| 1. |
- Birkhofer, Klaus, et al.
(författare)
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Methods to identify the prey of invertebrate predators in terrestrial field studies
- 2017
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 7:6, s. 1942-1953
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Tidskriftsartikel (refereegranskat)abstract
- Predation is an interaction during which an organism kills and feeds on another organism. Past and current interest in studying predation in terrestrial habitats has yielded a number of methods to assess invertebrate predation events in terrestrial ecosystems. We provide a decision tree to select appropriate methods for individual studies. For each method, we then present a short introduction, key examples for applications, advantages and disadvantages, and an outlook to future refinements. Video and, to a lesser extent, live observations are recommended in studies that address behavioral aspects of predator-prey interactions or focus on per capita predation rates. Cage studies are only appropriate for small predator species, but often suffer from a bias via cage effects. The use of prey baits or analyses of prey remains are cheaper than other methods and have the potential to provide per capita predation estimates. These advantages often come at the cost of low taxonomic specificity. Molecular methods provide reliable estimates at a fine level of taxonomic resolution and are free of observer bias for predator species of any size. However, the current PCR-based methods lack the ability to estimate predation rates for individual predators and are more expensive than other methods. Molecular and stable isotope analyses are best suited to address systems that include a range of predator and prey species. Our review of methods strongly suggests that while in many cases individual methods are sufficient to study specific questions, combinations of methods hold a high potential to provide more holistic insights into predation events. This review presents an overview of methods to researchers that are new to the field or to particular aspects of predation ecology and provides recommendations toward the subset of suitable methods to identify the prey of invertebrate predators in terrestrial field research.
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| 2. |
- Dalin, Peter, et al.
(författare)
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A novel infrared imager for studies of hydroxyl and oxygen nightglow emissions in the mesopause above northern Scandinavia
- 2024
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Ingår i: Atmospheric Measurement Techniques. - 1867-1381 .- 1867-8548. ; 17:5, s. 1561-1576
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Tidskriftsartikel (refereegranskat)abstract
- The paper describes technical characteristics and presents the first scientific results of a novel infrared imaging system (imager) for studies of nightglow emissions coming from the hydroxyl (OH) and molecular oxygen (O2) layers in the mesopause region (80–100 km) above northern Scandinavia. The OH imager was put into operation in November 2022 at the Swedish Institute of Space Physics in Kiruna (67.86° N, 20.42° E; 400 m altitude). The OH imager records selected emission lines in the OH(3-1) band near 1500 nm to obtain intensity and temperature maps at around 87 km altitude. In addition, the OH imager registers infrared emissions coming from the O2 IR A-band airglow at 1268.7 nm in order to obtain O2 intensity maps at a slightly higher altitude, around 94 km. This technique allows the tracing of wave disturbances in both horizontal and vertical domains in the mesopause region. Validation and comparison of the OH(3-1) rotational temperature with collocated lidar and Aura Microwave Limb Sounder (MLS) satellite temperatures are performed. The first scientific results obtained from the OH imager for the first winter season (2022–2023) are discussed.
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| 3. |
- Barabash, Victoria, et al.
