New sightings of tiger mosquitoes in Belgium

From May to September 2018, scientists from ITM identified tiger mosquitoes at five locations in four provinces: East Flanders, Hainaut, Namur and Luxembourg. They trapped 68 tiger mosquitoes at different stages of development (24 adult mosquitoes, 8 larvae and 36 eggs) in the Waasland harbor, which seems to indicate that the mosquitoes had a chance to propagate this summer. In the other provinces only a limited number of adult mosquitoes or their eggs were discovered.

In Luxembourg and Namur, eggs were detected in parking areas along the motorway, which may indicate that the tiger mosquito made its way by car from areas in France or Germany, where the species is prevalent. It is the first time the tiger mosquito has travelled to Belgium overland from a neighbouring country. The mosquito was last seen in 2016, when ITM researchers spotted it in second-hand tire companies, garden centres and the port of Antwerp. In those cases, the mosquitoes migrated from far way places via the shipped goods.

"The tiger mosquito may gain a foothold in Belgium. It now crosses the border into our country from neighbouring countries where it is already established. We must closely monitor their spread to prevent the species from permanently settling here so a control programme can be set up as quickly as possible. We have also detected more mosquitoes, because we monitor more intensively in Belgium," explained Dr Isra Deblauwe, who is in charge of the MEMO project’s day-to-day coordination.

In addition to the Asian tiger mosquito, three other exotic mosquito species were spotted last year, including Aedes japonicus and Aedes koreicus. The Asian forest mosquito or Aedes japonicus was once again found in Namur and near the German border. Aedes koreicus had already been identified in Belgium in 2008 and has settled in the Maasmechelen area. ITM researchers closely monitor these small mosquito populations and their spread. So far, the species has not yet caused a nuisance.

"It is crucial to continue this structural monitoring because locating these exotic mosquitoes early on enables effective control and helps defer their establishment in our country as long as possible. Even if the mosquitoes were able to settle here, careful surveillance of these populations is a must in order to assess the risk of disease transmission, " said Dr Wim Van Bortel, general coordinator of the MEMO project.

The MEMO project, short for 'Monitoring exotic mosquitoes in Belgium', is a three-year project (2017 - 2020), financed by the Flemish, Walloon and Brussels governments and the Federal Public Service Health, Food Chain Safety and Environment in the context of the National Environment and Health action plan (NEHAP). ITM carries out the project in collaboration with the Royal Belgian Institute of Natural Sciences (RBINS), and Barcoding Facility of Organisms and Tissues of Policy Concern (BopCo). With support from Avia-GIS, the VECMAP information system is used to integrate field and laboratory data. Flemish, Walloon and Brussels authorities are immediately informed each time tiger mosquitoes are detected so that control measures can quickly be initiated.

ITM has been carrying out surveillance of exotic mosquitoes at various locations in Belgium for many years. The Institute has expanded these activities since July 2017 and doubled the number of locations investigated by the MEMO project. As a result of these years of monitoring, ITM researchers have built up a unique expertise and dataset, which accurately maps the first introductions of exotic mosquitoes in our country.