| 1. |
- Birkhofer, Klaus, et al.
(författare)
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A framework to identify indicator species for ecosystem services in agricultural landscapes
- 2018
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Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X .- 1872-7034. ; 91, s. 278-286
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Tidskriftsartikel (refereegranskat)abstract
- Improving our understanding of the relationships between biodiversity and the delivery of ecosystem services is crucial for the development of sustainable agriculture. We introduce a novel framework that is based on the identification of indicator species for single or multiple ecosystem services across taxonomic groups based on indicator species analyses. We utilize multi-species community data (unlike previous single species approaches) without giving up information about the identity of species in our framework (unlike previous species richness approaches). We compiled a comprehensive community dataset including abundances of 683 invertebrate, vertebrate and plant species to identify indicator species that were either positively or negatively related to biological control, diversity of red-listed species or crop yield in agricultural landscapes in southern Sweden. Our results demonstrate that some taxonomic groups include significantly higher percentages of indicator species for these ecosystem services. Spider communities for example included a higher percentage of significant positive indicator species for biological control than ground or rove beetle communities. Bundles of indicator species for the analysed ecosystem service potentials usually included species that could be linked to the respective ecosystem service based on their functional role in local communities. Several of these species are conspicuous enough to be monitored by trained amateurs and could be used in bundles that are either crucial for the provision of individual ecosystem services or indicate agricultural landscapes with high value for red-listed species or crop yields. The use of bundles of characteristic indicator species for the simultaneous assessment of ecosystem services may reduce the amount of labour, time and cost in future assessments. In addition, future analysis using our framework in other ecosystems or with other subsets of ecosystem services and taxonomic groups will improve our understanding of service-providing species in local communities. In any case, expert knowledge is needed to select species from the identified subsets of significant indicator species and these species should be validated by existing data or additional sampling prior to being used for ecosystem service monitoring.
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| 2. |
- Birkhofer, Klaus, et al.
(författare)
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Relationships between multiple biodiversity components and ecosystem services along a landscape complexity gradient
- 2018
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Ingår i: Biological Conservation. - : Elsevier BV. - 0006-3207 .- 1873-2917. ; 218, s. 247-253
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Tidskriftsartikel (refereegranskat)abstract
- The assessment of effects of anthropogenic disturbance on biodiversity (BD) and ecosystem services (ES) and their relationships are key priorities of the Intergovernmental Panel for Biodiversity and Ecosystem Services. Agricultural landscapes and their associated BD provide multiple ES and it is crucial to understand how relationships between ES and BD components change along gradients of landscape complexity. In this study, we related eight ES potentials to the species richness of five invertebrate, vertebrate and plant taxonomic groups in cereal farming systems. The landscape complexity gradient ranged from areas dominated by annually tilled arable land to areas with high proportions of unfertilized, non-rotational pastures and uncultivated field borders. We show that after accounting for landscape complexity relationships between yield and bird richness or biological control became more positive, but relationships between bird richness and biological control became less positive. The relationship between bird and plant richness turned from positive to negative. Multidiversity (overall biodiversity), was positively related to landscape complexity, whereas multifunctionality (overall ES provision), was not significantly related to either one of these. Our results suggest that multidiversity can be promoted by increasing landscape complexity; however; we found no support for a simultaneous increase of several individual ES, BD components or multifunctionality. These results challenge the assumption that bio-diversity-friendly landscape management will always simultaneously promote multiple ES in agricultural landscapes. Future studies need to verify this pattern by using multi-year data, larger sets of ES and BD components and a study design that is appropriate to address larger spatial scales and relationships in several regions.
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| 3. |
- Bommarco, Riccardo, et al.
(författare)
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Conservation Biological Control in Agricultural Landscapes
- 2017
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Ingår i: Advances in Botanical Research. - : Elsevier. - 0065-2296. ; 81, s. 333-360
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Forskningsöversikt (refereegranskat)abstract
- Integrating supporting and regulating ecosystem functions provided by several components of biodiversity into cropping systems has been proposed as a promising way to decrease agrochemical inputs and negative environmental impacts while maximizing crop productivity. In this chapter, we illustrate how agroecological knowledge can be used to revisit crop protection and insect pest management using conservation biological control. We review how key management options, from the plant to the landscape level, affect natural enemy communities, insect pest abundance and the level of biological control. We particularly show that maintaining within-field diversity in space and time, reducing nitrogen fertilization or soil tillage as well as using organic farming practices at the farm scale or maintaining seminatural habitats at the landscape scale generally benefit natural enemies, increase biological control and limit pest abundance. We also summarize the body of knowledge of the relationship between natural enemy community structure and the level of pest control. Future research needs and applied perspectives are highlighted.
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| 4. |
- Gagic, Vesna, et al.
