Will the yellow fever mosquito colonise Europe? Assessing the re-introduction of Aedes aegypti using a process-based population dynamical model

Aedes aegypti are feared invasive mosquitoes as they transmit pathogens which cause debilitating diseases in humans. Although mainland Europe has not yet witnessed re-establishment and dispersal of Ae. aegypti populations, several urban areas along coastlines represent suitable habitats for the species. In addition, European coastal areas are characterised by high exotic species propagule pressure, due to dense international ship traffic. To assess the likelihood of establishment in order to guide surveillance and control planning, we applied a process-based population dynamical model to simulate both the life cycle and dispersal of Ae. aegypti at the local scale after its introduction through ship traffic. We selected five European ports along a latitudinal gradient by considering both environmental conditions and the economical importance of ports: Algeciras and Barcelona in Spain; Venice and Genoa in Italy and Rotterdam in the Netherlands. The model was informed using parameters relevant for Ae. aegypti biology, fine-scale temperature time-series, urban structures and road networks. According to model results, the introduction of small quantities of Ae. aegypti eggs (10−1000) has the potential to cause species establishment, high local densities and slow initial dispersal in the two southernmost study areas, Algeciras and Barcelona, whereas Genoa is at the edge of suitability. Barcelona had the highest simulated mosquito densities (584 females/ha), whereas Algeciras densities were never more than 32 females/ha, but were higher during the colder seasons. The median spatial spread of the species varied between a few hundred meters to 2 km/year and was affected by the structure of the road network, topography and urban sprawl along the coast in the surrounding of the port of introduction. The study areas of Genoa, Venice and Rotterdam were found not suitable for establishment of this mosquito species, however, climate change could create conditions for Ae. aegypti invasion in these regions in the next decades. It is commonly accepted that targeted monitoring and early control actions are the most effective methods to hinder the establishment of invasive species in new areas. Our findings and model framework may support surveillance initiatives for those European coastal urban areas which are known to have high propagule pressure and a high modelled probability of Ae. aegypti establishment.