Survival Following Exposure to Subzero Temperatures and Respiration in Cold Acclimatized Larvae of Enallagma boreale (Odonata:Zygoptera)

Larvae of Enallagma boreale survived exposure to -1.0° C (53%) and -4.0° C (10%). Ability to survive was not related to rate of cooling or duration of exposure. Respiration rates ranged from 0.10 ml O2/g/h at -1.0° C to 0.92 ml O2/g/h at 30.0° C. At -1.0° C the respiratory quotient of larvae was 0.72, indicating lipids were being metabolized. Calculated metabolic costs for the overwintering period were 40.5% of total body calories. It is suggested that overwintering frozen into ice at moderately cold temperatures may be energetically advantageous.