Aedes albopictus and Its Environmental Limits in Europe

Abstract

The Asian tiger mosquito Aedes albopictus, native to South East Asia, is listed as one of the worst invasive vector species worldwide. In Europe the species is currently restricted to Southern Europe, but due to the ongoing climate change, Ae. albopictus is expected to expand its potential range further northwards. In addition to modelling the habitat suitability for Ae. albopictus under current and future climatic conditions in Europe by means of the maximum entropy approach, we here focused on the drivers of the habitat suitability prediction. We explored the most limiting factors for Aedes albopictus in Europe under current and future climatic conditions, a method which has been neglected in species distribution modelling so far. Ae. albopictus is one of the best-studied mosquito species, which allowed us to evaluate the applied Maxent approach for most limiting factor mapping. We identified three key limiting factors for Ae. albopictus in Europe under current climatic conditions: winter temperature in Eastern Europe, summer temperature in Southern Europe. Model findings were in good accordance with commonly known establishment thresholds in Europe based on climate chamber experiments and derived from the geographical distribution of the species. Under future climatic conditions low winter temperature were modelled to remain the most limiting factor in Eastern Europe, whereas in Central Europe annual mean temperature and summer temperatures were modelled to be replaced by summer precipitation, respectively, as most limiting factors. Changes in the climatic conditions in terms of the identified key limiting factors will be of great relevance regarding the invasive potential of the Ae. albopictus. Thus, our results may help to understand the key drivers of the suggested range expansion under climate change and may help to improve monitoring programmes. The applied approach of investigating limiting factors has proven to yield valuable results and may also provide valuable insights into the drivers of the prediction of current and future distribution of other species. This might be particularly interesting for other vector species that are of increasing public health concerns.

Fig 1. Observed distribution and modelled habitat suitability for Ae. albopictus under current climatic conditions in Europe.

A) Occurrence records for Ae. albopictus used for modelling B) modelled habitat suitability (model 1) under consideration of mean temperature of coldest quarter, mean temperature of warmest quarter, annual mean temperature, precipitation of warmest quarter and annual precipitation and C) modelled habitat suitability (model 2) under consideration of mean temperature in January, mean temperature in summer, photoperiod, precipitation in spring and precipitation in summer. Geographical projection: Europe Albers Equal Area Conic. Maps were built using ESRI ArcGIS.

Fig 2

Limiting factors under current climatic conditions based on two Maxent models A) model 1 under consideration of mean temperature of coldest quarter, mean temperature of warmest quarter, annual mean temperature, annual precipitation and precipitation of warmest quarter and B) model 2 under consideration of mean temperature in January, mean temperature in summer, photoperiod, precipitation in spring and precipitation in summer. For any point, the limiting factor is the variable whose value influenced the model prediction the most. Cross-hatched areas indicate area with modelled habitat suitability for Ae. albopictus (dichotomous modelling results). Geographical projection: Europe Albers Equal Area Conic. Maps were built using ESRI ArcGIS.

Fig 3

Areas that match the establishment criteria (according to Medlock et al. 2015) under current climatic conditions: A) area with a mean temperature of the coldest quarter above 0°C, B) area with an annual mean temperature of > 11°C, C) area with an annual precipitation of > 500 mm, D) area for which criteria A), B) and C) are fulfilled. The cross-hatched area indicates suitable habitat conditions for Ae. albopictus according to the dichotomous modelling results based on model 1. Maps were built using ESRI ArcGIS.

Fig 4. The most limiting factors for the potential distribution of Ae. albopictus based on model 1 under consideration of mean temperature of coldest quarter, mean temperature of warmest quarter, annual mean temperature, annual precipitation and precipitation of warmest quarter under current and projected future climatic conditions according to the IPCC AR5 data GCM: CSIRO.

For any point, the limiting factor is the variable whose value influenced the model prediction the most. Geographical projection: Europe Albers Equal Area Conic. Maps were built using ESRI ArcGIS.

Fig 5. The most limiting factors for the potential distribution of Ae. albopictus based on model 2 under consideration of mean temperature in January, mean temperature in summer, photoperiod, precipitation in spring and precipitation in summer under current and projected future climatic conditions according to the IPCC AR5 data GCM: CSIRO.

For any point, the limiting factor is the variable whose value influences the model prediction the most. Geographical projection: Europe Albers Equal Area Conic. Maps were built using ESRI ArcGIS.