Staff Publications

Staff Publications

  • external user (warningwarning)
  • Log in as
  • language uk
  • About

    '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.

    We have a manual that explains all the features 

Records 1 - 20 / 947

  • help
  • print

    Print search results

  • export
    A maximum of 250 titles can be exported. Please, refine your queryYou can also select and export up to 30 titles via your marked list.
  • alert
    We will mail you new results for this query: q=Werf
Check title to add to marked list
Optimized sowing time windows mitigate climate risks for oats production under cool semi-arid growing conditions
Zhang, Yue ; Zhang, Lizhen ; Yang, Ning ; Huth, Neil ; Wang, Enli ; Werf, Wopke van der; Evers, Jochem B. ; Wang, Qi ; Zhang, Dongsheng ; Wang, Ruonan ; Gao, Hui ; Anten, Niels P.R. - \ 2019
Agricultural and Forest Meteorology 266-267 (2019). - ISSN 0168-1923 - p. 184 - 197.
APSIM-Oats - Climate change - Cumulative probability - Optimal sowing time window - Water limited potential yield - Yield gap

Year to year variability in weather poses serious risks to crop production in the environmentally fragile agro-ecosystems of cool semi-arid areas, and future climate changes might further aggravate those risks. This study aims to quantify the contribution of altered sowing time windows to reduce climate risk for the production of oats (Avena sativa), a crop that is well adapted to short growing seasons and low rainfall. The APSIM-Oats model was calibrated and validated for phenology, above-ground dry matter and yield using data from field experiments with five sowing dates, conducted from 2009 to 2013 in Inner Mongolia, China. The model was used to determine yield trends and yield-limiting factors under rain-fed conditions using historical weather data. Changes in temperature had greater impact on crop production than changes in rainfall and the simulations indicated the importance of changed sowing windows to lengthen the growth duration and optimize water use. Delayed sowing of oats, 10 days later than current practice, ensured more secure temperature and rainfall conditions from emergence to flowering and substantially increased yields and decreased climate risk. Delayed sowing also reduced climate risk under two future climate scenarios, RCP4.5 (stabilize growth) and RCP8.5 (high greenhouse gas emission). We conclude that adaptation of sowing time of oats provides a practical strategy for enhancing yield and mitigating climate risk under climate change.

Plastic film cover during the fallow season preceding sowing increases yield and water use efficiency of rain-fed spring maize in a semi-arid climate
Zhang, Zhe ; Zhang, Yanqing ; Sun, Zhanxiang ; Zheng, Jiaming ; Liu, Enke ; Feng, Liangshan ; Feng, Chen ; Si, Pengfei ; Bai, Wei ; Cai, Qian ; Yang, Ning ; Werf, Wopke van der; Zhang, Lizhen - \ 2019
Agricultural Water Management 212 (2019). - ISSN 0378-3774 - p. 203 - 210.
Film cover - Soil temperature - Water availability - Yield components

Plastic film mulch increases crop yields in rain-fed agriculture in cool semi-arid climates by warming the soil and reducing evaporative water losses. The semi-arid Khorchin area in Northeast China is an important production area for rain-fed maize. Drought stress occurs frequently, even if plastic film mulch is applied at sowing. We hypothesized that the yield and water capture of maize could be increased by reducing evaporative loss of water by use of plastic film cover during the autumn and winter preceding sowing. In this study, we compared maize growth, water uptake and yield in three film cover treatments: (1) film cover from the autumn before maize sowing until maize harvest (autumn mulching: AM), (2) film cover from maize sowing till harvest (conventional practice) (spring mulching: SM), (3) no film cover (no mulch: NM). Field experiments were conducted in Fuxin city, Khorchin region, Liaoning province, China in 2013/2014 and 2014/2015. Autumn mulching increased grain yield on average by 18% when compared to spring mulching and by 36% when compared to no mulching. The 1000-kernel weight in AM was 7% higher than in SM, and 12% higher than in NM. Soil water content in the root zone before sowing was 35 mm greater in AM than in SM and NM. Water uptake during the growing season was 34 mm greater in AM than in SM and NM. Water use efficiency for grain yield (yield per unit water uptake) in AM was on average 2.5% higher than in conventional mulching (SM) and 27% higher than in NM. Autumn mulching advanced development, with an advance of 5 days in tasseling time as compared to SM and 10 days when compared to NM. These results show that film cover during the fallow period before maize sowing can increase crop yield and water use efficiency, and reduce climate risks in rain-fed agriculture under semi-arid conditions.