(författare)
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Influence of water vapour on the height distribution of positive ions, effective recombination coefficient and ionisation balance in the quiet lower ionosphere
- 2014
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 32, s. 207-222
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Tidskriftsartikel (refereegranskat)abstract
- Mesospheric water vapour concentration effects on the ion composition and electron density in the lower ionosphere under quiet geophysical conditions were examined. Water vapour is an important compound in the mesosphere and the lower thermosphere that affects ion composition due to hydrogen radical production and consequently modifies the electron number density. Recent lower-ionosphere investigations have primarily concentrated on the geomagnetic disturbance periods. Meanwhile, studies on the electron density under quiet conditions are quite rare. The goal of this study is to contribute to a better understanding of the ionospheric parameter responses to water vapour variability in the quiet lower ionosphere. By applying a numerical D region ion chemistry model, we evaluated efficiencies for the channels forming hydrated cluster ions from the NO+ and O2+ primary ions (i.e. NO+.H2O and O2+.H2O, respectively), and the channel forming H+(H2O)nproton hydrates from water clusters at different altitudes using profiles with low and high water vapour concentrations. Profiles for positive ions, effective recombination coefficients and electrons were modelled for three particular cases using electron density measurements obtained during rocket campaigns. It was found that the water vapour concentration variations in the mesosphere affect the position of both the Cl2+ proton hydrate layer upper border, comprising the NO+(H2O)nand O2+(H2O)nhydrated cluster ions, and the Cl1+ hydrate cluster layer lower border, comprising the H+(H2O)npure proton hydrates, as well as the numerical cluster densities. The water variations caused large changes in the effective recombination coefficient and electron density between altitudes of 75 and 87 km. However, the effective recombination coefficient, αeff, and electron number density did not respond even to large water vapour concentration variations occurring at other altitudes in the mesosphere. We determined the water vapour concentration upper limit at altitudes between 75 and 87 km, beyond which the water vapour concentration ceases to influence the numerical densities of Cl2+ and Cl1+, the effective recombination coefficient and the electron number density in the summer ionosphere. This water vapour concentration limit corresponds to values found in the H2O-1 profile that was observed in the summer mesosphere by the Upper Atmosphere Research Satellite (UARS). The electron density modelled using the H2O-1 profile agreed well with the electron density measured in the summer ionosphere when the measured profiles did not have sharp gradients. For sharp gradients in electron and positive ion number densities, a water profile that can reproduce the characteristic behaviour of the ionospheric parameters should have an inhomogeneous height distribution of water vapour.
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| 4. |
- Berndt, Sonja, I, et al.
(författare)
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Distinct germline genetic susceptibility profiles identified for common non-Hodgkin lymphoma subtypes
- 2022
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Ingår i: Leukemia. - : Springer Nature. - 0887-6924 .- 1476-5551. ; 36:12, s. 2835-2844
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Tidskriftsartikel (refereegranskat)abstract
- Lymphoma risk is elevated for relatives with common non-Hodgkin lymphoma (NHL) subtypes, suggesting shared genetic susceptibility across subtypes. To evaluate the extent of mutual heritability among NHL subtypes and discover novel loci shared among subtypes, we analyzed data from eight genome-wide association studies within the InterLymph Consortium, including 10,629 cases and 9505 controls. We utilized Association analysis based on SubSETs (ASSET) to discover loci for subsets of NHL subtypes and evaluated shared heritability across the genome using Genome-wide Complex Trait Analysis (GCTA) and polygenic risk scores. We discovered 17 genome-wide significant loci (P < 5 × 10−8) for subsets of NHL subtypes, including a novel locus at 10q23.33 (HHEX) (P = 3.27 × 10−9). Most subset associations were driven primarily by only one subtype. Genome-wide genetic correlations between pairs of subtypes varied broadly from 0.20 to 0.86, suggesting substantial heterogeneity in the extent of shared heritability among subtypes. Polygenic risk score analyses of established loci for different lymphoid malignancies identified strong associations with some NHL subtypes (P < 5 × 10−8), but weak or null associations with others. Although our analyses suggest partially shared heritability and biological pathways, they reveal substantial heterogeneity among NHL subtypes with each having its own distinct germline genetic architecture.
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| 5. |
- Dalin, Peter
(författare)
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A comparison of the larval overwintering biology of the striped stem borer, Chilo suppressalis (Lepidoptera: Crambidae), in rice and water-oat fields
- 2013
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Ingår i: Applied Entomology and Zoology. - : Springer Science and Business Media LLC. - 0003-6862 .- 1347-605X. ; 48, s. 147-153
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Tidskriftsartikel (refereegranskat)abstract
- It has been suggested that the striped stem borer, Chilo suppressalis (Walker), has developed distinct populations inhabiting rice Oryza sativa (Linnaeus) and water-oats Zizania latifolia (Turcz). In this study, we compared several biological traits between overwintering larvae from rice and water-oat fields during the winter of 2010. The parasitism rate was significantly higher in the larvae that overwintered in the rice field than in those that overwintered in the water-oat field. The average body weight of overwintering larvae and the weight of 3-day-old pupae, as well as the number of eggs carried by adult females, were all significantly greater in the samples from the water-oat field. The diapause intensity, defined as the number of days required until pupation by overwintering larvae transferred to 25 A degrees C and L:D 16:8 h, decreased progressively from January to March but decreased more rapidly in the water-oat field. Our results demonstrate differences in the overwintering biology of C. suppressalis larvae from rice and water-oat fields. These differences may contribute to the differentiation and reproductive isolation between host-plant populations in this species.
