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The survival of moth larvae feeding on different plant species in northern Fennoscandia

Belsing, Ulrika LU (2015) In Student thesis series INES NGEM01 20152
Dept of Physical Geography and Ecosystem Science
Abstract
Northern Fennoscandia belongs to the sub-arctic environment and its forests are mostly composed of mountain birch trees (Betula pubescens ssp. czerepanovii). Outbreaks by autumn moth (Epirrita autumnata) and winter moth (Operophtera brumata) are one of the most important natural disturbance factors in the mountain birch forests, with important implications for future ecosystem functioning. If there will be a vegetation shift due to climate change or greater infestation and competition between different moth species, the moth larvae will have to feed more on alternative plant species. However, the ability of these species to feed, grow and survive on these alternative food sources is poorly understood.

The aim of this study was to see... (More)
Northern Fennoscandia belongs to the sub-arctic environment and its forests are mostly composed of mountain birch trees (Betula pubescens ssp. czerepanovii). Outbreaks by autumn moth (Epirrita autumnata) and winter moth (Operophtera brumata) are one of the most important natural disturbance factors in the mountain birch forests, with important implications for future ecosystem functioning. If there will be a vegetation shift due to climate change or greater infestation and competition between different moth species, the moth larvae will have to feed more on alternative plant species. However, the ability of these species to feed, grow and survive on these alternative food sources is poorly understood.

The aim of this study was to see if the pupae weight, the frass (excrement) amount and the survival rate differed for the autumn- and winter moth in Northern Fennoscandia, depending on which type of leaves the larvae feed on. The plant species chosen was the preferred food source mountain birch and two possible alternative food species; dwarf birch (Betula nana) and bilberry (Vaccinium myrtillus). The larvae and leaves were picked at random locations around Tromsø, northern Norway, and the autumn- and winter moth larvae were separated into different containers containing each of the three plant species.

A comparison between the two moth species showed that there was a significant difference in the pupae weight, but none in the frass amount and survival rate. The autumn moth’s pupae weight and frass amount did not significantly differ between the food sources. The survival rate for autumn moth, when feeding on dwarf birch, was much higher than when feeding on mountain birch or bilberry. The winter moth’s pupae weight did however differ significantly between the food sources. The frass amount and the survival rate between the plant species did not differ, suggesting that the winter moth is a feeding generalist less likely to be limited by food availability.

A greater infestation of moths in these sensitive ecosystems can alter the already ongoing climate changes and cause vegetation shifts. The winter moth has also over the past years expanded more and more into the autumn moths’ domain, but the autumn moth has also started to occur even in the coldest most continental regions. The moth species possible ability to easily change the main food source when another is unavailable, e.g. damaged from outbreaks, cause a more direct threat to the arctic vegetation. A different food pattern of the moths with other plant species as hosts might therefore change the nutrient cycle and permit greater impacts of warming than would otherwise occur. A key impact of moth activity in arctic ecosystems will be in regulating available nitrogen under future climate shifts. Further work in this area is required to advance the understanding of the underlying factors driving these interactions.


Advisor: Daniel Metcalfe
Master degree project 30 credits in Physical Geography and Ecosystem Science, 2015
Department of Physical Geography and Ecosystem Science, Lund University.
Student thesis series INES nr 369 (Less)
Popular Abstract
Northern Fennoscandian forests are mostly composed of mountain birch trees (Betula pubescens ssp. czerepanovii). Approximately every ten year there is an outbreak by autumn moth (Epirrita autumnata) and winter moth (Operophtera brumata). The outbreaks are one of the most important natural disturbance factors in the mountain birch forests. There is a possibility that the moth species will have to feed more on alternative plant species in the future. This due to possible vegetation shifts due to climate change or greater infestation and competition between different moth species. However, the ability of the moth larvae to feed, grow and survive on these alternative food sources is poorly understood.

The aim of this study was to see if... (More)
Northern Fennoscandian forests are mostly composed of mountain birch trees (Betula pubescens ssp. czerepanovii). Approximately every ten year there is an outbreak by autumn moth (Epirrita autumnata) and winter moth (Operophtera brumata). The outbreaks are one of the most important natural disturbance factors in the mountain birch forests. There is a possibility that the moth species will have to feed more on alternative plant species in the future. This due to possible vegetation shifts due to climate change or greater infestation and competition between different moth species. However, the ability of the moth larvae to feed, grow and survive on these alternative food sources is poorly understood.

The aim of this study was to see if the survival rate and pupae weight differed for the autumn- and winter moth in Northern Fennoscandia, depending on which type of leaves the larvae feed on. Both the pupae weight and the survival rate give indications on how well the moth larvae adapted to the given food. The plant species chosen was the preferred food source mountain birch and two possible alternative food species; dwarf birch (Betula nana) and bilberry (Vaccinium myrtillus). The larvae and leaves were picked at random locations around Tromsø, northern Norway. The autumn- and winter moth larvae were separated into different containers containing each of the three plant species. The larvae of the moths were picked and taken care of until pupation.