Understanding and optimizing species mixtures using functional–structural plant modelling
Evers, Jochem B. ; Werf, Wopke Van Der; Stomph, Tjeerd J. ; Bastiaans, Lammert ; Anten, Niels P.R. - \ 2018
Journal of Experimental Botany (2018). - ISSN 0022-0957 - 8 p.
Plant species mixtures improve productivity over monocultures by exploiting species complementarities for resource capture in time and space. Complementarity results in part from competition avoidance responses that maximize resource capture and growth of individual plants. Individual organs accommodate to local resource levels, e.g. with regard to nitrogen content and photosynthetic capacity or by size (e.g. shade avoidance). As a result, the resource acquisition in time and space is improved and performance of the community as a whole is increased. Modelling is needed to unravel the primary drivers and subsequent dynamics of complementary growth responses in mixtures. Here, we advocate using functional–structural plant (FSP) modelling to analyse the functioning of plant mixtures. In FSP modelling, crop performance is a result of the behaviour of the individual plants interacting through competitive and complementary resource acquisition. FSP models can integrate the interactions between structural and physiological plant responses to the local resource availability and strength of competition, which drive resource capture and growth of individuals in species mixtures. FSP models have the potential to accelerate mixed-species plant research, and thus support the development of knowledge that is needed to promote the use of mixtures towards sustainably increasing crop yields at acceptable input levels.
Intercropping potato (Solanum tuberosum L.) with hairy vetch (Vicia villosa) increases water use efficiency in dry conditions
Ren, Jianhong ; Zhang, Lizhen ; Duan, Yu ; Zhang, Jun ; Evers, Jochem B. ; Zhang, Yue ; Su, Zhicheng ; Werf, Wopke van der - \ 2018
Field Crops Research (2018). - ISSN 0378-4290
Biomass - Daily water use - Land equivalent ratio (LER) - Water equivalent ratio (WER) - Water saving

Protection from soil erosion and efficient use of water are vital to sustainable dryland potato production in semi-arid regions. Introducing legumes into semi-arid agricultural systems as intercrops improves soil quality due to biological nitrogen fixation and reduced wind erosion as a result of better soil cover, but the consequences of introducing legumes for the water use efficiency of the crop system are less predictable. Here we carried out field experiments from 2014 to 2017 in Inner Mongolia, China. We compared a rotational intercropping system of potato (Solanum tuberosum L.) and hairy vetch (Vicia villosa) with monocultures of potato and hairy vetch and quantified crop yield, water use efficiency and land productivity. While the relative density (the ratio of plant density in intercrop and the density in sole stand) of both crops in the intercropping was 0.5, the average relative yield of the potato over four years was 0.43, but that of the vetch was 0.87, indicating dominance of the vetch in the intercropping system. Land and water equivalent ratios, defined as the area of land or amount of water that would be needed in single cropping to achieve the same yield as in intercropping, averaged to 1.30 and 1.29 over the years, respectively, indicating high relative land and water productivity of potato/hairy vetch intercropping compared to monocultures. Vetch was a stronger competitor for water than potato with a partial water equivalent ratio of 0.83. We conclude that the potato/vetch intercropping system improves land productivity and system level water use efficiency under the rain-fed semi-arid conditions of the study site. These results are useful to optimize cropping systems for regional sustainability with consideration of both arable crop production (potato) and provision of fodder for animal husbandry (vetch).

The Importance of Combined Tidal and Meteorological Forces for the Flow and Sediment Transport on Intertidal Shoals
de Vet, P.L.M. ; van Prooijen, B.C. ; Schrijvershof, R.A. ; van der Werf, J.J. ; Ysebaert, T. ; Schrijver, M.C. ; Wang, Z.B. - \ 2018
Journal of Geophysical Research: Earth Surface 123 (2018)10. - ISSN 2169-9003 - p. 2464 - 2480.
hydrodynamics - intertidal area - morphology - numerical model - sediment transport - wind

