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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    Allergen-specific cytokine polarization protects shetland ponies against culicoides obsoletus-induced insect bite hypersensitivity
    Meulenbroeks, C. ; Lugt, J.J. van der; Meide, N.M.A. van der; Willemse, T. ; Rutten, V.P.M.G. ; Zaiss, D.M.W. - \ 2015
    PLoS ONE 10 (2015)4. - ISSN 1932-6203 - 12 p.
    e-bearing cells - mast-cells - british-columbia - friesian horses - skin biopsies - sweet itch - ige - antibodies - tolerance - immunotherapy
    The immunological mechanisms explaining development of an allergy in some individuals and not in others remain incompletely understood. Insect bite hypersensitivity (IBH) is a common, seasonal, IgE-mediated, pruritic skin disorder that affects considerable proportions of horses of different breeds, which is caused by bites of the insect Culicoides obsoletus (C. obsoletus). We investigated the allergen-specific immune status of individual horses that had either been diagnosed to be healthy or to suffer of IBH. Following intradermal allergen injection, skin biopsies were taken of IBH-affected and healthy ponies and cytokine expression was determined by RT-PCR. In addition, allergen-specific antibody titers were measured and cytokine expression of in vitro stimulated, allergen-specific CD4 T-cells was determined. 24 hrs after allergen injection, a significant increase in mRNA expression of the type-2 cytokine IL-4 was observed in the skin of IBH-affected Shetland ponies. In the skin of healthy ponies, however, an increase in IFN¿ mRNA expression was found. Analysis of allergen-specific antibody titers revealed that all animals produced allergen-specific antibodies, and allergen-specific stimulation of CD4 T-cells revealed a significant higher percentage of IFN¿-expressing CD4 T-cells in healthy ponies compared to IBH-affected ponies. These data indicate that horses not affected by IBH, in contrast to the so far established dogma, are not immunologically ignorant but have a Th1-skewed allergen-specific immune response that appears to protect against IBH-associated symptoms. To our knowledge this is the first demonstration of a natural situation, in which an allergen-specific immune skewing is protective in an allergic disorder.
    Mosquitoes and Culicoides biting midges: vector range and the influence of climate change
    Elbers, A.R.W. ; Koenraadt, C.J.M. ; Meiswinkel, R. - \ 2015
    Revue scientifique et technique / Office International des Epizooties 34 (2015)1. - ISSN 0253-1933 - p. 123 - 137.
    rift-valley fever - possible windborne spread - long-distance dispersal - bluetongue virus - variipennis diptera - borne disease - species range - british-columbia - aedes-albopictus - insect migration
    Vector-borne animal diseases pose a continuous and substantial threat to livestock economies around the globe. Increasing international travel, the globalisation of trade, and climate change are likely to play a progressively more important role in the introduction, establishment and spread of arthropod-borne pathogens worldwide. A review of the literature reveals that many climatic variables, functioning singly or in combination, exert varying effects on the distribution and range of Culicoides vector midges and mosquitoes. For example, higher temperatures may be associated with increased insect abundance – thereby amplifying the risk of disease transmission – but there are no indications yet of dramatic shifts occurring in the geographic range of Culicoides midges. However, the same cannot be said for mosquitoes: over the last few decades, multiple Asian species have established themselves in Europe, spread and are unlikely to ever be eradicated. Research on how insects respond to changes in climate is still in its infancy. The authors argue that we need to grasp how other annectant changes, such as extremes in precipitation (drought and flooding), may affect the dispersal capability of mosquitoes. Models are useful for assessing the interplay between mosquito vectors expanding their range and the native flora and fauna; however, ecological studies employing classical mark-release-recapture techniques remain essential for addressing fundamental questions about the survival and dispersal of mosquito species, with the resulting parameters fed directly into new-generation disease transmission models. Studies on the eventual impact of mosquitoes on animal and human health should be tackled through large-scale integrated research programmes. Such an approach calls for more collaborative efforts, along the lines of the One Health Initiative.
