Date of this Version
Published in Journal of Entomological Science 39:4 (October 2004), pp. 525–536.
Supercooling points were determined for untreated field-collected and untreated laboratory-maintained Reticulitermes flavipes (Kollar) workers and soldiers. Workers treated with antibiotics or had their hindgut-protozoa removed by exposing them to oxygen under pressure to determine the effects of absence of the hindgut fauna on supercooling. Supercooling points were compared be-tween live and freshly killed workers to determine whether supercooling in this species might be simply due to the biochemical properties of body fluids. Laboratory-maintained workers were also subjected to desiccation, starvation, or atmospheric pressure to determine their effects on supercool-ing. Supercooling points were lowest for laboratory workers treated with antibiotics and those that fed on brown paper-toweling for 7 d. Untreated field-collected workers had significantly higher su-percooling points than untreated laboratory-maintained workers (–6.06 ± 0.79°C vs –9.29 ± 2.38°C, P < 0.0001). Both untreated field-collected and laboratory soldiers had significantly lower supercool-ing points than their respective workers (–7.39 ± 2.01°C vs –6.06 ± 0.79°C, P < 0.0001; and –11.60 ± 2.53°C vs –9.29 ± 2.38°C, P < 0.0001, respectively). There was no significant association between ter-mite body mass and supercooling points for both laboratory and field termites (P = 0.0523 and P = 0.6242) or water content of laboratory termites and supercooling points (P = 0.1425). Defaunated workers had significantly lower supercooling points (–10.34 ± 2.38°C) than normally faunated work-ers (–9.48 ± 1.85°C)(P = 0.0095) suggesting that the symbiotic fauna may have higher supercooling points and act as ice nucleators in the termite hindgut. Starved and desiccated workers had signifi-cantly lower supercooling points (–10.38 ± 2.70°C and –10.39 ± 2.38°C, respectively) than their corre-sponding control groups (–9.87 ± 2.11°C and –9.89 ± 1.94°C; P = 0.0454; P = 0.0234, respectively) and untreated workers (–9.29 ± 2.38°C; P = 0.0021; P = 0.0011) suggesting that some forms of physical stress might lower the supercooling point.