Estuarine intertidal areas are shaped by combined astronomical and meteorological forces. This paper reveals the relative importance of tide, surge, wind, and waves for the flow and sediment transport on large intertidal shoals. Results of an intensive field campaign have been used to validate a numerical model of the Roggenplaat intertidal shoal in the Eastern Scheldt Estuary, the Netherlands, in order to identify and quantify the importance of each of the processes over time and space. We show that its main tidal creeks are not the cause for the dominant direction of the net flow on the shoal. The tidal flow over the shoal is steered by the water level differences between the surrounding channels. Also during wind events, the tidal flow (enhanced by surge) is dominant in the creeks. In contrast, wind speeds of order 40 times the typical tidal flow velocity are sufficient to completely alter the flow direction and magnitude on an intertidal shoal. This has significant consequences for the sediment transport patterns. Apart from this wind-driven flow dominance during these events, the wind also increases the bed shear stress by waves. For the largest intertidal part of the Roggenplaat, only ∼1–10% of the yearly transport results from the 50% least windy tides, even if the shoal is artificially lowered half the tidal range. This dominance of energetic meteorological conditions in the transports matches with field observations, in which the migration of the creeks and high parts of the shoal are in line with the predominant wind direction.

Biological control of an invasive pest eases pressures on global commodity markets
Wyckhuys, K.A.G. ; Zhang, W. ; Prager, S.D. ; Kramer, D.B. ; Delaquis, E. ; Gonzalez, C.E. ; Werf, W. van der - \ 2018
Environmental Research Letters 13 (2018)9. - ISSN 1748-9318
biological control - ecosystem services - invasion biology - social-ecological systems - sustainable intensification - tele-coupling

In an increasingly globalized world, invasive species cause major human, financial, and environmental costs. A cosmopolitan pest of great concern is the cassava mealybug Phenacoccus manihoti (Hemiptera: Pseudococcidae), which invaded Asia in 2008. Following its arrival, P. manihoti inflicted measurable yield losses and a 27% drop in aggregate cassava production in Thailand. As Thailand is a vital exporter of cassava-derived commodities to China and supplies 36% of the world's internationally-traded starch, yield shocks triggered price surges and structural changes in global starch trade. In 2009 a biological control agent was introduced in Asia-the host-specific parasitoid, Anagyrus lopezi (Hymenoptera: Encyrtidae). This parasitoid had previously controlled the cassava mealybug in Africa, and its introduction in Asia restored yield levels at a continent-wide scale. Trade network and price time-series analyses reveal how both mealybug-induced production loss and subsequent parasitoid-mediated yield recovery coincided with price fluctuations in futures and spot markets, with important cascading effects on globe-spanning trade networks of (cassava) starch and commodity substitutes. While our analyses may not imply causality, especially given the concurrent 2007-2011 food crises, our results do illuminate the important interconnections among subcomponents of the global commodity system. Our work underlines how ecologically-based tactics support resilience and safeguard primary productivity in (tropical) agro-ecosystems, which in turn help stabilize commodity markets in a similar way as pesticide-centered approaches. Yet, more importantly, (judiciously-implemented) biological control can deliver ample 'hidden' environmental and human-health benefits that are not captured by the prices of globally-traded commodities.

Monitoring emissions from the 2015 Indonesian fires using CO satellite data
Nechita-Banda, Narcisa ; Krol, Maarten ; Werf, Guido R. van der; Kaiser, Johannes W. ; Pandey, Sudhanshu ; Huijnen, Vincent ; Clerbaux, Cathy ; Coheur, Pierre ; Deeter, Merritt N. ; Röckmann, Thomas - \ 2018
Philosophical Transactions of the Royal Society B. Biological sciences 373 (2018)1760. - 9 p.
atmosphere - biomass burning - emissions - peat - satellite data

Southeast Asia, in particular Indonesia, has periodically struggled with intense fire events. These events convert substantial amounts of carbon stored as peat to atmospheric carbon dioxide (CO2) and significantly affect atmospheric composition on a regional to global scale. During the recent 2015 El Niño event, peat fires led to strong enhancements of carbon monoxide (CO), an air pollutant and well-known tracer for biomass burning. These enhancements were clearly observed from space by the Infrared Atmospheric Sounding Interferometer (IASI) and the Measurements of Pollution in the Troposphere (MOPITT) instruments. We use these satellite observations to estimate CO fire emissions within an inverse modelling framework. We find that the derived CO emissions for each sub-region of Indonesia and Papua are substantially different from emission inventories, highlighting uncertainties in bottom-up estimates. CO fire emissions based on either MOPITT or IASI have a similar spatial pattern and evolution in time, and a 10% uncertainty based on a set of sensitivity tests we performed. Thus, CO satellite data have a high potential to complement existing operational fire emission estimates based on satellite observations of fire counts, fire radiative power and burned area, in better constraining fire occurrence and the associated conversion of peat carbon to atmospheric CO2 A total carbon release to the atmosphere of 0.35-0.60 Pg C can be estimated based on our results.This article is part of a discussion meeting issue 'The impact of the 2015/2016 El Niño on the terrestrial tropical carbon cycle: patterns, mechanisms and implications'.