    Thermal regime, predation danger and the early marine exit of sockeye salmon Oncorhynchus nerka
    Katinic, P.J. ; Patterson, D.A. ; Ydenberg, R.C. - \ 2015
    Journal of Fish Biology 86 (2015)1. - ISSN 0022-1112 - p. 276 - 287.
    british-columbia - atlantic salmon - temperature - water - river - populations - mortality - migration - pacific - energetics
    Marine exit timing of sockeye salmon Oncorhynchus nerka populations on the Haida Gwaii Archipelago, British Columbia, Canada, is described, with specific focus on Copper Creek. Marine exit in Copper Creek occurs¿>¿130¿days prior to spawning, one of the longest adult freshwater residence periods recorded for any O. nerka population. Copper Creek presents an easy upstream migration, with mild water temperatures (7 to 14°¿ C), short distance (13·1¿km) and low elevation gain (41¿m) to the lake where fish hold prior to spawning. An energetic model estimates that
    Protecting Timber Supply on Public Land in Response to Catastrophic Natural Disturbance: A Principal-Agent Problem
    Bogle, T. ; Kooten, G.C. van - \ 2015
    Forest Science 61 (2015)1. - ISSN 0015-749X - p. 83 - 92.
    british-columbia - silvicultural investment - policy responses - forest tenure - beetle attack - economics - salvage - management - contracts - behavior
    Catastrophic natural disturbance creates a dilemma for the public forestland owner desiring to retain growing stock and salvaging some, if not all, of the damaged timber. If logging on public forestlands is conducted by private forest companies under various tenure arrangements, attainment of the government's objectives depends crucially on how companies respond to various incentives. This is a classic principal-agent (PA) problem. We investigate the PA problem in the case of catastrophic natural disturbance caused by the mountain pine beetle in British Columbia; we do so using a bilevel programming approach. The principal (government) uses harvest levels, contractual conditions, and stumpage fees to incentivize agents (forest companies) to harvest beetle-impacted pine while leaving sufficient living pine and nonpine species to ensure an adequate future timber supply. Results exploring volume-based tenures indicate that, as a response to catastrophic disturbance, the government should be circumspect in applying the three strategies unilaterally. Simply raising harvest levels to facilitate salvage is not adequate and will likely require a lowering of stumpage prices, which may lead to a reduction in government revenue. Our research also suggests that the government may wish to favor agents with established mills over those interested only in maximizing net returns from logging and selling logs on the open market.
    Dynamic conservation of forest genetic resources in 33 European countries
    Lefevre, F. ; Koskela, J. ; Hubert, J. ; Kraigher, H. ; Longauer, R. ; Olrik, D.C. ; Vries, S.M.G. de - \ 2013
    Conservation Biology 27 (2013)2. - ISSN 0888-8892 - p. 373 - 384.
    chloroplast dna - british-columbia - glacial refugia - climate-change - gap analysis - trees - populations - diversity - biodiversity - adaptation
    Dynamic conservation of forest genetic resources (FGR) means maintaining the genetic diversity of trees within an evolutionary process and allowing generation turnover in the forest. We assessed the network of forests areas managed for the dynamic conservation of FGR (conservation units) across Europe (33 countries). On the basis of information available in the European Information System on FGR (EUFGIS Portal), species distribution maps, and environmental stratification of the continent, we developed ecogeographic indicators, a marginality index, and demographic indicators to assess and monitor forest conservation efforts. The pan-European network has 1967 conservation units, 2737 populations of target trees, and 86 species of target trees. We detected a poor coincidence between FGR conservation and other biodiversity conservation objectives within this network. We identified 2 complementary strategies: a species-oriented strategy in which national conservation networks are specifically designed for key target species and a site-oriented strategy in which multiple-target units include so-called secondary species conserved within a few sites. The network is highly unbalanced in terms of species representation, and 7 key target species are conserved in 60% of the conservation units. We performed specific gap analyses for 11 tree species, including assessment of ecogeographic, demographic, and genetic criteria. For each species, we identified gaps, particularly in the marginal parts of their distribution range, and found multiple redundant conservation units in other areas. The Mediterranean forests and to a lesser extent the boreal forests are underrepresented. Monitoring the conservation efficiency of each unit remains challenging; however,
    Bioenergy from Mountain Pine Beetle Timber and Forest Residuals: A Cost Analysis
    Niquidet, K. ; Stennes, B. ; Kooten, G.C. van - \ 2012
    Canadian Journal of Agricultural Economics 60 (2012)2. - ISSN 0008-3976 - p. 195 - 210.