A comparison between the two moth species showed that the autumn moth’s pupae got larger than the winter moth, but there was no difference in survival. The autumn moth’s pupae weight did not differ between the food sources. However, the survival rate for autumn moth when feeding on dwarf birch was higher than when feeding on mountain birch or bilberry. The winter moth’s pupae weight did differ a bit between the food sources. The survival rate between the plant species did however not differ, suggesting that the winter moth is a feeding generalist less likely to be limited by food availability.

A greater infestation of moths in these sensitive environments can alter the already ongoing climate changes and cause vegetation shifts. The winter moth has also over the past years expanded more and more into the autumn moths’ domain, but the autumn moth has also started to occur even in the coldest most continental regions. This probably due to that the winter moth had a high survival no matter which plant species it was given. The moth species possible ability to easily change the main food source when another is unavailable, e.g. damaged from outbreaks, causes a direct threat to the vegetation. Further work in this area is required to advance the understanding of the underlying factors driving these interactions.


Advisor: Daniel Metcalfe
Master degree project 30 credits in Physical Geography and Ecosystem Science, 2015
Department of Physical Geography and Ecosystem Science, Lund University.
Student thesis series INES nr 369 (Less)
Please use this url to cite or link to this publication:
author
Belsing, Ulrika LU
supervisor
organization
course
NGEM01 20152
year
type
H2 - Master's Degree (Two Years)
subject
keywords
winter moth, ecosystem analysis, physical geography, autumn moth, northern Fennoscandia, outbreaks and sub-arctic environment
publication/series
Student thesis series INES
report number
369
language
English
id
8564889
date added to LUP
2016-01-22 11:58:58
date last changed
2018-10-14 03:50:10
@misc{8564889,
  abstract     = {Northern Fennoscandia belongs to the sub-arctic environment and its forests are mostly composed of mountain birch trees (Betula pubescens ssp. czerepanovii). Outbreaks by autumn moth (Epirrita autumnata) and winter moth (Operophtera brumata) are one of the most important natural disturbance factors in the mountain birch forests, with important implications for future ecosystem functioning. If there will be a vegetation shift due to climate change or greater infestation and competition between different moth species, the moth larvae will have to feed more on alternative plant species. However, the ability of these species to feed, grow and survive on these alternative food sources is poorly understood. 

The aim of this study was to see if the pupae weight, the frass (excrement) amount and the survival rate differed for the autumn- and winter moth in Northern Fennoscandia, depending on which type of leaves the larvae feed on. The plant species chosen was the preferred food source mountain birch and two possible alternative food species; dwarf birch (Betula nana) and bilberry (Vaccinium myrtillus). The larvae and leaves were picked at random locations around Tromsø, northern Norway, and the autumn- and winter moth larvae were separated into different containers containing each of the three plant species. 

A comparison between the two moth species showed that there was a significant difference in the pupae weight, but none in the frass amount and survival rate. The autumn moth’s pupae weight and frass amount did not significantly differ between the food sources. The survival rate for autumn moth, when feeding on dwarf birch, was much higher than when feeding on mountain birch or bilberry. The winter moth’s pupae weight did however differ significantly between the food sources. The frass amount and the survival rate between the plant species did not differ, suggesting that the winter moth is a feeding generalist less likely to be limited by food availability. 

A greater infestation of moths in these sensitive ecosystems can alter the already ongoing climate changes and cause vegetation shifts. The winter moth has also over the past years expanded more and more into the autumn moths’ domain, but the autumn moth has also started to occur even in the coldest most continental regions. The moth species possible ability to easily change the main food source when another is unavailable, e.g. damaged from outbreaks, cause a more direct threat to the arctic vegetation. A different food pattern of the moths with other plant species as hosts might therefore change the nutrient cycle and permit greater impacts of warming than would otherwise occur. A key impact of moth activity in arctic ecosystems will be in regulating available nitrogen under future climate shifts. Further work in this area is required to advance the understanding of the underlying factors driving these interactions.


Advisor: Daniel Metcalfe 
Master degree project 30 credits in Physical Geography and Ecosystem Science, 2015 
Department of Physical Geography and Ecosystem Science, Lund University. 
Student thesis series INES nr 369},
  author       = {Belsing, Ulrika},
  keyword      = {winter moth,ecosystem analysis,physical geography,autumn moth,northern Fennoscandia,outbreaks and sub-arctic environment},
  language     = {eng},
  note         = {Student Paper},
  series       = {Student thesis series INES},
  title        = {The survival of moth larvae feeding on different plant species in northern Fennoscandia},
  year         = {2015},
}