Data from: Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
Karp, Daniel S. ; Chaplin-Kramer, Rebecca ; Meehan, Timothy D. ; Martin, Emily A. ; DeClerck, Fabrice ; Grab, Heather ; Gratton, Claudio ; Hunt, Lauren ; Larsen, Ashley E. ; Martínez-Salinas, Alejandra ; Zhang, W. ; Bianchi, F.J.J.A. ; Werf, W. van der - \ 2018
agroecology - biological control - natural enemies - pest control - pest - ecosystem services - landscape
The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.
Herbivore-induced plant volatiles and tritrophic interactions: from local to landscape scale
Aartsma, Yavanna - \ 2018
Wageningen University. Promotor(en): Marcel Dicke, co-promotor(en): Felix Bianchi; Erik Poelman; Wopke van der Werf. - Wageningen : Wageningen University - ISBN 9789463433167 - 183
Survival analysis of brown plant hoppers (Nilaparvata lugens) in rice using video recordings of predation events
Hemerik, Lia ; Bianchi, Felix ; Wiel, Inge van de; Fu, Daomeng ; Zou, Yi ; Xiao, Haijun ; Werf, Wopke van der - \ 2018
Biological Control 127 (2018). - ISSN 1049-9644 - p. 155 - 161.
Biocontrol - Pest management - Survival analysis - Visual observation

The brown plant hopper, Nilaparvata lugens Stål, is a major rice pest in South-East Asia. While brown plant hopper (BPH) populations can be regulated by natural enemies, there is limited quantitative information available about the contribution of different predator species to BPH mortality. Our study has three aims: (i) assess the relative contribution of different predator species to BPH mortality in rice fields, (ii) assess diurnal patterns in BPH predation, and (iii) assess the seasonal variation in BPH predation. We quantified predation of live mobile BPH in three rice fields using video recording and assessed densities frogs, a major predator group, by direct counts. In 864 h of video recording, 102 mortality events were observed. Frogs (Ranidae), wolf spiders (Lycosidae) and jumping spiders (Salticidae) were the main predators, accounting for 76%, 13% and 9% of the BPH predation events, respectively. There were large differences in frog density across fields, and there was more predation during the evening (63% predation events) than during the day (37%). Survival analysis indicated that predation risk quickly decreased with time after the onset of recording sessions and that most predation happened within the first 10 min. The results confirm the often overlooked contribution of frogs to BPH predation, but also highlight the substantial variation in predator pressure and frog abundance across farmers’ fields. While camera observations provide compelling information on the identity and relative importance of natural enemies in predation of pests, further development of methods is needed to minimize possible biases resulting from disturbance when making camera observations to quantify predation risk.

Intraspecific variation in herbivore-induced plant volatiles influences the spatial range of plant–parasitoid interactions
Aartsma, Yavanna ; Leroy, Benjamin ; Werf, Wopke van der; Dicke, Marcel ; Poelman, Erik H. ; Bianchi, Felix J.J.A. - \ 2018
Oikos (2018). - ISSN 0030-1299 - 10 p.
animal behaviour - insect–plant interactions - plant odours - spatial ecology

Chemical information influences the behaviour of many animals, thus affecting species interactions. Many animals forage for resources that are heterogeneously distributed in space and time, and have evolved foraging behaviour that utilizes information related to these resources. Herbivore-induced plant volatiles (HIPVs), emitted by plants upon herbivore attack, provide information on herbivory to various animal species, including parasitoids. Little is known about the spatial scale at which plants attract parasitoids via HIPVs under field conditions and how intraspecific variation in HIPV emission affects this spatial scale. Here, we investigated the spatial scale of parasitoid attraction to two cabbage accessions that differ in relative preference of the parasitoid Cotesia glomerata when plants were damaged by Pieris brassicae caterpillars. Parasitoids were released in a field experiment with plants at distances of up to 60 m from the release site using intervals between plants of 10 or 20 m to assess parasitism rates over time and distance. Additionally, we observed host-location behaviour of parasitoids in detail in a semi-field tent experiment with plant spacing up to 8 m. Plant accession strongly affected successful host location in field set-ups with 10 or 20 m intervals between plants. In the semi-field set-up, plant finding success by parasitoids decreased with increasing plant spacing, differed between plant accessions, and was higher for host-infested plants than for uninfested plants. We demonstrate that parasitoids can be attracted to herbivore-infested plants over large distances (10 m or 20 m) in the field, and that stronger plant attractiveness via HIPVs increases this distance (up to at least 20 m). Our study indicates that variation in plant traits can affect attraction distance, movement patterns of parasitoids, and ultimately spatial patterns of plant–insect interactions. It is therefore important to consider plant-trait variation in HIPVs when studying animal foraging behaviour and multi-trophic interactions in a spatial context.

