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- Hederström, Veronica, et al.
(författare)
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Dispersal and spatiotemporal distribution of Protapion fulvipes in white clover fields : implications for pest management
- 2022
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Ingår i: Journal of Pest Science. - : Springer Science and Business Media LLC. - 1612-4758 .- 1612-4766. ; 95:2, s. 917-930
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Tidskriftsartikel (refereegranskat)abstract
- Yield loss caused by insect pests remains a substantial problem in agriculture. Chemical control, with potential negative effects on non-target organisms, is still the main tool for pest management. For pest species with limited dispersal capacity, rotation of the crop in time and space has potential as an alternative management measure. This is particularly important in organic farming, where most agrochemicals are prohibited, but also relevant as a complementary pest management strategy in conventional agriculture. Clover is an important crop used for animal feed and as green manure; however, seed-eating weevils can severely limit the seed yield. We hypothesized that the previous year’s clover seed fields constitute the major sources of weevil pests. Consequently, a greater distance to, and a smaller pest load from, this source should reduce the number of weevils colonizing the new seed fields. To map population dynamics and dispersal range of Protapion fulvipes, an economically important seed weevil specialized on white clover, we conducted field studies over four years in 45 white clover seed fields. We found that P. fulvipes overwinters close to its source field and disperses to new fields in early spring the following year. Pest abundance increased with pest load in the previous year’s seed field, but decreased by 68% per km distance to the previous year’s field. Thus, separation of seed production fields between years by 2–3 km would create a spatiotemporal pest management tool to reduce the pest infestation below the estimated economic injury level.
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- Hederström, Veronica, et al.
(författare)
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Do plant ploidy and pollinator tongue length interact to cause low seed yield in red clover?
- 2021
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Ingår i: Ecosphere. - : Wiley. - 2150-8925. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- The loss of long-tongued pollinator species and dominance of a few short-tongued generalist species, related to agricultural intensification in recent decades, may have consequences for the quality, quantity, and stability of yields in insect-pollinated crops. Interestingly, the changes in pollinator community coincide with an increase in poor and variable seed yield in red clover, an important crop for green manure and forage production. However, to date we lack a holistic understanding of the factors that drive seed yield in red clover crops. To remedy this, we related plant and pollinator traits to pollinator visitation, behavior, and pollination efficiency in four diploid and five tetraploid red clover cultivars during three years in a common garden setting. Tetraploid cultivars produced 52% fewer seeds and 41% lower seed weight per flower head compared with diploid cultivars. They also had fewer flower heads per plant, larger florets, and lower pollen viability than diploids. Pollinator species with shorter tongues visited diploid cultivars more frequently than tetraploid cultivars. Pollinator species with longer tongues deposited more pollen and showed higher pollination efficiency in terms of seeds produced after single visits. Our results suggest that while both diploid and tetraploid red clover cultivars benefit from the presence of longer-tongued pollinator species, seed yield in tetraploid cultivars may be more sensitive to the loss of these bumble bee species in intensively cultivated agricultural landscapes.
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- Hederström, Veronica
(författare)
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Ecology of pollinators, pests and natural enemies in agricultural landscapes : ensuring a sustainable supply of clover seeds
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The human population and its food consumption continues to grow and the environmental impact of meeting future food demands depends on how we expand the food supply. Already, agricultural intensification has led to biodiversity declines, which in turn can have direct and indirect effects on agricultural production. For future sustainable production there is a need to support ecosystems and their ability to provide ecosystem services. To do so, we need more knowledge on how functional insect groups such as pollinators, pests and natural enemies are affected by land use, and how they in turn affect agricultural systems and crop yields. Due to their ability to fix atmospheric nitrogen, clovers are grown worldwide for animal feed and for green manure. Clover is an important crop in organic farming where inorganic fertilizers are prohibited. However, producers of clover seeds are experiencing problems with varying yields. In this thesis I, therefore, investigated important factors affecting seed yield. I studied interactive effects of plant and pollinator traits on seed set in red clover in a common garden, and investigated spatiotemporal patterns of pollinators, pests and natural enemies in agricultural white clover seed fields. I found that pest abundance in white clover fields decreased with distance from the previous year’s field. Furthermore, pest abundance increased, whereas parasitism rates provided by natural enemies decreased, with proportion arable land in the surrounding landscape. These results point to the potential for using spatial planning as a pest management tool in clover seed production. Abundance of pollinating non- Apis bees was higher in conventionally managed fields compared to organic fields, and abundance of honey bees and total number of bees in organic fields were negatively related to proportion semi-natural land. If these observations are due to more preferable habitats elsewhere needs further investigation. I further showed that white clover fields do not always have sufficient amounts of pollinators as previously believed. In white clover, short tongued bees are good pollinators, but in red clover, and especially tetraploid cultivars, flower visits by medium- or long-tongued bees resulted in a higher seed set. Unexpectedly, medium- tongued bees on a diploid red clover cultivar gave much higher seed set than other combinations of bee tongue length and clover ploidy. This shows the importance of a diverse pollinator fauna, as different pollinators are unequally able to pollinate different species of plants.
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- Hederström, Veronica, et al.
(författare)
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Pollinator-mediated effects of landscape-scale land use on grassland plant community composition and ecosystem functioning – seven hypotheses
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Ingår i: Biological Reviews. - 1464-7931.
