Original research shows the role of car journeys in the spread of the Asian tiger mosquito in Europe. Accustomed to freight transportation, this invasive species also uses passenger vehicles to propagate. It is seemingly found in 5 out of 1,000 cars.
Asian tiger mosquitoes enjoy carpooling! For the first time, based on highly original methods, a scientific study has highlighted the role of cars in the spread of this invasive species in Europe. “We measured the impact of private vehicle traffic on the spread of this mosquito, a potential vector of tropical diseases in temperate regions”, explains medical entomologist David Roiz, co-author of a paper on the subject published in Scientific Reports 1. Commonly known as tiger mosquito, Aedes albopictus is native to Asia. It is responsible for the transmission of serious diseases, including the chikungunya virus, dengue fever, zika virus, and it is also believed that it can transmit yellow fever.
Aedes albopictus is considered one of the world’s most invasive species. This is due to its high physiological plasticity. It is capable of colonising a broad variety of environments, and its eggs can withstand desiccation, which facilitates their transport. This is how the species benefited from the development of global trade, particularly the trade in used tyres, to colonise many parts of the world. In the tropical regions colonised, it poses serious public health issues.
Out to conquer temperate countries
Over the past few years, the Asian tiger mosquito, whose temperate strains can withstand the cold winter weather, has also invaded Europe and North America. Its presence creates new risks, as it can spread tropical pathogens, after being contaminated by biting a subject infected on a trip to an endemic area. In less than fifteen years, Aedes albopictus has colonised many European countries, including half of France. “Active dispersal through flight is not enough to explain the extension of its geographical area in Europe, believes the young researcher, as it can only travel 100 to 300 metres under its own steam, so there is every reason to believe that it uses ground transportation”. In fact, research conducted in France by other scientists from the same laboratory has shown the importance of the spread of the species along motorway routes, depending on the volume of traffic 2. It is possible that eggs or larvae are transported in the trucks that travel along these routes. The Asian tiger mosquito could also travel in vehicles like any normal passenger.
Interception at the toll booth and citizen science
“To test the hypothesis of Aedes albopictus travelling in cars, we stopped motorists at toll gates with the police”, recalls the specialist. “We asked them about their route, the possible presence of insects in the car, the use of air conditioning during the trip, and we vacuumed the interior of the car.” By doing so, the scientists, who were working on a motorway in northern Spain, collected 4 “stowaways” out of 770 vehicles checked. While limited in absolute terms, this figure becomes significant when compared with the volume of road traffic. “Computational modelling suggests that 13,000 to 71,000 vehicles contribute to the passive dispersal of the Asian tiger mosquito on the roads of this region alone”, reveals David Roiz. “This means that 5 cars out of 1,000 could contribute to disseminating the vector along the main transport routes of southern Europe in summer!”
To enhance their knowledge of the car journeys of Aedes albopictus, the international team behind this research have just launched a citizen science smartphone application, allowing people to take photographs of the mosquitoes found in their car and communicate any relevant information on the insect’s journey. Health authorities also provide an Asian tiger mosquito participatory monitoring tool, where the general public can report the presence of the insect.
1. Eritja R, Palmer J, Roiz D, Sanpera-Calbet I, Bartumeus F., Direct Evidence of Adult Aedes albopictus Dispersal by Car . Scientific Reports , 2017
2. Roche B, Léger L, L’Ambert G, Lacour G, Foussadier R, Besnard G, Barré-Cardi H, Simard F, Fontenille D. The spread of Aedes albopictus in metropolitan France: contribution of environmental drivers and human activities and predictions for a near future .PLoS One , 2015
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