(författare)
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Interactive effects of pests increase seed yield
- 2016
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 6, s. 2149-2157
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Tidskriftsartikel (refereegranskat)abstract
- Loss in seed yield and therefore decrease in plant fitness due to simultaneous attacks by multiple herbivores is not necessarily additive, as demonstrated in evolutionary studies on wild plants. However, it is not clear how this transfers to crop plants that grow in very different conditions compared to wild plants. Nevertheless, loss in crop seed yield caused by any single pest is most often studied in isolation although crop plants are attacked by many pests that can cause substantial yield losses. This is especially important for crops able to compensate and even overcompensate for the damage. We investigated the interactive impacts on crop yield of four insect pests attacking different plant parts at different times during the cropping season. In 15 oilseed rape fields in Sweden, we estimated the damage caused by seed and stem weevils, pollen beetles, and pod midges. Pest pressure varied drastically among fields with very low correlation among pests, allowing us to explore interactive impacts on yield from attacks by multiple species. The plant damage caused by each pest species individually had, as expected, either no, or a negative impact on seed yield and the strongest negative effect was caused by pollen beetles. However, seed yield increased when plant damage caused by both seed and stem weevils was high, presumably due to the joint plant compensatory reaction to insect attack leading to overcompensation. Hence, attacks by several pests can change the impact on yield of individual pest species. Economic thresholds based on single species, on which pest management decisions currently rely, may therefore result in economically suboptimal choices being made and unnecessary excessive use of insecticides.
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| 5. |
- Jonsson, Mattias, et al.
(författare)
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Contrasting effects of shade level and altitude on two important coffee pests
- 2015
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Ingår i: Journal of Pest Science. - : Springer Science and Business Media LLC. - 1612-4758 .- 1612-4766. ; 88, s. 281-287
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Tidskriftsartikel (refereegranskat)abstract
- The diversity and abundance of natural enemies of insect pests is often higher in agroforestry plantations than in sun-exposed monocultures, and it is often assumed that this will lead to improved pest suppression. The effect that incorporating trees in cropping systems will have on pest populations, however, also depends on the habitat requirements of the pests themselves. In Eastern Uganda, we studied how shade level (full > 50 trees per acre, moderate 21-50 trees per acre, and low 0-20 trees per acre) and altitude (high 1,717-1,840 m.a.s.l. and low 1,511-1,605 m.a.s.l.) influenced the abundance of the white stem borer Monochamus leuconotus and the coffee berry borer Hypothenemus hampei. We found that the effect of shade trees differed between the two pest species. The coffee berry borer was more common on sun-exposed plantations, whereas the white stem borer was more common in shaded plantations. Furthermore, the effect of shade level on the white stem borer depended on altitude, with the differences between shade levels being most pronounced in plantations at low altitudes. This implies that the impact of agroforestry on pest regulation both under current conditions and in a global warming scenario will be highly context dependent; it will depend on the identity of the most important pests in the area, and on environmental factors such as altitude.
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| 6. |
- Jonsson, Mattias, et al.
(författare)
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Relating shading levels and distance from natural vegetation with hemipteran pests and predators occurrence on coffee
- 2015
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Ingår i: Journal of Applied Entomology. - : Wiley. - 0931-2048 .- 1439-0418. ; 139, s. 669-678
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Tidskriftsartikel (refereegranskat)abstract
- The study was carried out to determine the effect of shading levels and/ or distance from the natural alpine vegetation (NAV) on the occurrence of two insect functional groups: hemipteran herbivores and generalist predators in farmers' coffee fields in the Mt. Elgon region of Uganda. Three distance categories from the NAV, that is (i) 0-250 m; (ii) 250- 1000 m and (iii) 1000-1500 m, were used to demarcate farms in the first stage of selection, and within each distance category, three levels of shading, that is (i) no shade, (ii) moderate shade and (iii) full shade, were used for final selection of coffee farms for the study. A total of 90 individually owned coffee fields were studied; 30 for each distance category, of which 10 represented each shading level. In two separate rounds, inventories of scale insects (Coccus spp.), antestia bugs (Antestiopsis spp.), root mealybugs (Planococcus spp.) and aphids (Toxoptera aurantii) on coffee plants were made for the hemipteran herbivores, whereas ants (Formicidae) and spiders (Araneae) were recorded for the predatory taxa. The results showed that the interaction between distance from the NAV and shading level consistently influenced the occurrence of the insects in both functional groups. For scale insects, root mealybugs and ants, it was closest to the NAV that shading-level effects were most discernible and generally limiting. To the contrary, the occurrence of aphids and spiders increased with the increase in the level of shading for plants furthest from the NAV. These results indicate that if inclusion of shade trees is to be a strategy in ecological pest management, the level of shading should be determined basing on the insect taxa as well as other pertinent factors in the landscape.
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| 7. |
- Riggi, Laura, et al.
