Overwintering Physiology Of Arctic And Subarctic Insects From Interior Alaska

• Main Author: Sformo, Todd L.
• Other Authors: Barnes, Brian, Duman, John, Boyer, Berty, Martinson, Tracey
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: 2009
• Subjects: Zoology; Entomology; Arctic; Fairbanks; Subarctic; Alaska
• Online Access: http://hdl.handle.net/11122/9041

Dissertation (Ph.D.) University of Alaska Fairbanks, 2009 This dissertation focuses on the overwintering of three insects from Interior Alaska: a hemipteran, Elasmostethus interstinctus, and a coleopteran, Cucujus clavipes puniceus, that are freeze avoiding in the strict sense of the phrase, and a dipteran, Exechia nugatoria, that is simultaneously partially freeze avoiding and freeze tolerant. The variability within the freeze avoidance strategy itself is a key theme throughout this dissertation. Two significant contributions to comparative physiology are the confirmation of insect vitrification (glass formation) with its attendant extension of freeze avoidance and survival into a new, extreme low temperature record of -100�C and the simultaneous coupling of freeze avoidance and tolerance within an individual, which may more properly be described as a new overwintering strategy. Vitrification is the process by which ice crystallization is circumvented, resulting in a supercooled amorphous solid. Through a combination of antifreeze proteins that inhibit ice nucleation, dehydration tolerance, presence of high glycerol concentration, and low temperatures, the mobility of the remaining liquid water molecules is reduced, effectively by-passing the crystalline state. The second contribution is the discovery of a new overwintering strategy that combines freeze avoidance and freeze tolerance within an individual. In this case, the abdomen freezes (and the insect survives), while the contiguous head/thorax remains supercooled. These findings lead to the following evolutionary and trans-disciplinary questions. Is vitrification an adaptation? What is the selective advantage of compartmentalizing ice between body sections of an individual insect? Is this new overwintering strategy an example of a species transitioning between either becoming exclusively freeze avoiding or free tolerant? Applying new understanding of mechanisms of insect vitrification and avoidance of devitrification to cryomedicine may extend ...