Perspectives on the timing of ecosystem collapse in a changing climate.

Climate change is one of the most important drivers of ecosystem change, the global-scale impacts of which will intensify over the next 2 decades. Estimating the timing of unprecedented changes is not only challenging but is of great importance for the development of ecosystem conservation guidelines. Time of emergence (ToE) (point at which climate change can be differentiated from a previous climate), a widely applied concept in climatology studies, provides a robust but unexplored approach for assessing the risk of ecosystem collapse, as described by the C criterion of the International Union for Conservation of Nature's Red List of Ecosystems (RLE). We identified 3 main theoretical considerations of ToE for RLE assessment (degree of stability, multifactorial instead of one-dimensional analyses, and hallmarks of ecosystem collapse) and 4 sources of uncertainty when applying ToE methodology (intermodel spread, historical reference period, consensus among variables, and consideration of different scenarios), which aims to avoid misuse and errors while promoting a proper application of the framework by scientists and practitioners. The incorporation of ToE for the RLE assessments adds important information for conservation priority setting that allows prediction of changes within and beyond the time frames proposed by the RLE.

Perspectivas sobre el momento del colapso ecosistémico en un clima cambiante Resumen El cambio climático es uno de los principales causantes del cambio ecosistémico, cuyo impacto a escala global se intensificará en las próximas dos décadas. No sólo es un reto estimar el momento de los cambios sin precedentes, sino también es de gran importancia para el desarrollo de las directrices de conservación de los ecosistemas. El momento de aparición (MdA), el punto en el que el cambio climático puede diferenciarse de un clima previo; es un concepto de aplicación extensa en los estudios de climatología y proporciona una estrategia sólida pero poco explorada para evaluar el riesgo del colapso ecosistémico, como está descrito por el criterio C de la Lista Roja de Ecosistemas (LRE) de la Unión Internacional para la Conservación de la Naturaleza. Identificamos las tres consideraciones teóricas del MdA para la evaluación de la LRE (grado de estabilidad, análisis multifactoriales en vez de unidimensionales y distintivos del colapso ecosistémico) y cuatro fuentes de incertidumbre cuando se aplica la metodología MdA (difusión intermodelo, periodo de referencia histórica, consenso entre las variables y consideración de escenarios distintos), la cual busca evitar el mal uso y los errores mientras se promueve una aplicación adecuada del marco de los científicos y lo practicantes. La incorporación del MdA a las evaluaciones de la LRE añade información importante para el establecimiento de prioridades de conservación que permiten la predicción de cambios dentro y más allá del marco temporal propuesto por la LRE.

Understanding how environmental degradation, microclimate, and management shape honey production across different spatial scales.

Although the abundance, survival, and pollination performance of honeybees are sensitive to changes in habitat and climate conditions, the processes by which these effects are transmitted to honey production and interact with beekeeping management are not completely understood. Climate change, habitat degradation, and beekeeping management affect honey yields, and may also interact among themselves resulting in indirect effects across spatial scales. We conducted a 2-year, multi-scale study on Chiloe Island (northern Patagonia), where we evaluated the most relevant environmental and management drivers of honey produced by stationary beekeepers. We found that the effects of microclimate, habitat, and management variables changed with the spatial scale. Among the environmental variables, minimum temperature, and cover of the invasive shrub, gorse (Ulex europaeus) had the strongest detrimental impacts on honey production at spatial scales finer than 4 km. Specialized beekeepers who adopted conventional beekeeping and had more mother colonies were more productive. Mean and minimum temperatures interacted with the percentage of mother colonies, urban cover, and beekeeping income. The gorse cover increased by the combination of high temperatures and the expansion of urban lands, while landscape attributes, such as Eucalyptus plantation cover, influenced beekeeping management. Results suggest that higher temperatures change the available forage or cause thermal stress to honeybees, while invasive shrubs are indicators of degraded habitats. Climate change and habitat degradation are two interrelated environmental phenomena whose effects on beekeeping can be mitigated through adaptive management and habitat restoration.

High vulnerability of coastal wetlands in Chile at multiple scales derived from climate change, urbanization, and exotic forest plantations.

