Insects are cold-blooded. Low temperatures make them too slow to work, so there is a noticeable decrease in insect sightings in winter. But many bugs can survive the cold, and new research shows that one species, the snowfly, really defies common sense when it comes to surviving the winter.
The snow is flying (Chionea) are small, wingless insects that actively fly around the snow even when temperatures drop below freezing in winter. They are a mystery to researchers, but they are new Current Biology The study provides genetic evidence with surprising implications: snowflies generate their own body heat like mammals, but also produce antifreeze proteins reminiscent of Arctic fish rather than insects.
“We hope that this work will lead to new research on the mechanism of cold tolerance in insects and especially on the mechanisms of heat production in cold-adapted species.” Marcus Gallius and Marcus Stansmerethe study’s corresponding authors and entomologists from Sweden’s Northwestern University and Lund University told Gizmodo.
‘Weird’ is a mild way of saying
According to the researchers, extreme cold can be fatal for insects, causing “the water in their cells to freeze and ice crystals to form, which rupture the cells.” Because of this, insects usually hide from the cold and go to sleep, and some species produce sugar and antifreeze proteins to protect themselves from the harmful cold.
But snowflies do the opposite, scaling the snow to mate and lay eggs. To investigate what makes them special, the team sequenced the genome and RNA of snowflies, then compared the data to other well-studied insects. In the analysis, the team found some antifreeze proteins that “closely” resemble those of Arctic fish than those of other insects with similar functions.
In addition, the team also identified some genes commonly found in mammals, such as polar bears, whose brown fat generates heat through mitochondrial processes. Genetically, snowflies appeared to be a confusing mix of insects, fish, and mammals—an idea so strange that the team had to test it further.
Yes, this is the real deal
The team designed several experiments to understand how the antifreeze proteins work and whether the snowfly is actually generating heat on its own, as opposed to just another scrambling mechanism.
In one experiment, the team engineered fruit flies, a supposedly “normal” member of the fly family, compared to snow flies to produce the protein to place the modified fruit flies in the freezer. Interestingly, antifreeze acted as “microscopic ice blockers” in fruit flies, improving their survival in short freezes. statement.
Other experiments lowered the ambient temperature to see how snowflies would react. The team told Gizmodo that the snowflies were indeed able to keep themselves slightly warmer “by a few degrees, maybe 10 to 20 minutes.” They also appeared to be more tolerant of the reactive oxidants that cause “burning” pain in humans when exposed to cold.
“That doesn’t sound impressive,” the team noted, “but for a fly that has a favorite temperature of -3 degrees Celsius (26.6 degrees Fahrenheit) and dies at -10 degrees C (14 degrees F), seeking refuge may be enough when conditions change and things look bad.”
The team also looked at how bees or moths heat up their muscles by rapidly contracting them by “shivering”. According to the researchers, the muscle mass of snowflies is not very impressive. Mathematically, simple leg movements are not enough to significantly increase body temperature, they added.
Survivors
However, the team told Gizmodo that there is still no “smoking gun” in snowflies’ heat production mechanisms. Flies definitely generate heat – very unpredictable – but ideally the team hopes to gather evidence that this is the case at the cellular level. However, the researchers admitted that the experiments were “very difficult and hard to come by with snowflies.”
Still, the findings have important implications for genetic research. The possibility that insects, like animals and plants, can generate mitochondrial heat “is usually dismissed due to their small size,” the team explains. “It takes a lot of energy to produce heat using these pathways, and in a small insect, heat dissipates very quickly, so what does that mean?”
But snowflies show that “even a little warmth can be the difference between life and death,” he added, adding that the study’s results “may provide researchers with new opportunities to investigate cold adaptation in insects.”
“These insects are truly remarkable; we hope that the availability of the genome will inform further work on their adaptations and efforts to protect them and their unique environment,” the researchers said. “We need to study insects more and learn to appreciate their importance so that we can protect them for both our ecosystem and our own well-being.”
