Corrigendum: A balanced life table for Gynaephora groenlandica (Lepidoptera: Lymantriidae), a long-lived high arctic insect, and implications for the stability of its populations

1993 ◽  
Vol 71 (8) ◽  
pp. 1699-1701 ◽  
Author(s):  
P. G. Kevan ◽  
O. Kukal
Keyword(s):  
Life Table ◽  
High Arctic ◽  
The Stability ◽  
Gynaephora Groenlandica

An analysis of the stability of thawing slopes, Ellesmere Island, Nunavut, Canada

2000 ◽  
Vol 37 (2) ◽  
pp. 449-462 ◽  
Author(s):  
Charles Harris ◽  
Antoni G Lewkowicz
Keyword(s):  
Shear Strength ◽  
Pore Water ◽  
Active Layer ◽  
Factor Of Safety ◽  
High Arctic ◽  
Ellesmere Island ◽  
Sensitivity Analyses ◽  
Pore Water Pressures ◽  
Hot Weather ◽  
The Stability

Active-layer detachment slides are locally common on Fosheim Peninsula, Ellesmere Island, where permafrost is continuous, the active layer is 0.5-0.75 m thick, and summer temperatures are unusually high in comparison with much of the Canadian High Arctic. In this paper we report pore-water pressures at the base of the active layer, recorded in situ on two slopes in late July and early August 1995. These data form the basis for slope stability analyses based on effective stress conditions. During fieldwork, the factor of safety within an old detachment slide on a slope at Hot Weather Creek was slightly greater than unity. At "Big Slide Creek," on a slope showing no evidence of earlier detachment failures, the factor of safety was less than unity on a steep basal slope section but greater than unity elsewhere. In the upper slope, pore-water pressures were only just subcritical. Sensitivity analyses demonstrate that the stability of the shallow active layer is strongly influenced by changes in soil shear strength. Possible mechanisms for reduction in shear strength through time include weathering of soils and gradual increases in basal active layer ice content. However, we suggest here that soil shearing during annual gelifluction movements is most likely to progressively reduce shear strengths at the base of the active layer from peak values to close to residual, facilitating the triggering of active-layer detachment failures.Key words: detachment slides, Ellesmere Island, pore-water pressures, gelifluction.

Metabolic opportunists: feeding and temperature influence the rate and pattern of respiration in the high arctic woollybear caterpillar gynaephora groenlandica (Lymantriidae)

1999 ◽  
Vol 202 (1) ◽  
pp. 47-53 ◽  
Author(s):  
V.A. Bennett ◽  
O. Kukal ◽  
R.E. Lee
Keyword(s):  
Cold Adaptation ◽  
Freeze Tolerance ◽  
High Arctic ◽  
Temperature Influence ◽  
Temperature Changes ◽  
Respiration Rates ◽  
Polar Environment ◽  
Lepidopteran Larvae ◽  
Gynaephora Groenlandica ◽  
Metabolic Cold Adaptation

Arctic woollybear caterpillars, Gynaephora groenlandica, had the capacity to rapidly and dramatically increase respiration rates up to fourfold within 12–24 h of feeding and exhibited similar decreases in respiration of 60–85 % in as little as 12 h of starvation. At the peak of their feeding season, the respiration rates of caterpillars also increased significantly with temperature from 0.5 to 22 degreesC for both fed and starved caterpillars (Q10=1-5). Indicative of diapause, late season caterpillars had depressed respiration rates which were less sensitive to temperature changes (Q10 approximately 1.5), while respiration rates for caterpillars that had spun hibernacula were even lower. G. groenlandica did not appear to demonstrate metabolic cold adaptation compared with other temperate lepidopteran larvae. The seasonal capacity to adjust metabolic rate rapidly in response to food consumption and temperature (which can be elevated by basking) may promote the efficient acquisition of energy during the brief (1 month) summer growing and feeding season, while conserving energy by entering diapause when conditions are less favorable. These adaptations, along with their long 15–20 year life cycle and the retention of freeze tolerance year-round, promote the survival of G. groenlandica in this harsh polar environment.

