Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island
Understanding the mechanisms by which aphids survive low temperature is fundamental in forecasting the risk of pest outbreaks. Aphids are chill susceptible and die at a temperature close to that at which a small exothermal event is produced. This event, which can be identified using differential sca...
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Elsevier Ltd.
2011
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ftunstellenbosch:oai:scholar.sun.ac.za:10019.1/119955 2023-05-15T14:05:07+02:00 Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island Worland, M.R. Janion, C. Treasure, A.M. Chown, S.L. 2011-05-16T09:29:06Z 566849 bytes application/pdf http://hdl.handle.net/10019.1/119955 en eng Elsevier Ltd. Worland, M.R., Janion, C., Treasure, A.M. and Chown, S.L. (2010) Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island. Journal of Thermal Biology, 35, 255-262 http://hdl.handle.net/10019.1/119955 Cold tolerance Chill tolerance Insect Lethal temperature LT50 Marion Island JournalArticles 2011 ftunstellenbosch 2021-08-31T00:09:24Z Understanding the mechanisms by which aphids survive low temperature is fundamental in forecasting the risk of pest outbreaks. Aphids are chill susceptible and die at a temperature close to that at which a small exothermal event is produced. This event, which can be identified using differential scanning calorimetry(DSC), normally occurs at a higher temperature than the supercooling point(SCP)and has been termed a pre-freeze event(PFE). However, it is not known what causes the PFE or whether it signifies the death of the aphid. These questions are addressed here by using a sensitive DSC to quantify the PFE and SCP and to relate these thermal events to the lower lethal temperature(LT50) of sub-Antarctic aphids acclimated to low temperatures. PFEs were observed in each of the 3 species of aphids examined. They occurred over a narrower temperature range and at a higher temperature range than the SCP (-8.2 to -13.8 and -5.6 to -29.8°C, respectively). Increased acclimation temperature resulted in increased SCPs in Myzus ascalonicus but not in Rhopalosiphum padi. The LT50 reduced by approximately 1°C from -9.3 to -10.5°C with reduced acclimation temperature(10–0°C). The LT50 was close to the temperature at which the PFE occurred but statistically significantly higher than either the PFE or the SCP. In the majority of cases the PFE exotherm occurred well before the main exotherm produced by the bulk of the insect’s body water freezing SCP). However, in a few cases it occurred at the same temperature or before the super-cooling point making the term, pre-freeze event(PFE), rather misleading. The possible origins of the PFE are discussed. Centre of Excellence for Invasion Biology Other/Unknown Material Antarc* Antarctic Marion Island Stellenbosch University: SUNScholar Research Repository Antarctic |
institution |
Open Polar |
collection |
Stellenbosch University: SUNScholar Research Repository |
op_collection_id |
ftunstellenbosch |
language |
English |
topic |
Cold tolerance Chill tolerance Insect Lethal temperature LT50 Marion Island |
spellingShingle |
Cold tolerance Chill tolerance Insect Lethal temperature LT50 Marion Island Worland, M.R. Janion, C. Treasure, A.M. Chown, S.L. Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island |
topic_facet |
Cold tolerance Chill tolerance Insect Lethal temperature LT50 Marion Island |
description |
Understanding the mechanisms by which aphids survive low temperature is fundamental in forecasting the risk of pest outbreaks. Aphids are chill susceptible and die at a temperature close to that at which a small exothermal event is produced. This event, which can be identified using differential scanning calorimetry(DSC), normally occurs at a higher temperature than the supercooling point(SCP)and has been termed a pre-freeze event(PFE). However, it is not known what causes the PFE or whether it signifies the death of the aphid. These questions are addressed here by using a sensitive DSC to quantify the PFE and SCP and to relate these thermal events to the lower lethal temperature(LT50) of sub-Antarctic aphids acclimated to low temperatures. PFEs were observed in each of the 3 species of aphids examined. They occurred over a narrower temperature range and at a higher temperature range than the SCP (-8.2 to -13.8 and -5.6 to -29.8°C, respectively). Increased acclimation temperature resulted in increased SCPs in Myzus ascalonicus but not in Rhopalosiphum padi. The LT50 reduced by approximately 1°C from -9.3 to -10.5°C with reduced acclimation temperature(10–0°C). The LT50 was close to the temperature at which the PFE occurred but statistically significantly higher than either the PFE or the SCP. In the majority of cases the PFE exotherm occurred well before the main exotherm produced by the bulk of the insect’s body water freezing SCP). However, in a few cases it occurred at the same temperature or before the super-cooling point making the term, pre-freeze event(PFE), rather misleading. The possible origins of the PFE are discussed. Centre of Excellence for Invasion Biology |
format |
Other/Unknown Material |
author |
Worland, M.R. Janion, C. Treasure, A.M. Chown, S.L. |
author_facet |
Worland, M.R. Janion, C. Treasure, A.M. Chown, S.L. |
author_sort |
Worland, M.R. |
title |
Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island |
title_short |
Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island |
title_full |
Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island |
title_fullStr |
Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island |
title_full_unstemmed |
Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island |
title_sort |
pre-freeze mortality in three species of aphids from sub-antarctic marion island |
publisher |
Elsevier Ltd. |
publishDate |
2011 |
url |
http://hdl.handle.net/10019.1/119955 |
geographic |
Antarctic |
geographic_facet |
Antarctic |
genre |
Antarc* Antarctic Marion Island |
genre_facet |
Antarc* Antarctic Marion Island |
op_relation |
Worland, M.R., Janion, C., Treasure, A.M. and Chown, S.L. (2010) Pre-freeze mortality in three species of aphids from sub-Antarctic Marion Island. Journal of Thermal Biology, 35, 255-262 http://hdl.handle.net/10019.1/119955 |
_version_ |
1766276786300125184 |