices related to mosquito vector habitat and phenology, in addition to human demographic and socio-economic factors, were associated with WNV infection in the human population. Our results show that high habitat suitability of the main WNV vector in southerly locations of this region, Cx. pipiens/restuans (IRR = 2.0), and variables related to lower income (IRR = 2.8), and shelter infrastructure spending (IRR = 0.7), were key risk factors associated with WNV infection among blood donors from 2003 to 2022 across Ontario (R2 = 0.67). These results may inform points of entry for practical intervention aimed at reducing risk of mosquito-borne pathogens in Canada.

Spatial dynamics of Culex quinquefasciatus abundance: geostatistical insights from Harris County, Texas

Mosquito-borne diseases pose a significant public health threat, prompting the need to pinpoint high-risk areas for targeted interventions and environmental control measures. Culex quinquefasciatus is the primary vector for several mosquito-borne pathogens, including West Nile virus. Using spatial analysis and modeling techniques, we investigated the geospatial distribution of Culex quinquefasciatus abundance in the large metropolis of Harris County, Texas, from 2020 to 2022. Our geospatial analysis revealed clusters of high mosquito abundance, predominantly located in central Houston and the north-northwestern regions of Harris County, with lower mosquito abundance observed in the western and southeastern areas. We identified persistent high mosquito abundance in some of Houston's oldest neighborhoods, highlighting the importance of considering socioeconomic factors, the built environment, and historical urban development patterns in understanding vector ecology. Additionally, we observed a positive correlation between mosquito abundance and neighborhood-level socioeconomic status with the area deprivation index explaining between 22 and 38% of the variation in mosquito abundance (p-value < 0.001). This further underscores the influence of the built environment on vector populations. Our study emphasizes the utility of spatial analysis, including hotspot analysis and geostatistical interpolation, for understanding mosquito abundance patterns to guide resource allocation and surveillance efforts. Using geostatistical analysis, we discerned fine-scale geospatial patterns of Culex quinquefasciatus abundance in Harris County, Texas, to inform targeted interventions in vulnerable communities, ultimately reducing the risk of mosquito exposure and mosquito-borne disease transmission. By integrating spatial analysis with epidemiologic risk assessment, we can enhance public health preparedness and response efforts to prevent and control mosquito-borne disease.

Landscape level associations between birds, mosquitoes and microclimates: possible consequences for disease transmission?

BACKGROUND

Mosquito-borne diseases are on the rise. While climatic factors have been linked to disease occurrences, they do not explain the non-random spatial distribution in disease outbreaks. Landscape-related factors, such as vegetation structure, likely play a crucial but hitherto unquantified role.

METHODS

We explored how three critically important factors that are associated with mosquito-borne disease outbreaks: microclimate, mosquito abundance and bird communities, vary at the landscape scale. We compared the co-occurrence of these three factors in two contrasting habitat types (forest versus grassland) across five rural locations in the central part of the Netherlands between June and September 2021.

RESULTS

Our results show that forest patches provide a more sheltered microclimate, and a higher overall abundance of birds. When accounting for differences in landscape characteristics, we also observed that the number of mosquitoes was higher in isolated forest patches.

CONCLUSIONS

Our findings indicate that, at the landscape scale, variation in tree cover coincides with suitable microclimate and high Culex pipiens and bird abundance. Overall, these factors can help understand the non-random spatial distribution of mosquito-borne disease outbreaks.

The Role of Temperature, Wind Speed, and Precipitation on the Abundance of Culex Species and West Nile Virus Infection Rate in Rural West-Central Illinois

While most research on West Nile virus (WNV) and its main vector, the Culex mosquito, has been conducted in laboratory or urban settings, studies with field-caught mosquitoes in rural areas, such as west-central Illinois, are lacking. The objective of this research was to investigate key abiotic factors using macroclimate data, including temperature, precipitation, and wind speed, to determine their influence on field-caught mosquito abundance in 4 rural counties in Illinois from 2014 to 2016. Additionally, the relationship between minimum infection rate (MIR) and thermal time was examined. Using gravid traps at 15 sites, Culex mosquitoes were collected twice a week. A total of 5,255 adult female Culex mosquitoes (Cx. pipiens, Cx. quinquefasciatus, and Cx. restuans) were collected in 2014; 9,138 in 2015; and 5,702 in 2016. Regression models were developed based on outcomes of relationships between field-caught mosquitoes and abiotic factors. Precipitation and thermal time had the most significant relationship with mosquito abundance (r2 = 0.993 and r2 = 0.993, respectively), while wind speed was less (r2 = 0.714). The greatest number of Culex and the highest annual MIR were observed in 2015, which was also the driest of the 3 sampling seasons. Mosquito abundance was observed to increase with warmer degree days and MIR was found to increase with abundance in mosquitoes. These models can be used for other mosquito surveillance and monitoring studies in various climate types and environments.

