GEOGRAPHY

The warm winter “wipes out” the only native insect in Antarctica


Antarctic midge larvae Image source: RICK LEE JR

Antarctic midges may be smaller than peas, but they are the largest land animal in Antarctica and the only native insect. A new study recently published in Science found that Antarctic midges have evolved to survive extreme conditions, yet warming could pose a threat to them.

Unlike temperate midges, which live in flocks in the water, Antarctic midges do not fly and live in the humid areas of the Antarctic Peninsula and nearby islands. They also have a slower pace of life, with a life cycle of up to two years and spend most of their time in larval form.

Nicholas Teets, an insect physiologist at the University of Kentucky and one of the study’s authors, said the brown worm-like larvae “don’t look outstanding, but their ability to survive under stressful conditions is excellent.”

Midges have spent 40 million years perfecting their survival strategies. It can withstand harsh winter temperatures. To prevent ice from causing damage to their own internal tissues, overwintering larvae lose up to 70% of their body fluids. Once the body “freezes”, the larvae stay in a suspended state called diapause for about 6 months. During this time, they don’t eat, move, or do anything.

As climate change causes Rapid Warming in Antarctica, Teets and colleagues wanted to know how small changes in winter temperatures would affect Antarctic midges.

To do this, the team collected Antarctic midge larvae from several islands near the Antarctic continent and placed them in incubators at 3 temperatures: –5°C (representing a cold Antarctic winter), –3°C (typical winter), and –1°C (warm winter).

Earlier in June, researchers reported in Functional Ecology that after 6 months, they found that larvae in “warm winter” incubators had lower survival rates, slower movements, and smaller energy stores.

Depletion of stored energy can cause trouble for Antarctic midge breeding. This is because the larvae emerge from the diapause state and quickly become adults without a functional mouth, so they rely on their own reserve energy to survive the breeding season.

Joshua Benoit, an entomologist at the University of Cincinnati who was not involved in the work, said that if a warm winter meant “‘burning’ more larval sanctuaries, it will eventually become extinct on some islands.”

Since only a few species live on land in Antarctica, even if only one species disappears, it could reshape the food chain.

But , “it may not all be pessimistic.” “If the winter is both warm and short,” Teets said, then Antarctic midges can start eating earlier in the summer and enter the growth cycle to make up for the lost reserve energy.” ”

Teets said the next step is to monitor Antarctic midge populations in the wild to see how they respond to temperature changes. But he noted that winter fieldwork in Antarctica is challenging, so documenting any changes may take some time. (Source: China Science Daily Wang Fang)

Related paper information:https://doi.org/10.1126/science.add6860



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