    british-columbia - infested wood - canada
    In light of the large volumes of pine killed in the interior forests of British Columbia (BC) by the mountain pine beetle, many forest sector participants are keen to employ forest biomass as an energy source. To assess the feasibility of a wood biomass-fired power plant in the BC interior, it is necessary to know both how much physical biomass might be available over the life of a plant and its location as transportation cost is likely to be a major operating cost for any facility. To address these issues, we construct a mathematical programming model of fiber flows in the Quesnel Timber Supply Area of BC over a 25-year time horizon. The focus of the model is on minimizing the cost of supplying feedstock through space and time. Results indicate that over the life of the project, feedstock costs will more than double, increasing from $54.60/bone-dry tonnes (BDt) ($0.039/kWh) to $116.14/BDt ($0.083/kWh).
    Why Mountain Pine Beetle Exacerbates a Principal-agent Relationship: Exploring Strategic Policy Responses to Beetle Attack in a Mixed Species Forest
    Bogle, T. ; Kooten, G.C. van - \ 2012
    Canadian Journal of Forest Research 42 (2012)3. - ISSN 0045-5067 - p. 621 - 630.
    british-columbia - stands - wood
    The management of public forestland is often carried out by private forest companies, in which case the landowner needs to exercise care in dealing with catastrophic natural disturbance. We use the mountain pine beetle (Dendroctonus ponderosae Hopkins, 1902) damage in British Columbia to explore how the public resource owner can protect future timber supply while salvaging damaged stands. We examine the variability and timing of beetle attack in a mixed species forest using mathematical programming to schedule harvest but employ the novel strategy of maximizing the timber portfolio at the end of the 20 year time horizon rather than net present value. Various financial and even-flow constraints insure a modicum of stability during the salvage period. We also model supply of adequate feedstock for electricity generation. Based on our study, the optimal short-run response to beetle damage is to increase harvests in stands with 70% or more lodgepole pine (Pinus contorta var. latifolia Engelm. ex S. Watson) that would otherwise be uneconomic to harvest, similar to operational practice reported by the BC government. The government could focus on stable supply of individual forest products over the time horizon, thereby also stabilizing short-term revenues. Alternatively, it could emphasize an even-flow of total harvest to greatly enhance revenues (which also exhibit greater volatility) and rely more heavily on future harvests of damaged timber. Regardless of the strategy chosen, optimizing future timber supply potential means that a large proportion (about 25% in this study) of damaged pine is left for future harvest, although it will not be of sufficient quality to produce lumber.
    Evaluating competing hypotheses for the origin and dynamics of river anastomosis
    Kleinhans, M.G. ; Haas, T. de; Lavooi, E. ; Makaske, B. - \ 2012
    Earth Surface Processes and Landforms 37 (2012)12. - ISSN 0197-9337 - p. 1337 - 1351.
    rhine-meuse delta - upper columbia river - british-columbia - sediment transport - channel - netherlands - avulsion - canada - classification - bifurcation
    Anastomosing rivers have multiple interconnected channels that enclose flood basins. Various theories potentially explain this pattern, including an increased discharge conveyance and sediment transport capacity of multiple channels, deltaic branching, avulsion forced by base-level rise, or a tendency to avulse due to upstream sediment overloading. The former two imply a stable anabranching channel pattern, whereas the latter two imply disequilibrium and evolution towards a single-channel pattern in the absence of avulsion. Our objective is to test these hypotheses on morphodynamic scenario modelling and data of a well-documented case study: the upper Columbia River. Proportions of channel and floodplain sediments along the river valley were derived from surface mapping. Initial and boundary conditions for the modelling were derived from field data. A 1D network model was built based on gradually varied flow equations, sediment transport prediction, mass conservation, transverse slope and spiral meander flow effects at the bifurcations. The number of channels and crevasse splays decreases in a downstream direction. Also, measured sediment transport is higher at the upstream boundary than downstream. These observations concur with bed sediment overloading from upstream, which can have caused channel aggradation above the surrounding floodplain and subsequent avulsion. The modelling also indicates that avulsion was likely caused by upstream overloading. In the model, multi-channel systems inevitably evolve towards single-channel systems within centuries. The reasons are that symmetric channel bifurcations are inherently unstable, while confluenced channels have relatively less friction than two parallel channels, so that more discharge is conveyed through the path with more confluences and less friction. Furthermore, the present longitudinal profile curvature of the valley could only be reproduced in the model by temporary overfeeding.
