Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Crop pollination management needs flower-visitor monitoring and target values
    Garibaldi, Lucas A. ; Sáez, Agustín ; Aizen, Marcelo A. ; Fijen, Thijs ; Bartomeus, Ignasi - \ 2020
    Journal of Applied Ecology 57 (2020)4. - ISSN 0021-8901 - p. 664 - 670.
    agricultural management - bees - biodiversity - crop yield - decision-making - ecological intensification - farming practices - pollination

    Despite the crucial importance of biotic pollination for many crops, land managers rarely monitor the levels of crop pollination needed to guide farming decisions. The few existing pollination recommendations focus on a particular number of honeybee or bumblebee hives per crop area, but these guidelines do not accurately predict the actual pollination services that crops receive. We argue that pollination management for pollinator-dependent crops should be based on direct measures of pollinator activity. We describe a protocol to quickly perform such a task by monitoring flower visitation rates. We provide target values of visitation rates for crop yield maximization for several important crops by considering the number of visits per flower needed to ensure full ovule fertilization. If visitation rates are well below or above these target values, corrective measures should be taken. Detailed additional data on visitation rates for different species, morpho-species, or groups of species and/or flower-visitor richness can improve pollination estimates. Synthesis and applications. We present target values of visitation rates for some globally important pollinator-dependent crops and provide guidance on why monitoring the number and diversity of pollinators is important, and how this information can be used for decision-making. The implementation of flower monitoring programmes will improve management in many aspects, including enhanced quality and quantity of crop yield and a more limited spillover of managed (often exotic) pollinators from crop areas into native habitats, reducing their many potential negative impacts.

    A critical analysis of the potential for EU Common Agricultural Policy measures to support wild pollinators on farmland
    Cole, Lorna J. ; Kleijn, David ; Dicks, Lynn V. ; Stout, Jane C. ; Potts, Simon G. ; Albrecht, Matthias ; Balzan, Mario V. ; Bartomeus, Ignasi ; Bebeli, Penelope J. ; Bevk, Danilo ; Biesmeijer, Jacobus C. ; Chlebo, Róbert ; Dautartė, Anželika ; Emmanouil, Nikolaos ; Hartfield, Chris ; Holland, John M. ; Holzschuh, Andrea ; Knoben, Nieke T.J. ; Kovács-Hostyánszki, Anikó ; Mandelik, Yael ; Panou, Heleni ; Paxton, Robert J. ; Petanidou, Theodora ; Pinheiro de Carvalho, Miguel A.A. ; Rundlöf, Maj ; Sarthou, Jean Pierre ; Stavrinides, Menelaos C. ; Suso, Maria Jose ; Szentgyörgyi, Hajnalka ; Vaissière, Bernard E. ; Varnava, Androulla ; Vilà, Montserrat ; Zemeckis, Romualdas ; Scheper, Jeroen - \ 2020
    Journal of Applied Ecology 57 (2020)4. - ISSN 0021-8901 - p. 681 - 694.
    agri-environment schemes - bees - CAP Green Architecture - Common Agricultural Policy - Ecological Focus Areas - habitat complementarity - pollination services - pollinator conservation

    Agricultural intensification and associated loss of high-quality habitats are key drivers of insect pollinator declines. With the aim of decreasing the environmental impact of agriculture, the 2014 EU Common Agricultural Policy (CAP) defined a set of habitat and landscape features (Ecological Focus Areas: EFAs) farmers could select from as a requirement to receive basic farm payments. To inform the post-2020 CAP, we performed a European-scale evaluation to determine how different EFA options vary in their potential to support insect pollinators under standard and pollinator-friendly management, as well as the extent of farmer uptake. A structured Delphi elicitation process engaged 22 experts from 18 European countries to evaluate EFAs options. By considering life cycle requirements of key pollinating taxa (i.e. bumble bees, solitary bees and hoverflies), each option was evaluated for its potential to provide forage, bee nesting sites and hoverfly larval resources. EFA options varied substantially in the resources they were perceived to provide and their effectiveness varied geographically and temporally. For example, field margins provide relatively good forage throughout the season in Southern and Eastern Europe but lacked early-season forage in Northern and Western Europe. Under standard management, no single EFA option achieved high scores across resource categories and a scarcity of late season forage was perceived. Experts identified substantial opportunities to improve habitat quality by adopting pollinator-friendly management. Improving management alone was, however, unlikely to ensure that all pollinator resource requirements were met. Our analyses suggest that a combination of poor management, differences in the inherent pollinator habitat quality and uptake bias towards catch crops and nitrogen-fixing crops severely limit the potential of EFAs to support pollinators in European agricultural landscapes. Policy Implications. To conserve pollinators and help protect pollination services, our expert elicitation highlights the need to create a variety of interconnected, well-managed habitats that complement each other in the resources they offer. To achieve this the Common Agricultural Policy post-2020 should take a holistic view to implementation that integrates the different delivery vehicles aimed at protecting biodiversity (e.g. enhanced conditionality, eco-schemes and agri-environment and climate measures). To improve habitat quality we recommend an effective monitoring framework with target-orientated indicators and to facilitate the spatial targeting of options collaboration between land managers should be incentivised.

