Physiological basis of low temperature tolerance in antarctic insects
The airborne organic particles derived from indigenous organisms were relatively few at Arrival Heights and Lake Vanda, still fewer at McMurdo, and absent at South Pole Station. The particles in this group identified so far are from algae, fungi, lichens, a moss, and a very small arthropod. Two categories of introduced organic particles caught by the air samples greatly outweigh the numbers of native particles: first, (a) cells and tissue fragments of conifer wood, most abundant and pervasive; second, (b) clothing fibers, both natural and synthetic. The wood cells undoubtedly are derived from the wooden packing cases at camps and experimental sites. Snow samples collected at South Pole Station contained incompletely burned diesel fuel residue and small quantities of mineral grains as well as conifer wood cells and clothing fibers, all presumably introduced by station activity. The results suggest the usefulness of air and snow sampling for monitoring releases of airborne particles into the local environment. The Tauber traps were modified by coating surfaces around the aperture with conductive carbon paint. All these traps were exposed in pairs, one earthed, the other not (although earthing in the snow at South Pole is probably ineffective). At the McMurdo sampling site, the Cosmic Ray Laboratory, the electric fields were measured by a rotating
Physiological basis of low temperature tolerance in antarctic insects JOHN G. BAUST,'JOHN S. EDWARDS, 2 and ROBERT BROWN I
'Department of Biology University of Houston Houston, Texas 77004 'Department of Zoology University of Washington Seattle, Washington 98195
The strategies of low temperature tolerance utilized by various species of terrestrial insects has been studied by relatively few investigators. Cold hardiness, especially freezing tolerance, is most frequently correlated with the presence of cryoprotective compounds (Baust and Morrissey, 1977). Salt (1959), Somme (1964, 1965), Asahina (1966), Baust (1972), and Miller and Smith (1975) have described a variety of single-type cryoprotectant systems that utilize low molecular weight polyhydric alcohols as antifreeze agents. Other evidence now suggests that many species rely on mixed-type cryoprotectants that are sequentially synthesized upon cold exposure (Mansingh and Smallman, 1972; Morrissey and Baust, 1976). Following a first season of study (December 1977 and January 1978) of two antarctic species resident to the Palmer
164
dipole instrument (Stanford Radioscience Laboratory field ill 2) mounted on a wooden post 2.5 meters above the ground. During periods of blowing snow and dust, the electric field gradient was + 500 to + 2,500 volts per meter. In those intervals the Tauber traps with earthed covers collected two or more times as much snow and dust as the ones with insulated covers. During periods of falling snow, the electric field gradient was -1,000 to -1,500 volts per meter. In those intervals the insulated traps collected more, and in some instances almost twice as much, snow and dust as the traps with earthed covers. Dispersal of diaspores and minute organisms by wind over snow and ice has long been recognized in the polar regions. The relationships to electric fields shown here suggest that, during periods of blowing snow and/or dust, greater numbers of airborne particles would tend to be deposited on wet (i.e., earthed) soil or rock surfaces. This principle may be of basic significance in processes of diaspore (i.e., viable reproductive particle) lodgment and germination. The principle also may apply to differential accumulation of fine material and organic sediments on diversified terrain in cold or dry climates. This research was supported by National Science Foundation grant DPP 77-00202 to the University of Michigan.
Station area (64°S.64 0 W.), Belgica antarctica and Cryptopygus antarctica, two distinct mechanisms of adaptation have been identified.
Belgica larvae are freezing-tolerant during the austral summer and are capable of elaborating an array of cryoprotectant compounds. This species is the first identified to endure freezing in a non-overwintering state. Ambient larvae produce a cryoprotectant profile containing erythritol, glucose, sucrose, and trehalose. Adults are freezing-susceptible and contain only trace amounts of protective agents (figure 1). The identification of erythritol, a plant sugar derivative, has not been made or associated with cryoprotective function in other species. Preliminary evidence (figure 2) suggests that, at temperatures below 0°C, cryoprotectant accumulation is temperature dependent and independent of nutrient (carbon) source. Cryoprotectants include in increasing order of concentration: glycerol, erythritol, fructose, and glucose. At 0°C the triggers become biphasic. Temperature induces shifts in carbohydrate metabolism such that glycerol is built up. Simultaneously, dietary carbon sources cause accumulations of other protective sugars and/or polyhydric alcohols. A glycerol diet results in increased fructose levels, an eryrhritol diet in erythritol increases, a glucose diet in nonpatterned profiles, and a sucrose diet in a profile similar to the -5°C profile. It would be speculative to proceed with discussions of intermediary metabolism beyond this point. However, the Belgica data suggest a number of exciting prospects for continued study: 1. Erythritol metabolism and its apparent conversion to glycerol imply that an undescribed metabolic pathway exists. 2. The mechanism (site) of influence by the dicotomous triggers is unknown.
