Suchergebnisse

The restriction on seed treatments containing neonicotinoid insecticides in the European Union has brought crop protection into focus for oilseed rape (Brassica napus L.). In spring sown oilseed rape, neonicotinoid seed treatments have mainly been used for protection against flea beetles (Phyllotreta spp.), and there is now a need to evaluate alternative control methods. We investigated the effect of reduced tillage and altered seeding date on flea beetle crop damage in spring oilseed rape in eight field experiments over three years in south central Sweden. The average proportion of cotyledon area damaged by flea beetles was not affected by the tillage treatment. Proportion of crop damage was, however, lower in early seeded compared to late seeded plots (0.21 compared to 0.28). We conclude that earlier seeding holds promise to be incorporated into an integrated pest management program for flea beetles in spring oilseed rape, whereas further research on reduced or zero tillage strategies for flea beetle control is warranted.

We lack a thorough understanding of the ecological processes, like species interactions and dispersal, that mediate the ecological responses of whole ecosystems to global changes, and their variability in realistically complex ecosystems. These processes involve multiple interacting species that move freely about the landscapes and thus, understanding these processes demands measures that can account for this complexity, at both the local and landscape scale. I address this issue by combining the local population dynamics of complex food webs and their metacommunity dynamics (yielding so called meta-food-webs). This allows me to incorporate real-world complexity for both local and spatial processes to examine how food webs respond to global changes, focusing on land use changes that alter the spatial configuration of habitats. To delve into the underlying mechanisms governing the impacts of global changes on multitrophic communities in complex landscapes, and to explore variations in these responses among species, trophic groups, landscapes and global change drivers, I develop new theoretical frameworks in which I combine ecology and mathematics. I demonstrate that local and spatial processes mediate meta-food-web responses to global changes in complex landscapes. Specifically, I show that there is a strong trophic dependency in the response of species to land use changes and emphasize that especially (large-bodied) consumer species at high trophic positions have elevated extinction risks when habitat becomes increasingly isolated (research chapters 1 and 2). In research chapter 3, by jointly considering multiple aspects of global change (land use changes and biological invasions), I demonstrate the interdependence of different environmental stressors. Overall, this thesis presents a major step towards a clearer understanding of food web responses to global change impacts.

Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue.

Erratum : DOI : 10.1371/journal.pone.0091459 Clé UT : 000332396200255 ; International audience ; Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue.

Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue.

Declines in insect pollinators across Europe have raised concerns about the supply of pollination services to agriculture. Simultaneously, EU agricultural and biofuel policies have encouraged substantial growth in the cultivated area of insect pollinated crops across the continent. Using data from 41 European countries, this study demonstrates that the recommended number of honeybees required to provide crop pollination across Europe has risen 4.9 times as fast as honeybee stocks between 2005 and 2010. Consequently, honeybee stocks were insufficient to supply >90% of demands in 22 countries studied. These findings raise concerns about the capacity of many countries to cope with major losses of wild pollinators and highlight numerous critical gaps in current understanding of pollination service supplies and demands, pointing to a pressing need for further research into this issue.

Background and aims – Agricultural intensification and loss of farmland heterogeneity have contributed to population declines of wild bees and other pollinators, which may have caused subsequent declines in insect-pollinated wild plants. Material and methods – Using data from 37 studies on 22 pollinator-dependent wild plant species across Europe, we investigated whether flower visitation and seed set of insect-pollinated plants decline with an increasing proportion of arable land within 1 km. Key results – Seed set increased with increasing flower visitation by bees, most of which were wild bees, but not with increasing flower visitation by other insects. Increasing proportion of arable land had a strongly variable effect on seed set and flower visitation by bees across studies. Conclusion – Factors such as landscape configuration, local habitat quality, and temporally changing resource availability (e.g. due to mass-flowering crops or honey bee hives) could have modified the effect of arable land on pollination. While our results highlight that the persistence of wild bees is crucial to maintain plant diversity, we also show that pollen limitation due to declining bee populations in homogenized agricultural landscapes is not a universal driver causing parallel losses of bees and insect-pollinated plants. ; EU FP5 QLRT-2001-01495 ; Swiss Federal Office for Science and Technology (01·0524-2) ; FORMAS ; Estonian Ministry of Education and Research IUT (IUT20-33) ; Internal Grant Agency of the Faculty of Environmental Sciences Czech University of Life Sciences Prague 42900/1312/3166 ; MC-CIG BeeFun project: PCIG14-GA-2013-631653 ; DAFM ; IRC ; Formas (2018-01466) ; German Ministry of Research and Education (FKZ: 01LC1104A) ; NKFIH project (FK123813) ; NKFIH (KKP 133839) ; European Union in the 7th Framework Programme (grant 244090), ; MTA Bolyai Fellow ; Peer reviewed