    Upstream and downstream controls of recent avulsions on the Taquari megafan, Pantanal, south-western Brazil
    Makaske, B. ; Maathuis, B.H.P. ; Padovani, C.R. ; Stolker, C. ; Mosselman, E. ; Jongman, R.H.G. - \ 2012
    Earth Surface Processes and Landforms 37 (2012)12. - ISSN 0197-9337 - p. 1313 - 1326.
    rhine-meuse delta - upper columbia river - british-columbia - channel belts - bighorn basin - netherlands - floodplain - deposits - architecture - aggradation
    Avulsion, the natural relocation of a river, is a key process in the evolution of subaerial fans, river floodplains and deltas. The causes of avulsion are poorly understood, which is partly due to the scarcity of field studies of present avulsions. At present, two avulsions are occurring on the middle and lower Taquari megafan, Pantanal basin, south-western Brazil. Here we present an analysis of the causes of these avulsions based on field and remote sensing data and show that avulsions on megafans can be controlled by both upstream and downstream processes. The middle fan avulsion (started in 1997–1998) is a result of upstream control: overbank aggradation was caused by the (variable) input of sandy sediment into the system, which caused channel-belt superelevation and also created an easily erodible subsurface favouring bank retreat, crevassing, and scour of deep floodplain channels. The sandy subsurface in this area is inferred to have been a major factor in the causation of this avulsion under conditions of little gradient advantage. The lower fan avulsion (started c. 1990) results from interplay of upstream and downstream controls, the latter being related to the local base level (the Paraguay River floodplain) at the toe of the fan. Channel and overbank aggradation on the lower fan was influenced by fan sub-lobe progradation and channel backfilling. Fan sub-lobe progradation caused a significant gradient advantage of the avulsion channel over the parent channel. Avulsions are commonly supposed to be preferentially triggered by high-magnitude floods, when there is considerable channel-belt superelevation. However, both avulsions studied by us were triggered by small to average floods, with modest channel-belt superelevation. We conclude that flood magnitude and channel-belt superelevation have been overrated as causes of avulsion, and demonstrate additional causes that influence the growth of crevasses into avulsions.
    Culicoides obsoletus extract relevant for diagnostics of insect bite hypersensitivity in horses
    Meide, N.M.A. van der; Meulenbroeks, C. ; Altena, S.E.C. van; Schurink, A. ; Ducro, B.J. ; Wagner, B. ; Leibold, W. ; Rohwer, J. ; Jacobs, F. ; Sloet van Oldruitenborgh-Oosterbaan, M.M. ; Savelkoul, H.F.J. ; Tijhaar, E. - \ 2012
    Veterinary Immunology and Immunopathology 149 (2012)3-4. - ISSN 0165-2427 - p. 245 - 254.
    dermatitis sweet itch - dermal hypersensitivity - icelandic horses - british-columbia - summer eczema - equine ige - antibodies - ceratopogonidae - identification - netherlands
    Insect bite hypersensitivity (IBH) is an allergic dermatitis in horses caused by the bites of Culicoides species. The aim of the present study was to evaluate the applicability of whole body extracts of C. obsoletus (the main species found feeding on horses in the Netherlands), C. nubeculosus (rarely found in The Netherlands) and C. sonorensis (typical for North America) for diagnosis of IBH in horses in The Netherlands. Blood and serum samples of 10 clinically confirmed IBH affected and 10 healthy control horses were used to evaluate the IgE titers (ELISA) against the Culicoides whole body extracts of the three Culicoides species. Basophil degranulation was assessed by histamine release test (HRT) after stimulation with these extracts at 5, 0.5 and 0.05 µg/ml. IBH affected horses had significantly higher IgE titers against C. obsoletus than against C. nubeculosus and C. sonorensis. Furthermore, C. obsoletus induced significantly higher histamine release in whole blood of IBH affected horses compared to the other extracts at 0.5 µg/ml. Western blot data revealed IgE binding to many proteins in C. obsoletus extract. This interaction was absent or weak in C. nubeculosus and C. sonorensis extracts for IBH affected horses. Results on individual level indicate that the HRT is more sensitive than ELISA in diagnosing IBH. However, ELISA is more practical as a routine test, therefore the ELISA was further evaluated using C. obsoletus extract on 103 IBH affected and 100 healthy horses, which resulted in a test sensitivity and specificity of 93.2% and 90.0%, respectively. The IgE ELISA readings enabled the analysis of the predicted probability of being IBH affected. From an optical density 450 nm value of 0.33 onwards, the probability of IBH affected was more than 0.9. The results presented in this paper show that the use of native Culicoides spp. that feed on horse, is important for improved diagnosis and that the described ELISA based on C. obsoletus can be used routinely to diagnose IBH in countries where this species is the main Culicoides feeding on horses
    Comparative Analysis of Avian Influenza Virus Diversity in Poultry and Humans during a Highly Pathogenic Avian Influenza A (H7N7) Virus Outbreak
    Jonges, M. ; Bataille, A. ; Enserink, R. ; Meijer, A. ; Fouchier, R.A.M. ; Stegeman, A. ; Koch, G. ; Koopmans, M. - \ 2011
    Journal of Virology 85 (2011)20. - ISSN 0022-538X - p. 10598 - 10604.