ANTARCTIC JOURNAL
I
0° 10° 200 prasiola
M
I
1-51.7 1IUIII • 5 248.9 0 3-47.6 — 6.7 5-30.2
1,
I4 IU L I– 0
''' 2 6 31117 4 47— ?
11
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22 52 22
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1
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3 F S 3 F S X ? 46T 4 6 R D Figure 1. Cryoprotectant profiles for ambient Beigica antarctica and a primary food source, Prisioia crispa. (Abscissa key: 3-glycerol, 4-erythrltol, F-fructose, 6-glucose, S-sucrose, T-trehaiose, R-ribose, X=xylose, D?-unidentified disaccharides.) 3. The role and significance of the noncarbohydrate intermediates is unknown. 4. The fate of dietary carbon sources in ambient specimens is unknown. 5. The pivotal temperature concept appears to be a key in determining metabolic routes. Other factors complicate the wintering picture. First, both adults and larvae have limited supercooling capabilities ( = supercooling points -5.3°C and -5.7°C). Therefore, early freezing is ensured in larval specimens. Adults, however, represent a nonfeeding, short-lived reproductive stage (few days) and are sufficiently mobile to avoid subfreezing exposures by vertical migration (Baust and Edwards, in preparation). Second, snowmelt, precipitation, and wind combine to present many terrestrial habitats with transient freshwater or saline conditions. Larvae survive well in distilled water (50 percent survival after 9 days) or seawater (75 percent survival after 4 days). Fifty percent seawater or less results in survivals equivalent to distilled water. The data suggest a remarkable degree of euryhalinity and strong ion-regulating capacities at near freezing temperatures. Third, Belgica are tolerant to anaerobic conditions. Whether or not the decayed detritus habitat containing larvae is anaerobic is unknown. However, occasional bouts of anaerobiosis may be necessary. Larvae are capable of 90 percent survival after 6 days in an aqueous nitrogen environment. Preliminary electrophoretic evidence (Baust and Edwards, in preparation) indicates that Belgzca is capable of anaerobiosis in that the frequency of appropriate transaminase and oxidase isozymes increases, suggesting a shift toward anaerobic metabolism. What effects, if any, the latter two factors have on low temperature tolerance is unknown. A number of authors have, however, demonstrated
October 1978
0.
0
C
6 Cl2 4 2
3 F S 46T
3FS 461
Figure 2. Cryoprotectant profiles for Beigica antarctica maintained at fixed temperatures and on controlled diets. (Abscissa key: 3-glycerol, 4-erythritol, F-fructose, 6-glucose, S-sucrose, T-trehalose.) that anaerobic conditions facilitate cryoprotectant accumulation (Conradi-Larsen and Somme, 1973a, 1973b). This project was supported by National Science Foundation grant oPt' 76-24205 to the University of Houston. The field team comprisedJohn G. Baust, Robert Brown, andJohn S. Edwards.
