DOI: 10.5061/dryad.15dv41nvr
title: Metabolic cost of freeze-thaw and source of CO2 production in the freeze-tolerant cricket Gryllus veletis

description: Freeze-tolerant insects can survive the conversion of a substantial
 portion of their body water to ice. While the process of freezing induces
 active responses from some organisms, these responses appear absent from
 freeze-tolerant insects. Recovery from freezing likely requires energy
 expenditure to repair tissues and re-establish homeostasis, which should
 be evident as elevations in metabolic rate after thaw. We measured carbon
 dioxide (CO2) production in the spring field cricket (Gryllus veletis) as
 a proxy for metabolic rate during cooling, freezing and thawing and
 compared the metabolic costs associated with recovery from freezing and
 chilling. We hypothesized that freezing does not induce active responses,
 but that recovery from freeze-thaw is metabolically costly. We observed a
 burst of CO2release at the onset of freezing in all crickets that froze,
 including those killed by either cyanide or an insecticide (thiacloprid),
 implying that the source of this CO2was neither aerobic metabolism or a
 coordinated nervous system response. These results suggest that freezing
 does not induce active responses from G. veletis, but may
 liberate buffered CO2 from hemolymph. There was a transient
 ‘overshoot’ in CO2release during the first hour of recovery, and elevated
 metabolic rates at 24, 48 and 72 hours, in crickets that had been frozen
 compared to crickets that had been chilled (but not frozen). Thus,
 recovery from freeze-thaw and the repair of freeze-induced damage appears
 metabolically costly in G. veletis, and this cost persists for
 several days after thawing. 
description: <b>Gas exchange during cooling, freezing and thawing:
 Flow-through respirometry data</b> Respirometry
 parameters (CO<sub>2</sub> production, Q10, critical thermal
 minimum, supercooling point, etc.) measured with flow-through respirometry
 during cooling, freezing and thawing, or during cooling and rewarming.
 Data was used to construct Table 2, Figure 3 and Figure S5. The excel file
 contains a metadata tab that explains each column. See manuscript for
 details of methodology. 
 flowthrough_respirometry_July2020.xlsx 
 <b>Recovery from freeze-thaw: Stop-flow respirometry
 data</b> Respirometry
 parameters (CO<sub>2</sub> production,
 O<sub>2</sub> consumption, and calculated metabolic rates)
 measured with stop respirometry during recovery from chilling or
 freeze-thaw. Data was used to construct Table 3, Figure 4, Figure S2 and
 Figure S6. The excel file contains a metadata tab that explains each
 column. See manuscript for methodology. 
 stopflow_respirometry_July2020.xlsx 
 <strong>Total hemolymph
 CO<sub>2 </sub>data</strong> Total
 hemolymph CO<sub>2</sub> measured in acclimated, but unchilled
 crickets. The excel file contains a metadata tab that explains each
 column. See manuscript for methodology. 
 TCO2_July2020.xlsx 
 <b>Sex-specific stop-flow respirometry
 data</b> Respirometry
 parameters (CO<sub>2</sub> production) measured with stop
 respirometry in acclimated crickets 72 h after chilling. The excel file
 contains a metadata tab that explains each column. See manuscript for
 methodology. 
 sexspecific_stopflow_July2020.xlsx