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Global change effects on plant- insect
interactions
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| Increasing levels of atmospheric CO2 are changing
the chemical composition of plants, both through direct effects and
indirectly through the greenhouse effect (causing globally increasing
temperatures). Of particular interest is how food plant quality (levels
of nutrients and plant defense substances) is altered, and how this
affects important herbivores, e.g. pest species. My main research programme
is focussed on how predicted changes in atmospheric CO2 and temperature
affects plant growth and plant chemistry, and therby insect herbivore
performance. This project has two parts: |
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1. CO2 and temperature effects on crop plants and pest insects |
| Within this project I study how
alfalfa and cotton respond to environmental changes, and how this
affect performance of a model pest insect: the Egyptian cotton
leafworm (Spodoptera littoralis). Plants are grown in
controlled and manipulated environments and are after harvest
used for growth measurements, phytochemical analyses and bioassays
with larvae. The bioassays examine larval growth, development,
survival, reproduction etc., but also changes in larval host plant
preferences. Parallel to this work
I examine the genetic and phenotypic variation in host plant
preferences (i.e. food plant and egg laying preferences) in
order to determine if changes in host plant preferences caused
by altered host phytochemistry will come about through immidiate
behavioural responses (phenotypic plasticity), or through the
more slow process of natural selection (genetic changes). |
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Spodoptera littoralis
on alfalfa |
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2. Global change effects on deciduous trees and defoliating insects |
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Forest tent caterpillar
feeding on red oak |
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In this co-operation with the Dept.
of Entomology (Univ. of Wisconsin) we examine how levated levels
of CO2 and ozone (O3) may affect behaviour and population dynamics
of defoliating insects (e.g. larvae of the White-marked tussock
moth, Gypsy moth, and Forest tent caterpillar). Plants are grown
either in Biotron or FACE (Free Air Carbondioxide
Enrichment, specifically FACTS
II) system, and the foliage is used for phytochemical analyses
of nutrients and various phenolic compounds, and bioassays determining
effects on demography and behaviour of larvae.
The studies are focussed around aspen, and compare global change
effects on various clones of this species, as well as effects
on aspen compared with other species (birch, maple). Also, the
project investigates how other environmental factors (e.g. light
and defoliation) modify responses to elevated levels of atmospheric
CO2.
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Small
mammal behaviour and population dynamics
| Small mammals have for long functioned
as "model" organisms in research on population dynamics
and behaviour of vertebrates. My experimental studies have been
focussed on the field vole (Microtus agrestis), a small
rodent which show cyclic population dynamics in northern and irregular
fluctuations in southern Scandinavia. The main objective here
is to determine factors, intrinsic and extrinsic, that may determine
and/or regulate population density. Through this work I also examine
social behaviour in more detail, e.g. regarding territoriality
and infanticide. Apart from experimental studies in enclosed natural
areas and laboratory run-ways, I also work on a more theoretical
basis, e.g. regarding evolution of infanticde. |
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Since food quality may be one factor
affecting small rodent populations, I have also studied food preferences
and potential effects of food plant secondary metabolites. During
later years I have also been able to include lemmings in this
work. This was the possibility was given me during the ship bound
expedition to the Canadian arctic archipelago in summer 1999,
TNW 99, sponsored by the Swedish Polar Research Secreteriat.
Here co-operative work made it possible to examine inter- and
intra-specific variation in food plant preferences, and how this
may relate to plant defesive compounds. This work is focussed
on the Collared lemming (Dicrostonyx groenlandicus),
which feeds primarily on dicotelydones as e.g. willows, and the
Brown lemming (Lemmus trimucronatus), which mostly has
a diet consisting of monocotelydones (e.g. grasses and sedges).
In addition metabolism of the lemming species was investigated.
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| For results published so far, see Selected
publications, for co-workers, see Collaboration.
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