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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Data from: Artificial night lighting inhibits feeding in moths
Langevelde, F. van; Grunsven, R.H.A. van; Veenendaal, E.M. ; Fijen, T.P.M. - \ 2017
nocturnal light pollution - feeding behaviour - Lepidoptera - moth population declines - sublethal effect
One major, yet poorly studied, change in the environment is nocturnal light pollution, which strongly alters habitats of nocturnally active species. Artificial night lighting is often considered as driving force behind rapid moth population declines in severely illuminated countries. To understand these declines, the question remains whether artificial light causes only increased mortality or also sublethal effects. We show that moths subjected to artificial night lighting spend less time feeding than moths in darkness, with the shortest time under light conditions rich in short wavelength radiation. These findings provide evidence for sublethal effects contributing to moth population declines. Because effects are strong under various types of light compared with dark conditions, the potential of spectral alterations as a conservation tool may be overestimated. Therefore, restoration and maintenance of darkness in illuminated areas is essential for reversing declines of moth populations.
Food reward from a behavioural and (neuro)physiological perspective
Bruijn, Suzanne E.M. - \ 2017
Wageningen University. Promotor(en): Kees de Graaf; Renger Witkamp, co-promotor(en): Gerry Jager. - Wageningen : Wageningen University - ISBN 9789463436748 - 154
food - physiological functions - feeding behaviour - food preferences - perception - hormones - responses - neurohormonal control - stomach bypass - gastric bypass - satiety - voedsel - fysiologische functies - voedingsgedrag - voedselvoorkeuren - perceptie - hormonen - reacties - neurohormonale controle - maag bypass - buik bypass - verzadigdheid

Food reward is an important driver of food intake and triggers consumption of foods for pleasure, so-called hedonic eating, even in the absence of any energy deficits. Hedonic eating can trigger overeating and may therefore lead to obesity. Given the rise in obesity rates and the health risks associated with being obese, hedonic eating and food reward are important phenomena to study. This thesis aimed to add on to the existing knowledge on food reward. The phenomenon was approached from a behavioural, sensory and (neuro)physiological perspective in healthy, lean and in obese gastric bypass populations.

For the behavioural perspective, the main outcome measure used in this thesis was food preferences. To be able to study food preferences for four macronutrient and two taste categories, a new food preference task was developed. In chapter 2, the development and validation of the Macronutrient and Taste Preference Ranking Task (MTPRT) were described. The MTPRT uses a ranking method to determine preferences for four macronutrient (high-carbohydrate, high-fat, high-protein, low-energy) and two taste (sweet and savoury) categories.

For the sensory and physiological perspective, focus was put on the endocannabinoid system (ECS): a neuromodulatory system that plays a role in food reward. To gain more insight into this role, the effect of ECS modulation with pharmacological challenges on sensory perception of sweet taste and on food preferences were studied, as well as endocannabinoid responses to food intake. In chapter 3 it was shown that inhaling Cannabis with low doses of Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) does not alter sweet taste intensity perception and liking in humans, nor does it affect food preferences. Vice versa, in chapter 4 it was found that liking of a food taste does not affect endocannabinoid responses to food intake, after controlling for expectations. When palatability of the food is unknown until the first bite, response of endocannabinoids, ghrelin and pancreatic polypeptide did not differ between a palatable and a neutral food across anticipatory, consummatory and post-ingestive phases of food intake. Endocannabinoid and ghrelin plasma concentrations decreased after food intake, which suggests an orexigenic function for endocannabinoids.

In chapters 5, 6 and 7, studies with patients who underwent Roux-en-Y gastric bypass surgery were described. These studies were intended to gain more insight into alterations in food reward in relation to (morbid) obesity and in response to surgical treatment by RYGB surgery.

First, in chapter 5 food preferences were assessed before, and at two months and one year after RYGB. It was shown that patients have decreased preference for high-carbohydrate and high-fat foods, and increased preference for low-energy foods after compared with before surgery. In addition, liking ratings for the high-carbohydrate and high-fat foods were decreased after RYGB surgery, whereas liking of low-energy products changed minimally. Potential mechanisms behind these alterations in food preferences include changes in neural processing of food cues and changes in appetite-related gut hormones.

In chapter 6, it was shown that alterations in food preferences after RYGB surgery are indeed related to changes in neural activation in response to food cues. With regards to the appetite-related hormones it was shown that plasma concentrations of the endocannabinoid anandamide were increased after compared with before surgery. Plasma concentrations of other endocannabinoids and ghrelin did not change. Moreover, changes in endocannabinoid or ghrelin concentrations did not correlate with changes in food preferences or neural response to food cues. Together, these results suggest that changes in neural processing of food cues contribute to changes in food preferences towards low-energy foods, and provide a first indication that the endocannabinoid system does not seem to play a role in this process.