    human transmissibility - respiratory-tract - british-columbia - replication - host - neuraminidase - infection - h9n2 - hemagglutinin - netherlands
    Although increasing data have become available that link human adaptation with specific molecular changes in nonhuman influenza viruses, the molecular changes of these viruses during a large highly pathogenic avian influenza virus (HPAI) outbreak in poultry along with avian-to-human transmission have never been documented. By comprehensive virologic analysis of combined veterinary and human samples obtained during a large HPAI A (H7N7) outbreak in the Netherlands in 2003, we mapped the acquisition of human adaptation markers to identify the public health risk associated with an HPAI outbreak in poultry. Full-length hemagglutinin (HA), neuraminidase (NA), and PB2 sequencing of A (H7N7) viruses obtained from 45 human cases showed amino acid variations at different codons in HA (n = 20), NA (n = 23), and PB2 (n = 23). Identification of the avian sources of human virus infections based on 232 farm sequences demonstrated that for each gene about 50% of the variation was already present in poultry. Polygenic accumulation and farm-to-farm spread of known virulence and human adaptation markers in A (H7N7) virus-infected poultry occurred prior to farm-to-human transmission. These include the independent emergence of HA A143T mutants, accumulation of four NA mutations, and farm-to-farm spread of virus variants harboring mammalian host determinants D701N and S714I in PB2. This implies that HPAI viruses with pandemic potential can emerge directly from poultry. Since the public health risk of an avian influenza virus outbreak in poultry can rapidly change, we recommend virologic monitoring for human adaptation markers among poultry as well as among humans during the course of an outbreak in poultry.
    Do staging semipalmated sandpipers spend the high-tide period in flight over the Ocean to Avoid Falcon Attacks along Shore?
    Dekker, D. ; Dekker, I. ; Christie, D. ; Ydenberg, R.C. - \ 2011
    Waterbirds 34 (2011)2. - ISSN 1524-4695 - p. 195 - 201.
    calidris-pusilla - peregrine falcon - raptor predation - british-columbia - fall migration - boundary bay - dunlins - fundy - selection - flocking
    The interaction of aerial predators and migrant Semipalmated Sandpipers (Calidris pusilla) was studied at Mary's Point in the upper Bay of Fundy, New Brunswick, Canada, during August of 2009 and 2010. Peregrine Falcons (Falco peregrinus) were locally reintroduced and increased from one active nest site in 1989 to 27 in 2010, which coincided with a decline of sandpipers roosting at Mary's Point from an annual mean of 161,000 in 1976â€"1982 to 15,000 or less during this study. Mean roosting time of flocks was 33 min (range = 10 to 40 min; N = 6). Sandpipers returned to the beach 1 h:36 min after high-tide (range = 1 h:10 to 2 h:13 min; N = 5), but were soon flushed again by falcons. On ten of 19 days, during part of the high-tide period, flocks of sandpipers remained in flight over the ocean. Termed Over-Ocean Flocking (OOF), this behavior was seen on days when spring tides inundated all beach habitat, and also at lower tides, which supports the hypothesis that OOF is an antipredator strategy intended to avoid surprise attacks by falcons near the shore. Raptors sighted during 128 hours afield included 226 Peregrines, 20 Merlins (Falco columbarius) and two Sharp-shinned Hawks (Accipiter striatus). At 1.0â€"3.2 Peregrine sightings/h-1 (mean 1.8) the level of disturbance is high and supports the hypothesis that the decline in roosting sandpipers at Mary's Point is linked to predation danger.
