Journal of Comparative Physiology B

, Volume 179, Issue 7, pp 897–902

Simultaneous freeze tolerance and avoidance in individual fungus gnats, Exechia nugatoria


    • Institute of Arctic BiologyUniversity of Alaska Fairbanks
  • F. Kohl
    • Institute of Arctic BiologyUniversity of Alaska Fairbanks
  • J. McIntyre
    • Department of Mathematics and StatisticsUniversity of Alaska Fairbanks
  • P. Kerr
    • Plant Pest Diagnostics Branch, California State Collection of ArthropodsCalifornia Department of Food and Agriculture
  • J. G. Duman
    • Department of Biological SciencesUniversity of Notre Dame
  • B. M. Barnes
    • Institute of Arctic BiologyUniversity of Alaska Fairbanks
Original Paper

DOI: 10.1007/s00360-009-0369-x

Cite this article as:
Sformo, T., Kohl, F., McIntyre, J. et al. J Comp Physiol B (2009) 179: 897. doi:10.1007/s00360-009-0369-x


Freeze tolerance and freeze avoidance are typically described as mutually exclusive strategies for overwintering in animals. Here we show an insect species that combines both strategies. Individual fungus gnats, collected in Fairbanks, Alaska, display two freezing events when experimentally cooled and different rates of survival after each event (mean ± SEM: −31.5 ± 0.2°C, 70% survival and −50.7 ± 0.4°C, 0% survival). To determine which body compartments froze at each event, we dissected the abdomen from the head/thorax and cooled each part separately. There was a significant difference between temperature levels of abdominal freezing (−30.1 ± 1.1°C) and head/thorax freezing (−48.7 ± 1.3°C). We suggest that freezing is initially restricted to one body compartment by regional dehydration in the head/thorax that prevents inoculative freezing between the freeze-tolerant abdomen (71.0 ± 0.8% water) and the supercooled, freeze-sensitive head/thorax (46.6 ± 0.8% water).


Mycetophilidae Exechia nugatoria Supercooling Exotherm



Supercooling point 1


Supercooling point 2


Relative humidity


Water content

Copyright information

© Springer-Verlag 2009