To gain more insight into behavioural responses to food cues, a response-inhibition paradigm was used in chapter 7, in which response-inhibition to high-energy and low-energy food cues was assessed during brain imaging. The behavioural data did not show differences in performance when comparing before and two months after RYGB surgery. The brain imaging data showed that activation in reward-related brain areas was decreased in response to both high- and low-energy food pictures after RYGB surgery. Also, prefrontal brain areas were more activated in response to the high-energy pictures, which suggests improved response inhibition.

In conclusion, the findings in this thesis show that modulating the ECS with low doses of THC and CBD does not influence sweet taste perception and liking and food preferences, and vice versa, food taste liking in the absence of expectations does not affect endocannabinoid responses to food intake. With regards to RYGB surgery it was uncovered that changes in food preferences after RYGB surgery are related to altered brain reward processing, but no relation with changes in endocannabinoid tone was found. The success of RYGB surgery and the changes in food choice might in part be caused by an improved inhibitory response to high-energy foods.

Between odours and overeating : behavioural and neurobiological mechanisms of olfactory food-cue reactivity
Zoon, Harriët F.A. - \ 2017
Wageningen University. Promotor(en): Kees de Graaf, co-promotor(en): Sanne Boesveldt. - Wageningen : Wageningen University - ISBN 9789463431675 - 178
geurstoffen - overeten - neurobiologie - voedingsgedrag - reukstimulatie - obesitas - eetlust - overgewicht - buik bypass - verzadigdheid - odours - overeating - neurobiology - feeding behaviour - olfactory stimulation - obesity - appetite - overweight - gastric bypass - satiety

The obesogenic environment we live in is characterized by an abundance of available foods and food cues that tempt us to eat. Throughout our lives we learn to associate these food cues (odours, pictures) with physiological consequences of food consumption. The sense of smell is suggested to be very important for determining food quality, guiding us away from spoilt food and towards rewarding foods. Increased sensitivity to environmental cues of rewarding food, decreased sensitivity to physiological cues of hunger and a decreased ability to control impulses are thought to contribute to overeating and obesity. With the research in this thesis we aimed to elucidate the role of odours in (over)eating, to better understand how sensory food cues and hunger feelings are involved in determining our eating pattern.

We assessed the appetizing effects of exposure to odours signalling food with a certain taste (sweet/savoury) and energy density (high/low). Our findings show that smelling a food odour increases appetite for foods that are similar to the odour, both in terms of taste and energy density. These appetizing effects were present when participants were hungry but also when they had just eaten, indicating a possible role in overeating.

Further, consumption of a high-energy food with a certain taste (sweet/savoury) led to a decrease in liking and wanting of foods with a similar taste and energy density. Next to this, we observed more pronounced changes in early neural processing of pictures of high-energy/sweet food after consumption of a high-energy/sweet meal.

Food preferences and -intake after ambient exposure to odours signalling high-energy food, low-energy food and non-food were not different. Odours did not affect these measures of eating behaviour differently in a hungry or satiated state and in normal-weight or overweight participants.

In a group of patients who underwent Roux-en-Y Gastric Bypass weight-loss surgery, we found a shift in food preferences away from high-fat/high-sugar and towards low-fat/low-sugar foods and altered activation in the frontoparietal neural network during (food) cue processing. After compared to before surgery we also found altered prefrontal neural responses when patients inhibited their responses to pictures of high-energy food. These results suggest that RYGB leads to changes in cognitive control of attention and increased neural inhibitory control over behavioural responses.

In conclusion, odours have a specific appetizing function in the anticipatory phase of eating. They are important in determining the taste quality and energy-density and may be involved in the selection of foods for macronutrient regulation. Orthonasal odours should be used to guide food selection towards a healthier eating pattern.

Undernutrition management and the role of protein-enriched meals for older adults
Ziylan, Canan - \ 2016
Wageningen University. Promotor(en): Lisette de Groot; Stefanie Kremer; Annemien Haveman-Nies. - Wageningen : Wageningen University - ISBN 9789462579323 - 148
elderly - elderly nutrition - undernutrition - enrichment - protein - eating patterns - feeding behaviour - meals - nursing homes - ouderen - ouderenvoeding - ondervoeding - verrijking - eiwit - eetpatronen - voedingsgedrag - maaltijden - verpleeghuizen

Undernutrition is a major health problem in the growing elderly population. It is estimated that one in ten Dutch community-dwelling older adults is suffering from undernutrition, and one in three Dutch older adults who receive home care. Undernutrition may lead to many negative consequences, ranging from fatigue and falls to impaired immune function and death. This makes undernutrition an obvious target for preventive measures.

