Thursday, June 11, 2020

Where do Insects go when the Cold starts? |Favytech|

Insects in Winter

Now you see me, now you don't see me, the insects seem to tell us throughout the year. During the milder seasons, we share our spaces with legions of six-legged creatures that in some cases can exasperate us. However, when the dark and cold months arrive, the vast majority mysteriously disappear; Although only to resurface as if by magic in the spring. But where do they hide during winter? Do they just die? How do they manage to emerge from their ashes when the heat returns?

The answer is not as simple as you might imagine since there is no single common solution for insects to save the winter months: some try to escape the cold in some way, while others simply endure it, freezing and living to tell the tale. Of these two options, "the most important strategy is to avoid the cold," Brent Sinclair, an entomologist at Western University of Ontario (Canada) specializing in the winter biology of insects, sums up OpenMind.

Among those fleeing from the cold, a minority migrate to warmer regions, such as monarch butterflies ( Danaus plexippus ), which in late summer fly thousands to cover distances as immense as the one that separates Canada from Mexico. Other insects considered agricultural pests also target migration. On the contrary, those who decide to stay to face winter are more abundant. Bees huddle in the hive to escape the weather and conserve heat. The ants go deep into the anthill and plug the entrance with plant debris. But all the insects that have to face the winter rigors have a good arsenal of countermeasures, which start when the autumn days begin to shorten.


Decreasing daylight hours sets off an alarm on the insect's biological clock. For many of them, it is the order to go into diapause, a state that reduces their metabolism stops development and mobilizes their fat reserves to keep them alive. "The photoperiod (shortening of the day) is the main factor, but the decrease in temperature in connection with this decrease reinforces the response," Harper Adams University entomologist (United Kingdom) Simon Leather, author of The Ecology, explains to OpenMind of Insect Overwintering (Cambridge University Press, 1993).

The cold helps other measures to work. According to Sinclair, "the potato beetle is diapaused by the photoperiod regardless of the temperature, but only becomes cold-tolerant on exposure." This exposure to cold triggers a chemical revolution in the bodies of insects.

"All wintering insects use cryoprotectants of some kind," says Leather. Freeze-tolerant species, those that can freeze without dying, produce compounds such as ice-nucleating proteins, which control crystal formation so that they do not harm cell structures.


But the truth is that a frequent solution for many adult insects is simply to die, once they have ensured the survival of their species for the coming spring, leaving behind their descendants, whether in the form of an egg, larva or pupa; immature forms that will resist winter with the help of their antifreeze and shelters in tree holes,

A striking case is that of social wasps, which have integrated winter death into the complex life cycle of their colonies. At the end of the summer, these Hymenoptera are the terror of outdoor meals, and this insidious behavior at a specific time has an explanation: by then all the larvae have grown, which during the spring and summer fed the colony producing a sugary juice.

Despite their efforts, almost all wasps will die; not from cold, but hunger. Only the queens will manage to get through winter, hidden in a cozy coat, and the following spring they will found a new colony thanks to a prodigy of evolution: throughout the winter they have kept the sperm of the autumn mating inside their bodies to fertilize the eggs of which will be the birth of the new generation of workers.

The secrets of wintering insects still amaze scientists. Recently, a group of chemists from the Universities of Utah and California discovered that antifreeze proteins do not interpose in ice, simulating their structure as previously believed, but rather adhere to the forming ice to prevent its growth. What's more, the researchers point out that this system may inspire the design of new compounds useful in freezing food, preserving organs for transplantation, or thawing aircraft. So when insects start to exasperate us again next spring, let's not forget that we still have a lot to learn from them.

Thus, a multitude of worker wasps must go out to find their livelihoods, which they often find in our barbecues.

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