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| 6. |
- Dalin, Peter A., et al.
(författare)
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Wave influence on polar mesosphere summer echoes above Wasa : experimental and model studies
- 2012
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 30:8, s. 1143-1157
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Tidskriftsartikel (refereegranskat)abstract
- Comprehensive analysis of the wave activity in the Antarctic summer mesopause is performed using polar mesospheric summer echoes (PMSE) measurements for December 2010–January 2011. The 2-day planetary wave is a statistically significant periodic oscillation in the power spectrum density of PMSE power. The strongest periodic oscillation in the power spectrum belongs to the diurnal solar tide; the semi-diurnal solar tide is found to be a highly significant harmonic oscillation as well. The inertial-gravity waves are extensively studied by means of PMSE power and wind components. The strongest gravity waves are observed at periods of about 1, 1.4, 2.5 and 4 h, with characteristic horizontal wavelengths of 28, 36, 157 and 252 km, respectively. The gravity waves propagate approximately in the west-east direction over Wasa (Antarctica). A detailed comparison between theoretical and experimental volume reflectivity of PMSE, measured at Wasa, is made. It is demonstrated that a new expression for PMSE reflectivity derived by Varney et al. (2011) is able to adequately describe PMSE profiles both in the magnitude and in height variations. The best agreement, within 30%, is achieved when mean values of neutral atmospheric parameters are utilized. The largest contribution to the formation and variability of the PMSE layer is explained by the ice number density and its height gradient, followed by wave-induced perturbations in buoyancy period and the turbulent energy dissipation rate
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| 7. |
- Dalin, Peter
(författare)
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Diapause induction and termination in a commonly univoltine leaf beetle (Phratora vulgatissima)
- 2011
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Ingår i: Insect Science. - : Wiley. - 1672-9609 .- 1744-7917. ; 18, s. 443-450
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Tidskriftsartikel (refereegranskat)abstract
- The leaf beetle Phratora vulgatissima (Linnaeus 1758) is commonly univoltine in south-central Sweden but may sometimes initiate a partial second generation. The current study was set out to investigate under what abiotic conditions the beetles initiate a second generation. Using climate chamber experiments, the beetles were shown to have a facultative reproductive diapause induced by declining day-length. The critical day-length (CDL) for diapause induction was estimated to be 18 h and 10 min. In the field, first-generation beetles developing to adulthood before August in 2009 became reproductively active and produced a second generation, but most individuals emerged later and were in reproductive diapause. P. vulgatissima overwinter as adults and diapause was shown to be maintained until mid-winter in 2008/2009. The cumulative temperature requirement for oviposition after diapause termination was estimated to be 222 day-degrees with a 5.5 degrees C temperature threshold. Three different day-degree models that were developed to predict the phenology of female oviposition in the spring were validated by comparing model results with field data on the timing of oviposition in previous years. The study suggests that P. vulgatissima may initiate a second generation in Sweden if development of the first generation is completed before August. Warmer spring and summer temperatures due to ongoing climate change may cause advanced insect phenology and faster completion of insect life-cycles at northern latitudes, which will affect the proportion of insects that initiate a second generation.
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| 8. |
- Dalin, Peter
(författare)
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Evolution of critical day length for diapause induction enables range expansion of Diorhabda carinulata, a biological control agent against tamarisk (Tamarix spp.)
- 2012
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Ingår i: Evolutionary applications. - : Wiley. - 1752-4571. ; 5, s. 511-523
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Tidskriftsartikel (refereegranskat)abstract
- In classical weed biological control, small collections of arthropods are made from one or a few sites in the native range of the target plant and are introduced to suppress the plant where it has become invasive, often across a wide geographic range. Ecological mismatches in the new range are likely, and success using the biocontrol agent may depend on postrelease evolution of beneficial life history traits. In this study, we measure the evolution of critical day length for diapause induction (day length at which 50% of the population enters dormancy), in a beetle (Diorhabda carinulata) introduced into North America from China to control an exotic shrub, Tamarix spp. Beetle populations were sampled from four sites in North America 7 years after introduction, and critical day length was shown to have declined, forming a cline over a latitudinal gradient At one field site, decreased critical day length was correlated with 16 additional days of reproductive activity, resulting in a closer match between beetle life history and the phenology of Tamarix. These findings indicate an enhanced efficacy and an increasingly wider range for D. carinulata in Tamarix control.
