Arctic Mosquitoes

Oct. 1, 2015, 8:15 a.m.

Warming temperatures in the Arctic are causing mosquitoes to show up earlier and spread faster, according to a new study published in the Proceedings of the Royal Society B: Biological Sciences. This is bad news for the area’s caribou population — the main food source for mosquitoes in the Arctic. The caribou are likely to change their behavior to avoid being bitten, which can make it harder for the animals to find food, the study authors suggest. For this, we have climate change to thank.

Environmental temperatures greatly influence how mosquitoes grow and survive. When temperatures get cold, the insects become inactive and enter a hibernation-like state called diapause. But the pests thrive in warmer climates — usually those around 80 degrees Fahrenheit — since heat allows mosquitoes grow faster and larger.

THIS IS BAD NEWS FOR THE AREA’S CARIBOU POPULATION

So as it warms, the Arctic is becoming an ideal place for mosquitoes to prosper. Average temperatures in the region — which includes the Arctic Ocean, Alaska, Greenland, and parts of Russia — are increasing at more than twice the rate of the global average. This can be seen directly in the shrinking levels of ice in the region. Just today, NASA announced that the amount of Arctic sea ice this summer was the fourth lowest ever recorded.

The Proceedings study used climate data to come up with a model for how the mosquito population will change in the Arctic with the temperature. They combined that information with field and lab studies on the populations of mosquitoes in Greenland. With all of these factors considered, the model predicted that mosquitoes will be 50 percent more likely to survive in the Arctic if the temperature rises 3.6 degrees Fahrenheit. As if that weren’t vexing enough, rising temperatures will also lead to mosquitoes emerging in the Arctic two weeks earlier than normal. (An increase of just 1.8 degrees Fahrenheit shortens the developmental time of mosquito larvae by 10 percent.)

The 2015 Arctic sea ice summertime minimum is shown here as a gold line. (NASA)

This change in timing could be detrimental for the Arctic's caribou population. The caribou give birth to their calves in the springtime — the mosquitos’ new arrival date. That means that more of the insects will be looking for a fresh blood meal as the caribou are being born. And calves offer an easy target since they are slow and vulnerable.

The mosquitoes don’t usually harm the caribou — though there have been stories of calves succumbing to too many bites, according study author Lauren Culler. "I have heard horrible anecdotes about calves or young caribou dying from excessive biting by mosquitoes and blood loss," Culler, a postdoctoral researcher at Dartmouth College, toldThe Verge in an email. "I have never seen this myself, thankfully."

CARIBOU CALVES OFFER AN EASY TARGET FOR MOSQUITOES

The main issue is how the mosquitoes alter the caribou’s behavior, said Culler. The animals have been known to avoid the insects by moving to windy ridges or snow patches that have fewer mosquitoes. But those areas many not have enough food. And if the caribou don’t get enough food during the calving season, it can be harder for their young to stay alive. Less caribou also means less food to eat for nearby communities.

Climate change’s effects on insects aren’t limited to the Arctic. The drought in California, which has been exacerbated by the warming climate, has triggered an increase in pests that are harming crops in the area. The drought has also led to an influx of bark beetles, which have dried out trees in the state — making the plants prime for starting wildfires. If what’s happening in California holds true for the Arctic, this boon of mosquitoes may have farther-reaching consequences for humans that we have yet to realize.

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