Revision of the life history of the High Arctic moth Gynaephora groenlandica (Wocke) (Lepidoptera: Lymantriidae)

1998 ◽  
Vol 76 (7) ◽  
pp. 1371-1381 ◽  
Author(s):  
W Dean Morewood ◽  
Richard A Ring
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Head Capsule ◽  
High Arctic ◽  
The Arctic ◽  
Base Line ◽  
Laboratory Rearing ◽  
History Information ◽  
History Of ◽  
Gynaephora Groenlandica

Many studies have explored the adaptations of arctic and alpine Gynaephora species (Lepidoptera: Lymantriidae) to their environment, and base-line life-history information is important for the interpretation of such studies. Data and observations on G. groenlandica (Wocke) collected in recent years at Alexandra Fiord, Ellesmere Island, Canada, contradict some of the life-history information previously published for this species from the same site. Detailed analysis of larval head capsule widths and consideration of growth ratios indicate that there are seven rather than six larval instars and that the pattern of development does not deviate significantly from that defined by the Brooks-Dyar rule. Field-rearing of larvae indicates that first-instar larvae overwinter, while field- and laboratory-rearing both indicate that larvae moult once per year, every year. These data and observations greatly shorten and simplify the life history from that previously published and suggest a life cycle of 7 rather than 14 years. This revised life cycle is not presented as an absolute, in recognition of the potential for individual variation, but rather as typical of the developmental pattern of most of the population. As such, it should provide a useful base line for further studies, especially those addressing the influence of predicted climate change in the Arctic.

Hypersaline Gradients in Two Canadian High Arctic Lakes

1986 ◽  
Vol 43 (9) ◽  
pp. 1795-1803 ◽  
Author(s):  
Kenton M. Stewart ◽  
Robert F. Platford
Keyword(s):  
High Arctic ◽  
Arctic Lakes ◽  
Canadian High Arctic ◽  
Salt Fingers ◽  
The Stability ◽  
Freeze Out

The meromictic Sophia and Garrow lakes are probably saline relicts of cutoff fjords on the uplifted Cornwallis and Little Cornwallis islands in the High Arctic of the Canadian Archipelago. Sophia and Garrow have brackish (S = 2–4) upper and hypersaline (S = 55–90) lower waters with ion ratios (especially the lower waters) similar to that of the sea. Substantial oxygen extends well below the chemocline in Sophia. The stability of these lakes is among the highest known. Because of their size, depth, and unusually warm lower waters, it seems likely that an unfrozen "thermal chimney" extends beneath the lakes through the surrounding permafrost. We feel that the hypersaline gradients evolved primarily by descent of "salt fingers" during freeze out from above, and not by solute rejection from the ground during uplift and permafrost growth, or through taliks connected to the sea, as proposed by Page et al. (1984. Limnol. Oceanogr. 29: 564–573).

Behavioural Thermoregulation in the Freeze-Tolerant Arctic Caterpillar, Gynaephora Groenlandica

1988 ◽  
Vol 138 (1) ◽  
pp. 181-193 ◽  
Author(s):  
OLGA KUKAL ◽  
BERND HEINRICH ◽  
JOHN G. DUMAN
Keyword(s):  
Solar Radiation ◽  
Growth And Development ◽  
High Arctic ◽  
The Sun ◽  
Metabolic Rates ◽  
Behavioural Thermoregulation ◽  
Body Temperatures ◽  
Feeding Site ◽  
Freeze Tolerant ◽  
Gynaephora Groenlandica

Larvae of the high arctic caterpillar, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae) spent most (60 %) of their time orienting towards the sun (i.e. basking) and only 20% feeding, primarily near midday. Larvae usually basked after feeding, then either fed again or moved to a new feeding site. Basking larvae reached their highest body temperatures (Tb) of ≊30°C (≊20°C in excess of the ambient temperature) when surrounded by snow on a calm day in the midday sun. Setae significantly decreased larval cooling rates. Maximal metabolic rates were attained in basking larvae, but at body temperatures below 10°C oxygen uptake was greatly reduced. Our studies indicate that G. groenlandica larvae are behaviourally adapted to utilize available solar radiation for growth and development.

Winter mortality and the function of larval hibernacula during the 14-year life cycle of an arctic moth, Gynaephora groenlandica

1995 ◽  
Vol 73 (4) ◽  
pp. 657-662 ◽  
Author(s):  
Olga Kukal
Keyword(s):  
Plant Cover ◽  
Late Summer ◽  
High Arctic ◽  
The Arctic ◽  
Mortality Factor ◽  
Winter Mortality ◽  
Mortality Factors ◽  
Primary Host ◽  
Larval Behaviour ◽  
Gynaephora Groenlandica