Coastal wetlands are considered one of the most vulnerable ecosystems worldwide; the ecosystem services they provide and the conservation of their biodiversity are threatened. Despite the high ecological and socioenvironmental value of coastal wetlands, regional and national vulnerability assessments are scarce. In this study we aimed to assess the vulnerability of coastal wetlands in Chile from 18°S to 42°S (n = 757) under a multiscale approach that included drivers associated with climate change and land cover change. We assessed multiple drivers of vulnerability at three spatial scales (10 m, 100 m, and 500 m) by analyzing multiple remote sensing data (16 variables) on land cover change, wildfires, climatic variables, vegetation functional properties, water surface and importance for biodiversity. We constructed a multifactorial vulnerability index based on the variables analyzed, which provided a map of coastal wetland vulnerability. Then we explored the main drivers associated with the vulnerability of each coastal wetland by performing a Principal Components Analysis with Agglomerative Hierarchical Clustering, which allowed us to group coastal wetlands according to the drivers analyzed. We found that 42.6 ± 9.2 % of the coastal wetlands evaluated have high or very high vulnerability, with higher vulnerability at the 500 m scale (51.4 %). We identified four groups of coastal wetlands: two located in central Chile, mainly affected by climate change-associated drivers (41.9 ± 2.1 %), and one in central Chile which is affected by land cover change (52.8 ± 6.2 %); the latter has a lower vulnerability level. The most vulnerable coastal wetlands were located in central Chile. Our results present novel findings about the current vulnerability of coastal wetlands, which could be validated by governmental institutions in field campaigns. Finally, we believe that our methodological approach could be useful to generate similar assessments in other world zones.

Unraveling the socio-environmental drivers during the early COVID-19 pandemic in China.

The effect of environmental and socioeconomic conditions on the global pandemic of COVID-19 had been widely studied, yet their influence during the early outbreak remains less explored. Unraveling these relationships represents a key knowledge to prevent potential outbreaks of similar pathogens in the future. This study aims to determine the influence of socioeconomic, infrastructure, air pollution, and weather variables on the relative risk of infection in the initial phase of the COVID-19 pandemic in China. A spatio-temporal Bayesian zero-inflated Poisson model is used to test for the effect of 13 socioeconomic, urban infrastructure, air pollution, and weather variables on the relative risk of COVID-19 disease in 122 cities of China. The results show that socioeconomic and urban infrastructure variables did not have a significant effect on the relative risk of COVID-19. Meanwhile, COVID-19 relative risk was negatively associated with temperature, wind speed, and carbon monoxide, while nitrous dioxide and the human modification index presented a positive effect. Pollution gases presented a marked variability during the study period, showing a decrease of CO. These findings suggest that controlling and monitoring urban emissions of pollutant gases is a key factor for the reduction of risk derived from COVID-19.

Effects of air pollution and weather on the initial COVID-19 outbreaks in United States, Italy, Spain, and China: A comparative study.

Contrasting effects have been identified in association of weather (temperature and humidity) and pollutant gases with COVID-19 infection, which could be derived from the influence of lockdowns and season change. The influence of pollutant gases and climate during the initial phases of the pandemic, before the closures and the change of season in the northern hemisphere, is unknown. Here, we used a spatial-temporal Bayesian zero-inflated-Poisson model to test for short-term associations of weather and pollutant gases with the relative risk of COVID-19 disease in China (first outbreak) and the countries with more cases during the initial pandemic (the United States, Spain and Italy), considering also the effects of season and lockdown. We found contrasting association between pollutant gases and COVID-19 risk in the United States, Italy, and Spain, while in China it was negatively associated (except for SO2 ). COVID-19 risk was positively associated with specific humidity in all countries, while temperature presented a negative effect. Our findings showed that short-term associations of air pollutants with COVID-19 infection vary strongly between countries, while generalized effects of temperature (negative) and humidity (positive) with COVID-19 was found. Our results show novel information about the influence of pollution and weather on the initial outbreaks, which contribute to unravel the mechanisms during the beginning of the pandemic.

Multiscale spatial analysis of headwater vulnerability in South-Central Chile reveals a high threat due to deforestation and climate change.