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| 9. |
- Dalin, Peter
(författare)
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Geographic variation in photoperiodic diapause induction and diapause intensity in Sericinus montelus (Lepidoptera: Papilionidae)
- 2012
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Ingår i: Insect Science. - : Wiley. - 1672-9609 .- 1744-7917. ; 19, s. 295-302
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Tidskriftsartikel (refereegranskat)abstract
- Due to the risk of extinction and ornamental value of the swallowtail butterfly, Sericinus montelus Gray (Lepidoptera: Papilionidae) in China, knowledge about local adaptations is important for the conservation and economical utilization of the species. In the present study, photoperiodic diapause induction and diapause intensity of S. montelus populations from Jiamusi (46 degrees 37'N), Beijing (40 degrees 15'N), Zibo (36 degrees 48'N), Fangxian (32 degrees 36'N), Wuhan (30 degrees 33'N) and Huaihua (27 degrees 33'N) were characterized at 25 degrees C. Logistic regression analysis revealed a significant population x hours of light interaction, confirming that photoperiodic responses varied among populations. The critical photoperiod was positively correlated with latitude and increased toward the north at a rate of about 1 h for each 6.67 degrees of latitude. Survival analyses indicated that survival time of diapausing pupae before adult eclosion differed significantly among populations at 25 degrees C and 16 : 8 L : D h. The mean duration of pupal diapause was also positively correlated with latitude. Our study reveals geographic variation in the critical photoperiod for diapause induction and in diapause intensity of S. montelus. These results provide useful information for our general understanding about seasonal adaptation in insects and may also be used to predict how geographic populations respond to climate warming.
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| 10. |
- Dalin, Peter, et al.
(författare)
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Global land-use change and the importance of zoophytophagous bugs in biological control: Coppicing willows as a timely example
- 2011
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Ingår i: Biological Control. - : Elsevier BV. - 1049-9644 .- 1090-2112. ; 59, s. 6-12
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Tidskriftsartikel (refereegranskat)abstract
- Perennial plants, such as willows, miscanthus, and hybrid poplars, are promising bioenergy crops while lowering atmospheric CO(2). Increases in the acreage of perennial bioenergy crops will pose new challenges and opportunities for biological control. In this review, we suggest that zoophytophagous bugs could be expected to become increasingly important in biological control of arthropod pests in perennial bioenergy crops. The main reasons are: (1) perennial bioenergy crops provide suitable habitats for arboreal natural enemies like zoophytophagous bugs; (2) zoophytophagous bugs often increase in response to low disturbance frequencies; and (3) plant-feeding by zoophytophagous bugs will not likely affect plant biomass production in perennial crops. We review aspects of the biology of zoophytophagous bugs expected to be important in biological control of pests in perennial systems. We also present a predator-prey model investigating how alternative harvest methods affect biological control of herbivorous pests by zoophytophagous bugs in willow biomass plantations. Although there is good evidence that zoophytophagous bugs can provide pest control, more research is needed about factors affecting the dispersal and population dynamics of zoophytophagous bugs in agricultural landscapes. (C) 2011 Elsevier Inc. All rights reserved.
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| 11. |
- Dalin, Peter, et al.
(författare)
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Host-plant quality adaptively affects the diapause threshold : evidence from leaf beetles in willow plantations
- 2012
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 37:6, s. 490-499
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Tidskriftsartikel (refereegranskat)abstract
- 1. Voltinism of herbivorous insects can vary depending on environmental conditions. The leaf beetle Phratora vulgatissima L. is univoltine in Sweden but will sometimes initiate a second generation in short-rotation coppice (SRC) willow plantations. 2. The study investigated whether increased voltinism by P. vulgatissima in plantations can be explained by (i) rapid life-cycle development allowing two generations, or (ii) postponed diapause induction on coppiced willows. 3. In the field, no difference was found in the phenology or development of first-generation broods between plantations (S. viminalis) and natural willow habitats (S. cinerea). However, the induction of diapause occurred 12 weeks later in SRC willow plantations. 4. Laboratory experiments indicated no genetic difference in the critical day-length for diapause induction between beetles originating from plantations and natural habitats. Development time was unaffected by host-plant quality but critical day-length was prolonged by almost an hour when the beetles were reared on a non-preferred willow species (S. phylicifolia). When reared on new leaves from re-sprouting shoots of recently coppiced willow plants, diapause incidence was significantly less than when the beetles were reared on mature leaves from uncoppiced plants. 5. The study suggests that P. vulgatissima has a plastic diapause threshold influenced by host-plant quality. The use of host-plant quality as a diapause-inducing stimulus is likely to be adaptive in cases where food resources are unpredictable, such as when new host-plant tissue is produced after a disturbance. SRC willows may allow two beetle generations due to longer growing seasons of coppiced plants that grow vigorously.