(författare)
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Insecticide resistance in pollen beetles over 7 years - a landscape approach
- 2016
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Ingår i: Pest Management Science. - : Wiley. - 1526-498X .- 1526-4998. ; 72, s. 780-786
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUNDIn spite of considerable interest in the impact of pesticides on pest populations, few attempts have been made to link resistance patterns of insect pests to land-use features across spatial and temporal scales. We hypothesise that pollen beetle pesticide resistance increases in areas with a high proportion of oilseed rape and with an even mixture of winter and spring oilseed rape owing to high pesticide selection pressure in such areas.RESULTSHere, we investigated 7 years of lambda-cyhalothrin (Karate((R))) resistance in field-collected pollen beetle adults from a total of 180 sampling points across ten regions in Sweden. We found a positive effect on pollen beetle pesticide resistance of proportion of oilseed rape and even spring-winter oilseed rape mixture. However, this was true only for the regional spatial scale. Significant land-use effects in the long-term models, with oilseed rape data averaged over a longer (4 years) period of time, suggested an effect of regional landscape history on current pest resistance.CONCLUSIONFor successful control of pollen beetle pesticide resistance, we suggest a long-term regional strategy for oilseed rape management. This land-use approach provides a framework for further investigations that integrate resistance management into landscape research. (c) 2015 Society of Chemical Industry
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| 8. |
- Riggi, Laura, et al.
(författare)
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Pollen beetle mortality is increased by ground-dwelling generalist predators but not landscape complexity
- 2017
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Ingår i: Agriculture, Ecosystems and Environment. - : Elsevier BV. - 0167-8809 .- 1873-2305. ; 250, s. 133-142
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Tidskriftsartikel (refereegranskat)abstract
- Biological control of crop pests by naturally occurring arthropods depends on the entire community of natural enemies, but generalist predators and parasitoids are rarely considered in the same study. Also, the level of biological control in the field is affected by both within-field and landscape scale management. A multi-taxa approach that integrates multiple scales of management is needed to understand drivers for pest mortality. We examined local (weed cover and soil characteristics) and landscape (proportions of semi-natural and oilseed rape habitat) effects on natural enemy communities and biological control of pollen beetles in 15 oilseed rape (OSR) fields in Sweden. We found that agricultural intensification at the local (low weed cover) and landscape scale (low proportion of semi-natural area) increased evenness of generalist predators, but had no effect on the densities of pests and their natural enemies. This suggests that the generalist predators in OSR are well adapted to crop lands, at least within the examined gradient. Increasing OSR in the landscape decreased parasitoid densities and increased pest density, indicating a potential loss of pest control services by specialist natural enemies in landscapes with a high proportion of OSR. Finally, pollen beetle mortality increased with ground dwelling generalist predator abundance and soil clay content. Parasitism rates did not affect pest mortality, which is interesting as parasitoids have been considered major control agents in OSR. The hypothesis that increasing semi-natural habitat in the landscape enhances natural enemy abundances and species richness in agricultural landscapes was not supported. Local measures targeting generalist predators appear as a reasonable strategy to maximize pollen beetle control.
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| 9. |
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| 10. |
- Roubinet, Eve, et al.
(författare)
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Diet of generalist predators reflects effects of cropping period and farming system on extra- and intraguild prey
- 2017
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Ingår i: Ecological Applications. - : Wiley. - 1051-0761 .- 1939-5582. ; 27:4, s. 1167-1177
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Tidskriftsartikel (refereegranskat)abstract
- The suppression of agricultural pests by natural enemies, including generalist arthropod predators, is an economically important regulating ecosystem service. Besides pests, generalist predators may also consume non-pest extraguild and intraguild prey, which can affect their impact on pest populations. This may either reduce the impact of generalist predators on pest populations, because they are diverted from pest predation, or increase it, as it helps them survive periods of low pest availability. However, the availability of pest prey and alternative, non-pest prey can vary over the crop growing season and between farming systems, potentially affecting predator-prey interactions and the levels of biological control. We have limited information about how farming systems and environmental variation over the crop growing season influence predator diets. This limits our ability to predict the importance of generalist predators as natural enemies of agricultural pests. Here we utilize molecular gut content analyses to assess detection frequencies of extra- and intraguild prey DNA in generalist predator communities in replicated organically and conventionally managed cereal fields at two key periods of the cropping season for aphid biological control. This is done in order to understand how farming system, crop season, prey availability and predator community composition determine the composition of predator diets. Aphid pests and decomposers (springtails) were equally important prey for generalist predators early in the growing season. Later in the season, the importance of aphid prey increased with increasing aphid densities while springtail predation rates were positively correlated to abundance of this prey at both early and late crop growth stages. Intraguild predation was unidirectional: carabids fed on spiders, whereas spiders rarely fed on carabids. Carabids had higher detection frequencies for the two most common spider families in organically compared to conventionally managed fields. Our study documents that predation by generalist predator communities on aphid pests increases with pest numbers independently of their generally widespread consumption of alternative, non-pest prey. Therefore, conservation strategies in agricultural fields could promote biological control services by promoting high levels of alternative non-pest prey for generalist predator communities.
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