Headwaters represent an essential component of hydrological, ecological, and socioeconomical systems, by providing constant water streams to the complete basin. However, despite the high importance of headwaters, there is a lack of vulnerability assessments worldwide. Identifying headwaters and their vulnerability in a spatially explicit manner can enable restauration and conservation programs. In this study, we assess the vulnerability of headwaters in South-Central Chile (38.4 to 43.2°S) considering multiple degradation factors related to climate change and land cover change. We analyzed 2292 headwaters, characterizing multiple factors at five spatial scales by using remote sensing data related to Land Use and Cover Change (LUCC), human disturbances, vegetation cover, climate change, potential water demand, and physiography. We then generated an index of vulnerability by integrating all the analyzed variables, which allowed us to map the spatial distribution of headwater vulnerability. Finally, to estimate the main drivers of degradation, we performed a Principal Components Analysis with an Agglomerative Hierarchical Clustering, that allowed us to group headwaters according to the analyzed factors. The largest proportion of most vulnerable headwaters are located in the north of our study area with 48.1 %, 62.1 %, and 28.1 % of headwaters classified as highly vulnerable at 0, 10, and 30 m scale, respectively. The largest proportion of headwaters are affected by Climate Change (63.66 %) and LUCC (23.02 %) on average across all scales. However, we identified three clusters, in which the northern cluster is mainly affected by LUCC, while the Andean and Coastal clusters are mainly affected by climate change. Our results and methods present an informative picture of the current state of headwater vulnerability, identifying spatial patterns and drivers at multiple scales. We believe that the approach developed in this study could be useful for new studies in other zones of the world and can also promote Chilean headwater conservation.

Multiple environmental drivers for the Patagonian forest-dwelling beetles: Contrasting functional and taxonomic responses across strata and trophic guilds.

Forest disturbances modify microhabitats along the different vertical strata, triggering structural and functional changes in forest-dwelling beetle communities. However, the effects of multiple environmental factors can be complex to detect in ecosystems that offer a broad variety of microhabitats for a great variety of beetle species. This is the case in Patagonian temperate forests, where the use of remote sensing provides an opportunity to evaluate the sensitivity of beetle species to environmental changes. Here, we identified the environmental drivers of forest-dwelling beetle communities in the ground and canopy of 34 north Patagonian-forest landscapes. We analyzed the associations of the taxonomic and functional diversity of five trophic guilds with 30 remote-sensing variables of landscape structure, composition, and disturbances; vegetation and soil properties; and climate and physical variables. Hierarchical clustering analysis was used to identify trophic guilds responding similarly to predictors. Segmented regression analysis was used to evaluate functional redundancy from taxonomic-functional richness relationships. A total of 583 species (23,848 individuals) of beetles were recorded for both strata. The effects of environmental variables were heterogeneous across strata and guilds. Canopy beetles were especially sensitive to early successional conditions, and canopy attributes, but also benefited from the canopy openness. Forest specialists of the ground and canopy responded differently to environmental variables. Ground-dwelling beetles were mostly affected by fires, human modifications, edge closeness, high temperatures, and soil properties, responding weakly to canopy properties. Functional redundancy varied weakly along environmental gradients, being more likely in local communities of ground-dwelling beetles mostly composed of species with overlapping functional roles. Contrasting environmental responses between ground and canopy beetles, as well as among beetles of different trophic guilds, should arise from microhabitats that vary across strata and interact differently with response traits.

Climate-induced tree senescence leads to a transient increase in reproductive success of a large woodpecker species.

Climate change-induced mortality of trees is a concerning phenomenon for global forest ecosystems. The rapid decay and death of long-lived trees can significantly impact forest dynamics, with effects that transmit through ecological networks, becoming more evident in organisms occupying high trophic levels, such as large and specialized woodpecker species. However, understanding how populations of high trophic level species respond to climate change is still a challenge. In this study it was analyzed 32-year data of social groups of the Magellanic Woodpecker (Campephilus magellanicus) in North Patagonia, a region facing increasingly frequent droughts and increased temperatures. A positive trend in the size of woodpecker social groups as a response to climate-induced tree senescence was tested. A causal structural equation model examining climate- tree senescence- woodpecker relationships was used. Increasing nonlinear trends and positive interannual growth rates (>10%) for tree senescence and group size were found. Lowland forest sites had higher levels of tree senescence and more numerous social groups. The causal model supported the positive effect of mean temperature on tree senescence and the positive association of woodpeckers with tree senescence. These results provide evidence of a climate-induced increase in tree senescence that causes an increase in the size of woodpecker social groups. It is suggested that accelerated decay and mortality of trees in the northern Patagonian forests will decrease the stocks of deadwood in the long term, threatening the persistence of this large woodpecker species.