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| 12. |
- Dalin, Peter, et al.
(författare)
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Importance of temperature for the performance and biocontrol efficiency of the parasitoid Perilitus brevicollis (Hymenoptera: Braconidae) on Salix
- 2012
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Ingår i: BioControl. - : Springer Science and Business Media LLC. - 1386-6141 .- 1573-8248. ; 57, s. 611-618
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Tidskriftsartikel (refereegranskat)abstract
- With the prospect of warmer temperatures as a consequence of ongoing climate change, it is important to investigate how such increases will affect parasitoids and their top-down suppression of herbivory in agroecosystems. Here we studied how the performance and biocontrol efficiency of the willow "bodyguard" Perilitus brevicollis Haliday (Hymenoptera: Braconidae) were affected at different constant temperatures (10, 15, 20, 25A degrees C) when parasitizing a pest insect, the blue willow beetle (Phratora vulgatissima L., Coleoptera: Chrysomelidae). Parasitism did not reduce herbivory at all at 10A degrees C, indicating poor biocontrol efficiency at low temperatures. At higher temperatures, however, parasitism reduced herbivory substantially, implying that biocontrol may be promoted by a warmer climate. Parasitoid performance (survival and development rate) generally increased with increasing temperature up to 20A degrees C. The only exception was body size, which followed the temperature-size rule and decreased with increasing temperature. Our results indicate that a warmer climate may enhance the biocontrol of the blue willow beetle in environments that currently are cooler than the parasitoid's optimal temperature for development.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Dalin, Peter
(författare)
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Seasonal Adaptations to Day Length in Ecotypes of Diorhabda spp. (Coleoptera: Chrysomelidae) Inform Selection of Agents Against Saltcedars (Tamarix spp.)
- 2010
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Ingår i: Environmental Entomology. - 0046-225X .- 1938-2936. ; 39, s. 1666-1675
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Tidskriftsartikel (refereegranskat)abstract
- Seasonal adaptations to daylength often limit the effective range of insects used in biological control of weeds. The leaf beetle Diorhabda carinulata (Desbrochers) was introduced into North America from Fukang, China (latitude 44 degrees N) to control saltcedars (Tamarix spp.), but failed to establish south of 38 degrees N latitude because of a mismatched critical daylength response for diapause induction. The daylength response caused beetles to enter diapause too early in the season to survive the duration of winter at southern latitudes. Using climate chambers, we characterized the critical daylength response for diapause induction (CDL) in three ecotypes of Diorhabda beetles originating from 36,38, and 43 degrees N latitudes in Eurasia. In a field experiment, the timing of reproductive diapause and voltinism were compared among ecotypes by rearing the insects on plants in the field. CDL declined with latitude of origin among Diorhabda ecotypes. Moreover, CDL in southern (<39 degrees N latitude) ecotypes was shortened by more than an hour when the insects were reared under a fluctuating 35-15 degrees C thermoperiod than at a constant 25 degrees C. In the northern (>42 degrees N latitude) ecotypes, however. CDL was relatively insensitive to temperature. The southern ecotypes produced up to four generations when reared on plants in the field at sites south of 38 degrees N, whereas northern ecotypes produced only one or two generations. The study reveals latitudinal variation in how Diorhabda ecotypes respond to daylength for diapause induction and how these responses affect insect voltinism across the introduced range.
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| 17. |
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| 18. |
- Dalin, Peter
(författare)
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Tamarix as invertebrate habitat
- 2013
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Ingår i: Tamarix - a case study of ecological change in the American west. - 9780199898206 ; , s. 207-224
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Bokkapitel (refereegranskat)
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| 19. |
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| 20. |
- Eriksson, Daniel, et al.
