i genuinly curious how bugs such as flies and mosquitoos survive during winter and come back i. summer/spring, how can we eradicate mosquitoos permanently ? cold weather seems to be the optimal way so why it dont work ? do i have to move to siberia to never encounter one of those blood sucking vermin ? elp.
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Entomologist here! Insects are great are surviving winter or cold periods in a wide variety of ways. The simplest is they simply avoid cold temperatures by migrating to warmer areas! Insects that live in cold area that don’t migrate have several different strategies for surviving the cold.
Most will seek out relatively warm and drier area to hibernate such as deep in the soil, in caves and burrows, under leaf litter and often even in your homes. This means they will experience less cold temperatures, reducing the risk of freezing. Many of these insects will still experience freezing temperatures however, and they must avoid having ice form within their cells which would be very damaging. They have evolved two common strategies for avoiding ice formation which we call freeze-avoidance and freeze tolerance.
Freeze avoidance is where insects undergo physiological changes to avoid ice formation at all. They can produce essentially anti-freeze chemicals which lowers their freezing points and they have also have strategies which allow them to supercool, where the liquids in their bodies will actually stay liquid even below the freezing point! Ice needs what is called a nucleation site to form, something like a particle that the ice can form on. Insects will actively purge as many particles (like tiny bits of food for example) from their body as they can to avoid ice having places to form, so the liquids in their bodies can’t become ice even below their freezing point. Insects also will produce special proteins which will attach to any ice molecules that form and prevent them from growing bigger!
The other strategy is freeze-tolerance, where insects actually allow themselves to freeze! They avoid damage to their bodies by concentrating the freezing in the spaces between their cells (extracellular space) where the ice will cause less damage. They produce specific proteins called ice nucleators which will cause ice to form on them, so they can control where ice forms based on where they store those proteins. These insects also have those special proteins which latch on to ice molecules and prevent them from growing, making sure that the ice between their cells doesn’t grow too big. They also produce chemicals that attract water and store them in their cells so that the ice growing between the cells doesn’t suck the necessary water out of their cells! This strategy is often found in insects which experience shorter cold periods, such as those found in the Southern Hemisphere.
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