Indicators of resilience during the transition period in dairy cows : A case study
Dixhoorn, I.D.E. van; Mol, R.M. de; Werf, J.T.N. van der; Mourik, S. van; Reenen, C.G. van - \ 2018
Journal of Dairy Science 101 (2018)11. - ISSN 0022-0302 - p. 10271 - 10282.
behavior - dairy cow - dynamic indicator - resilience - transition period
The transition period is a demanding phase in the life of dairy cows. Metabolic and infectious disorders frequently occur in the first weeks after calving. To identify cows that are less able to cope with the transition period, physiologic or behavioral signals acquired with sensors might be useful. However, it is not yet clear which signals or combination of signals and which signal properties are most informative with respect to disease severity after calving. Sensor data on activity and behavior measurements as well as rumen and ear temperature data from 22 dairy cows were collected during a period starting 2 wk before expected parturition until 6 wk after parturition. During this period, the health status of each cow was clinically scored daily. A total deficit score (TDS) was calculated based on the clinical assessment, summarizing disease length and intensity for each cow. Different sensor data properties recorded during the period before calving as well as the period after calving were tested as a predictor for TDS using univariate analysis of covariance. To select the model with the best combination of signals and signal properties, we quantified the prediction accuracy for TDS in a multivariate model. Prediction accuracy for TDS increased when sensors were combined, using static and dynamic signal properties. Statistically, the most optimal linear combination of predictors consisted of average eating time, variance of daily ear temperature, and regularity of daily behavior patterns in the dry period. Our research indicates that a combination of static and dynamic sensor data properties could be used as indicators of cow resilience.
Effects of land use on infestation and parasitism rates of cabbage seed weevil in oilseed rape
Kovács, Gabriella ; Kaasik, Riina ; Lof, Marjolein E. ; Werf, Wopke van der; Kaart, Tanel ; Holland, John M. ; Luik, Anne ; Veromann, Eve - \ 2018
Pest Management Science (2018). - ISSN 1526-498X - 9 p.
Ceutorhynchus obstrictus - conservation biological control - hymenopteran parasitoids - landscape ecology - semi-natural habitats

BACKGROUND: This study investigated how infestation rates of an important oilseed rape pest, the cabbage seed weevil (Ceutorhynchus obstrictus) and rates of parasitization by its parasitoids are affected by land use, up to 1000 m from 18 focal fields. RESULTS: The mean proportion of C. obstrictus-infested pods per plant was 8% (2–19.5%). Infestation rates were higher if the adjacent habitat was a herbaceous semi-natural habitat than if it was either another crop or a woody habitat. Infestation rates were positively related to the area of herbaceous semi-natural vegetation, permanent grassland and wheat (which followed oilseed rape in the crop rotation) at a spatial scale of at least 1 km. The mean parasitism rate of C. obstrictus larvae was 55% (8.3–87%), sufficient to provide efficient biocontrol. Parasitism rates were unrelated to adjacent habitats, however, they were positively related to the presence of herbaceous linear elements in the landscape and negatively related to permanent grasslands at a spatial scale of 200 m. CONCLUSION: Proximity of herbaceous elements increased both infestation rates and parasitism, while infestation was also related to landscape factors at larger distances. The findings provide an empirical basis for designing landscapes that suppress C. obstrictus, at both field and landscape scales.