Undernutrition can be defined as “a state of nutrition in which a deficiency or excess (or imbalance) of energy, protein, and other nutrients causes measurable adverse effects on tissue/body form (body shape, size and composition) and function, and clinical outcome”. In addition, it is often described as protein energy malnutrition. Adequate protein intake may to some extent prevent and reverse this process. However, throughout ageing, it becomes increasingly difficult to reach adequate protein intake due to higher protein needs and lower protein intakes. Finding solutions to assist older adults in reaching their optimal protein intake is necessary.

In our overall research project, we considered 1.2g protein per kg weight per day (g/kg/d) as adequate protein intake. In Dutch community-dwelling older adults, protein intake is around 1.0 g/kg/d, implying room for improvement. However, it is possible that many of these older adults deal with physiological changes, medical conditions, and physical and mental limitations that impair their appetite and food provision. For these older adults with higher protein needs, merely recommending that they eat more would not be realistic. It would be more realistic to explore strategies that increase protein intake without having to increase food intake. This calls for the exploration of instruments that match the needs and preferences of older adults: protein-enriched regular products.

One particular group that can be identified as a target group for such products, are older adults who receive home care. Undernutrition prevalence is high in this group, which may be explained by their health problems that led to this dependence on home care. Likewise, many of these older adults also depend on meals-on-wheels. These meals-on-wheels recipients, regardless of whether they receive home care or not, often risk undernutrition too. In both these (overlapping) care-dependent groups, difficulties in adhering to energy and protein recommendations can be discerned. For this reason, enriching the readymade meals that these older adults receive may contribute to the prevention of protein undernutrition by increasing protein intake while keeping food intake the same. Here, protein enrichment instruments can be used to prevent undernutrition, but only when implemented in a timely manner. Adequate undernutrition management systems are therefore necessary to facilitate timely intervention, ensuring that the developed protein-enriched meals are actually offered and effective. For this reason, the overall aim of our research project was to gain insight into the current state of undernutrition management in community-dwelling older adults in the Netherlands and explore the role of protein-enriched regular products as a supportive instrument in protein undernutrition management.

In Study 1 (chapter 2) we explored the experiences of 22 Dutch nutrition and care professionals and researchers with undernutrition awareness, monitoring, and treatment among community-dwelling older adults. This qualitative study among, for example, dietitians, general practitioners, nurse practitioners, and home care nurses provided insight into the current bottlenecks within the existing undernutrition management guidelines. In these telephone interviews, these experts also discussed the current dietary behaviour problems of older adults and their impact on undernutrition risk. The experts’ experiences implied that undernutrition awareness is limited, among both older adults and care professionals. In addition, the interviewees were unclear about which professionals are responsible for monitoring and which monitoring procedures are preferred. The dietitians feel that they become involved too late, leading to decreased treatment effectiveness. In general, the interviewees desired more collaboration and a coherent and feasible allocation of responsibilities regarding undernutrition monitoring and treatment. This implied that the available guidelines on undernutrition management require more attention and facilitation.

In the following mixed-methods study (chapter 3), with interviews, we qualitatively explored the dietary behaviour and undernutrition risk of 12 Dutch elderly meals-on-wheels clients, one of the largest at-risk groups. We followed up on this information by quantifying the topics that emerged from the qualitative exploration of experienced bottlenecks in performing adequate dietary behaviour. For this, we used a survey among 333 meals-on-wheels clients. The interviews with elderly meals-on-wheels clients made clear that they have fixed and habitual eating patterns, while at the same time their appetite had decreased throughout the years. This was confirmed by the survey finding that regular portion size meals were perceived as too large by the oldest group aged over 75y. In addition, as the professionals suggested earlier, the interviewed elderly clients indeed showed limited awareness of undernutrition risk. Simultaneously, the survey showed that almost one in four elderly meals-on-wheels clients was undernourished. These findings led to the conclusion that staying close to the identified dietary habits may facilitate small yet effective modifications within these habits to prevent inadequate nutritional intake. Still, the limited awareness of undernutrition risk was expected to play a limiting role in whether clients believe they need dietary modifications. Consequently, informing them about this need could facilitate their motivation to implement modifications.