(författare)
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Common genetic variation in the autoimmune regulator (AIRE) locus is associated with autoimmune Addison’s disease in Sweden
- 2018
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Autoimmune Addison's disease (AAD) is the predominating cause of primary adrenal failure. Despite its high heritability, the rarity of disease has long made candidate-gene studies the only feasible methodology for genetic studies. Here we conducted a comprehensive reinvestigation of suggested AAD risk loci and more than 1800 candidate genes with associated regulatory elements in 479 patients with AAD and 2394 controls. Our analysis enabled us to replicate many risk variants, but several other previously suggested risk variants failed confirmation. By exploring the full set of 1800 candidate genes, we further identified common variation in the autoimmune regulator (AIRE) as a novel risk locus associated to sporadic AAD in our study. Our findings not only confirm that multiple loci are associated with disease risk, but also show to what extent the multiple risk loci jointly associate to AAD. In total, risk loci discovered to date only explain about 7% of variance in liability to AAD in our study population.
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| 21. |
- Eriksson, D, et al.
(författare)
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Extended exome sequencing identifies BACH2 as a novel major risk locus for Addison's disease
- 2016
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 286:6, s. 595-608
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Autoimmune disease is one of the leading causes of morbidity and mortality worldwide. In Addison's disease, the adrenal glands are targeted by destructive autoimmunity. Despite being the most common cause of primary adrenal failure, little is known about its aetiology.METHODS: To understand the genetic background of Addison's disease, we utilized the extensively characterized patients of the Swedish Addison Registry. We developed an extended exome capture array comprising a selected set of 1853 genes and their potential regulatory elements, for the purpose of sequencing 479 patients with Addison's disease and 1394 controls.RESULTS: We identified BACH2 (rs62408233-A, OR = 2.01 (1.71-2.37), P = 1.66 × 10(-15) , MAF 0.46/0.29 in cases/controls) as a novel gene associated with Addison's disease development. We also confirmed the previously known associations with the HLA complex.CONCLUSION: Whilst BACH2 has been previously reported to associate with organ-specific autoimmune diseases co-inherited with Addison's disease, we have identified BACH2 as a major risk locus in Addison's disease, independent of concomitant autoimmune diseases. Our results may enable future research towards preventive disease treatment.
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| 22. |
- Kirkwood, Sheila, et al.
(författare)
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Response of polar mesosphere summer echoes to geomagnetic disturbances in the Southern and Northern Hemispheres : The importance of nitric oxide
- 2013
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 31:2, s. 333-347
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Tidskriftsartikel (refereegranskat)abstract
- The relationship between polar mesosphere summer echoes (PMSE) and geomagnetic disturbances (represented by magnetic I K indices) is examined. Calibrated PMSE reflectivities for the period May 2006-February 2012 are used from two 52.0/54.5 MHz radars located in Arctic Sweden (68 N, geomagnetic latitude 65 ) and at two different sites in Queen Maud Land, Antarctica (73/72 S, geomagnetic latitudes 62/63 ). In both the Northern Hemisphere (NH) and the Southern Hemisphere (SH) there is a strong increase in mean PMSE reflectivity between quiet and disturbed geomagnetic conditions. Mean volume reflectivities are slightly lower at the SH locations compared to the NH, but the position of the peak in the lognormal distribution of PMSE reflectivities is close to the same at both NH and SH locations, and varies only slightly with magnetic disturbance level. Differences between the sites, and between geomagnetic disturbance levels, are primarily due to differences in the high-reflectivity tail of the distribution. PMSE occurrence rates are essentially the same at both NH and SH locations during most of the PMSE season when a sufficiently low detection threshold is used so that the peak in the lognormal distribution is included. When the local-time dependence of the PMSE response to geomagnetic disturbance level is considered, the response in the NH is found to be immediate at most local times, but delayed by several hours in the afternoon sector and absent in the early evening. At the SH sites, at lower magnetic latitude, there is a delayed response (by several hours) at almost all local times. At the NH (auroral zone) site, the dependence on magnetic disturbance is highest during evening-to-morning hours. At the SH (sub-auroral) sites the response to magnetic disturbance is weaker but persists throughout the day. While the immediate response to magnetic activity can be qualitatively explained by changes in electron density resulting from energetic particle precipitation, the delayed response can largely be explained by changes in nitric oxide concentrations. Observations of nitric oxide concentration at PMSE heights by the Odin satellite support this hypothesis. Sensitivity to geomagnetic disturbances, including nitric oxide produced during these disturbances, can explain previously reported differences between sites in the auroral zone and those at higher or lower magnetic latitudes. The several-day lifetime of nitric oxide can also explain earlier reported discrepancies between high correlations for average conditions (year-by-year PMSE reflectivities and indices) and low correlations for minute-to-day timescales
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| 23. |
- Liman, Anna-Sara, et al.