    Effectiveness of agri-environmental management on pollinators is moderated more by ecological contrast than by landscape structure or land-use intensity
    Marja, Riho ; Kleijn, David ; Tscharntke, Teja ; Klein, Alexandra Maria ; Frank, Thomas ; Batáry, Péter - \ 2019
    Ecology Letters 22 (2019)9. - ISSN 1461-023X - p. 1493 - 1500.
    Agri-environmental schemes - bees - biodiversity - butterflies - ecosystem services - flower strips - hoverflies - land-use intensity - meta-analysis

    Agri-environment management (AEM) started in the 1980s in Europe to mitigate biodiversity decline, but the effectiveness of AEM has been questioned. We hypothesize that this is caused by a lack of a large enough ecological contrast between AEM and non-treated control sites. The effectiveness of AEM may be moderated by landscape structure and land-use intensity. Here, we examined the influence of local ecological contrast, landscape structure and regional land-use intensity on AEM effectiveness in a meta-analysis of 62 European pollinator studies. We found that ecological contrast was most important in determining the effectiveness of AEM, but landscape structure and regional land-use intensity played also a role. In conclusion, the most successful way to enhance AEM effectiveness for pollinators is to implement measures that result in a large ecological improvement at a local scale, which exhibit a strong contrast to conventional practices in simple landscapes of intensive land-use regions.

    Data from: How much would it cost to monitor farmland biodiversity in Europe?
    Geijzendorffer, I.R. ; Targetti, Stefano ; Schneider, Manuel K. ; Brus, D.J. ; Jongman, R.H.G. ; Knotters, M. ; Bogers, M.M.B. ; Staritsky, I.G. - \ 2015
    Wageningen University & Research
    species richness - farmland biodiversity - habitat - plants - spiders - bees - earth worms - agriculture - agri-environment schemes - biodiversity indicator - common agricultural policy - empirical data - farming system - sampling design - species trend - power analysis
    To evaluate progress on political biodiversity objectives, biodiversity monitoring provides information on whether intended results are being achieved. Despite scientific proof that monitoring and evaluation increase the (cost) efficiency of policy measures, cost estimates for monitoring schemes are seldom available, hampering their inclusion in policy programme budgets. Empirical data collected from 12 case studies across Europe were used in a power analysis to estimate the number of farms that would need to be sampled per major farm type to detect changes in species richness over time for four taxa (vascular plants, earthworms, spiders and bees). A sampling design was developed to allocate spatially, across Europe, the farms that should be sampled. Cost estimates are provided for nine monitoring scenarios with differing robustness for detecting temporal changes in species numbers. These cost estimates are compared with the Common Agricultural Policy (CAP) budget (2014–2020) to determine the budget allocation required for the proposed farmland biodiversity monitoring. Results show that the bee indicator requires the highest number of farms to be sampled and the vascular plant indicator the lowest. The costs for the nine farmland biodiversity monitoring scenarios corresponded to 0·01%–0·74% of the total CAP budget and to 0·04%–2·48% of the CAP budget specifically allocated to environmental targets. Synthesis and applications. The results of the cost scenarios demonstrate that, based on the taxa and methods used in this study, a Europe-wide farmland biodiversity monitoring scheme would require a modest share of the Common Agricultural Policy budget. The monitoring scenarios are flexible and can be adapted or complemented with alternate data collection options (e.g. at national scale or voluntary efforts), data mobilization, data integration or modelling efforts.
