Cold tolerance of the Antarctic springtail Gomphiocephalus hodgsoni (Collembola, Hypogastruridae)

Abstract

Cold tolerance of the springtail Gomphiocephalus hodgsoni Carpenter (Collembola: Hypogastruridae) was studied at Cape Bird, Ross Island, Antarctica (77°13′S, 166°26′E). Microclimate temperatures indicate a highly seasonal thermal environment, with winter minima <–39°C. Snow cover significantly buffers both minimum temperatures and cooling rates. Gomphiocephalus hodgsoni survives low temperatures by avoiding freezing. Mean low group supercooling points (SCPs) ranged from –35.4°C in October to –28.3°C in January. The lowest SCP measured was –38.0°C. The high SCP group was very small, making up only 18% of the population in January. In October, G. hodgsoni had a very high glycerol content (>80 μg mg−1 dry weight), although this declined rapidly to low levels (c. 7–10 μg mg−1 dry weight) in January. Quantities of glucose and trehalose were low during October, but steadily increased throughout the summer. Haemolymph osmolality was exceptionally high (up to 1755 mOsm kg−1) at the end of November, but this rapidly declined to c. 500 mOsm kg−1 by late December. The presence of thermal hystersis proteins was indicated by both osmometry on haemolymph samples and recrystallization inhibition studies of springtail homogenates. There was a strong relationship between glycerol content and SCP, but the relationship between haemolymph osmolality, SCP and carbohydrates is uncertain.

An invitation to measure insect cold tolerance: Methods, approaches, and workflow

“…Sinclair et al, 2003a;Sinclair and Sjursen, 2001); unfortunately, neither of these devices (nor designs for them) are commercially available, so they must be custom-designed and -built (Wharton and Rowland, 1984). However, they are light and robust and use little power, so are ideal for field situations.…”

Surviving in a frozen desert: environmental stress physiology of terrestrial Antarctic arthropods

“…Generally, collembolans have extensive supercooling capacities, with supercooling points around −30°C in some species (Cannon and Block, 1988;Worland and Convey, 2001;Worland and Block, 2003). Extensive supercooling in this group is achieved by a combination of extremely high hemolymph osmolality (Sinclair and Sjursen, 2001) and a moderate degree of thermal hysteresis (Sinclair et al, 2006). Seasonal regulation of supercooling points in Antarctic collembolans appears to be primarily regulated by the molt cycle.…”

“…Another mite, Styerotydeus mollis, has a supercooling point around −20°C in early summer that increases over the course of the summer, likely because of feeding (Sjursen and Sinclair, 2002). While overwintering supercooling points have not been measured, they are assumed to be much lower than −20°C, as winter microhabitat temperatures can reach −40°C (Sinclair and Sjursen, 2001). The seabird tick Ixodes uriae has a supercooling capacity similar to that of mites (approximately -30°C), but can also tolerate high temperatures (>25°C), perhaps to permit survival and activity both on-and off-host .…”

Activity and dormancy in relation to body water and cold tolerance in a winter-active springtail (Collembola)

“…In comparison to lowland species, winter values of both haemolymph MP and FP are higher in C. sigillata, whereas summer values are similar. Three species of sub Antarctic Collembola showed no detectable thermal hys teresis (Sinclair & Chown, 2002), whereas a maximum thermal hysteresis of 1.1°C was reported for the Antarc tic springtail Gomphiocephalus hodgsoni (Sinclair & Sjursen, 2001).…”