Increasing importance of heat stress for cattle farming under future global climate scenarios.

In the last decades, livestock species have been severely affected by heat stress because of increasing temperatures, which has threatened animal welfare and decreased production. Based on thermal comfort indices and ensemble climate projections, we analyzed the current and future global spatiotemporal patterns of the heat exposure of cattle in 10 agroclimatic zones. The results show that ~7% of the global cattle population is currently exposed to dangerous heat conditions. This percentage is projected to increase to ~48% before 2100 under a scenario of growing emissions. Tropical agroclimatic zones are expected to face an early increase in the exposure to intense heat before 2050. Heat exposure was negatively correlated with the socioeconomic variables, showing that poor and livestock-dependent tropical countries are the most affected. Our results demonstrate the near-future consequences of heat stress on livestock, emphasizing the limited time available to implement effective abatement strategies.

Tree decay modulates the functional response of lichen communities in Patagonian temperate forests.

Epiphytic and epixylic lichens respond negatively to forest degradation, climate change and pollution, but those effects may depend on functional traits or interact with the stage of tree decay. Disentangling the main drivers of lichen communities remains a challenge in regions where lichens are diverse and poorly known, as the case of Patagonian temperate forests. We used a multi-scale approach to evaluate the relationship between environmental variables, tree decay stage and lichens. We sampled lichens across three increasing scales (tree â‰ª site â‰ª landscape) by selecting 19 landscape units, where trees in four decay stages (snags, logs, cavity trees and healthy trees) were selected within sampling plots. A total of 35 predictors were measured over different scales, including 25 remote sensing indices of forest conditions, climate and air pollutants. Structural Equation Models were used to test the causal linkages of predictors with lichens, distinguishing functional categories (size, growth and reproductive strategy). A total of 69 lichen species were recorded. Cavity trees and logs supported the largest diversity, while snags and healthy trees had the lowest diversity. Functional lichen groups responded differently to fine-scale variables, including the diameter, height, density and pH of trees. Air pollutants affected species with sexual and mixed strategies. Lichens were sensitive to precipitation, temperature and wind speed, with foliose and sexual species responding positively to the latter. The abundance of all species and macrolichens increased with tree senescence and decreased with canopy continuity. Lichens occupying snags and logs responded negatively to primary productivity and tree senescence, but positively to soil organic matter. Our findings suggest: i) the functional structure of lichen communities varies non-linearly with the wood decay process; ii) the reproductive strategy influences the sensitivity to air pollutants, iii) climate variables influence dispersal and colonization of woody substrates; and iv) forest structure/succession interacts with tree decay.

The failed invasion of Harmonia axyridis in the Azores, Portugal: Climatic restriction or wrong population origin?

We tested two questions: (i) whether the climatic conditions of the Azorean Islands in Portugal may have restricted the invasion of Harmonia axyridis across this archipelago and (ii) determine what population of this species could have a higher probability of invading the islands. We used MaxEnt to project the climate requirements of different H. axyridis populations from three regions of the world, and the potential global niche of the species in the Azorean islands. Then we assessed the suitability of the islands for each of the three H. axyridis populations and global potential niche through histograms analysis, Principal Component Analysis (PCA) of climate variables, and a variable-by-variable assessment of the suitability response curves compared with the climatic conditions of the Azores. Climatic conditions of the Azores are less suitable for the U.S. and native Asian populations of H. axyridis, and more suitable for European populations and the global potential niche. The PCA showed that the climatic conditions of the islands differed from the climatic requirements of H. axyridis. This difference is mainly explained by precipitation of the wettest month, isothermality, and the minimum temperature of the coldest month. We concluded that the climatic conditions of the Azores could have influenced the establishment and spread of H. axyridis on these islands from Europe. Our results showed that abiotic resistance represented by the climate of the potentially colonizable zones could hinder the establishment of invasive insects, but it could vary depending of the origin of the colonizing population.

