Mosquito initiative launched in Imatra, Finland to combat persistent population

In the Finnish town of Imatra, efforts to combat a persistent mosquito problem are set to continue into autumn with a new initiative. Previous attempts involving the introduction of three types of water butterfly larvae over the summer have proven insufficient to alleviate the significant mosquito nuisance faced by residents. The Finnish Environment Institute has announced plans to introduce additional larvae of the northern pike, a natural predator of mosquitoes, specifically in the Vuoksi River. This move marks the first time such an initiative has been implemented globally.

Mosquitoes have plagued Imatra and its surrounding areas for several years, with climate change potentially contributing to their increased population. Extended summers allow mosquitoes to undergo two generations of flight each season. Additionally, the natural predators that usually control mosquito populations, such as the stonefly, are absent in the region, partly due to water pollution and the construction of hydroelectric facilities.

This summer, around a thousand larvae of various aquatic insects were released into the Vuoksi area, but the number of northern pike larvae collected was alarmingly low—only about a dozen were found. Efforts are underway to collect more predators from the Rauan River and transport them to Vuoksi.

These larvae will be introduced to the riverbed among moss stones soon, targeting early October for the placement. Experts stress that one summer’s introduction of these predators won’t be enough; consistent transfers over several years are necessary to stabilize the predator populations. Additionally, habitat restoration efforts, such as the transplantation of aquatic mosses, are being planned to further support the ecosystem.