Mosquito community composition shapes virus prevalence patterns along anthropogenic disturbance gradients

Previously unknown pathogens often emerge from primary ecosystems, but there is little knowledge on the mechanisms of emergence. Most studies analyzing the influence of land-use change on pathogen emergence focus on a single host-pathogen system and often observe contradictory effects. Here, we studied virus diversity and prevalence patterns in natural and disturbed ecosystems using a multi-host and multi-taxa approach. Mosquitoes sampled along a disturbance gradient in Côte d'Ivoire were tested by generic RT-PCR assays established for all major arbovirus and insect-specific virus taxa including novel viruses previously discovered in these samples based on cell culture isolates enabling an unbiased and comprehensive approach. The taxonomic composition of detected viruses was characterized and viral infection rates according to habitat and host were analyzed. We detected 331 viral sequences pertaining to 34 novel and 15 previously identified viruses of the families Flavi-, Rhabdo-, Reo-, Toga-, Mesoni- and Iflaviridae and the order Bunyavirales. Highest host and virus diversity was observed in pristine and intermediately disturbed habitats. The majority of the 49 viruses was detected with low prevalence. However, nine viruses were found frequently across different habitats of which five viruses increased in prevalence towards disturbed habitats, in congruence with the dilution effect hypothesis. These viruses were mainly associated with one specific mosquito species (Culex nebulosus), which increased in relative abundance from pristine (3%) to disturbed habitats (38%). Interestingly, the observed increased prevalence of these five viruses in disturbed habitats was not caused by higher host infection rates but by increased host abundance, an effect tentatively named abundance effect. Our data show that host species composition is critical for virus abundance. Environmental changes that lead to an uneven host community composition and to more individuals of a single species are a key driver of virus emergence.

Ecological Niche and Positive Clusters of Two West Nile Virus Vectors in Ontario, Canada

West Nile virus (WNV) is a mosquito-borne pathogen associated with uncommon but severe neurological complications in humans, especially among the elderly and immune-compromised. In Northeastern North America, the Culex pipiens/restuans complex and Aedes vexans are the two principal vector mosquito species/species groups of WNV. Using a 10-year surveillance dataset of WNV vector captures at 118 sites across an area of 40,000 km2 in Eastern Ontario, Canada, the ecological niches of Cx. pipiens/restuans and Aedes vexans were modeled by random forest analysis. Spatiotemporal clusters of WNV-positive mosquito pools were identified using Kulldorf's spatial scan statistic. The study region encompasses land cover types and climate representative of highly populated Southeastern Canada. We found highest vector habitat suitability in the eastern half of the study area, where temperatures are generally warmer (variable importance > 0.40) and residential and agricultural cropland cover is more prominent (variable importance > 0.25). We found spatiotemporal clusters of high WNV infection rates around the city of Ottawa in both mosquito vector species. These results support the previous literature in the same region and elsewhere suggesting areas surrounding highly populated areas are also high-risk areas for vector-borne zoonoses such as the WNV.

Future land-use change predictions using Dyna-Clue to support mosquito-borne disease risk assessment

Mosquitoes are known vectors for viral diseases in Canada, and their distribution is driven by climate and land use. Despite that, future land-use changes have not yet been used as a driver in mosquito distribution models in North America. In this paper, we developed land-use change projections designed to address mosquito-borne disease (MBD) prediction in a 38 761 km2 area of Eastern Ontario. The landscape in the study area is marked by urbanization and intensive agriculture and hosts a diverse mosquito community. The Dyna-CLUE model was used to project land-use for three time horizons (2030, 2050, and 2070) based on historical trends (from 2014 to 2020) for water, forest, agriculture, and urban land uses. Five scenarios were generated to reflect urbanization, agricultural expansion, and natural areas. An ensemble of thirty simulations per scenario was run to account for land-use conversion uncertainty. The simulation closest to the average map generated was selected to represent the scenario. A concordance matrix generated using map pair analysis showed a good agreement between the simulated 2020 maps and 2020 observed map. By 2050, the most significant changes are predicted to occur mainly in the southeastern region's rural and forested areas. By 2070, high deforestation is expected in the central west. These results will be integrated into risk models predicting mosquito distribution to study the possibility of humans' increased exposure risk to MBDs.

