Poster, 1st Conference on Spatial Statitics: Mapping Global Change, Enschede (The Netherlands): 23.03.2011 - 25.03.2011
Abstract:
The spatial patterns of many vector-borne diseases have changed significantly during the last couple of years. Especially climate-sensitive arthropod vectors react significantly to climatic changes with shifting or spreading tendencies (Fischer et al., 2010a). Phlebotomine sandflies are known vectors of the pathogen Leishmania infantum which causes leishmaniasis in humans in Southern Europe. Recent sandfly catches at higher latitudes of Central Europe indicate spreading tendencies. In a previous study, Fischer et al. (2010b) pointed out that warming may support sandfly establishment at higher latitudes during the 21st century. Here, we model bioclimatic envelopes for six Phlebotomus-species using the Maximum Entropy approach. The species occur naturally in South-West or South-East Europe, depending on their capacity to tolerate seasonal temperature changes. The bioclimatic envelopes based on the most significant variables were transferred to the expected future climate conditions of Europe by using projected data of the spatio-temporal highly resolved regional climate model Cosmo-CLM (scenarios A1B and B1) in order to identify potentially suitable habitats of the disease vectors. However, projected bioclimatic suitability does not necessarily imply vector establishment in the detected regions. For this purpose, species dispersal pathways and potential barriers have to be included in spatio-temporal risk assessments. We integrate expert knowledge to develop a “cost surface” which includes absolute and relative barriers that cannot or hardly be crossed by the sandfly species. Finally, we identify the “least-cost path” as the most likely pathway species will chose to disperse to climatically suitable regions of Central Europe. Results indicate that in Central Europe the climate will develop towards the preferred bioclimatic niche of 5 Phlebotomus-species in the 21st century. However, only species with (south-) western focus of distribution seem to disperse via river valleys, as the Alps act as an impassable barrier. Hence, Phlebotomus-species may not be able to occupy all projected climatically suitable habitats. As it is known that sandflies are not active during windy seasons we integrate projections of wind speed in our analysis. High wind speed would limit the dispersal of such wind-sensitive vectors, even if temperature and moisture requirements are fulfilled. The integration of dispersal mechanisms and limitations substantially improves bioclimatic envelope modelling in the light of a rapidly changing European climate. Improved knowledge in this field of disease vectors is urgently needed for political decision making and for the preparation of efficient surveillance systems. Climate-related health hazards require proactive strategies.