References
Asahina, E. 1966. Freezing and frost resistance in insects. In: Cryobiology (H. T. Meryman, ed.). Academic Press, New York, New York. pp. 451-484. 165
Baust, J . G. 1972. Mechanisms of insect freezing protectionPterostichus brevicornis. Nature, 236(68): 219-220. Baust, J. C., and J . S. Edwards. In preparation. Molecular basis of anaerobiosis in an antarctic insect. Baust, J . C., and R. Morrissey. 1977. Strategies of low temperature adaptation. Proceedings of the International Congress on Entomology, 173-184. Conradi-Larsen, E., and L. Somme. 1973. Anaerobiosis in the overwintering beetle Pelophila borealis. Nature, 245: 388-390. Conradi-Larsen, E., and L. Somme. 1973. The overwintering of Pelophia boreolis Payk. II Aerobic and anaerobic metabolism. NORSK Entomologisk Tidsskr!fi, 20: 325-332. Mansingh, L. A., and B. N. Smallman. 1972. Variations in polyhydric alcohol in relation to diapause and cold-hardiness in the larvae of Isia isabella. Journal of Insect Physiology, 18: 1565-1571. Miller, L. K., and J. S. Smith. 1975. Production of threitol and sorbitol by an insect: Association with freezing tolerance. Nature, 258: 519-520. Morrissey, R., and J. C. Baust. 1976. The ontogeny of cold tolerance in the gall fly, Eurosta Solidagensis. Journal of Insect Physiology, 22: 431-437. Salt, R. W. 1959. Role of glycerol in the cold hardening of Bracon cephi. Canadian Journal of Zoology, 37: 59-69. Somme, L. 1964. Effects glycerol on cold hardiness in insects. (widian journal of Zoology, 42: 87-101. Somme, L. 1965. Further observations on glycerol and cold-hardiness in insects. Canadian journal of Zoo/og, 43: 764-770.
-- ,?. --
M
Figure 1. Langway Mt. An outcrop rich in mites.
Terrestrial arthropods, Marie Byrd Land, Antarctica R. W. STRANDTMANN
Department of Biological Sciences Texas Tech University Lubbock, Texas 79409
The project objective was to determine the presence or absence of terrestrial arthropods in Marie Byrd Land. None previously had been reported from that region of Antarctica. The research quadrant was bounded by latitudes 740 to 76°S. and longitudes 132°30' to 140°W. The area is covered by deep snow, with widely scattered, relatively small, rocky outcrops (figure 1). I visited 32 exposures, some of them twice. I made collections between 20 November and 14 December 1977 as weather permitted (a total of 11 collecting days) using several research methods. One was to locate a likely habitat (i.e., a moist substrate of coarse sand and pebbles with some evidence of plant life such as mosses, algae, fungi, lichens) and then to look for mites or insects on the indersurface of pebbles. Indirect search methods included (1) putting a spoonful of moist sand and plants in a shallow dish and covering with water, and (2) putting algae mats, moss, and loose sand in a plastic jar and subsequently floating the mites or insects in the lab. All methods were successful in locating arthropods, but the last was most efficient. 166
Figure 2. Scanning electron microscope photo of Nanorchestes sp. found on Cox Point.
4l
d
r I..
* 1I ' 41
'
4I
I &è$i t:
Figure 3. Scanning electron microscope photo shows setae and cuticular detail of Nanorchestes sp.
ANTARCTIC JOURNAL
Physiological basis of low temperature tolerance in antarctic insects JOHN G. BAUST,'JOHN S. EDWARDS, 2 and ROBERT BROWN I
'Department of Biology University of Houston Houston, Texas 77004 'Department of Zoology University of Washington Seattle, Washington 98195
The strategies of low temperature tolerance utilized by various species of terrestrial insects has been studied by relatively few investigators. Cold hardiness, especially freezing tolerance, is most frequently correlated with the presence of cryoprotective compounds (Baust and Morrissey, 1977). Salt (1959), Somme (1964, 1965), Asahina (1966), Baust (1972), and Miller and Smith (1975) have described a variety of single-type cryoprotectant systems that utilize low molecular weight polyhydric alcohols as antifreeze agents. Other evidence now suggests that many species rely on mixed-type cryoprotectants that are sequentially synthesized upon cold exposure (Mansingh and Smallman, 1972; Morrissey and Baust, 1976). Following a first season of study (December 1977 and January 1978) of two antarctic species resident to the Palmer
164
dipole instrument (Stanford Radioscience Laboratory field ill 2) mounted on a wooden post 2.5 meters above the ground. During periods of blowing snow and dust, the electric field gradient was + 500 to + 2,500 volts per meter. In those intervals the Tauber traps with earthed covers collected two or more times as much snow and dust as the ones with insulated covers. During periods of falling snow, the electric field gradient was -1,000 to -1,500 volts per meter. In those intervals the insulated traps collected more, and in some instances almost twice as much, snow and dust as the traps with earthed covers. Dispersal of diaspores and minute organisms by wind over snow and ice has long been recognized in the polar regions. The relationships to electric fields shown here suggest that, during periods of blowing snow and/or dust, greater numbers of airborne particles would tend to be deposited on wet (i.e., earthed) soil or rock surfaces. This principle may be of basic significance in processes of diaspore (i.e., viable reproductive particle) lodgment and germination. The principle also may apply to differential accumulation of fine material and organic sediments on diversified terrain in cold or dry climates. This research was supported by National Science Foundation grant DPP 77-00202 to the University of Michigan.