Giants are coming? Predicting the potential spread and impacts of the giant Asian hornet (Vespa mandarinia, Hymenoptera:Vespidae) in the USA.

BACKGOUND: Biological invasions are a global concern in agriculture, food production and biodiversity. Among the invasive species, some hornets are known to have serious effects on honey bees, as found during the invasion of Vespa velutina in Europe. The recent findings of Vespa mandarinia individuals in Washington state in the west coast of the USA have raised alarm in the whole country. Here we estimate the potential spread of V. mandarinia in the USA, analyzing its potential impacts on honey bee colonies, economic losses in the honey bee industry and bee-pollinated croplands. RESULTS: We found that V. mandarinia could colonize Washington and Oregon states in the west coast and a significant proportion of the east coast. If this species spread across the country, it could threaten 95 216 ± 5551 honey bee colonies, threatening an estimated income of US$11.9 and 101.8 million for hive derived products and bee-pollinated crops production, respectively, while colonizing 60 837.8 km2 of bee-pollinated croplands. CONCLUSION: Our results suggest that V. mandarinia will have serious effects in the USA, raising the need for prompt monitoring actions and planning at different administrative levels to avoid its potential spread.

Expansion of the Emerging Fungal Pathogen Cryptococcus bacillisporus Into America: Linking Phylogenetic Origin, Geographical Spread and Population Under Exposure Risk.

In 2018 the fungal pathogen Cryptococcus bacillisporus (AFLP5/VGIII) was isolated for the first time in Chile, representing the only report in a temperate region in South America. We reconstructed the colonization process of C. bacillisporus in Chile, estimating the phylogenetic origin, the potential spread zone, and the population at risk. We performed a phylogenetic analysis of the strain and modeled the environmental niche of the pathogen projecting its potential spread zone into the new colonized region. Finally, we generated risk maps and quantified the people under potential risk. Phylogenetic analysis showed high similarity between the Chilean isolate and two clonal clusters from California, United States and Colombia in South America. The pathogen can expand into all the temperate Mediterranean zone in central Chile and western Argentina, exposing more than 12 million people to this pathogen in Chile. This study has epidemiological and public health implications for the response to a potential C. bacillisporus outbreak, optimizing budgets, routing for screening diagnosis, and treatment implementation.

Current and future spatial assessment of biological control as a mechanism to reduce economic losses and carbon emissions: the case of Solanum sisymbriifolium in Africa.

BACKGROUND: Solanum sisymbriifolium is a native plant of South America introduced into Africa, which has detrimental effects on crop yields, and on the environment due to weed control treatment by burning. In South America, S. sisymbriifolium is naturally controlled by the beetle Gratiana spadicea, making this a potential option for its control in Africa. Here, we aim to generate current and future scenarios for the introduction of G. spadicea as a biocontrol agent in Africa, analysing: (i) current and future effective biocontrol areas; (ii) potentially avoided economic losses (AEL), and chemical control costs and savings; and (iii) avoided carbon emissions (ACE) associated with the non-burning of crop fields. We combine species distribution models (SDM) with land cover maps to estimate current and future effective biocontrol considering Representative Concentration Pathways (RCP) 4.5 and 8.5 climate change scenarios. We then estimate AEL and ACE using biocontrol, and chemical control costs and savings. RESULTS: The effective biocontrol area reached 392 405 km2 in 18 countries, representing 40% of potentially affected croplands. Climate change induced a decrease in affected croplands and effective biocontrol. The estimated AEL reached US$45 447.2 ± 5617.3 billion distributed across 16 countries, while the estimated chemical control costs and savings reached US$1988.5 billion and 1411.8 billion, respectively. Potential ACE reached 36.3 ± 5.4 Tg. CONCLUSIONS: Our study provides evidence for the potential benefits of biological controllers on economic losses and carbon emissions, which can be incorporated into sustainable development in low-income countries.

Spatial Quantification of the Population Exposed to Cryptococcus neoformans and Cryptococcus gattii Species Complexes in Europe: Estimating the Immunocompetent and HIV/AIDS Patients Under Risk.