Background and aims: Agricultural intensification and loss of farmland heterogeneity have contributed to population declines of wild bees and other pollinators, which may have caused subsequent declines in insect-pollinated wild plants. Material and methods: Using data from 37 studies on 22 pollinator-dependent wild plant species across Europe, we investigated whether flower visitation and seed set of insect-pollinated plants decline with an increasing proportion of arable land within 1 km. Key results: Seed set increased with increasing flower visitation by bees, most of which were wild bees, but not with increasing flower visitation by other insects. Increasing proportion of arable land had a strongly variable effect on seed set and flower visitation by bees across studies. Conclusion:Factors such as landscape configuration, local habitat quality, and temporally changing resource availability (e.g. due to mass-flowering crops or honey bee hives) could have modified the effect of arable land on pollination. While our results highlight that the persistence of wild bees is crucial to maintain plant diversity, we also show that pollen limitation due to declining bee populations in homogenized agricultural landscapes is not a universal driver causing parallel losses of bees and insect-pollinated plants. ; The original idea was conceived aspart of the project 'STEP - Status and trends of Europeanpollinators' funded by the European Union in the 7thFramework Programme (grant 244090), which fundedRB, ISD, HGS, SP, MR, LH, JME, and KS. JE and PCwere funded by MULTAGRI/FORMAS. MA was fundedby the EU FP5 project 'Evaluating current European agri-environment schemes to quantify and improve natureconservation efforts in agricultural landscapes' (EASY;QLRT-2001-01495) and the Swiss Federal Office for Scienceand Technology (01·0524-2). AJ and EÖ were funded byFORMAS. TTe and VS were supported by institutionalresearch funding IUT (IUT20-33) of the Estonian Ministryof Education and Research, and TTe also received funding(grant no. 42900/1312/3166) from the Internal Grant Agencyof the Faculty of Environmental Sciences, Czech Universityof Life Sciences Prague. IB was funded by MC-CIG BeeFunproject: PCIG14-GA-2013-631653 and thanks the DoñanaNP staff members for granting access to the Park and CurroMolina for conducting the field work. JS, EFP, and SM werefunded by DAFM and IRC. LH was funded by a grant fromFormas to HGS and by a mobility grant from Formas (2018-01466). ALH was funded by the FarmLand project supportedby the German Ministry of Research and Education (FKZ:01LC1104A). AKH was supported by the NKFIH project 348Pl. Ecol. Evol.154 (3), 2021(FK123813) and was a Bolyai Fellow of MTA. PB wassupported by the NKFIH (KKP 133839).

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society. [Abstract copyright: Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).]

Human land use threatens global biodiversity and compromises multiple ecosystem functions critical to food production. Whether crop yield-related ecosystem services can be maintained by a few dominant species or rely on high richness remains unclear. Using a global database from 89 studies (with 1475 locations), we partition the relative importance of species richness, abundance, and dominance for pollination; biological pest control; and final yields in the context of ongoing land-use change. Pollinator and enemy richness directly supported ecosystem services in addition to and independent of abundance and dominance. Up to 50% of the negative effects of landscape simplification on ecosystem services was due to richness losses of service-providing organisms, with negative consequences for crop yields. Maintaining the biodiversity of ecosystem service providers is therefore vital to sustain the flow of key agroecosystem benefits to society. Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).