Mapping the abundance of endemic mosquito-borne diseases vectors in southern Quebec

BACKGROUND

Climate change is increasing the dispersion of mosquitoes and the spread of viruses of which some mosquitoes are the main vectors. In Quebec, the surveillance and management of endemic mosquito-borne diseases, such as West Nile virus or Eastern equine encephalitis, could be improved by mapping the areas of risk supporting vector populations. However, there is currently no active tool tailored to Quebec that can predict mosquito population abundances, and we propose, with this work, to help fill this gap.

METHODS

Four species of mosquitos were studied in this project for the period from 2003 to 2016 for the southern part of the province of Quebec: Aedes vexans (VEX), Coquillettidia perturbans (CQP), Culex pipiens-restuans group (CPR) and Ochlerotatus stimulans group (SMG) species. We used a negative binomial regression approach, including a spatial component, to model the abundances of each species or species group as a function of meteorological and land-cover variables. We tested several sets of variables combination, regional and local scale variables for landcover and different lag period for the day of capture for weather variables, to finally select one best model for each species.

RESULTS

Models selected showed the importance of the spatial component, independently of the environmental variables, at the larger spatial scale. In these models, the most important land-cover predictors that favored CQP and VEX were 'forest', and 'agriculture' (for VEX only). Land-cover 'urban' had negative impact on SMG and CQP. The weather conditions on the trapping day and previous weather conditions summarized over 30 or 90 days were preferred over a shorter period of seven days, suggesting current and long-term previous weather conditions effects on mosquito abundance.

CONCLUSIONS

The strength of the spatial component highlights the difficulties in modelling the abundance of mosquito species and the model selection shows the importance of selecting the right environmental predictors, especially when choosing the temporal and spatial scale of these variables. Climate and landscape variables were important for each species or species group, suggesting it is possible to consider their use in predicting long-term spatial variationsin the abundance of mosquitoes potentially harmful to public health in southern Quebec.

Worldwide impacts of landscape anthropization on mosquito abundance and diversity: A meta-analysis

In recent decades, the emergence and resurgence of vector-borne diseases have been well documented worldwide, especially in tropical regions where protection and defense tools for human populations are still very limited. In this context, the dynamics of pathogens are influenced by landscape anthropization (i.e., urbanization, deforestation, and agricultural development), and one of the mechanisms through which this occurs is a change in the abundance and/or diversity of the vectors. An increasing number of empirical studies have described heterogeneous effects of landscape anthropization on vector communities; therefore, it is difficult to have an overall picture of these effects on a global scale. Here, we performed a meta-analysis to quantify the impacts of landscape anthropization on a global scale on the presence/abundance and diversity of mosquitoes, the most important arthropods affecting human health. We obtained 338 effect sizes on 132 mosquito species, compiled from 107 studies in 52 countries that covered almost every part of the world. The results of the meta-analysis showed an overall decline of mosquito presence/abundance and diversity in response to urbanization, deforestation, and agricultural development, except for a few mosquito species that have been able to exploit landscape anthropization well. Our results highlighted that these few favored mosquito species are those of global concern. They, thus, provide a better understanding of the overall effect of landscape anthropization on vector communities and, more importantly, suggest a greater risk of emergence and transmission of vector-borne diseases in human-modified landscapes.