Station area (64°S.64 0 W.), Belgica antarctica and Cryptopygus antarctica, two distinct mechanisms of adaptation have been identified.
Belgica larvae are freezing-tolerant during the austral summer and are capable of elaborating an array of cryoprotectant compounds. This species is the first identified to endure freezing in a non-overwintering state. Ambient larvae produce a cryoprotectant profile containing erythritol, glucose, sucrose, and trehalose. Adults are freezing-susceptible and contain only trace amounts of protective agents (figure 1). The identification of erythritol, a plant sugar derivative, has not been made or associated with cryoprotective function in other species. Preliminary evidence (figure 2) suggests that, at temperatures below 0°C, cryoprotectant accumulation is temperature dependent and independent of nutrient (carbon) source. Cryoprotectants include in increasing order of concentration: glycerol, erythritol, fructose, and glucose. At 0°C the triggers become biphasic. Temperature induces shifts in carbohydrate metabolism such that glycerol is built up. Simultaneously, dietary carbon sources cause accumulations of other protective sugars and/or polyhydric alcohols. A glycerol diet results in increased fructose levels, an eryrhritol diet in erythritol increases, a glucose diet in nonpatterned profiles, and a sucrose diet in a profile similar to the -5°C profile. It would be speculative to proceed with discussions of intermediary metabolism beyond this point. However, the Belgica data suggest a number of exciting prospects for continued study: 1. Erythritol metabolism and its apparent conversion to glycerol imply that an undescribed metabolic pathway exists. 2. The mechanism (site) of influence by the dicotomous triggers is unknown.
ANTARCTIC JOURNAL
I
0° 10° 200 prasiola
M
I
1-51.7 1IUIII • 5 248.9 0 3-47.6 — 6.7 5-30.2
1,
I4 IU L I– 0
''' 2 6 31117 4 47— ?
11
6
C3
4 2
0
0
03 >Cr U
22 52 22
C4
E
I-.
1
Z
I,U I-. 0
3 F S 3 F S X ? 46T 4 6 R D Figure 1. Cryoprotectant profiles for ambient Beigica antarctica and a primary food source, Prisioia crispa. (Abscissa key: 3-glycerol, 4-erythrltol, F-fructose, 6-glucose, S-sucrose, T-trehaiose, R-ribose, X=xylose, D?-unidentified disaccharides.) 3. The role and significance of the noncarbohydrate intermediates is unknown. 4. The fate of dietary carbon sources in ambient specimens is unknown. 5. The pivotal temperature concept appears to be a key in determining metabolic routes. Other factors complicate the wintering picture. First, both adults and larvae have limited supercooling capabilities ( = supercooling points -5.3°C and -5.7°C). Therefore, early freezing is ensured in larval specimens. Adults, however, represent a nonfeeding, short-lived reproductive stage (few days) and are sufficiently mobile to avoid subfreezing exposures by vertical migration (Baust and Edwards, in preparation). Second, snowmelt, precipitation, and wind combine to present many terrestrial habitats with transient freshwater or saline conditions. Larvae survive well in distilled water (50 percent survival after 9 days) or seawater (75 percent survival after 4 days). Fifty percent seawater or less results in survivals equivalent to distilled water. The data suggest a remarkable degree of euryhalinity and strong ion-regulating capacities at near freezing temperatures. Third, Belgica are tolerant to anaerobic conditions. Whether or not the decayed detritus habitat containing larvae is anaerobic is unknown. However, occasional bouts of anaerobiosis may be necessary. Larvae are capable of 90 percent survival after 6 days in an aqueous nitrogen environment. Preliminary electrophoretic evidence (Baust and Edwards, in preparation) indicates that Belgzca is capable of anaerobiosis in that the frequency of appropriate transaminase and oxidase isozymes increases, suggesting a shift toward anaerobic metabolism. What effects, if any, the latter two factors have on low temperature tolerance is unknown. A number of authors have, however, demonstrated
October 1978
0.
