| 1. |
- Dahlin, Iris, et al.
(författare)
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Aphid performance and population development on their host plants is affected by weed–crop interactions
- 2013
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 50, s. 1281-1288
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Tidskriftsartikel (refereegranskat)abstract
- Some farming practices, like organic farming, lead to greater numbers of weed plants incrop fields. These fields may give us some insights into any benefits that may be gained frombiodiversity (e.g. improved pest control services) and allow us to understand the mechanismsbehind crop–weed interactions.2. The influence of two common weeds, lamb’s-quarters Chenopodium album and charlockSinapis arvensis, on performance of the bird cherry-oat aphid Rhopalosiphum padi in springsownbarley Hordeum vulgare is evaluated in three field experiments. Observations in fieldexperiments indicated that the presence of S. arvensis reduced aphid population developmentin the barley crop significantly, but this effect was not observed in barley grown withC. album.3. Observed effects in the field were further studied in laboratory experiments with regard toaphid growth and reproductive performance. Above- and below-ground interactions ofS. arvensis and C. album with barley were tested using twin-exposure cages. Aphid performancewas negatively affected when barley plants had root contact with S. arvensis. Theresults of these laboratory experiments showed a difference in mode of action of the twoweeds.4. Synthesis and applications. The results support the potential of associated resistance, mediatedby neighbouring plants, in minimizing herbivore damage of focal plants and highlightedthe mechanism by which herbivores might be affected. Since chemical exchange between plantneighbours can potentially occur in any plant community, increased understanding could bevaluable for existing and new agroecosystems, invasion biology and sustainable crop production.To get a balance between herbicide and insecticide control, agricultural production systemsneed to focus on the thresholds of weed and insect tolerance, taking the associatedresistance of biodiversity (here weeds) into account. Agricultural biodiversity may providemany long-term benefits over monoculture, from reducing pesticide pollution to preventinginsecticide resistance. Our study is an important step forward in general understanding of theeffects of vegetational diversity on herbivore population dynamics.
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| 2. |
- Dahlin, Iris, et al.
(författare)
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Changed host plant volatile emissions induced by chemical interaction between unattacked plants reduce aphid plant acceptance with intermorph variation
- 2015
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Ingår i: Journal of Pest Science. - : Springer Science and Business Media LLC. - 1612-4758 .- 1612-4766. ; 88, s. 249-257
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Tidskriftsartikel (refereegranskat)abstract
- Olfactory orientation by aphids is guided by specific volatile blends released from their hosts. Host plants that co-exist with other plants may be less attractive for aphids due to volatile interactions between neighboring plants which can lead to changes in their volatile emissions. These changes in host plant volatile profiles induced by interactions between undamaged plants could be used to manage aphid populations in crops. When potato plants are exposed to volatiles from onion plants, the volatile profile of potato changes in relation to that of unexposed plants with consistently greater quantities of two terpenoids released. We examined the host plant searching behavior of aphids and showed that induced changes in plant volatile emissions affect aphid behavior. We assessed olfactory responses of winged and wingless aphids, Myzus persicae Sulzer (Hemiptera: Aphididae) to the changed volatile emissions. Both morphs were significantly less attracted to odors of potato plants that had been exposed to volatiles from onion than to odors of unexposed potato plants. Further, both morphs were significantly less attracted to synthetic blends mimicking volatiles emitted by onion-exposed potato plants than to blends mimicking non-exposed controls, and to single compounds emitted in greater quantities by exposed potato. Aphid morphs were repelled differently depending on the concentration of odor sources; winged aphids responded to higher doses than did wingless aphids. The aphid responses to changes in plant volatile profiles induced by neighboring plants may facilitate refinement of habitat manipulation strategies (e.g., intercropping) for integrated pest management to reduce aphid occurrence in crops.
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| 3. |
- Dahlin, Iris, et al.
