Wide variety of mosquitoes found in Rotterdam

Researchers from Naturalis and PDPC produced an overview of all mosquitoes spotted in Rotterdam. This will make it easier to follow future changes in the city, such as the effects of climate change.

The researchers discovered that over the past 90 years, a total of 16 Dutch mosquito species have been observed in Rotterdam. This means that almost half of all Dutch mosquito species are found in the city. Researchers Jordy van der Beek and Maarten Schrama reported their findings in Straatgras, the magazine of the Natural History Museum Rotterdam.

Wet city

Until now, an overview of the mosquito species of Rotterdam was non-existent. Surprisingly so, as the river Maas flows through Rotterdam, and the city lies partly below sea level. This means Rotterdam is a ‘wet city’ that provides many breeding places for mosquitoes. Furthermore, large cities such as Rotterdam often have a rich biodiversity, sometimes even more significant than that of the surrounding countryside. Despite this, the diversity of bloodsucking insects has received little attention so far. With this overview, the researchers from Leiden and Rotterdam have changed that.

A problem

‘Interestingly, not all mosquito species cause a problem’, says van der Beek. ‘Only a limited number of species actually enter houses. These mosquitoes mainly breed in urban gardens, developing in small water reservoirs such as rain barrels, flowerpots and gutters.’

Besides mosquitoes in urban gardens, the researchers have identified three other communities of mosquitoes in Rotterdam, namely mosquitoes that live in ponds and ditches, temporarily flooded areas and those linked to the river that occasionally burst its banks. Here, species that cause fewer or only localized problems are found.

A changing world

‘This overview of the mosquitoes in Rotterdam is a good starting point for further research’, states Van der Beek. ‘From now on, we can measure changes in the distribution and occurrence of different mosquito species.’ The researchers expect that changing climate, rising water levels and modifications to Rotterdam will increase the quantity and diversity of breeding places for mosquitoes in the city.

Furthermore, invasive exotic mosquitoes, such as the Asian tiger mosquito, will probably become permanent residents of Rotterdam. So far, the permanent establishment of these mosquitoes in the city has been stopped by preventative measures taken by land managers and the Netherlands Food and Consumer Product Safety Authority, who intervened at locations where exotic mosquitoes were found in previous years.

‘In Rotterdam, mosquitoes are now mainly experienced as annoying,’ says Van der Beek, ‘but they do not currently form a major health risk. It is nevertheless important to keep a close eye on them. Therefore, we are currently carrying out various research projects in Rotterdam with other parties to closely monitor any changes.’

Help to map mosquitoes

Despite all the research done in Rotterdam over the past 90 years, species could still be missing from the current overview. Additional research is therefore needed. Residents or visitors of Rotterdam can help by reporting sightings of mosquitoes. This will enable the researchers to improve the accuracy of the list of mosquitoes in Rotterdam. 

Would you like to help? Make clear photos of a mosquito if you find one, including the side view of the mosquito, and share these via Waarneming.nl. Via the website muggenradar.nl, you can also report how much or little mosquito nuisance you experience.

Van der Beek: “In this way, everybody can contribute to further research, and we will also gain a better understanding of these city residents that often go unnoticed.”

More information

Would you like to know more about the research projects on mosquitoes and the diseases they transmit in the Dutch Delta? Take a look at the project pages of the Frontrunner project of the Pandemic & Disaster Preparedness Center and the IDalert project.