    Genetic parameters of insect bite hypersensitivity in Dutch Friesian broodmares
    Schurink, A. ; Ducro, B.J. ; Heuven, H.C.M. ; Arendonk, J.A.M. van - \ 2011
    Journal of Animal Science 89 (2011)5. - ISSN 0021-8812 - p. 1286 - 1293.
    icelandic horses - british-columbia - summer eczema - sweet itch - culicoides hypersensitivity - netherlands - ceratopogonidae - identification - population - diptera
    Insect bite hypersensitivity (IBH) is a seasonal allergic skin disease in horses caused by bites of certain Culicoides spp. The aim of our study was to investigate the maternal effect on IBH and to estimate the heritability and repeatability of IBH in the Dutch Friesian horse population. Data consisted of 3,453 Dutch Friesian broodmares with 3,763 visual observations on IBH clinical symptoms scored by 12 inspectors during organized foal inspections in 2004 and 2008. Nine percent of the mares (n = 310) were scored in both years. Mares descended from 144 sires and 2,554 dams and 26.2% of the dams (n = 669) had more than 1 offspring in the data set (range: 2 to 6). Insect bite hypersensitivity was analyzed as a binary trait with a threshold animal model with and without a maternal effect, using a Bayesian approach. Observed IBH prevalence in Dutch Friesian broodmare population was 18.2%. Heritability on the liability scale was 0.16 (SD = 0.06); heritability on the observed scale was 0.07; and repeatability was 0.89 (SD = 0.03). Maternal effect was 0.17 (SD = 0.06) and significantly differed from zero, although the animal model without a maternal effect fitted the data better. These results show that genetic and permanent environmental factors affect IBH in Dutch Friesian horses. The dam affected the IBH development of her offspring through an additive genetic influence but also by being part of their rearing environment
    Seabird seasonal trophodynamics: isotopic patterns in a community of Pacific alcids
    Davies, W.E. ; Hipfner, J.M. ; Hobson, K.A. ; Ydenberg, R.C. - \ 2009
    Marine Ecology Progress Series 382 (2009). - ISSN 0171-8630 - p. 211 - 219.
    auklets ptychoramphus-aleuticus - stable-isotopes - trophic relationships - rhinoceros auklets - british-columbia - triangle island - ocean climate - piscivorous seabird - breeding success - foraging areas
    We measured delta N-15 and delta C-13 values in the blood of breeding adults and nestlings of 5 species of alcids at Triangle Island, British Columbia, to estimate the extent to which these seabirds alter their foraging ecology across successive breeding stages. Considerable intraspecific (stage-to-stage) and interspecific variation was found. Two species-common murre Uria aalge and pigeon guillemot Cepphus columba-fed consistently at high trophic levels (i.e. diets of fish) in inshore or benthically linked habitats. The foraging ecology of 3 others-Cassin's auklet Ptychoramphus aleuticus, rhinoceros auklet Cerorhinca monocerata and tufted puffin Fratercula cirrhata-was more variable. Tufted puffins exhibited especially dramatic trophic and habitat shifts between early and late-season diets. With the exception of tufted puffin, the diet of provisioning adults differed from that. fed to their nestlings. Trophic level of the community as a whole increased as the season progressed due to the combination of trophic shifting by rhinoceros auklets and tufted Puffins, and earlier breeding by zooplanktivorous Cassin's auklets than by piscivorous murres and guillemots. Our results contribute to a growing body of evidence that marine bird species exhibit considerable flexibility in their foraging behaviour and also shed new light on seasonal patterns in the trophic relations within marine bird communities.
