Wageningen University made its announcement in early June based on research using what is known as the mosquito radar. The expected record number of mosquitoes is linked to the extremely wet spring. This provided mosquitoes with a great number of breeding sites, allowing the first generation to emerge early spring. Only a very dry summer could limit the infestation, according to the research study.
Biophysicist Felix Hol, who also studies mosquito behaviour, was surprised by the article. Journalists from radio, TV and various newspapers contacted him to ask whether things would really get that bad this summer, and what we could do about it. His sobering message: this summer's infestation is by no means guaranteed. “In the longer term, we can expect an increase in mosquito numbers, which is linked to climate change. But whether there will really be an infestation this summer is hard to predict; I think it might not be that bad. There’ll be nuisance in some places, and this depends on random, local factors, such as the presence of pools.”
Elegant critters
Hol calls mosquitoes useful and elegant critters, considering their role in the ecosystem, as food for birds, fish and other insects. Their elegance lies in their survival ingenuity, especially in the way they manage to gather their main food source – human blood. “They have a particularly good sense of smell to detect us, and when they bite, they manage to land and take off again almost unhindered.”
It is precisely because of their intrusive relationship with humans that mosquitoes really cause irritation - they drive us mad by buzzing at night and their bites are really itchy. But even this summer, there is no need for anything more than the usual home-and-kitchen remedies. Hol recommends screen doors and ointments. “There’s all kinds of products on the market, and not everything works equally well. If there’s DEET in the ointment, it will work.”
Pools and ponds
It is best to tackle the mosquito problem at its source, says Hol, pointing to the large amount of free-standing water in residential areas. Think of water that accumulates in flower pots, rainwater barrels, or pools and puddles around the home. “Under ideal conditions, the stage from larva to hatching takes about seven days, so you need to empty out the stagnant water from these flower pots, etc. every week. And there are anti-insecticides on the market for rain barrels, which are a feast for mosquitoes, even when covered. That residential areas are often teeming with pools and puddles is a given, says Hol. “This has its benefits for biodiversity around the water. The nuisance caused by mosquitoes is the price you pay for this.”
Asian tiger mosquito
But the future is not entirely carefree, as Hol points to the invasion of the Asian tiger mosquito, which, if higher temperatures persist, may become an established species in the Netherlands. That is reason for concern, says Hol. It is not for nothing that control teams from the Netherlands Food and Consumer Product Safety Authority are rushing out to tackle the larvae of this exotic mosquito, and in the ‘mainports’ of Schiphol and the Port of Rotterdam, officials are being tasked with combating it.
The Asian tiger mosquito has a bad reputation for spreading dengue fever. The exotic species that has appeared in the Netherlands can only do its pathogenic work if there are people around who were infected with the dengue virus by the mosquito elsewhere. The disease is not transmitted from person to person, but through the bites of the Asian tiger mosquito. With a few exceptions, the disease is irritating but not fatal.
As elegant as mosquitoes may be, Hol has no problem with control measures. His advice: fight them at the source, develop a good eye for the mosquito, and report any swarm of Asian tiger mosquitoes to the control teams. “So being able to recognise them is useful,” says Hol, and that is easy: tiger mosquitoes are larger than our regular mosquitoes and they have characteristic white stripes on their front legs. “Just kill them, there are enough of them anyway.”
This story is part of Recharge's summer series in which readers are given the opportunity to ask scientists a question. The Recharge editors then go and talk with Radboud University scientists to find the answers. This time the question was: What to do about the mosquito infestation this summer?