Landscape Composition Affects Elements of Metacommunity Structure for Culicidae Across South-Eastern Illinois

The interplay among invasive alien vectors and the species assemblage of native potential vectors in areas of range expansion may affect the dynamics of pathogen transmission. In this study we investigate how Aedes albopictus, an invasive mosquito of considerable public health concern fits within mosquito communities at the edge of its range of distribution. This was addressed using a 2-year field survey of mosquitoes in south-eastern Illinois. We found that Ae. albopictus was more broadly distributed in this region than previously realized, with new occurrence records for nine counties. Abundance of this species varied strongly and peaked in locations of low-intermediate overall mosquito species richness. This differed from overall mosquito abundance, as well as abundance of another important vector, Cx. pipiens, for which the abundance-richness relationships were best described with power functions. Metacommunity analyses revealed that mosquito communities showed a non-random distribution with a Clementsian gradient, which suggests a pattern whereby distinct species assemblages are associated with specific habitats or environmental conditions. Land use was a significant underlying factor shaping mosquito community structure and species assemblages. Multivariate analyses showed that while Ae. canadensis and Cx. pipiens complex mosquitoes were associated with high and low proportions of wetlands in the environment, respectively, Ae. albopictus was most strongly associated with urban settlements. This work sheds light on landscape-level processes, such as niche differentiation driven by urban and agricultural development, structuring mosquito communities. We suggest that mosquito community assessments across habitats be incorporated as part of a One Health vector surveillance approach to aid in the goal of prediction and prevention of new and (re-)emerging vector-borne diseases.

The community-wide effectiveness of municipal larval control programs for West Nile virus risk reduction in Connecticut, USA

BACKGROUND

Mosquito larval control through the use of insecticides is the most common strategy for suppressing West Nile virus (WNV) vector populations in Connecticut (CT), USA. To evaluate the ability of larval control to reduce entomological risk metrics associated with WNV, we performed WNV surveillance and assessments of municipal larvicide application programs in Milford and Stratford, CT in 2019 and 2020. Each town treated catch basins and nonbasin habitats (Milford only) with biopesticide products during both WNV transmission seasons. Adult mosquitoes were collected weekly with gravid and CO₂ -baited light traps and tested for WNV; larvae and pupae were sampled weekly from basins within 500 m of trapping sites, and Culex pipiens larval mortality was determined with laboratory bioassays of catch basin water samples.

RESULTS

Declines in 4th instar larvae and pupae were observed in catch basins up to 2-week post-treatment, and we detected a positive relationship between adult female C. pipiens collections in gravid traps and pupal abundance in basins. We also detected a significant difference in total light trap collections between the two towns. Despite these findings, C. pipiens adult collections and WNV mosquito infection prevalence in gravid traps were similar between towns.

CONCLUSION

Larvicide applications reduced pupal abundance and the prevalence of host-seeking adults with no detectable impact on entomological risk metrics for WNV. Further research is needed to better determine the level of mosquito larval control required to reduce WNV transmission risk.

Using Earth observation images to inform risk assessment and mapping of climate change-related infectious diseases

The number of human cases of several climate-related infectious diseases, including tick- and mosquito-borne diseases, has increased in Canada and other parts of the world since the end of the last century. Predicting and mapping the risks associated with these diseases using environmental and climatic determinants derived from satellite images is an emerging method that can support research, surveillance, prevention and control activities and help to better assess the impacts of climate change in Canada. Earth observation images can be used to systematically monitor changes in the Earth's surface and atmosphere at different scales of time and space. These images can inform estimation and monitoring of environmental and climatic determinants, and thus disease prediction and risk mapping. The current array of Earth observation satellites provides access to a large quantity and variety of data. These data have different characteristics in terms of spatial, temporal and thematic precision and resolution. The objectives of this overview are to describe how Earth observation images may inform risk assessment and mapping of tick-borne and mosquito-borne diseases in Canada, their potential benefits and limitations, the implications and next steps.

