The government has recently granted the Nedre Dalälven region, north of Stockholm, more money to use this method. Now the Övertorneå municipality in the Norrboten county, near the Finnish border, is also asking for governmental subsidies with the same purpose.
"It is difficult to foresee the long-term ecological effects. This spraying could actually affect ecosystems and alter their natural balance. Our viewpoint is that this method should progressively be replaced by other alternatives," says Niklas Egriell, a researcher at HaV.
HaV does not deny the problem caused by mosquitoes in certain areas, but questions the appropriateness of using this method with bacteria to kill mosquito larvae.
The method has been used for many years in the Nedre Dalälven region.
HaV argues that, besides potential ecological consequences, it has not been proved that the biological spraying has any beneficial effects for the local population.
Jan Lundström, a researcher at Uppsala university who is also in charge of the spraying in Nedre Dalälven, disagrees:
"If you interviewed somebody from Österfärnebo, they would tell you that they found 23,000 mosquitoes per trap in August 2000 and that since we use this method, they rarely find more than a few tens or hundreds in each trap," he says.