Iceland, characterized by its harsh, inhospitable winters, was long one of the only places in the world without mosquitoes. In late October, the country recorded its first sighting of the insects within its borders.
The mosquitoes were discovered by insect enthusiast Björn Hjaltason in Kiðafell, Kjós, about 20 miles from the capital, Reykjavík. “At dusk on October 16, I caught sight of a strange fly on a red white ribbon,” Hjaltason wrote in his post on the Facebook group Insects in Iceland. “I immediately suspected what was going on and quickly collected the fly. It was a female.” He later found 2 more — one male and one female — and sent them to the Icelandic Institute of Natural History for confirmation. There, entomologist Matthías Alfreðsson confirmed his suspicions and identified the mosquitoes as Culiseta annulata, a species native to the Eastern Hemisphere. These mosquitoes are well adapted to colder climates, as they have the ability to overwinter in sheltered areas or closed containers.
Studies in the past have shown that Culiseta annulata is unable to transmit deadly diseases such as Malaria or the West Nile virus. Still, more research has to be done to confirm their harmlessness. How this species reached Iceland is unknown, but many speculate that they had been latched onto ships or cargo.“One always suspects Grundartangi — it’s only about six kilometers from me, and things often arrive with ships and containers, so it’s possible something came in that way,” Alfreðsson remarked.
With Iceland experiencing record-high temperatures this year, conditions may have allowed the mosquitoes to survive and breed. In May, the country reached 80°F, which is more than 18°F above normal temperatures during that month. Moreover, the duration of heat waves has extended to ten consecutive days across many parts of the country.
Though climate change can be a major driving factor in the introduction of new species to previously inhospitable areas, species also undergo random mutations that introduce new traits. In this case, some mosquitoes of the species might have developed resistance to colder temperatures. Colin J. Carlson, an assistant professor of epidemiology at Yale University School of Public Health, believes that climate change does not directly impact the change in a mosquito species’ niche. “The truth is, we just don’t know a lot about endemic mosquito range shifts that are already happening,” said Carlson.
Whether mosquitoes appeared in Iceland because of climate change or endemic range shifts, local authorities will closely monitor the population to prevent the mosquitoes from disrupting the local ecosystem.