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Lecture 5

Lecture 5 - Insect Cold Tolerance

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Western University
Biology 2601A/B
Graeme Taylor

LECTURE 5 – INSECT COLD-TOLERANCE  Insects deal with temperatures changes in different ways – behavioral, physiological, and biochemical changes  Insects are: o Most successful group of terrestrial animals o Pollinators o Biological control – related to crops, and sustaining humans and other animals that we depend on o Products (silk, honey, etc.) o Food  Preparation: o Eat lots before winter and store fat o Stop growing and reproducing, as these are costly in terms of metabolism o Find the right overwintering site  Why is being cold so bad? o Chilling injury  Damage to cells without actually freezing  Loss of membrane fluidity and loss of ion homeostasis  Two types:  Acute – result of quick exposure to low temperatures (not freezing) and possibly caused by changes in cell membrane  Chronic – caused by loss of ion homeostasis which eventually leads to loss of water balance o Freezing injury  Damaging because of ice crystal formation o Death – if either chilling or freezing injuries are sustained, this will inevitably lead to death Classifications of Cold Tolerance 1. Die before freezing – chill susceptible  Keep warm 2. Keep from freezing – freeze avoiding  Lower freezing point  Mask ice nucleators  Prevent ice growth and recrystallization 3. Survive freezing – freeze tolerant  Be a general “bad-ass”  Prevent recrystallization Supercooling  Small amounts of pure water can get
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