Cryptococcus is an important fungal pathogen worldwide, causing serious clinical manifestations that can affect immunocompetent patients and can be particularly severe for immunocompromised patients. The Cryptococcus gattii s.s. (AFLP4/VGI), Cryptococcus tetragattii (AFLP/VGIV), Cryptococcus neoformans, and Cryptococcus deneoformans have been isolated from both clinical and environmental sources in Europe. We aim to quantify the people in Europe and the entire Mediterranean area who are under risk associated with each of the three fungal pathogens in a spatially explicit way, generating a series of maps and population statistics per country. Niche modeling was applied to estimate the potential distribution of each fungal pathogen, then these models were overlapped with a map of population density to estimate risk levels. The potential number of people per risk level and per country was quantified using a map of population count per pixel. Prevalence of HIV per country was also included in the analysis to quantify the HIV-infected population under potential risk. People under risk associated with exposure to C. gattii species (C. gattii s.s. and C. tetragattii) reached 137.65 million, whereas those exposed to C. neoformans and C. deneoformans were 268.58 and 360.78 million people, respectively. More than a half million HIV-infected patients are exposed to each of the two species of the C. neoformans species complex, and more than 200,000 to the C. gattii species complex. The present results can be useful for public health planning by European governments, focusing on the provision of inputs for a "screen-and-treat" approach, availability of medical resources, and continuous monitoring programs in risk zones.

Spatial global assessment of the pest Bagrada hilaris (Burmeister) (Heteroptera: Pentatomidae): current and future scenarios.

BACKGROUND: The insect Bagrada hilaris (Burmeister) an important pest worldwide, mainly due to the serious economic losses incurred and the large number of zones invaded. However, current and future spatial distributions of this pest, and the total area of cropland potentially affected have not been estimated. Here, we aim to: (1) estimate the potential geographic distribution of B. hilaris; (2) quantify the total area of cropland potentially affected worldwide, and in two recently colonized zones (California and Chile); and (3) estimate future changes in distribution under different climate change scenarios. RESULTS: We found that B. hilaris shows high environmental suitability in Mediterranean and arid regions, potentially affecting 1 108 184.1 km2 of cropland worldwide. The most affected continents were Asia and America, with 309 659.8 and 294 638.6 km2 of cropland at risk. More than 50% of cropland areas are at risk in seven countries. In California and central Chile, 43.7% and 50% of susceptible crops are at a high level of risk, respectively. Climate change scenarios predict an increase in the potential distribution of B. hilaris worldwide; America being the most affected continent. CONCLUSIONS: Our results provide a spatially explicit baseline from which to focus efforts on the prevention, management and control of this pest worldwide. © 2018 Society of Chemical Industry.

Global spatial assessment of Aedes aegypti and Culex quinquefasciatus: a scenario of Zika virus exposure.

Zika virus (ZIKV) is an arbovirus transmitted mainly by Aedes aegypti mosquitoes. Recent scientific evidence on Culex quinquefasciatus has suggested its potential as a vector for ZIKV, which may change the current risk zones. We aimed to quantify the world population potentially exposed to ZIKV in a spatially explicit way, considering the primary vector (A. aegypti) and the potential vector (C. quinquefasciatus). Our model combined species distribution modelling of mosquito species with spatially explicit human population data to estimate ZIKV exposure risk. We estimated the potential global distribution of C. quinquefasciatus and estimated its potential interaction zones with A. aegypti. Then we evaluated the risk zones for ZIKV considering both vectors. Finally, we quantified and compared the people under risk associated with each vector by risk level, country and continent. We found that C. quinquefasciatus had a more temperate distribution until 42° in both hemispheres, while the risk involving A. aegypti is concentrated mainly in tropical latitudes until 35° in both hemispheres. Globally, 4.2 billion people are under risk associated with ZIKV. Around 2.6 billon people are under very high risk associated with C. quinquefasciatus and 1 billion people associated with A. aegypti. Several countries could be exposed to ZIKV, which emphasises the need to clarify the competence of C. quinquefasciatus as a potential vector as soon as possible. The models presented here represent a tool for risk management, public health planning, mosquito control and preventive actions, especially to focus efforts on the most affected areas.