(författare)
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Fishing cyprinids for food - Evaluation of ecosystem effects and contaminants in cyprinid fish
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We conclude that a coastal cyprinid fishery may have positive effects on the ecosystem and with regard to levels of toxic contaminants, the fish is safe for humans to eat. There is, however, a need to scale up the targeted cyprinid fishery in order to evaluate and quantify the effects on the ecosystem. Scaling up from the pilot scale fisheries requires a change in consumer’s attitude and product development, so that larger quantities of cyprinid fish can be harvested and sold. Several wild fish stocks in the Baltic Sea are in poor condition and today the supply of fish for human consumption in Sweden heavily relies on farmed and imported fish. At the same time, eutrophication and climate change has led to increasing populations of cyprinid fish (e.g. bream, roach, ide) in many coastal areas of the Baltic Sea, which threatens to violate Swedish and international environmental goals. During recent years, there has been an increased interest to fish cyprinids for human consumption in Finland and Sweden. This report evaluates potential ecosystem effects resulting from an increased cyprinid fishery, and how to monitor and assess these effects in the Baltic Sea. We also assess potential barriers to increased cyprinid fisheries for human consumption due to food safety issues resulting from environmental contaminants and market incentives for fishers. In a literature review on biomanipulation targeting cyprinids in lakes, we show that removing cyprinids as a measure to improve water quality has been successful in around 60% of the cases where it has been tested. In the Baltic Sea, however, there have only been a few pilot projects of biomanipulation of cyprinids. Differences between coastal areas and lakes makes it unlikely that the same success rate as in lakes would also apply to coastal areas, especially when considering lowering of nutrient concentrations. Still, we think that a sustainable fishery targeting cyprinids may promote at least positive effects on water transparency and macrophytes in the Baltic Sea on a longer time-scale. In line with results from our literature review, we suggest a monitoring program for evaluation of a targeted cyprinid fishery in coastal areas. Based on the potential ecosystem effects of a cyprinid fishery we suggest that monitoring should prioritize fish community composition, water transparency, chlorofyll α, and submerged macrophytes. For more thorough scientific evaluations, the monitoring program should also include abundance of phyto- and zooplankton, as well as and nutrient and oxygen levels. An increased use of cyprinids from the Baltic Sea as human food will also have societal impacts. To examine if human consumption of cyprinid fish entails any increased risk of exposure to contaminants, we analysed concentration levels of several toxins (mercury, cadmium, dioxins, PCBs, PFAS and PBDE) in bream, ide and roach from five sites along the Swedish coast of the northern Baltic Sea. Our results show that, based on the regulations in Sweden today, cyprinids meet all health regulations for human food. Based on recommendations of weekly intake there are no apparent health risks of consuming cyprinid fish from the Baltic Sea at least weekly. However, since knowledge and regulations of certain environmental toxins are poor or non-existent, we believe it is important to conduct a more comprehensive study, especially for PFAS. An increased fishery targeting cyprinids would diversify the small-scale coastal fishery in Sweden, but the currently low demand makes it risky for fishers to invest in equipment and distribution becomes relatively expensive.
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| 4. |
- Dahlin, Iris, et al.
(författare)
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Pest suppression in cultivar mixtures is influenced by neighbor-specific plant-plant communication
- 2018
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 28, s. 2187-2196
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Tidskriftsartikel (refereegranskat)abstract
- Increased plant genotypic diversity in crop fields can promote ecosystem services including pest control, but understanding of mechanisms behind herbivore population responses to cultivar mixtures is limited. We studied aphid settling on barley plants exposed to volatiles from different cultivars, aphid population development in monocultures and two-cultivar mixtures, and differences in volatile composition between studied cultivars. Aphid responses to one cultivar in a mixture were neighbor-specific and this was more important for pest suppression than the overall mixture effect, aphid colonization patterns, or natural enemy abundance. Aphid populations decreased most in a mixture where both cultivars showed a reduced aphid-plant acceptance after reciprocal volatile exposure in the laboratory, and reduced population growth compared to monocultures in the field. Our findings suggest that herbivore population responses to crop genotypic diversity can depend on plant-plant volatile interactions, which can lead to changes in herbivore response to individual cultivars in a mixture, resulting in slower population growth. The impact of plant-plant interaction through volatiles on associated herbivore species is rarely considered, but improved understanding of these mechanisms would advance our understanding of the ecological consequences of biodiversity and guide development of sustainable agricultural practices. Combining cultivars in mixtures based on how they interact with each other is a promising strategy for sustainable pest management.
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| 5. |
- Dahlin, Iris, et al.
(författare)
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Plasticity of barley in response to plant neighbors in cultivar mixtures
- 2020
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Ingår i: Plant and Soil. - : Springer Science and Business Media LLC. - 0032-079X .- 1573-5036. ; 447, s. 537-551
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Tidskriftsartikel (refereegranskat)abstract
- Aims Cultivar mixtures can increase productivity through complementarity in resource use, but reported results are often conflicting and the role of plasticity in shaping plant-plant interactions is poorly understood. We aim to determine if individual cultivars show different phenotypic responses when grown in a mixture, whether these responses depend on the neighboring cultivar identity, and how they contribute to variations in productivity and nitrogen (N) use. Methods Five spring barley cultivars were field-grown in pure stands and in mixtures during 2 years. Plant traits related to development, growth, N use, and reproduction were measured to identify temporal patterns of plastic responses to neighboring plants. Results Plants in mixtures were shorter and developed slower early in the season, but later on they grew faster and produced more grain than the corresponding pure stands. Some cultivars showed complementary N accumulation only when grown together with specific neighbors. Mechanisms of improved productivity differed between the individual mixtures. Conclusions Plastic plant-plant interaction between cultivars is an important driver behind the variability in mixing effects. Results contribute to a better understanding of how productivity in cultivar mixtures is affected by plastic adaptation and differentiation of plant traits, depending on the environment created by neighboring genotypes.
