As Antarctica’s largest native land animal, the Antarctic midge—a flightless insect measuring less than one centimeter long—spends around nine months of the year frozen solid. But Belgica antarctica’s impressive abilities don’t end there: Devi Lockwood of the New York Times reports that midge larvae can also survive temperatures as low as -15 degrees Celsius, the loss of up to 70 percent of their bodily fluids and as long as a month without oxygen.
A new study published in the Journal of Experimental Biology suggests the invertebrate species owes its resilience to a combination of rapid cold hardening (a physiological process that enables animals to endure in freezing environments) and slightly warmer temperatures in its underground habitat. The research is still in early stages, but as Lockwood points out, a better understanding of midges’ survival in extreme conditions could eventually lead to innovations centered on human health.
Researchers led by Nicholas Teets of the University of Kentucky assessed B. antarctica’s endurance strategies during a field survey conducted in early 2018. According to the Times, the entomologist and his colleagues collected specimens by digging through seal and penguin excrement. Next, the scientists note in the paper, they exposed the midge larvae to a range of freezing conditions: Some were housed at 2 degrees Celsius for the duration of the experiment, while others were “directly frozen,” or plunged straight from 2 degrees to -9 degrees. The third group, subjected to rapid cold hardening, spent two hours adjusting from 2 degrees to -5 degrees, then 24 hours acclimating to -9 degrees.
Ultimately, the team found that larvae treated with rapid cold hardening bounced back from stress faster than their directly frozen counterparts; members of the group also exhibited significantly higher metabolic rates during recovery. Although the exact science behind the process remains unclear, the researchers point out that changes associated with rapid cold hardening appear to occur at the cellular level.
“These results provide strong evidence that RCH protects against a variety of sublethal freezing injuries,” Teets and his team write in the study. The mechanism further “allows insects to rapidly finetune their performance in thermally variable environments.”
Another factor in midges’ survival is their microhabitat. As the Times’ Lockwood notes, larvae live beneath Antarctica’s soil and snowpack. Here, temperatures hover around just below zero—considerably warmer than the southernmost continent’s average air temperature of below -20 degrees Celsius.
Speaking with the Gleaner’s Douglas White, co-author Leslie Potts—a graduate student in Teets’ Insect Stress Biology Lab—says studying midges and other native Antarctic species could one day help scientists develop better methods of preserving organs for transplant. Additional research may also yield insights on how extreme cold can help fight disease.
Come February 2020, Teets, Potts and an international group of collaborators will build on these findings during a return trip to Antarctica. According to a University of Kentucky press release, the scientists hope to compare the Antarctic midge with three other insect species, further explore how it survives in such a challenging environment and gauge how the continent’s changing climate has affected the species.
“I’ve always been interested in life at the extremes,” Teets tells the Lexington Herald-Leader’s Sydney Momeyer. “… And here’s an insect that is one of the most, if not the most, stress tolerant of its time.”
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