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Tidskriftsartikel (refereegranskat)abstract
- Environmental change is disrupting mutualisms between organisms worldwide. Reported declines in insect populations and changes in pollinator community compositions in response to land use and other environmental drivers have put the spotlight on the need to conserve pollinators. While this is often motivated by their role in supporting crop yields, the role of pollinators for reproduction and resulting taxonomic and functional assembly in wild plant communities has received less attention. Recent findings suggest that observed and experimental gradients in pollinator availability can affect plant community composition, but we know little about when such shifts are to be expected, or the impact they have on ecosystem functioning. Correlations between plant traits related to pollination and plant traits related to other important ecosystem functions, such as productivity, nitrogen uptake or palatability to herbivores, lead us to expect non-random shifts in ecosystem functioning in response to changes in pollinator communities. At the same time, ecological and evolutionary processes may counteract these effects of pollinator declines, limiting changes in plant community composition, and in ecosystem functioning. Despite calls to investigate community- and ecosystem-level impacts of reduced pollination, the study of pollinator effects on plants has largely been confined to impacts on plant individuals or single-species populations. With this review we aim to break new ground by bringing together aspects of landscape ecology, ecological and evolutionary plant–insect interactions, and biodiversity–ecosystem functioning research, to generate new ideas and hypotheses about the ecosystem-level consequences of pollinator declines in response to land-use change, using grasslands as a focal system. Based on an integrated set of seven hypotheses, we call for more research investigating the putative pollinator-mediated links between landscape-scale land use and ecosystem functioning. In particular, future research should use combinations of experimental and observational approaches to assess the effects of changes in pollinator communities over multiple years and across species on plant communities and on trait distributions both within and among species.
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- Hederström, Veronica, et al.
(författare)
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White clover pollinators and seed set in relation to local management and landscape context
- 2024
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Ingår i: Agriculture, Ecosystems and Environment. - 0167-8809. ; 365
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Tidskriftsartikel (refereegranskat)abstract
- Bees are declining, which is worrisome since they both have intrinsic conservation value and play a major role as pollinators in both natural and managed ecosystems. Land use change and lack of suitable habitats are often suggested as driving forces of bee decline. To propose mitigation measures to halt bee decline, it is important to understand how land use relates to bee abundance and diversity, and to explore consequences for their provision of pollination services. White clover, Trifolium repens, is an outcrossing mass-flowering crop, which could serve as an abundant, although ephemeral, food resource for bees. We investigated how the bee community in 39 fields of white clover grown for seed, related to local field management (organic, conventional without insecticides and conventional with insecticides) and landscape context (proportion semi-natural land), and how this pollinator community related to white clover seed set. The honey bee, Apis mellifera, was the most commonly observed bee species, and two generalist bumble bee species, Bombus terrestris and B. lapidarius, were the subsequently most common. We observed fewer non-Apis bees, and a lower bee species richness in organic white clover seed fields compared to conventional fields independent of insecticide treatment. Bee species richness in both conventional and organic fields were positively related to the proportion of semi-natural land in the landscape, likely because of a larger species pool in such landscapes. Initial seed set in immature inflorescences was positively related to bee abundance, whereas final seed set in mature inflorescences was unrelated to bee abundance, possibly as a consequence of seed-eating weevils consuming a large proportion of the seeds. We conclude that both bee visitation and seed set in white clover benefit from conventional management and that landscapes rich in semi-natural habitats will make future crop production more resilient. The observed positive relationship between bee abundance and initial seed set suggests that if we can mitigate pest impacts and increase bee abundance in clover seed fields, the final seed yield can be increased. Thus, bee decline should be considered and mitigated both to maintain biodiversity in general and for crop seed production specifically.
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| 9. |
- Lundin, Ola, et al.
(författare)
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The role of pollinators, pests and different yield components for organic and conventional white clover seed yields
- 2017
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Ingår i: Field Crops Research. - : Elsevier BV. - 0378-4290 .- 1872-6852. ; 210, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- A high and stable seed production of both organic and conventional white clover (Trifolium repens L.) is needed to meet market requirements. Seed yields of white clover are, however, known to vary greatly, and organic yields are often considerably lower than conventional yields. Our aim in this study was to estimate the roles of pollinators, pests and different yield components for organic and conventional white clover seed yields. We surveyed pollinators (honey bees, bumble bees and solitary bees), reared the main insect pests (Protapion fulvipes Geoffroy and Hypera spp. weevils) from flowers and measured the yield components (inflorescences per area, flowers per inflorescence, seeds per flower and weight per seed) in organic, conventional untreated and conventional insecticide treated plots in 27 white clover seed fields over two years in southernmost Sweden. Unexpectedly, densities of bees other than honey bees were higher in insecticide treated plots compared to organic plots, but pollinator densities were not related to seed set. The lower pollinator visitation in organic plots might have been caused by pest damage to the flowers, as P. fulvipes and Hypera spp. weevils were more common in organic plots than in conventional insecticide treated plots. The abundances of both P. fulvipes and Hypera spp. weevils were negatively related to seed set, with P. fulvipes being most damaging for seed set. Seed yield was considerably lower (42%) in organic plots compared to conventional insecticide treated plots, and this was driven by a lower (36%) seed set. Taken together, our results indicate that pollinator densities are not limiting yields in either conventional or organic white clover seed production, whereas P. fulvipes crop damage is an important factor limiting organic yields via negative effects on seed set. Research efforts to raise white clover seed yield with minimized environmental impacts should include a focus on integrated pest management of P. fulvipes, including the development of control methods accepted in organic farming.
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| 10. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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