Oesterdam sand nourishment : Ecological and morphological development of a local sand nourishment
Boersema, Matthijs P. ; Werf, Jebbe van der; Salvador de Paiva, João N. ; Brink, Anneke M. van den; Soissons, Laura ; Walles, Brenda ; Bouma, Tjeerd J. ; Vet, P.L.M. de; Ysebaert, Tom J.W. ; Paree, Edwin ; Bijleveld, Mariska ; Zanten, Eric van; Westenbrugge, Kees van; Stronkhorst, Joost ; Jong, Dick de - \ 2018
Vlissingen : Centre of Expertise Delta Technology - 78
Multidecadal, county-level analysis of the effects of land use, Bt cotton, and weather on cotton pests in China
Zhang, Wei ; Lu, Yanhui ; Werf, Wopke van der; Huang, Jikun ; Wu, Feng ; Zhou, Ke ; Deng, Xiangzheng ; Jiang, Yuying ; Wu, Kongming ; Rosegrant, Mark W. - \ 2018
Proceedings of the National Academy of Sciences of the United States of America 115 (2018)33. - ISSN 0027-8424 - p. E7700 - E7709.
Bt-cotton - Climate change - Insecticide use - Integrated pest management - Land use diversity

Long-term changes in land use, climate, and agricultural technologies may affect pest severity and management. The influences of these major drivers can only be identified by analyzing long-term data. This study examines panel data on land use, adoption of genetically modified Bacillus thuringiensis (Bt) insect-resistant cotton, weather, pest severity, and insecticide use on three major cotton pests for 51 counties in China during 1991–2015. Bt cotton had pervasive effects on the whole pest complex in cotton and its management. Adoption resulted in major reductions in insecticide use for bollworm control. The resulting restoration of aphid biological control decreased aphid severity. However, mirid bugs, which have few effective natural enemies in cotton, increased in severity with warming May and reduced insecticide spraying against bollworm. The effects of landscape on pest severity were pest specific. The severity of cotton aphid and mirid bugs decreased with higher land use diversity, but the severity of highly polyphagous cotton bollworm was unrelated to land use diversity. Shares of forest, water body, and unused land area were negatively associated with the severity of mirid bugs, whereas cotton bollworm responded positively to the shares of water body and unused land area. Farmers sprayed insecticides at mild infestation levels and responded aggressively to severe bollworm outbreaks. Findings support the usefulness of Bt-based plant resistance as a component of integrated pest management (IPM) but highlight the potential for unexpected outcomes resulting from agro-ecosystem feedback loops as well as the importance of climate.

Sensitivity of the breeding values for growth rate and worm egg count to environmental worm burden in Australian Merino sheep
Hollema, Baukje L. ; Bijma, Piter ; Werf, Julius H.J. van der - \ 2018
Journal of Animal Breeding and Genetics 135 (2018)5. - ISSN 0931-2668 - p. 357 - 365.
Environmental mean - Faecal egg count - Gastrointestinal nematode infection - Tolerance

The objective of this study was to explore the sensitivity of breeding values for growth rate and worm egg count (WEC, cube root transformed) to environmental worm burden, measured as the average WEC for each contemporary group (CGWEC). Growth rate and WEC were measured on 7,818 naturally infected Merino lambs in eight flocks across Australia, linked through common use of AI sires. Through bivariate analysis, genetic correlations of 0.55 ± 0.23 and 0.30 ± 0.16 were found for growth rate and WEC between low and high CGWEC, respectively. In a second analysis, breeding values for growth rate and WEC were regressed on CGWEC with a random regression model. The heritability for growth rate varied from 0.23 to 0.16 from low to high CGWEC, and the heritability for WEC varied from 0.25 to 0.36. Results suggest that breeding values for both growth rate and WEC are sensitive to environmental worm burden. Animals expressed less genetic variation for growth rate and more genetic variation for WEC in high CGWEC than in low CGWEC. This form of genotype-by-environment interaction should therefore be considered in genetic evaluation of both growth rate and WEC, to increase the efficiency of selection for animals that are more parasite resistant and more resilient to environmental worm challenge.

Ecological Recovery and Resilience in Environmental Risk Assessments at the European Food Safety Authority
Brock, Theo ; Bigler, Franz ; Frampton, Geoff ; Hogstrand, Christer ; Luttik, Robert ; Martin-Laurent, Fabrice ; Topping, Christopher John ; Werf, Wopke van der; Rortais, Agnes - \ 2018
Integrated Environmental Assessment and Management 14 (2018)5. - ISSN 1551-3793 - p. 586 - 591.
Ecological resilience - Ecosystem services delivery - Internal and external recovery - Normal operating range - Systems approach

A conceptual framework was developed by a working group of the Scientific Committee of the European Food Safety Authority (EFSA) to guide risk assessors and risk managers on when and how to integrate ecological recovery and resilience assessments into environmental risk assessments (ERA). In this commentary we advocate that a systems approach is required to integrate the diversity of ecosystem services (ES) providing units, environmental factors, scales, and stressor-related responses necessary to address the context dependency of recovery and resilience in agricultural landscapes. A future challenge in the resilience assessment remains to identify the relevant bundles of ecosystem services provided by different types of agroecosystem that need to be assessed in concert. Integr Environ Assess Manag 2018;14:586–591.

Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
Karp, Daniel S. ; Chaplin-Kramer, Rebecca ; Meehan, Timothy D. ; Martin, Emily A. ; Declerck, Fabrice ; Grab, Heather ; Gratton, Claudio ; Hunt, Lauren ; Larsen, Ashley E. ; Martínez-Salinas, Alejandra ; O’Rourke, Megan E. ; Rusch, Adrien ; Poveda, Katja ; Jonsson, Mattias ; Rosenheim, Jay A. ; Schellhorn, Nancy A. ; Tscharntke, Teja ; Wratten, Stephen D. ; Zhang, Wei ; Iverson, Aaron L. ; Adler, Lynn S. ; Albrecht, Matthias ; Alignier, Audrey ; Angelella, Gina M. ; Zubair Anjum, Muhammad ; Avelino, Jacques ; Batáry, Péter ; Baveco, Johannes M. ; Bianchi, Felix J.J.A. ; Birkhofer, Klaus ; Bohnenblust, Eric W. ; Bommarco, Riccardo ; Brewer, Michael J. ; Caballero-López, Berta ; Carrière, Yves ; Carvalheiro, Luísa G. ; Cayuela, Luis ; Centrella, Mary ; Ćetković, Aleksandar ; Henri, Dominic Charles ; Chabert, Ariane ; Costamagna, Alejandro C. ; La Mora, Aldo De; Kraker, Joop De; Desneux, Nicolas ; Diehl, Eva ; Diekötter, Tim ; Dormann, Carsten F. ; Eckberg, James O. ; Entling, Martin H. ; Fiedler, Daniela ; Franck, Pierre ; Veen, F.J.F. van; Frank, Thomas ; Gagic, Vesna ; Garratt, Michael P.D. ; Getachew, Awraris ; Gonthier, David J. ; Goodell, Peter B. ; Graziosi, Ignazio ; Groves, Russell L. ; Gurr, Geoff M. ; Hajian-Forooshani, Zachary ; Heimpel, George E. ; Herrmann, John D. ; Huseth, Anders S. ; Inclán, Diego J. ; Ingrao, Adam J. ; Iv, Phirun ; Jacot, Katja ; Johnson, Gregg A. ; Jones, Laura ; Kaiser, Marina ; Kaser, Joe M. ; Keasar, Tamar ; Kim, Tania N. ; Kishinevsky, Miriam ; Landis, Douglas A. ; Lavandero, Blas ; Lavigne, Claire ; Ralec, Anne Le; Lemessa, Debissa ; Letourneau, Deborah K. ; Liere, Heidi ; Lu, Yanhui ; Lubin, Yael ; Luttermoser, Tim ; Maas, Bea ; Mace, Kevi ; Madeira, Filipe ; Mader, Viktoria ; Cortesero, Anne Marie ; Marini, Lorenzo ; Martinez, Eliana ; Martinson, Holly M. ; Menozzi, Philippe ; Mitchell, Matthew G.E. ; Miyashita, Tadashi ; Molina, Gonzalo A.R. ; Molina-Montenegro, Marco A. ; O’Neal, Matthew E. ; Opatovsky, Itai ; Ortiz-Martinez, Sebaastian ; Nash, Michael ; Östman, Örjan ; Ouin, Annie ; Pak, Damie ; Paredes, Daniel ; Parsa, Soroush ; Parry, Hazel ; Perez-Alvarez, Ricardo ; Perović, David J. ; Peterson, Julie A. ; Petit, Sandrine ; Philpott, Stacy M. ; Plantegenest, Manuel ; Plećaš, Milan ; Pluess, Therese ; Pons, Xavier ; Potts, Simon G. ; Pywell, Richard F. ; Ragsdale, David W. ; Rand, Tatyana A. ; Raymond, Lucie ; Ricci, Benoît ; Sargent, Chris ; Sarthou, Jean-Pierre ; Saulais, Julia ; Schäckermann, Jessica ; Schmidt, Nick P. ; Schneider, Gudrun ; Schüepp, Christof ; Sivakoff, Frances S. ; Smith, Henrik G. ; Stack Whitney, Kaitlin ; Stutz, Sonja ; Szendrei, Zsofia ; Takada, Mayura B. ; Taki, Hisatomo ; Tamburini, Giovanni ; Thomson, Linda J. ; Tricault, Yann ; Tsafack, Noelline ; Tschumi, Matthias ; Valantin-Morison, Muriel ; Trinh, Mai Van; Werf, Wopke Van Der; Vierling, Kerri T. ; Werling, Ben P. ; Wickens, Jennifer B. ; Wickens, Victoria J. ; Woodcock, Ben A. ; Wyckhuys, Kris ; Xiao, Haijun ; Yasuda, Mika ; Yoshioka, Akira - \ 2018
Proceedings of the National Academy of Sciences of the United States of America 115 (2018)33. - ISSN 0027-8424 - p. E7863 - E7870.
IPM
The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies.
Forest plantations’ investments in social services and local infrastructure : an analysis of private, FSC certified and state-owned, non-certified plantations in rural Tanzania
Degnet, Mohammed B. ; Werf, Edwin van der; Ingram, Verina ; Wesseler, Justus - \ 2018
Land Use Policy 79 (2018). - ISSN 0264-8377 - p. 68 - 83.
Certification - FSC - Perceptions - Private forest plantations - Social services - Tanzania