    Environmental factors driving the effectiveness of European agri-environmental measures in mitigating pollinator loss – a meta-analysis
    Scheper, J.A. ; Holzschuh, A. ; Kuussaari, M. ; Potts, S.G. ; Rundlöf, M. ; Smith, H. ; Kleijn, D. - \ 2013
    Ecology Letters 16 (2013)7. - ISSN 1461-023X - p. 912 - 920.
    agricultural landscapes - farmland biodiversity - species richness - conservation - communities - management - bees - intensity - countries - schemes
    In Europe, agri-environmental schemes (AES) have been introduced in response to concerns about farmland biodiversity declines. Yet, as AES have delivered variable results, a better understanding of what determines their success or failure is urgently needed. Focusing on pollinating insects, we quantitatively reviewed how environmental factors affect the effectiveness of AES. Our results suggest that the ecological contrast in floral resources created by schemes drives the response of pollinators to AES but that this response is moderated by landscape context and farmland type, with more positive responses in croplands (vs. grasslands) located in simple (vs. cleared or complex) landscapes. These findings inform us how to promote pollinators and associated pollination services in species-poor landscapes. They do not, however, present viable strategies to mitigate loss of threatened or endangered species. This indicates that the objectives and design of AES should distinguish more clearly between biodiversity conservation and delivery of ecosystem services. Keywords: Agri-environmental schemes, ecological contrast, ecosystem services, landscape context, land-use intensity, pollinators.
    Spatial and temporal variation of metal concentrations in adult honeybees (Apis mellifera L.)
    Steen, J.J.M. van der; Kraker, J. ; Grotenhuis, J.T.C. - \ 2012
    Environmental Monitoring and Assessment 184 (2012)7. - ISSN 0167-6369 - p. 4119 - 4126.
    heavy-metals - bees - contamination - products - pollen
    Honeybees (Apis mellifera L.) have great potential for detecting and monitoring environmental pollution, given their wide-ranging foraging behaviour. Previous studies have demonstrated that concentrations of metals in adult honeybees were significantly higher at polluted than at control locations. These studies focused at a limited range of heavy metals and highly contrasting locations, and sampling was rarely repeated over a prolonged period. In our study, the potential of honeybees to detect and monitor metal pollution was further explored by measuring the concentration in adult honeybees of a wide range of trace metals, nine of which were not studied before, at three locations in the Netherlands over a 3-month period. The specific objective of the study was to assess the spatial and temporal variation in concentration in adult honeybees of Al, As, Cd, Co, Cr, Cu, Li, Mn, Mo, Ni, Pb, Sb, Se, Sn, Sr, Ti, V and Zn. In the period of July-September 2006, replicated samples were taken at 2-week intervals from commercial-type beehives. The metal concentration in micrograms per gram honeybee was determined by inductive coupled plasma-atomic emission spectrometry. Significant differences in concentration between sampling dates per location were found for Al, Cd, Co, Cr, Cu, Mn Sr, Ti and V, and significant differences in average concentration between locations were found for Co, Sr and V. The results indicate that honeybees can serve to detect temporal and spatial patterns in environmental metal concentrations, even at relatively low levels of pollution. Keywords: Metals . Bioindication . Pollution . Honeybee
    The Swiss agri-environment scheme enhances pollinator diversity and plant reproductive succes in nearby intensively managed farmland
    Albrecht, M. ; Duelli, P. ; Müller, C. ; Kleijn, D. ; Schmid, B. - \ 2007
    Journal of Applied Ecology 44 (2007)4. - ISSN 0021-8901 - p. 813 - 822.
    agricultural landscapes - renosterveld shrublands - promoting biodiversity - habitat fragmentation - community structure - crop pollination - seed production - bees - forest - extinction
    1. Agri-environment schemes attempt to counteract the loss of biodiversity and associated ecosystem services such as pollination and natural pest control in agro-ecosystems. However, only a few studies have evaluated whether these attempts are successful. 2. We studied the effects of managing meadows according to the prescriptions of ecological compensation areas (ECA), the most widely adopted agri-environment scheme in Switzerland, on both pollinator species richness and abundance, and the reproductive success of plants in nearby intensively managed meadows (IM). 3. We established arrays of four pots, each containing individuals of three insect-pollinated, non-autogamous `phytometer¿ species (Raphanus sativus, Hypochaeris radicata and Campanula glomerata), in ECA and adjacent IM at increasing distances from the ECA at 13 sites. 4. Species richness and abundance of hoverflies, solitary bees and large-sized pollinators (mainly social bees and butterflies) were significantly higher in ECA than in adjacent IM. Species richness and abundance of small-sized pollinators in IM declined significantly with increasing distance from ECA, whereas large-sized pollinators were not significantly affected by distance. Plant species richness and flower abundance were the major drivers of pollinator species richness and abundance; the area of an ECA had no significant influence. 5. Individual plants of R. sativus and C. glomerata produced more and heavier seeds in ECA than in IM. Furthermore, the number of seeds of these two phytometer species was positively correlated with species richness and abundance of bees. No such effects were observed for individual plants of H. radicata. The number of fruits and seeds per plant of R. sativus in IM decreased with increasing distance from ECA. 6. Synthesis and applications. We conclude that establishing ECA is an effective method of enhancing both pollinator species richness and abundance and pollination services to nearby intensely managed farmland. Our study emphasizes the importance of connectivity between ECA in maintaining diverse pollinator communities and thereby providing pollination services in agricultural landscapes.