    Heritability and repeatability of insect bite hypersensitivity in Dutch Shetland breeding mares
    Schurink, A. ; Grevenhof, E.M. van; Ducro, B.J. ; Arendonk, J.A.M. van - \ 2009
    Journal of Animal Science 87 (2009). - ISSN 0021-8812 - p. 484 - 490.
    dermatitis sweet itch - british-columbia - icelandic horses - culicoides hypersensitivity - summer eczema - ceratopogonidae - diptera - israel
    Insect bite hypersensitivity (IBH) is a seasonal recurrent allergic reaction of horses to the bites of certain Culicoides spp. and is found throughout the world. The aim of our study was to estimate the heritability and repeatability of IBH in the Dutch Shetland pony population. A total of 7,924 IBH scores on 6,073 mares were collected during foal inspections in 2003, 2005, and 2006. Mares were scored for clinical symptoms of IBH from June until February by 16 inspectors. Of all mares, 74.4% (n = 4,520) had a single observation, 20.7% (n = 1,255) had 2 observations, and 4.9% (n = 298) had 3 observations in different years. The overall mean IBH prevalence was 8.8%. Heritability was 0.08 (SE = 0.02) on the observed binary scale and 0.24 (SE = 0.06) on the underlying continuous scale. Repeatability was 0.30 (SE = 0.02) and indicates that including repeated observations of the clinical symptoms of IBH will improve the accuracy of breeding values for IBH. We conclude that IBH, based on clinical symptoms, is a heritable trait in the Dutch Shetland pony population. Therefore, the IBH prevalence in this population can be decreased by selection
    Intradermal testing of horses with and without insect bite hypersensitivity in the Netherlands using an extract of native Culicoides species
    Sloet van Oldruitenborgh-Oosterbaan, M.M. ; Poppel, M. van; Raat, I.J. de; Boom, R. van den; Savelkoul, H.F.J. - \ 2009
    Veterinary Dermatology 20 (2009)5-6. - ISSN 0959-4493 - p. 607 - 614.
    sweet itch - icelandic horses - british-columbia - summer eczema - challenge - ceratopogonidae - dermatitis - permethrin - diptera - norway
    Intradermal tests using a Culicoides nubeculosus extract have proven unreliable for diagnosis of equine insect bite hypersensitivity (IBH) in the Netherlands. The aim of this study was to evaluate the diagnostic value of an extract derived from the Dutch species C. obsoletus and C. pulicaris. Thirteen pairs of horses were tested, each pair consisting of one horse with IBH and the other a healthy control. Each horse was injected intradermally with 0.1 mL of three concentrations of Culicoides whole body extract (1 : 1000 w/v, 1 : 10,000 w/v and 1 : 25,000 w/v), histamine solution (0.01 mg/mL, positive control) and phosphate-buffered saline (negative control). Skin responses were evaluated after 30 min and at 1, 4 and 24 h. At all time points the absolute wheal diameter elicited by Culicoides extract 1 : 1000 w/v was significantly larger (P <0.01) in the IBH horses than in the control horses. Using the 1 : 10,000 w/v extract the difference was significant at 1, 4 and 24 h and using the 1 : 25,000 w/v extract only at 24 h. The relative wheal diameter was greater in IBH than in control horses at all concentrations and time points except at 0.5 h for the 1 : 10,000 w/v and 1 : 25,000 w/v concentrations. At the 1 : 1000 w/v concentration, the sensitivity and specificity was 92% using the relative wheal diameter. These results indicate that intradermal testing using 1 : 1000 w/v concentration Culicoides extracts relevant to the locality provides useful support for a clinical diagnosis of equine insect hypersensitivity
    Landsliding and its multiscale influence on mountainscapes
    Restrepo, C. ; Walker, L.R. ; Bussmann, R. ; Claessens, L. - \ 2009
    Bioscience 59 (2009)8. - ISSN 0006-3568 - p. 685 - 698.
    puerto-rican landslides - british-columbia - new-zealand - land-cover - vegetation - forest - soil - disturbance - succession - recovery
    Landsliding is a complex process that modifies mountainscapes worldwide. Its severe and sometimes long-lasting negative effects contrast with the less-documented positive effects on ecosystems, raising numerous questions about the dual role of landsliding, the feedbacks between biotic and geomorphic processes, and, ultimately, the ecological and evolutionary responses of organisms. We present a conceptual model in which feedbacks between biotic and geomorphic processes, landslides, and ecosystem attributes are hypothesized to drive the dynamics of mountain ecosystems at multiple scales. This model is used to integrate and synthesize a rich, but fragmented, body of literature generated in different disciplines, and to highlight the need for profitable collaborations between biologists and geoscientists. Such efforts should help identify attributes that contribute to the resilience of mountain ecosystems, and also should help in conservation, restoration, and hazard assessment. Given the sensitivity of mountains to land-use and global climate change, these endeavors are both relevant and timely
    Culicoides species attracted to horses with and without insect hypersensitivity
    Rijt, R. van der; Boom, R. van den; Jongema, Y. ; Sloet van Oldruitenborgh-Oosterbaan, M.M. - \ 2008
    The Veterinary Journal 178 (2008)1. - ISSN 1090-0233 - p. 91 - 97.
