5 March 2025 Articles

Don't let the (tiger) mosquito buzz you

Exotic mosquitoes, such as the Asian tiger mosquito, are on the rise in Belgium. How can we halt their spread? An interview with Entomologist Dr Wim Van Bortel.

Tiger mosquito (Aedes albopictus)

Can you briefly explain what MEMO+ is?

WIM MEMO+ is a monitoring project for the tiger mosquito. Our goal is to map the presence of this mosquito in Belgium. This is crucial because knowing its exact locations helps us understand its spread and, where possible, limit it.

What is the Asian tiger mosquito, and why does it pose a threat?

WIM The Asian tiger mosquito (Aedes albopictus) can transmit viruses that our native mosquitoes cannot. The most well-known viruses are dengue, chikungunya and zika, which are diseases we certainly don't want here. Since the 1980s, the mosquito has established itself in Europe, first in Albania, then spreading to Italy and France. Now, we're also seeing it appear in our area, mainly through car traffic. Our aim is to map its presence and explore which measures we can take.

In the MEMO+ project, we monitor exotic mosquitoes at known import sites. Additionally, citizens can report mosquito sightings to help us map the spread of the tiger mosquito.

Can you give an example of a location in Belgium where the tiger mosquito has already been detected?

WIM Since 2000, we have detected the tiger mosquito in roughly 48 locations across Belgium. However, this does not mean that it has effectively established itself in those areas. It may have been a single detection. In 2022, we launched MEMO+ as a citizen science project, which gave us much more insight into its distribution. Previously, our focus was mainly on so-called ‘points of entry’ such as tyre companies, plant shops, and ports. But since 2018, we have been seeing them more frequently at car parks along highways, particularly along routes to the south of France, where the mosquito is well-established. Thanks to citizen science, we are now also finding them in residential areas, with numerous reports along the Brussels-Antwerp axis and around Ghent. So far, reports have been more frequent in Flanders than in Wallonia.

The MEMO project is entering a fourth wave of funding. Why is additional funding still needed?

WIM The tiger mosquito is an invasive species. While it used to appear only sporadically, we now see it returning annually to several locations. Monitoring these introductions is essential. In fact, structural funding would be even better, as the problem will not resolve itself. The mosquito can survive the Belgian winter and establish itself here. On the one hand, we aim to map its spread; on the other, we work to control the population to reduce the risk of virus transmission.

Tiger mosquito (Aedes albopictus)

What would the situation look like in 15-20 years without mosquito research?

WIM The tiger mosquito would likely establish itself here permanently, and we would be much more affected. Through monitoring and prevention, we aim to intervene early and mitigate its impact.

Can people who are interested also participate in the project?

WIM Absolutely! Anyone in Belgium can contribute by uploading photos of tiger mosquitoes to mosquitosurveillance.be. If someone suspects they have seen a tiger mosquito, they can take a photo and upload it. We ask a few questions to refine the sighting. If we suspect that it is indeed an Aedes albopictus and the location is of interest, we will visit the site for verification. Initially, we received many reports of mosquitoes, but increasingly, they turn out to be tiger mosquitoes.

Dr Wim Van Bortel

Could mosquitoes also be useful insects? We recently read in De Morgen that they can help detect natural disasters, for example.

WIM That's the eternal question. Mosquitoes are part of our ecosystem and serve as food for aquatic life, among other things. But they mainly cause nuisance and health risks to humans. That's why we focus on controlling the species that can spread diseases. Completely eliminating mosquitoes is neither realistic nor desirable, but reducing the risk of virus transmission is.

What can people do at home to prevent the tiger mosquito? Should they be concerned?

WIM Currently, the risk of virus transmission in Belgium is still low, but we want to keep it that way. The most important measure is to prevent the mosquito from reproducing. Tiger mosquitoes lay their eggs in stagnant water, often in small containers such as buckets, toys, plant trays, or pet water bowls. So, it's crucial to regularly change or remove stagnant water. There's no need to remove plants or trees, as long as you take care that no water collects in them.

Do you have a remarkable story from your research?

WIM What we often hear from people we visit locally is that they have a clear link to regions where the tiger mosquito is already established. For example, ‘Since I moved from France, I've been bothered by these mosquitoes,’ or "I brought plants from France, and I've been seeing them ever since.’ This shows how the mosquito spreads. It hitches a ride on our traffic and settles in suitable habitats.

Can people who want to contribute to the project do so voluntarily?

WIM Yes. Just take a photo and upload it to mosquitosurveillance.be. If we suspect that it's a tiger mosquito, we'll get in touch. Depending on the situation, we may conduct an on-site visit.

What happens if a tiger mosquito is found?

WIM MEMO+ is a monitoring programme funded by the federal government and the regions. When we receive a report, it is passed on to the relevant authorities, who then decide on possible control measures. Effective control actions are also taken in places where the tiger mosquito has settled.

Does this align with the major campaign that will be launched by the Department of Care in May?

WIM Yes, until now the main focus has been on larvicides, such as Bti and door-to-door visits to remove or treat breeding sites. Now the Department of Care wants to focus more on proactive measures: What can you do yourself to prevent the need for professional control? It's great that more and more attention is being paid to this, both at regional and federal level. There's still a lot of work to be done, but we are making progress in the right direction.

Contact

Do you have questions after reading this interview? Don't hesitate to contact us:

Communications: communicatie@itg.be
Wim Van Bortel: wvanbortel@itg.be

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Dr Wim Van Bortel

Wim Van Bortel

Wim Van Bortel (PhD) is a medical entomologist with more than 25 years of experience in vector research and vector-borne diseases in Europe, Africa and Asia. He obtained his master's degree in biology from the University of Antwerp in 1990, after which he specialised in medical entomology at the Institut Pasteur in Paris. In 2002, he obtained his PhD from the University of Antwerp. From 2010 to 2016, he was senior expert in vector-borne diseases at the European Centre for Disease Prevention and Control (ECDC), where he was deputy head of the Emerging and Vector-borne Diseases Programme. Since 2017, he has been working as a senior researcher at the Unit of Entomology and the Outbreak Research Team of ITM .

His research focuses on unravelling the role of arthropod vectors in transmission systems, with the aim of improving prevention and control of vector-borne diseases in a public health context. As a member of ITM's Outbreak Research Team, he aims to better understand the factors influencing the transmission and spread of outbreak-prone diseases and to evaluate different outbreak prevention and control strategies.

Will you help Wim with his research?

Stay alert for the tiger mosquito! Think you've seen one? Take a picture, upload it to muggensurveillance.be, and help Wim and his colleagues to curb the spread of the tiger mosquito!

Report a tiger mosquito