WASHINGTON • Rising temperatures at the top of the world are bad news for Arctic denizens such as polar bears but good news for the local mosquitoes - pesky bloodsuckers that thrive in warmer weather.
Researchers say that the rising temperatures are enabling Arctic mosquitoes to grow faster and emerge sooner from their pupal stage, greatly expanding their numbers and menacing the caribou whose blood they suck.
The findings illustrate the complex and at times unpredictable consequences of climate change, particularly in sensitive regions such as the Arctic, the researchers say.
Arctic mosquitoes develop in shallow springtime tundra ponds formed by melting snow. The researchers studied mosquito populations in ponds near Kangerlussuaq, Greenland. They monitored the number of mosquitoes and their life stages.
They also conducted lab experiments to measure the effects of temperature on mosquito development. They concluded that if Arctic temperatures rise by 2 deg C - a level in the mid-range of predictions by a UN panel for Arctic warming this century - mosquitoes will have a 53 per cent better chance of maturing to adulthood.
The researchers say mosquitoes are already emerging two weeks sooner than in the past and experiencing accelerated growth that allows them to reduce their time in the ponds where they can be eaten by their main predators, diving beetles.
"In response to biting insects, caribou have been observed to run to the top of a windy ridge where there are fewer mosquitoes but their food may be of lower quality," said ecologist Lauren Culler of Dartmouth College's Institute of Arctic Studies, who led the mosquito study published in the journal Proceedings of the Royal Society B: Biological Sciences.
Caribou health could decline if the animals spend more time avoiding insects and less time foraging for high-quality food, she said.
Dr Culler said that while mosquitoes may thrive in the short term, Arctic warming eventually could disrupt their ability to reproduce if they begin to emerge too early before the animals whose blood they suck are available on the landscape.
"In addition, if winters become more variable such that ponds go through freeze and thaw cycles, it could completely disrupt the biology of Arctic mosquitoes and kill many of the larvae early on in development. It's not all good news for the mosquitoes," she said.