    Gustatory response and appetitive learning in Microplitis croceipes in relation to sugar type and concentration
    Wäckers, F.L. ; Bonifay, C. ; Vet, L.E.M. ; Lewis, W.J. - \ 2006
    Animal Biology 56 (2006)2. - ISSN 1570-7555 - p. 193 - 203.
    proboscis extension - honeydew sugars - long-term - host - bees - parasitoids - behavior - memory - nectar
    Insects can be conditioned to respond to odours through associative learning. Various learning parameters, such as the rate of odour acquisition, are known to depend on the type of conditioned stimulus. Here we investigate to what extent appetitive conditioning in the parasitoid Microplitis croceipes is also affected by characteristics of the food reward (unconditioned stimulus). We tested 1 M solutions of eight sugars naturally occurring in nectar and honeydew with respect to their effect on parasitoid gustatory response and their suitability as an unconditioned stimulus in the process of associative odour learning. To test for concentration effects, a separate experiment compared parasitoid performance with 1 M and 0.25 M of sucrose, respectively. Only exposure to glucose, fructose, sucrose and melezitose enhanced feeding relative to control individuals provided water. Raffinose, mannose, galactose and melibiose did not increase or decrease consumption, indicating that these sugars are neither phagostimulants nor phagodeterrents. In the conditioning experiments, parasitoids were allowed to feed on a particular sugar solution while being exposed to the floral odour cineole. Parasitoids that had been trained with the stimulatory sugars subsequently showed a clear conditioned feeding response to the cineole. Conditioning with galactose, mannose and melibiose, on the other hand, did not lead to successful odour acquisition. Conditioning with raffinose increased the tendency of the parasitoid to exhibit a conditioned feeding response, even though this response was significantly shorter than the response following training with stimulatory sugars. The level of cineole response was not significantly influenced by the concentration of a sucrose solution, even though the 0.25 M concentration was a weaker feeding stimulant. Our findings indicate that gustatory perception is the principal unconditioned stimulus in appetitive learning. The results with raffinose indicate that postingestive feedback may be involved in food associative learning as well
    Differential feeding of worker larvae affects caste characters in the Cape honeybee, Apis mellifera capensis
    Allsopp, M.H. ; Boot, W.J. ; Calis, J.N.M. - \ 2003
    Behavioral Ecology and Sociobiology 54 (2003). - ISSN 0340-5443 - p. 555 - 561.
    ovary development - scutellata colonies - bees - queen - brood - pheromone - behavior - esters - food
    Sections of brood from colonies of the Cape honeybee ( Apis mellifera capensis), the African honeybee ( A. m. scutellata), and hybrid bees of the two races were exchanged between colonies to study the effect of different brood-origin/nurse-bee combinations on development of caste characters. When Cape larvae were raised by African workers the amount of food provided almost doubled in comparison with Cape larvae reared by their own workers. In contrast, African larvae raised by Cape workers were provided with only half the amount they received from their own workers. After the bees emerged, we found a large degree of plasticity in characters related to caste differentiation, which corresponded closely to the amount of food provided. Super-fed Cape bees had enlarged spermathecae, were heavier than normal workers and developed more rapidly, and had reduced pollen combs, all typical for a more queen-like condition. Ovariole numbers did not appear to be enhanced by additional feeding. Cape bees that behave as social parasites in African bee colonies were most queen-like in the characters studied, albeit within the range that was found for Cape bees from normal colonies, suggesting within-colony selection for characters that enhance reproduction.
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