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Climate change a boon for arctic mosquitoes

As caribou have to exert more energy avoiding the bloodsucking pests, the grazers may have less time to store up the nutrients necessary to survive the hardships of winter.

By Brooks Hays
Climate change a boon for arctic mosquitoes
Giant arctic mosquitoes. Photo by Dartmouth/Lauren Culler

HANOVER, N.H., Sept. 16 (UPI) -- Many studies have highlighted species made more vulnerable by a warming climate, but global warming has proven a boon to some. One of those species is the arctic mosquito.

According to researchers at Dartmouth College, warmer temperatures in the arctic have enabled mosquitoes there to emerge earlier in the year and grow to larger sizes, thus boosting population sizes.

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In a new study, arctic researchers at Dartmouth's John Sloan Dickey Center for International Understanding used their field observations to model the effects of temperature changes on arctic mosquitoes. Their analysis predicts a 50 percent increase in the survival rate of adult mosquitoes with just a 2-degree Celsius temperature rise.

Mosquitoes may be small, but they're a significant member of the arctic food chain and ecosystem. The new analysis -- detailed in a new paper published in Proceedings of the Royal Society B -- aims to help biologists better predict how a growing mosquito population might affect the caribou they feed on, the birds and insects that feed on them and the plants they pollinate.

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To build their model, Dartmouth scientists combined their field results with results of their lab experiments, which looked at how temperature affects the insect's growth and susceptibility to predation.

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While a rise in temperature makes developing mosquitoes more vulnerable to diving beetles, it also gives them a head start in the spring and makes their larval development faster and more efficient -- a net positive.

More mosquitoes likely means a growing population -- but only as big as the insects' food sources can sustain. The ability for mosquitoes to turn their improved survivability rate into an improved reproductive rate depends on their ability to secure a blood meal.

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Right now, only about 15 percent of females are able to suck enough blood to reproduce -- the life cycle moves fast in the insect world. But that rate may go up.

A warming climate will also bring the mosquito's development into closer alignment with caribou calving season. During calving season, newborns make caribou herds less mobile and less able to escape hungry mosquitoes.

"Increased mosquito abundance, in addition to northward range expansions of additional pest species, will have negative consequences for the health and reproduction of caribou," lead study author Lauren Culler, a postdoctoral researcher with Dickey Center's Institute of Arctic Studies, explained in a press release. "Warming in the Arctic can thus challenge the sustainability of wild caribou and managed reindeer in Fennoscandia (Norway, Sweden, Finland and parts of northwest Russia), which are an important subsistence resource for local communities."

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Though it's possible for a swarm of mosquitoes to take down a young caribou -- or a cow, via asphyxiation -- it's more likely that larger numbers of mosquitoes will indirectly hurt caribou numbers. As caribou have to exert more energy avoiding the bloodsucking pests, the grazers may have less time to store up the nutrients necessary to survive the hardships of winter.

"Every moment that a caribou spends avoiding insects is another minute that they're not doing what caribou need to do so that they feed so that they can successfully raise calves," Culler told VICE early this summer.

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