Simplification of vector communities during suburban succession

Suburbanization is happening rapidly on a global scale, resulting in changes to the species assemblages present in previously undeveloped areas of land. Community-level changes after anthropogenic land-use change have been studied in a variety of organisms, but the effects on arthropods of medical and veterinary importance remain poorly characterized. Shifts in diversity, abundance, and community composition of such arthropods, like mosquitoes, can significantly impact vector-borne disease dynamics due to varying vectorial capacity between different species. In light of these potential implications for vector-borne diseases, we investigated changes in mosquito species assemblage after suburbanization by sampling mosquitoes in neighborhoods of different ages in Wake County, North Carolina, US. We found that independent of housing density and socioeconomic status, mosquito diversity measures decreased as suburban neighborhoods aged. In the oldest neighborhoods, the mosquito assemblage reached a distinct suburban climax community dominated by the invasive, peridomestic container-breeding Aedes albopictus, the Asian tiger mosquito. Aedes albopictus is a competent vector of many pathogens of human concern, and its dominance in suburban areas places it in close proximity with humans, allowing for heightened potential of host-vector interactions. While further research is necessary to explicitly characterize the effects of mosquito community simplification on vector-borne disease transmission in highly suburbanized areas, the current study demonstrates that suburbanization is disrupting mosquito communities so severely that they do not recover their diversity even 100 years after the initial disturbance. Our understanding of the community-level effects of anthropogenic land-use change on arthropod vectors will become increasingly important as we look to mitigate disease spread in a global landscape that is continually developed and altered by humans.

Long-term surveillance defines spatial and temporal patterns implicating Culex tarsalis as the primary vector of West Nile virus

West Nile virus (WNV) has become the most epidemiologically important mosquito-borne disease in the United States, causing ~50,000 cases since its introduction in 1999. Transmitted primarily by Culex species, WNV transmission requires the complex interplay between bird reservoirs and mosquito vectors, with human cases the result of epizootic spillover. To better understand the intrinsic factors that drive these interactions, we have compiled infection data from sentinel chickens, mosquito vectors, and human cases in Iowa over a 15 year period (2002-2016) to better understand the spatial and temporal components that drive WNV transmission. Supplementing these findings with mosquito abundance, distribution, and host preferences data, we provide strong support that Culex tarsalis is the most important vector of human WNV infections in the region. Together, our analysis provides new insights into WNV infection patterns in multiple hosts and highlights the importance of long-term surveillance to understand the dynamics of mosquito-borne-disease transmission.

Mosquitoes of field and forest: the scale of habitat segregation in a diverse mosquito assemblage

Knowledge of the distribution of arthropod vectors across a landscape is important in determining the risk for vector-borne disease. This has been well explored for ticks, but not for mosquitoes, despite their importance in the transmission of a variety of pathogens. This study examined the importance of habitat, habitat edges, and the scale at which mosquito abundance and diversity vary in a rural landscape by trapping along transects from grassland areas into forest patches. Significant patterns of vector diversity and distinct mosquito assemblages across habitats were found. The scale of individual species' responses to habitat edges was often dramatic, with several species rarely straying even 10 m from the edge. The present results suggest blood-seeking mosquito species are faithful to certain habitats, which has consequences for patterns of vector diversity and risk for pathogen transmission. This implies that analysts of risk for pathogen transmission and foci of control, and developers of land management strategies should assess habitat at a finer scale than previously considered.

Effect of two commercial herbicides on life history traits of a human disease vector, Aedes aegypti, in the laboratory setting

Some mosquito species utilize the small niches of water that are abundant in farmland habitats. These niches are susceptible to effects from agricultural pesticides, many of which are applied aerially over large tracts of land. One principal form of weed control in agricultural systems involves the development of herbicide-tolerant crops. The impact of sub-agricultural levels of these herbicides on mosquito survival and life-history traits of resulting adults have not been determined. The aim of this study was to test the effect of two commercial herbicides (Beyond and Roundup) on the survivorship, eclosion time, and body mass of Aedes aegypti. First instar A. aegypti larvae were exposed to varying concentrations (270, 550 and 820 μg/m(2) of glyphosate and 0.74, 1.49, 2.24 μL imazamox/m(2)), all treatments being below recommended application rates, of commercial herbicides in a controlled environment and resulting adult mosquitoes were collected and weighed. Exposure to Roundup had a significant negative effect on A. aegypti survivorship at medium and high sub-agricultural application concentrations, and negatively affected adult eclosion time at the highest concentration. However, exposure to low concentrations of Beyond significantly increased A. aegypti survivorship, although adult female mass was decreased at medium sub-agricultural concentrations. These results demonstrate that low concentrations of two different herbicides, which can occur in rural larval habitats as a result of spray drift, can affect the same species of mosquito in both positive and negative ways depending on the herbicide applied. The effects of commercial herbicides on mosquito populations could have an important effect on disease transmission within agricultural settings, where these and other herbicides are extensively applied to reduce weed growth.