(författare)
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Detectability of landscape effects on recolonization increases with regional population density
- 2015
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 5, s. 2694-2702
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Tidskriftsartikel (refereegranskat)abstract
- Variation in population size over time can influence our ability to identify landscape-moderated differences in community assembly. To date, however, most studies at the landscape scale only cover snapshots in time, thereby overlooking the temporal dynamics of populations and communities. In this paper, we present data that illustrate how temporal variation in population density at a regional scale can influence landscape-moderated variation in recolonization and population buildup in disturbed habitat patches. Four common insect species, two omnivores and two herbivores, were monitored over 8years in 10 willow short-rotation coppice bio-energy stands with a four-year disturbance regime (coppice cycle). The population densities in these regularly disturbed stands were compared to densities in 17 undisturbed natural Salix cinerea (grey willow) stands in the same region. A time series approach was used, utilizing the natural variation between years to statistically model recolonization as a function of landscape composition under two different levels of regional density. Landscape composition, i.e. relative amount of forest vs. open agricultural habitats, largely determined the density of re-colonizing populations following willow coppicing in three of the four species. However, the impact of landscape composition was not detectable in years with low regional density. Our results illustrate that landscape-moderated recolonization can change over time and that considering the temporal dynamics of populations may be crucial when designing and evaluating studies at landscape level.
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| 24. |
- Liman, Anna-Sara, et al.
(författare)
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Enhanced leaf nitrogen status stabilizes omnivore population density
- 2017
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 183, s. 57-65
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits can mediate the strength of interactions between omnivorous predators and their prey through density effects and changes in the omnivores' trophic behavior. In this study, we explored the established assumption that enhanced nutrient status in host plants strengthens the buffering effect of plant feeding for omnivorous predators, i.e., prevents rapid negative population growth during prey density decline and thereby increases and stabilizes omnivore population density. We analyzed 13 years of field data on population densities of a heteropteran omnivore on Salix cinerea stands, arranged along a measured leaf nitrogen gradient and found a 195 % increase in omnivore population density and a 63 % decrease in population variability with an increase in leaf nitrogen status from 26 to 40 mgN x g(-1). We recreated the leaf nitrogen gradient in a greenhouse experiment and found, as expected, that increasing leaf nitrogen status enhanced omnivore performance but reduced per capita prey consumption. Feeding on high nitrogen status host plants can potentially decouple omnivore-prey population dynamics and allow omnivores to persist and function effectively at low prey densities to provide "background level" control of insect herbivores. This long-term effect is expected to outweigh the short-term effect on per capita prey consumption-resulting in a net increase in population predation rates with increasing leaf nitrogen status. Conservation biological control of insect pests that makes use of omnivore background control could, as a result, be manipulated via management of crop nitrogen status.
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| 25. |
- Marquardt, Kristina, et al.
(författare)
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Farmer perspectives on introducing perennial cereal in Swedish farming systems: A sustainability analysis of plant traits, farm management, and ecological implications
- 2016
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Ingår i: Agroecology and Sustainable Food Systems. - : Informa UK Limited. - 2168-3565 .- 2168-3573. ; 40, s. 432-450
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Tidskriftsartikel (refereegranskat)abstract
- Agriculture is currently dominated by annual crops. A shift from annual to perennial cereals has been suggested as a way to improve the sustainability of agriculture. Such a shift may have impacts at multiple levels, from the field, to the farm, and the landscape. With a focus on Swedish farm production systems, farmers' views on the potential risks and possibilities of cultivating perennial cereals are discussed in light of the available knowledge regarding plant traits and ecological implications of perennial systems. Farmer interviews showed that potential changes in agricultural sustainability, if perennial cereals were to be introduced, are highly complex, and context specific. Perennial cereals could be part of a transition toward a more sustainable agriculture depending on how they are used in the local farming system and in the larger landscape. Efforts to increase the use of perennial crops require linking specific plant traits of the perennial crop to the properties of the farming systems where these crops would be employed.
