Gynaephora groenlandica

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Gynaephora groenlandica
Gynaephora groenlandica.jpg
Arctic Woolly Bear, Baffin Island
Scientific classification
Kingdom: Animalia
Phylum: Arthropoda
Class: Insecta
Order: Lepidoptera
Family: Lymantriidae
Subfamily: Lymantrinae
Tribe: Lymantrini
Genus: Gynaephora
Hübner, 1819
Binomial name
Gynaephora groenlandica
(Wocke, 1874)

Gynaephora groenlandica (common name: Arctic Woolly Bear Moth) is a Lymantriid moth found within the Arctic circle, in Greenland and Canada. It is best known for its very slow rate of development. It was once estimated that it had a 14-year life cycle from egg to adult moth, a unique life cycle among the Lepidoptera with the ability to withstand temperatures below −60 °C. The larvae degrade their mitochondria in preparation for overwintering and re-synthesize them in the spring, and each instar of the caterpillar takes about a year. Subsequent studies have revised the life-cycle duration to 7 years.[1]

The arctic woolly-bear caterpillars are unique in their combination of adaptations to the polar extremes. They spend nearly 90% of their life frozen and only about 5% feeding on the tundra during the month of June; the remainder is spent in summer aestivation within hibernacula (protective cocoons).

Hiding within hibernacula serves several functions: 1) protection from insect parasitoids that kill ca. 75% of the larvae and pupae, 2) avoidance of secondary metabolites built up in their food source, the arctic willow, 3) degradation of mitochondria linked to hypometabolism and antifreeze synthesis, 4) conservation of energy reserves needed to synthesize cryoprotective compounds required for freezing survival.

Two insect parasitoids (i.e. parasites that kill the host) attack woolly bear moth caterpillars: an ichneumonid wasp (reported as Hyposoter pectinatus but probably Hyposoter deichmanni[2]) and a tachinid fly (Exorista thula[3]). The wasp, a solitary parasitoid, kills about 20% of the 3rd and 4th instars of the host while the gregarious bristle fly causes ca. 50% mortality in the instar V, VI and pupae.

The extreme winter temperatures are not as detrimental to Gynaephora caterpillars as are the parasitoids. The larvae are extremely freeze tolerant, able to survive temperatures down to -70°C. As temperatures decrease during the late arctic summer the larvae start synthesizing cryoprotective compounds, such as glycerol, in addition to some unusual ones, e.g. betaine. Accumulation of these "antifreezes“ is aided by bottle-necking of oxidative phosphorylation through mitochondrial degradation. The woolly-bears re-synthesize the mitochondria the following spring upon resumption of their activity.

The specialized adaptations to environmental constraints adopted by arctic woolly bear moths and other cold-tolerant insects have been during the past 15 years used to develop new technologies for the preservation of cells and tissues.[citation needed]

In popular culture[edit]

The Natural History Unit of the BBC filmed arctic woolly bear moths in their natural habitat on Ellesmere Island during June 2009. The sequence became part of the BBC's sequel to Planet Earth called Frozen Planet, broadcast on BBC One in Autumn 2011 (with the US broadcast following on Discovery Channel in spring 2012).[4]

References[edit]

  1. ^ Morewood, W. Dean & Richard A. Ring (1998). "Revision of the life history of the High Arctic moth Gynaephora groenlandica (Wocke) (Lepidoptera: Lymantriidae)". Can. J. Zool. 76 (7): 1371–1381. doi:10.1139/cjz-76-7-1371. 
  2. ^ Varkonyi, Gergely & Tomas Roslin (2013). "Freezing cold yet diverse: dissecting a high-Arctic parasitoid community associated with Lepidoptera hosts". Can. Entomol. 145: 193–218. doi:10.4039/tce.2013.9. 
  3. ^ Morewood, W. Dean & D. Monty Wood (2002). "Host utilization by Exorista thula Wood (sp. nov.) and Chetogena gelida (Coquillett) (Diptera: Tachinidae), parasitoids of arctic Gynaephora species (Lepidoptera: Lymantriidae)". Polar Biol. 25: 575–582. doi:10.1007/s00300-002-0382-y. 
  4. ^ Levin, Gary (April 8, 2008). "Another sweeping nature special when 'Planet' freezes over". USA Today. Retrieved May 25, 2010. 

Further reading[edit]

  • Bernd Heinrich (1993). The hot-blooded insects: strategies and mechanisms of thermoregulation. Harvard University Press. 
  • R. F. Chapman (1998). The insects: structure and function. Cambridge University Press. ISBN 978-0-521-57890-5. 
  • Kukal, O. and P.G. Kevan. (1987) The influence of parasitism on the life history of a high arctic insect, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae). Can. J. Zool. 65: 156-163.
  • Kukal, O. 1988. Caterpillars on ice. Natural History 97: 36-41.
  • Kukal, O., Duman, J.G. and A.S. Serianni. (1988) Glycerol metabolism in a freeze-tolerant arctic insect: An in vivo 13-C NMR study. J. Comp. Physiol. B 158: 175-183.
  • Kukal, O., Heinrich, B. and J.G. Duman. (1988) Behavioural thermoregulation in the freeze-tolerant arctic caterpillar, Gynaephora groenlandica. J. Exp. Biol. 138: 181-193.
  • Kukal, O. and T.E. Dawson. (1989) Temperature and food quality influences feeding behavior, assimilation efficiency and growth rate of arctic woolly-bear caterpillars. Oecologia 79: 526-532.
  • Kukal, O., Duman, J.G. and A.S. Serianni. (1989) Cold-induced mitochondrial degradation and cryoprotectant synthesis in freeze-tolerant arctic caterpillars. J. Comp. Physiol. B 158: 661-671.
  • Kukal, O. 1990. Energy budget for activity of a high arctic insect, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae). In: C.R. Harington (ed) Canadian Arctic Islands: Canada's Missing Dimension. National Museum of Natural History, Ottawa, Canada.
  • Kukal, O. 1991. Behavioral and physiological adaptations to cold in a freeze-tolerant arctic insect. In: R.E. Lee and D.L. Denlinger (eds) Insects at Low Temperature. Chapman and Hall, N.Y.
  • Kukal, O. 1993. Biotic and abiotic constraints on foraging of arctic caterpillars. In: N.E. Stamp and T.M. Casey (eds) Caterpillars: Ecological and Evolutionary Constraints on Foraging. Chapman and Hall, N.Y.
  • Kevan, P.G. and O. Kukal. (1993) A balanced life table for Gynaephora groenlandica (Lepidoptera: Lymantriidae) a long-lived high arctic insect, and implications for the stability of its populations. Can. J. Zool. 65: 156-163.
  • Danks, H.V., Kukal, O. and R.A. Ring. (1994) Insect cold-hardiness: Insights from the arctic. Arctic 47 (4): 391-404.
  • Kukal, O. (1995) Winter mortality and the function of larval hibernacula during the 14-year life cycle of an arctic moth, Gynaephora groenlandica. Can. J. Zool. 73: 657-662.
  • Bennett, V. A, Kukal, O. and R.E. Lee. (1999) Metabolic opportunists: Feeding and temperature influence the rate and pattern of respiration in the high arctic woollybear caterpillar, Gynaephora groenlandica (Lymantriidae). J. Exp. Biol. 202: 47-53.
  • Bennett, V.A., Lee, R. E., Jr., Nauman, J.S. and Kukal, O. (2003) Selection of overwintering microhabitats used by the arctic woollybear caterpillar, Gynaephora groenlandica. CryoLetters 24(3): 191-200.

External links[edit]