Get ready for longer mosquito seasons as Canada and the world warm
TORONTO -- As if rising sea levels, increased drought, and more extreme weather events won't be enough to deal with, climate change will also bring us longer mosquito seasons.
That's the conclusion reached by scientists at the University of Florida, who say their research on the pesky insects shows that the bugs can very quickly adapt to changes in the temperature around them.
In regions poised to experience newly tropical temperatures in a warmer world, they report, mosquitoes could become a year-round nuisance. In places that won't get quite that warm – Canada, for example – they may still be able to reduce the amount of time they spend dormant due to chilly conditions, leaving us fending off mosquitoes for much longer than we're used to.
The findings come from experiments the researchers conducted on 1,000 mosquitoes that were gathered in and around Gainesville, Fla.
As they detail in a study published this month in the journal Ecology, they placed the mosquitoes in vials and then placed the vials into a water bath. They then adjusted the water temperature, which in turn altered the temperature inside the vials.
As the temperature fluctuated, the researchers made note of when each mosquito became what is known as "cold bounded" – the hibernation-like dormant state that they enter when conditions are too cold for them to thrive.
Over a period of several months, they found that mosquitoes had a larger acceptable range of temperatures in the spring and fall than during the summer, suggesting the insects have evolved to cope with the wild fluctuations that can occur during spring and fall.
“We found that the mosquitoes in our study are what we call 'plastic,' meaning that, like a rubber band, the range of temperatures they can tolerate stretches and contracts at different times of year,” Brett Scheffers, senior author of the study and an assistant professor in the University of Florida's wildlife ecology and conservation department, said in a press release.
“That tells us that as climate change makes our autumns and winters warmer, mosquitoes in more temperate regions are well prepared to be active during those times."
By some estimates, summers in the Northern Hemisphere will last for as long as six months by the end of the century.
The researchers say it's not clear what allows the mosquitoes to adapt so quickly to changing temperatures, or if other insects are able to do the same.
One possibility is natural selection. Because most mosquitoes only live for a few days, it could be that those born during spring and fall need to be able to adapt to temperature swings, whereas those born in the summer can survive without developing that skill.
The next step for the Florida researchers is to determine whether that theory could be true, or whether there is something else at play.
Either way, the researchers are warning us about more than the nuisance aspect of mosquitoes. Because the insects are major carriers of infections such as West Nile virus and dengue fever, they say their findings point to the need to prepare for increased prevalence of mosquito-borne diseases as the planet warms.