With the rapid expansion of forest plantations worldwide, communities, NGOs and researchers are increasingly expressing their concerns about the outcomes of plantations’ activities for local households. This study investigates the perceptions of local households about forest plantations’ investments in social services and local infrastructure in rural Tanzania. We consider households living in villages adjacent to private, FSC certified forest plantations and households in villages adjacent to a state-owned, non-certified plantation. We use survey data from 338 households to analyze perceived changes in school enrolment, quality of education, and the number and quality of health centers, roads and bridges associated with investments by plantations. We use a mixed method approach and complement the results from a logistic regression model with observations of the size and quality of social services and infrastructure in the villages and with findings from focus group discussions. The results show that households in the villages adjacent to both the private, FSC certified and state-owned, non-certified forest plantations associate the plantations with improved social services and local infrastructure in the study villages. Moreover, we find that the private, FSC certified forest plantations are viewed more favorably than the state-owned, non-certified plantation in terms of their contributions to social services and local infrastructure in the study areas. Richer households tend to perceive the investments of the plantations more favorably than poorer households in the study villages.

Uncovering the economic value of natural enemies and true costs of chemical insecticides to cotton farmers in China
Huang, Jikun ; Zhou, Ke ; Zhang, Wei ; Deng, Xiangzheng ; Der Werf, Wopke van; Lu, Yanhui ; Wu, Kongming ; Rosegrant, Mark W. - \ 2018
Environmental Research Letters 13 (2018)6. - ISSN 1748-9318
biological control - economic value - insecticides - natural enemies - smallholder farming

Little empirical evidence on the economic value of biological control of pests at farm level is available to improve economic decision-making by farmers and policy makers. Using insect sampling and household survey in an integrated bio-economic analysis framework, this paper studies farmers' crop management practices in cotton in the North China Plain, and estimates the marginal value of natural enemies and costs of chemical insecticides to farmers. Ladybeetles (mainly Harmonia axyridis, Propylea japonica, and Coccinella septempunctata), the dominant natural enemy group that controls the primary pest (aphid) in cotton in our study area, provide a significant economic benefit that is unknown to the farmers. Even at the current high levels of insecticide use, an additional ladybeetle provides an economic benefit of 0.05 CNY (almost USD 0.01) to farmers. The use of broad-spectrum insecticides by farmers is alarmingly excessive, not only undermining farmers' cotton profitability but also inducing social costs as well as disruption of the natural pest suppression system. Doubling current ladybeetle density in cotton field could gain an estimated USD 300 million for cotton farmers in China, providing a strong economic case for policies to move the pest control system towards a more ecologically-based regime, with positive consequences for farm income and environmental health. With rising use of biological control service provided by natural enemies such as ladybeetles in cotton fields, significant falls in farmers' insecticide use would be expected, which could raise the value of ladybeetles and other natural enemies even further. The results indicate that there is an urgent need to rationalize inputs and move forward to improved agro-ecosystem management in smallholder farming system. Raising knowledge and awareness on the costs and value of biological pest control versus insecticides among farmers and policy makers and having effective extension service, are priorities towards achieving a more ecologically-based approach to crop protection on smallholder farms.

Check title to add to marked list
<< previous | next >>

Show 20 50 100 records per page

 
Please log in to use this service. Login as Wageningen University & Research user or guest user in upper right hand corner of this page.