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| 26. |
- Ronnås, Cecilia, et al.
(författare)
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Evergreen foliage allows early hatching in a pine processionary moth and escape from predation
- 2014
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Ingår i: Ecological Entomology. - : Wiley. - 0307-6946 .- 1365-2311. ; 39, s. 445-452
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Tidskriftsartikel (refereegranskat)abstract
- 1. Seasonal variation in leaf quality and climate conditions often imposesconstraints on the temporal occurrence of tree-feeding insect larvae, but the seasonaleffects of predation have received limited attention. In temperate climate zones, both theabundance and activity of predators can be expected to vary over time.2. The study reported herein examined the impact of temporal variation in predatoractivity levels on the life history of an herbivorous insect feeding on a constant foodsource: previous-year needles of Scots pine (Pinus sylvestrisL.). In field experiments,the survival and growth rates of colonies ofThaumetopoea pinivoraTreitschke larvaethat had been manipulated to hatch at three different dates were compared. Eggs ofT. pinivorausually hatch by mid-April in southern Sweden, which is earlier than mostother herbivorous insects that overwinter as eggs in this region.3. Predator exclusion experiments indicated that larvae which hatched later than Aprilexperienced a higher level of predator activity, mainly by ants. The final larval size andthe timing of pupation were not affected by hatching date. First instar larvae were moreextensively preyed on than second instars.4. The life history of herbivore species can be affected by seasonal variation inpredation pressures. This study suggests that early hatching in a lepidopteran speciescan allow a temporal escape from predation during the vulnerable early life stages.
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| 27. |
- Schroeder, Martin, et al.
(författare)
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Differences in photoperiod-induced diapause plasticity among different populations of the bark beetle Ips typographus and its predator Thanasimus formicarius
- 2017
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Ingår i: Agricultural and Forest Entomology. - : Wiley. - 1461-9555 .- 1461-9563. ; 19, s. 146-153
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Tidskriftsartikel (refereegranskat)abstract
- 1 Photoperiod is a common cue for diapause induction in insects. In a warmer climate, the photoperiod-sensitive life stage can be expected to be reached earlier in the season, when day length is still long, thereby increasing the probability of an additional generation.2 Populations from four latitudes in Sweden of the tree-killing bark beetle Ips typographus (L.) and its predator Thanasimus formicarius (L.) (Coleoptera, Cleridae) were reared at day lengths from 8 to 23.5 h. Ips typographus adults were classified as being reproductive or in diapause by dissection. Thanasimus formicarius new generation adults were classified as direct developers, whereas last-instar larvae in pupal chambers were classified as in developmental diapause.3 The frequency of reproductive diapause among new generation I. typographus adults was negatively correlated with day length and positively correlated with latitude of population origin. The two northernmost populations included a considerable proportion of individuals that entered reproductive diapause even at the longest day lengths. By contrast, diapause entry in the predator T. formicarius was generally independent of photoperiod and geographical origin.4 In awarmer climate, two generations per year may bemore common for I. typographus in Sweden. The predator is less likely to increase voltinism.
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| 28. |
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| 29. |
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| 30. |
- Watts, Nick, et al.
(författare)
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The 2020 report of The Lancet Countdown on health and climate change : responding to converging crises
- 2021
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Ingår i: The Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 397:10269, s. 129-170
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Forskningsöversikt (refereegranskat)abstract
- The Lancet Countdown is an international collaboration established to provide an independent, global monitoring system dedicated to tracking the emerging health profile of the changing climate.The 2020 report presents 43 indicators across five sections: climate change impacts, exposures, and vulnerabilities; adaptation, planning, and resilience for health; mitigation actions and health co-benefits; economics and finance; and public and political engagement. This report represents the findings and consensus of the 35 leading academic institutions and UN agencies that make up The Lancet Countdown, and draws on the expertise of climate scientists, geographers, engineers, experts in energy, food, and transport, economists, social, and political scientists, data scientists, public health professionals, and doctors.
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