When you think of animals in Antarctica, the first name that crosses your mind would be penguins. However, there is another lesser-known yet fascinating creature known as the Antarctic midge (Belgica antarctica), the continent’s only native insect. Scientists have now cracked the code to their survival amidst extreme climate.
An international research team led by Osaka Metropolitan University has discovered how the tiny insect Antarctic midge copes with freezing temperatures. They believe this discovery could hold clues for humans about subjects like cryopreservation.
Graduate School of Science Professor Shin G. Goto and Dr. Mizuki Yoshida, a graduate student at the time of the research who is now a postdoc at Ohio State University, found that the midges cope with the seasons during its two-year life cycle by undergoing quiescence and obligate diapause.
In the first year, they enter a stage of quiescence, which is a form of dormancy in immediate response to adverse conditions. When conditions improve, the organism becomes active again. In the second year, they go into obligate diapause, a dormant period naturally induced at a fixed time in an organism’s life cycle, a rare form seen in insects in temperate regions.
“We were able to establish a method for rearing the Antarctic midge over a period of six years to find out some of their environmental adaptation mechanisms,” Dr. Yoshida said in a note.
The researchers found that the insect’s larvae usually grow to their second instar by the first winter and undergo quiescence so that they can quickly resume development at any moment in favourable conditions (when it suddenly becomes warmer).
When the second winter approaches, the larvae reach the final fourth instar, but they do not pupate. Instead, they enter obligate diapause so that they all emerge as adults when summer arrives. The adults only have a few days of life and should find a mate, hence this timing mechanism is key to their survival.
“We determined that for the Antarctic midge obligate diapause ends with the onset of low temperatures in winter so that the larvae all pupate at the same time and emerge as adults at the same time. Although seasonal adaptation strategies involving overwintering multiple times using both quiescence and obligate diapause have not been reported in other organisms, we believe that insects inhabiting harsh environments such as the Arctic and high altitudes might be employing similar strategies,” Professor Goto added.
Pic courtesy: Yuta Shimizu / Osaka Metropolitan University