Larvae of the arctic moth Gynaephora groenlandica stop feeding and spin silk hibernacula before the peak of summer season in the Canadian High Arctic Archipelago. This study examines the function of these hibernacula in relation to the biotic and abiotic mortality factors of parasitism and temperature. Winter mortality of 10% among larvae in cages on the tundra was compared with previous results on parasitism (56% mortality). Prior to winter, the cages were used to record larval behaviour and the location of hibernacula. The majority of the larvae (81%) spun hibernacula, most of which were concealed between the stems of arctic heather, Cassiope tetragona. Fewer hibernacula were found on the primary host plant, arctic willow, Salix arctica, than on C. tetragona or Dryas integrifolia, which formed the dominant plant cover. Nearly one-half of all the larvae that spun hibernacula made joint hibernacula with other larvae. Frequency of larvae sharing hibernacula declined with increasing numbers of larvae per cage. At low population density about half of the larvae occupied communal hibernacula, whereas only one-quarter of the larvae at high density shared hibernacula. In most cases only 2 larvae spun a common hibernaculum, 3 larvae shared hibernacula less frequently, and greater numbers of larvae were rarely found in a single hibernaculum. Unlike the high excess body temperatures usually achieved through thermoregulation by feeding larvae and pupae, temperatures within hibernacula were nearly identical with those of the surrounding substrate over 18 h and rose < 5 °C during the afternoon. This study suggests that larval hibernacula lower summer and winter mortality of G. groenlandica larvae. Hibernacula are an effective barrier to parasitism, which is the primary mortality factor. Furthermore, the behavioural shift from feeding to spinning hibernacula may prevent energy depletion by inducing metabolic depression during mid to late summer, which may be essential for winter survival.

The influence of parasitism on the life history of a high arctic insect, Gynaephora groenlandica (Wöcke) (Lepidoptera: Lymantriidae)

1987 ◽  
Vol 65 (1) ◽  
pp. 156-163 ◽  
Author(s):  
Olga Kukal ◽  
Peter G. Kevan
Keyword(s):  
Life History ◽  
Life Cycle ◽  
Larval Instar ◽  
Adult Emergence ◽  
High Arctic ◽  
Winter Mortality ◽  
Short Period ◽  
History Of ◽  
Gynaephora Groenlandica ◽  
Overall Mortality

The life history of Gynaephora groenlandica was studied in the high arctic at Alexandra Fiord, Ellesmere Island. Life history events (larval development, pupation, adult emergence, mating, oviposition, hatching, and moulting to the second larval instar) occurred only in the 3–4 weeks before mid-July. Larvae fed mainly on Salix arctica. They stopped feeding by the end of June, hid, and spun hibernacula. Nineteen percent of third- and fourth-instar larvae were parasitized by the wasp Hyposoter pectinatus (Ichenumonidae); 52% of fifth- and sixth-instar larvae and pupae were parasitized by the fly Exorista sp. (Tachinidae). We estimated that G. groenlandica has a life cycle lasting 14 years. Parasitism caused 56% of overall mortality, whereas cumulative winter mortality was calculated as 13% of a cohort passing through a 14-year life cycle. Peak of activity of adult parasitoids coincided with inactivity of Gynaephora larvae during July. Selective pressure of parasitism may restrict development of G. groenlandica to a short period before adult parasitoids are most active. The importance of parasitoids in the life history of G. groenlandica suggests that parasitism is as significant as climate in population regulation of insects living in the high arctic.

Diet breadth of Gynaephora groenlandica (Lepidoptera: Erebidae): is polyphagy greater in alpine versus Arctic populations?

2014 ◽  
Vol 147 (2) ◽  
pp. 215-221 ◽  
Author(s):  
I.C. Barrio ◽  
D.S. Hik ◽  
J.Y. Liu
Keyword(s):  
Host Plants ◽  
Life History Traits ◽  
Extreme Environments ◽  
Diet Breadth ◽  
High Arctic ◽  
Published Data ◽  
Cold Adapted ◽  
Local Adaptations ◽  
Larval Host ◽  
Gynaephora Groenlandica

AbstractGynaephora groenlandica (Wocke) (Lepidoptera: Erebidae) is a cold-adapted species, whose life history traits are dictated by cold and short Arctic summers. We used a recently discovered alpine tundra population in southwestern Yukon, Canada to investigate local adaptations to habitats with different environmental conditions (alpine versus Arctic). Using cafeteria-type experiments and field observations we examined the diet breadth of alpine populations of G. groenlandica beringiana Schmidt and Cannings, and compared these to published data on High Arctic populations of G. groenlandica groenlandica and to the closely related G. rossii Curtis. Gynaephora groenlandica beringiana appears to have a broader diet than High Arctic populations, but similar to that exhibited by alpine populations of G. rossii. Such trends could emerge from reduced synchrony between herbivores and their host plants in less extreme environments, and possibly from a reduced incidence of parasitoids in the life cycle of these populations. Our findings indicate the larval host plant plasticity of G. groenlandica in different environments, and are relevant to predictions regarding the fate of these populations under climate warming scenarios.

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