    sweet-itch - intradermal challenge - icelandic horses - british-columbia - ceratopogonidae - diptera - extracts - trap - dermatitis - mosquitos
    The aims of this study were to determine (1) which species of Culicoides is most commonly attracted to horses, (2) whether horses suffering insect hypersensitivity attract more Culicoides spp. than unaffected horses, and (3) the times when Culicoides spp. are most active. Horses affected by insect hypersensitivity and unaffected horses were placed inside mosquito netting tents for 30 min at different times of the day. All Culicoides spp. trapped inside the tents were collected and identified. C. obsoletus was the most common species found, followed by C. pulicaris. Healthy horses attracted slightly more midges than horses that were affected with insect hypersensitivity. All of the Culicoides species were most active at sunset, less so at sunrise and very few or no midges were trapped in the afternoon or at night.
    Identification of factors associated with the development of insect bite hypersensitivity in horses in the Netherlands
    Boom, R. van den; Ducro, B.J. ; Sloet van Oldruitenborgh-Oosterbaan, M.M. - \ 2008
    Tijdschrift voor Diergeneeskunde 133 (2008)13. - ISSN 0040-7453 - p. 554 - 563.
    paardenziekten - zomereczeem - insectenbeten - allergieën voor geleedpotigen - overgevoeligheid - paarden - horse diseases - sweet itch - insect bites - arthropod allergies - hypersensitivity - horses - dermatitis sweet itch - british-columbia - culicoides hypersensitivity - dermal hypersensitivity - icelandic horses - genetic-basis - ceratopogonidae - diptera - israel - diseases
    An Internet-based questionnaire among horse owners was carried out to identify factors affecting the incidence of insect bite hypersensitivity (IBHI) among horses in the Netherlands. Information was obtained for 794 horses of various breeds, but the breed distribution was not representative for the Dutch horse population. Of the horses for which information was available, 56% suffered from IBH and 44% did not. The most common clinical symptoms were pruritus, scaling, and hair loss, occurring mainly at the base of the tail and along the mane. Breed, age, region (and local habitat), stabling, type of bedding in the stable, use of the horse, deworming frequency, and season were associated with significant differences in IBH incidence. Knowledge of the factors influencing the incidence of IBH may make it possible to reduce the number of animals affected and help alleviate symptoms in affected horses.
    Ecological factors associated with the breeding and migratory phenology of high-latitude breeding western sandpipers
    Niehaus, A.C. ; Ydenberg, R.C. - \ 2006
    Polar Biology 30 (2006)1. - ISSN 0722-4060 - p. 11 - 17.
    yukon-kuskokwim delta - climate-change - calidris-mauri - british-columbia - bird migration - north-america - sex-ratio - alaska - shorebirds - chronology
    Environmental conditions influence the breeding and migratory patterns of many avian species and may have particularly dramatic effects on longdistance migrants that breed at northern latitudes. Environment, however, is only one of the ecological variables affecting avian phenology, and recent work shows that migration tactics may be strongly affected by changes in predator populations. We used long-term data from 1978 to 2000 to examine the interactions between snowmelt in western Alaska in relation to the breeding or migration phenologies of small shorebirds and their raptor predators. Although the sandpipers¿ time of arrival at Alaskan breeding sites corresponded with mean snowmelt, late snowmelts did delay breeding. These delays, however, did not persist to southward migration through British Columbia, likely due to the birds¿ ability to compensate for variance in the length of the breeding season. Raptor phenology at an early stopover site in British Columbia was strongly related to snowmelt, so that in years of early snowmelt falcons appeared earlier during the sandpipers¿ southbound migration. These differential effects indicate that earlier snowmelt due to climate change may alter the ecological dynamics of the predator¿prey system.
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