Gynaephora groenlandica
Encyclopedia
Gynaephora groenlandica (common name: Arctic Woolly Bear Moth) is a Lymantriid
moth found in the Arctic circle
found 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.
The Natural History Unit of the BBC
filmed arctic woolly bear moths in their natural habitat on Ellesmere Island
during June 2009. The sequence will become a part of the BBC‘s sequel to Planet Earth
called Frozen Planet due to be broadcast on BBC One
in autumn 2011, with the US broadcast on Discovery Channel
following in spring 2012.
Not many invertebrates that are of no economic importance, e.g. insect pests, manage to attract public attention. The arctic woolly-bear caterpillars are unique in their combination of fascinating 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, Hyposoter pectinatus, and a tachinid fly, Exorista sp.n. The wasp, a solitary parasitoid, kills about 20% of the 3rd and 4th instars of the host while the multiparasitic bristle fly causes ca. 50% mortality in the instar V, VI and pupae.
Interestingly, 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.
Lymantriidae
Lymantriidae is a family of moths. Many of its component species are referred to as "Tussock moths" of one sort or another. The caterpillar, or larval, stage of these species often has a distinctive appearance of alternating bristles and haired projections...
moth found in the Arctic circle
Arctic Circle
The Arctic Circle is one of the five major circles of latitude that mark maps of the Earth. For Epoch 2011, it is the parallel of latitude that runs north of the Equator....
found in Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
and Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
. 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
Lepidoptera
Lepidoptera is a large order of insects that includes moths and butterflies . It is one of the most widespread and widely recognizable insect orders in the world, encompassing moths and the three superfamilies of butterflies, skipper butterflies, and moth-butterflies...
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
Instar
An instar is a developmental stage of arthropods, such as insects, between each molt , until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form. Differences between instars can often be seen in altered body proportions, colors, patterns, or...
of the caterpillar
Caterpillar
Caterpillars are the larval form of members of the order Lepidoptera . They are mostly herbivorous in food habit, although some species are insectivorous. Caterpillars are voracious feeders and many of them are considered to be pests in agriculture...
takes about a year. Subsequent studies have revised the life-cycle duration to 7 years.
The Natural History Unit of the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
filmed arctic woolly bear moths in their natural habitat on Ellesmere Island
Ellesmere Island
Ellesmere Island is part of the Qikiqtaaluk Region of the Canadian territory of Nunavut. Lying within the Canadian Arctic Archipelago, it is considered part of the Queen Elizabeth Islands, with Cape Columbia being the most northerly point of land in Canada...
during June 2009. The sequence will become a part of the BBC‘s sequel to Planet Earth
Planet Earth (TV series)
Planet Earth is a 2006 television series produced by the BBC Natural History Unit. Five years in the making, it was the most expensive nature documentary series ever commissioned by the BBC, and also the first to be filmed in high definition...
called Frozen Planet due to be broadcast on BBC One
BBC One
BBC One is the flagship television channel of the British Broadcasting Corporation in the United Kingdom. It was launched on 2 November 1936 as the BBC Television Service, and was the world's first regular television service with a high level of image resolution...
in autumn 2011, with the US broadcast on Discovery Channel
Discovery Channel
Discovery Channel is an American satellite and cable specialty channel , founded by John Hendricks and distributed by Discovery Communications. It is a publicly traded company run by CEO David Zaslav...
following in spring 2012.
Not many invertebrates that are of no economic importance, e.g. insect pests, manage to attract public attention. The arctic woolly-bear caterpillars are unique in their combination of fascinating 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
Larvae
In Roman mythology, lemures were shades or spirits of the restless or malignant dead, and are probably cognate with an extended sense of larvae as disturbing or frightening...
and pupae, 2) avoidance of secondary metabolites built up in their food source, the arctic willow
Arctic Willow
Salix arctica is a tiny creeping willow . It is adapted to survive in harsh Arctic and subarctic environments, and has a circumpolar distribution round the Arctic Ocean.-Distribution:...
, 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, Hyposoter pectinatus, and a tachinid fly, Exorista sp.n. The wasp, a solitary parasitoid, kills about 20% of the 3rd and 4th instars of the host while the multiparasitic bristle fly causes ca. 50% mortality in the instar V, VI and pupae.
Interestingly, 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.
Other sources
- 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.