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| 6. |
- Dahlin, Iris
(författare)
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Volatile mediated plant-plant communication in cultivar mixtures : from plant to aphid responses
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Modern agriculture is characterized by simplified cropping systems, associated with negative effects on environment, biodiversity and biological control potential. Cultivar mixtures are often presented as a more efficient and sustainable alternative due to additive effects of cultivar properties and pest reduction, but previous studies have provided equivocal results for this claim. Therefore, a better understanding of the processes underlying the effects of crop genotypic diversity on plant and herbivore responses is needed. Our review of published studies on volatile interactions between plants demonstrates that plant communication is a general event not limited to damaged plants, and that it is more a phenomenon of volatile eavesdropping rather than signalling. Empirical studies in this thesis show that barley plants perceive the growth pattern of their neighbours via volatiles and adapt their own growth strategy accordingly, which can be seen as a preparation for future competition. Field experiments show different trait responses of cultivars grown in mixtures, and that these responses depend on the neighbouring cultivar identity. Plants responded to their neighbours with adaptive and maladaptive growth responses, with increased nitrogen accumulation efficiency, biomass production and grain yield as a result. Aphid populations were generally supressed in these cultivar mixtures; not due to aphid colonization pattern or natural enemy abundance, but possibly induced by volatile interactions between neighbouring plants of different cultivars. Aphid responses to one cultivar in a mixture were neighbour specific and pest suppression was most pronounced when both cultivars in a mixture showed a reduced aphid-plant acceptance after reciprocal volatile exposure in the laboratory. Such individual neighbour responses mediated by volatiles can explain the inconsistent effects of cultivar mixtures in previous research. The findings of this thesis establish a better understanding of volatile communication between plants adding a new dimension to plant behaviour and community processes. Combining cultivars in mixtures based on how they interact with each other is a promising strategy for productive and sustainable agriculture.
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| 7. |
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| 8. |
- Ninkovic, Velemir, et al.
(författare)
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Decoding neighbour volatiles in preparation for future competition and implications for tritrophic interactions
- 2016
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Ingår i: Perspectives in Plant Ecology, Evolution and Systematics. - : Elsevier BV. - 1433-8319 .- 1618-0437. ; 23, s. 11-17
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Forskningsöversikt (refereegranskat)abstract
- Plant volatile signals can provide important information about the physiological status and genetic identity of the emitter, and nearby plants can use this information to detect competitive neighbours. The novelty of these signals is that plants eavesdropping to volatiles of undamaged neighbours respond with typical competition responses, even before competition takes place, initiating specific growth responses that can increase their competitive capacity. This preparing for future competition mechanism affects the behaviour and abundance of herbivore pests and their natural enemies. Previously, such responses were only known to occur in response to volatiles released by damaged plants. However, volatile interactions occur only in specific combination of species/genotypes, indicating that plants use volatile signals in the detection and adaption only to substantial competitive neighbours. (C) 2016 The Author(s). Published by Elsevier GmbH.
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| 9. |
- Ninkovic, Velemir, et al.
(författare)
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Samodla kornsorter... och minska bladlusangreppen.
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Samodling av specifika sortkombinationer mobiliserar kornets försvar mot bladlöss, vilket kan vara en viktig del av ett förebyggande växtskydd i ekologisk produktion. Men vilka sorter ska man samodla? Ett pågående SLU- och Formasprojekt kommer ge svar.
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| 10. |
- Ninkovic, Velemir, et al.
(författare)
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Volatile exchange between undamaged plants - a new mechanism affecting insect orientation in intercropping : Plant Communication Changes Host Plant Odour
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Changes in plant volatile emission can be induced by exposure to volatiles from neighbouring insect-attacked plants.However, plants are also exposed to volatiles from unattacked neighbours, and the consequences of this have not beenexplored. We investigated whether volatile exchange between undamaged plants affects volatile emission and plant-insectinteraction. Consistently greater quantities of two terpenoids were found in the headspace of potato previously exposed tovolatiles from undamaged onion plants identified by mass spectrometry. Using live plants and synthetic blends mimickingexposed and unexposed potato, we tested the olfactory response of winged aphids, Myzus persicae. The altered potatovolatile profile deterred aphids in laboratory experiments. Further, we show that growing potato together with onion in thefield reduces the abundance of winged, host-seeking aphids. Our study broadens the ecological significance of thephenomenon; volatiles carry not only information on whether or not neighbouring plants are under attack, but alsoinformation on the emitter plants themselves. In this way responding plants could obtain information on whether theneighbouring plant is a competitive threat and can accordingly adjust their growth towards it. We interpret this as aresponse in the process of adaptation towards neighbouring plants. Furthermore, these physiological changes in theresponding plants have significant ecological impact, as behaviour of aphids was affected. Since herbivore host plants arepotentially under constant exposure to these volatiles, our study has major implications for the understanding of howmechanisms within plant communities affect insects. This knowledge could be used to improve plant protection andincrease scientific understanding of communication between plants and its impact on other organisms.
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