Meeting Abstract

50.3  Monday, Jan. 5  Simultaneous freeze tolerance and avoidance in individual fungus gnats, Exechia nugatoria SFORMO, T*; KOHL, F; MCINTYRE, J; KERR, P; DUMAN, J; BARNES, B; Univ. Alaska Fairbanks; Univ. Alaska Fairbanks; Univ. Alaska Fairbanks; California Department of Food and Agriculture; Univ. of Notre Dame; Univ. Alaska Fairbanks rfts@uaf.edu

Freeze tolerance and freeze avoidance are described as mutually exclusive strategies in overwintering animals. We describe an insect species that combines both strategies under winter field conditions. The fungus gnat Exechia nugatoria (Diptera: Mycetophilidae), collected in Fairbanks, Alaska, displays two freezing events when cooled to -50C; they survive the first but not the second freezing event. To determine which body compartments froze, we dissected the abdomen from the thorax and cooled the parts separately. Results indicate a significant difference between abdominal and head/thoracic freezing. The abdomen froze at -30C, and gnats showed 70% survival. The head/thorax froze at -50C, and gnats showed 100% mortality. We suggest that differential freezing and subsequent survival is accomplished by regional dehydration that prevents inoculative freezing between the frozen abdomen and the supercooled thorax. NSF 0618436