Zika: probabilidad de establecimiento de su vector, Aedes aegypti, en Chile / Zika: probability of establishment of its vector, Aedes aegypti, in Chile

Resumen El virus Zika ha despertado una alarma mundial en los últimos años, representando un problema importante para la salud pública. En este estudio evaluamos el riesgo potencial de exposición a virus Zika en Chile, asociado a la probabilidad de establecimiento del vector Aedes aegypti en el país. Se utilizaron técnicas de modelación de nicho para proyectar los requerimientos bioclimáticos del vector (nicho global), identificando las zonas de alta idoneidad para la especie en el país. Luego, se superpuso la distribución potencial del vector en Chile con la densidad de población humana, estimando en forma espacialmente explícita el riesgo asociado a la co-ocurrencia potencial de ambos. Identificamos que existe idoneidad bioclimática para A. aegypti en Chile continental, desde el área tropical del norte hasta regiones templadas, principalmente en zonas costeras. La población potencialmente expuesta podría alcanzar 1,8 millones de personas, con 1,3 millones en nivel medio y 21.000 en niveles altos de riesgo potencial de exposición. Los resultados expuestos aquí muestran que existe una significativa probabilidad de éxito de colonización del vector principal de virus Zika en Chile continental en caso de una introducción. Por lo tanto, la prevención, monitoreo y control se vuelven un tema importante para evitar la llegada de este vector a Chile continental.

The Zika virus has raised world alarm in recent years, representing a major public health problem. In this study we evaluated the potential risk of exposure to Zika virus in Chile, associated with the probability of establishment of the vector Aedes aegypti in the country. Niche modelling techniques were used to project the bioclimatic requirements of the vector (global niches), identifying zones of high suitability for the species within the country. Then, the potential distribution of the vector in Chile was overlapped with the human population density, estimating the risk associated to the potential co-occurrence of both in a spatially explicit manner. We identified bioclimatic suitability for A. aegypti in continental Chile, from the northern tropical area to temperate regions, mainly in coastal zones. The exposed population could reach 1.8 million people, with 1.3 million in a medium level of potential risk and 21,000 in a high level. These results support that there is a significant probability of success for the Zika virus main vector to colonize continental Chile in case of an introduction. Therefore, prevention, monitoring, and control play an important role in avoiding the arrival of this vector to our country.

Spatial quantification of the world population potentially exposed to Zika virus.

Background: Zika virus is an emerging Flaviviridae virus, which has spread rapidly in the last few years. It has raised concern because it has been associated with fetus microcephaly when pregnant women are infected. The main vector is the mosquito Aedes aegypti , distributed in tropical areas. Methods: Niche modelling techniques were used to estimate the potential distribution area of A. aegypti. This was overlapped with human population density, determining areas of potential transmission risk worldwide. Afterwards, we quantified the population at risk according to risk level. Results: The vector transmission risk is distributed mainly in Asia and Oceania on the shores of the Indian Ocean. In America, the risk concentrates in the Atlantic coast of South America and in the Caribbean Sea shores in Central and North America. In Africa, the major risk is concentrated in the Pacific and Atlantic coasts of Central and South Africa. The world population under high and very high risk levels includes 2.261 billion people. Conclusions: These results illustrate Zika virus risk at the global level and provide maps to target the prevention and control measures especially in areas with higher risk, in countries with less sanitation and poorer resources. Many countries without previous vector reports could become active transmission zones in the future, so vector surveillance should be implemented or reinforced in these areas.

[Zika: Probability of establishment of its vector, Aedes aegypti, in Chile]. / Zika: Probabilidad de establecimiento de su vector, Aedes aegypti, en Chile.

The Zika virus has raised world alarm in recent years, representing a major public health problem. In this study we evaluated the potential risk of exposure to Zika virus in Chile, associated with the probability of establishment of the vector Aedes aegypti in the country. Niche modelling techniques were used to project the bioclimatic requirements of the vector (global niches), identifying zones of high suitability for the species within the country. Then, the potential distribution of the vector in Chile was overlapped with the human population density, estimating the risk associated to the potential co-occurrence of both in a spatially explicit manner. We identified bioclimatic suitability for A. aegypti in continental Chile, from the northern tropical area to temperate regions, mainly in coastal zones. The exposed population could reach 1.8 million people, with 1.3 million in a medium level of potential risk and 21,000 in a high level. These results support that there is a significant probability of success for the Zika virus main vector to colonize continental Chile in case of an introduction. Therefore, prevention, monitoring, and control play an important role in avoiding the arrival of this vector to our country.