The snow flea has a remarkable repertoire of adaptations to protect itself against freezing temperatures. The insect, which thrives at low temperatures, produces antifreeze proteins and generates heat to withstand the cold. These findings are published on 24 March in Current Biology.
The snow flea (Chionea alexandriana) prefers to live at temperatures between 0 and −6 degrees Celsius, whilst other insects at these temperatures typically hibernate or burrow into the ground. By comparing the snow flea’s genome with those of other insects such as Drosophila and Aedes aegypti, the researchers were able to see how the snow flea adapts to freezing conditions.
Using antifreeze proteins, the insect prevents ice crystals from forming in its cells. This means it barely freezes and remains active. In addition, the flea also generates its own heat to prevent freezing. At temperatures around −6 degrees Celsius, it produces short pulses of heat comparable to the way mammals generate warmth. The researchers speculate that these heat pulses buy the insect time to seek out warmer temperatures.
One drawback of this heat generation is that reactive oxygen species are released, which trigger pain signals. But the snow flea has a solution for this too: the TRPA1 receptor, which produces a pain signal in response to reactive oxygen species, has a threshold that is 35 times higher in snow fleas. The snow flea thus proves to be uniquely adapted to freezing conditions.