Culex pipiens and Culex restuans mosquitoes harbor distinct microbiota dominated by few bacterial taxa

BACKGROUND

Mosquitoes host diverse microbial communities that influence many aspects of their biology including reproduction, digestion, and ability to transmit pathogens. Unraveling the composition, structure, and function of these microbiota can provide new opportunities for exploiting microbial function for mosquito-borne disease control.

METHODS

MiSeq® sequencing of 16S rRNA gene amplicons was used to characterize the microbiota of adult females of Culex pipiens L. and Cx. restuans Theobald collected from nine study sites in central Illinois.

RESULTS

Out of 195 bacterial OTUs that were identified, 86 were shared between the two mosquito species while 16 and 93 OTUs were unique to Cx. pipiens and Cx. restuans, respectively. The composition and structure of microbial communities differed significantly between the two mosquito species with Cx. restuans hosting a more diverse bacterial community compared to Cx. pipiens. Wolbachia (OTU836919) was the dominant bacterial species in Cx. pipiens accounting for 91% of total microbiota while Sphingomonas (OTU817982) was the dominant bacterial species in Cx. restuans accounting for 31% of total microbiota. Only 3 and 6 OTUs occurred in over 60% of individuals in Cx. pipiens and Cx. restuans, respectively. There was little effect of study site on bacterial community structure of either mosquito species.

CONCLUSION

These results suggest that the two mosquito species support distinct microbial communities that are sparsely distributed between individuals. These findings will allow investigations of the role of identified microbiota on the spatial and temporal heterogeneity in WNV transmission and their potential application in disease control.

Impact of an Alien Invasive Shrub on Ecology of Native and Alien Invasive Mosquito Species (Diptera: Culicidae)

We examined how leaf litter of alien invasive honeysuckle (Lonicera maackii Rupr.) either alone or in combination with leaf litter of one of two native tree species, sugar maple (Acer saccharum Marshall) and northern red oak (Quercus rubra L.), affects the ecology of Culex restuans Theobald, Ochlerotatus triseriatus Say, and Ochlerotatus japonicus Theobald. Experimental mesocosms containing single species litter or a mixture of honeysuckle and one of two native tree species litter were established at South Farms and Trelease Woods study sites in Urbana, IL, and examined for their effect on 1) oviposition site selection by the three mosquito species, and 2) adult production and body size of Oc. triseriatus and Oc. japonicus. There were no significant effects of study site and leaf treatment on Oc. japonicus and Oc. triseriatus oviposition preference and adult production. In contrast, significantly more Cx. restuans eggs rafts were collected at South Farms relative to Trelease Woods and in honeysuckle litter relative to native tree species litter. Significantly larger adult females of Oc. japonicus and Oc. triseriatus were collected at South Farms relative to Trelease Woods and in honeysuckle litter relative to native tree species litter. Combining honeysuckle litter with native tree species litter had additive effects on Cx. restuans oviposition preference and Oc. japonicus and Oc. triseriatus body size, with the exception of honeysuckle and northern red oak litter combination, which had antagonistic effects on Oc. triseriatus body size. We conclude that input of honeysuckle litter into container aquatic habitats may alter the life history traits of vector mosquito species.

Identifying the environmental conditions favouring West Nile Virus outbreaks in Europe

West Nile Virus (WNV) is a globally important mosquito borne virus, with significant implications for human and animal health. The emergence and spread of new lineages, and increased pathogenicity, is the cause of escalating public health concern. Pinpointing the environmental conditions that favour WNV circulation and transmission to humans is challenging, due both to the complexity of its biological cycle, and the under-diagnosis and reporting of epidemiological data. Here, we used remote sensing and GIS to enable collation of multiple types of environmental data over a continental spatial scale, in order to model annual West Nile Fever (WNF) incidence across Europe and neighbouring countries. Multi-model selection and inference were used to gain a consensus from multiple linear mixed models. Climate and landscape were key predictors of WNF outbreaks (specifically, high precipitation in late winter/early spring, high summer temperatures, summer drought, occurrence of irrigated croplands and highly fragmented forests). Identification of the environmental conditions associated with WNF outbreaks is key to enabling public health bodies to properly focus surveillance and mitigation of West Nile virus impact, but more work needs to be done to enable accurate predictions of WNF risk.