0
C
6 Cl2 4 2
3 F S 46T
3FS 461
Figure 2. Cryoprotectant profiles for Beigica antarctica maintained at fixed temperatures and on controlled diets. (Abscissa key: 3-glycerol, 4-erythritol, F-fructose, 6-glucose, S-sucrose, T-trehalose.) that anaerobic conditions facilitate cryoprotectant accumulation (Conradi-Larsen and Somme, 1973a, 1973b). This project was supported by National Science Foundation grant oPt' 76-24205 to the University of Houston. The field team comprisedJohn G. Baust, Robert Brown, andJohn S. Edwards.
References
Asahina, E. 1966. Freezing and frost resistance in insects. In: Cryobiology (H. T. Meryman, ed.). Academic Press, New York, New York. pp. 451-484. 165
Baust, J . G. 1972. Mechanisms of insect freezing protectionPterostichus brevicornis. Nature, 236(68): 219-220. Baust, J. C., and J . S. Edwards. In preparation. Molecular basis of anaerobiosis in an antarctic insect. Baust, J . C., and R. Morrissey. 1977. Strategies of low temperature adaptation. Proceedings of the International Congress on Entomology, 173-184. Conradi-Larsen, E., and L. Somme. 1973. Anaerobiosis in the overwintering beetle Pelophila borealis. Nature, 245: 388-390. Conradi-Larsen, E., and L. Somme. 1973. The overwintering of Pelophia boreolis Payk. II Aerobic and anaerobic metabolism. NORSK Entomologisk Tidsskr!fi, 20: 325-332. Mansingh, L. A., and B. N. Smallman. 1972. Variations in polyhydric alcohol in relation to diapause and cold-hardiness in the larvae of Isia isabella. Journal of Insect Physiology, 18: 1565-1571. Miller, L. K., and J. S. Smith. 1975. Production of threitol and sorbitol by an insect: Association with freezing tolerance. Nature, 258: 519-520. Morrissey, R., and J. C. Baust. 1976. The ontogeny of cold tolerance in the gall fly, Eurosta Solidagensis. Journal of Insect Physiology, 22: 431-437. Salt, R. W. 1959. Role of glycerol in the cold hardening of Bracon cephi. Canadian Journal of Zoology, 37: 59-69. Somme, L. 1964. Effects glycerol on cold hardiness in insects. (widian journal of Zoology, 42: 87-101. Somme, L. 1965. Further observations on glycerol and cold-hardiness in insects. Canadian journal of Zoo/og, 43: 764-770.
-- ,?. --
M
Figure 1. Langway Mt. An outcrop rich in mites.
Terrestrial arthropods, Marie Byrd Land, Antarctica R. W. STRANDTMANN
Department of Biological Sciences Texas Tech University Lubbock, Texas 79409
The project objective was to determine the presence or absence of terrestrial arthropods in Marie Byrd Land. None previously had been reported from that region of Antarctica. The research quadrant was bounded by latitudes 740 to 76°S. and longitudes 132°30' to 140°W. The area is covered by deep snow, with widely scattered, relatively small, rocky outcrops (figure 1). I visited 32 exposures, some of them twice. I made collections between 20 November and 14 December 1977 as weather permitted (a total of 11 collecting days) using several research methods. One was to locate a likely habitat (i.e., a moist substrate of coarse sand and pebbles with some evidence of plant life such as mosses, algae, fungi, lichens) and then to look for mites or insects on the indersurface of pebbles. Indirect search methods included (1) putting a spoonful of moist sand and plants in a shallow dish and covering with water, and (2) putting algae mats, moss, and loose sand in a plastic jar and subsequently floating the mites or insects in the lab. All methods were successful in locating arthropods, but the last was most efficient. 166
Figure 2. Scanning electron microscope photo of Nanorchestes sp. found on Cox Point.
4l
d
r I..
* 1I ' 41
'
4I
I &è$i t:
Figure 3. Scanning electron microscope photo shows setae and cuticular detail of Nanorchestes sp.
ANTARCTIC JOURNAL