After learning about the general dietary behaviour of these older adults, we used this information for Study 3 (chapter 4). We developed two kinds of protein-enriched readymade meals that are in line with the needs and preferences of older adults: one of regular size (450g) and one of reduced size (400g). We tested these meals in a lab setting in 120 community-dwelling older adults in a single-blind randomised crossover trial. One day a week at lunchtime, for four weeks, participants had to consume and evaluate a readymade meal. Overall, regardless of portion size, the protein-enriched meals led to higher protein intakes in vital older adults in a lab setting during lunch. In this crossover study, the participants liked the protein-enriched meals and the regular meals equally. However, we did not find the expected lower ratings of satiety after the reduced-size meals, while one reduced-size enriched meal and another regular-size enriched meal led to higher ratings of subsequent satiety. This higher satiety in the enriched meals could lead to compensational behaviour on the remainder of the day.

After establishing that the protein-enriched meals were effective and acceptable in the lab setting, we moved to the homes of older adults to test the meals in a longer-term study in Study 4 (chapter 5). In this double-blind randomised controlled trial of two weeks, we also included protein-enriched bread to assess whether both this bread and the meals could increase daily protein intake to 1.2g/kg/d in 42 community-dwelling older adults to reach optimal protein intake. We found that the enriched products again led to higher protein intakes and a high liking. The mean protein intake per day was 14.6g higher in the intervention group, which amounted to a protein intake of 1.25g/kg/d, compared with 0.99g/kg/d in the control group. In addition, the meals scored 7.7 out of 10, while the bread scored 7.8 out of 10, which both were comparable with their regular counterparts. Lastly, we found no negative effect of compensational behaviour throughout the day. These promising findings indicated that we achieved a good match between older adults’ needs and preferences regarding protein intake.

In the general discussion of this thesis (chapter 6), we combined our learnings from the four studies to reflect on protein undernutrition management in community-dwelling older adults and the possible role of protein-enriched regular products. We have discussed a conceptual framework consisting of three wheels of protein undernutrition management. In the first wheel regarding awareness, we proposed that limited awareness of adequate nutrition and body composition forms the largest bottleneck in undernutrition management. When this awareness is generated among both older adults and professionals, it will benefit the second wheel of monitoring. Here, we argued that a policy and the actual facilitation of that policy are required for this monitoring to succeed. When the monitoring is performed adequately, in the third wheel, the appropriate treatment can be carried out. We discussed that personalisation and evaluation of this treatment are important conditions. All in all, the public health implications that we have discussed on the basis of our findings can be summarised by the three key messages that could help us ace in adequate protein undernutrition management: address awareness in both older adults and professionals, facilitate continuous collaboration between professionals, and offer protein-enriched products expediently.

Bruinvis verhongert soms in zee vol vis : tien jaar onderzoek naar menu zeezoogdier
Leopold, Mardik - \ 2016
phocoena - animal behaviour - animal ecology - population ecology - feeding behaviour - feeding ecology - marine biology
Foraging behaviour of parasitoids in multi-herbivore communities
Rijk, M. de - \ 2016
Wageningen University. Promotor(en): Marcel Dicke, co-promotor(en): Erik Poelman. - Wageningen : Wageningen University - ISBN 9789462576377 - 217 p.
016-3931 - parasitoids - parasitoid wasps - feeding behaviour - plant-herbivore interactions - hosts - host parasite relationships - host preferences - host-seeking behaviour - cotesia glomerata - pieris brassicae - brassica oleracea - parasitoïden - sluipwespen - voedingsgedrag - plant-herbivoor relaties - gastheren (dieren, mensen, planten) - gastheer parasiet relaties - gastheerpreferenties - gedrag bij zoeken van een gastheer

Foraging behaviour of parasitoids in multi-herbivore communities

Parasitic wasps, or parasitoids, use herbivore-induced plant volatiles and infochemicals produced directly by the herbivore to locate their herbivorous hosts. This process could be interrupted by the presence of herbivores that are not suitable for the development of parasitoid offspring. These non-host herbivores could affect the behaviour of parasitoids both when parasitoids are foraging for host-infested plants by using plant volatiles and when parasitoids are foraging for hosts on the plant by using herbivore infochemicals.

The aim of this thesis was to study the impact of non-host presence on the parasitoid-host-food plant complex of the parasitoid Cotesia glomerata with its host caterpillar Pieris brassicae and a monoculture of the cultivated plant Brassica oleracea. To study the influence of non-hosts on the plant-volatile-based searching behaviour of the parasitoid, a wind-tunnel set-up in the laboratory was used. In this set-up, the parasitoids were given a choice between two plants or between the leaves of one plant. The plant/leaf on which the parasitoid landed was considered the preferred plant/leaf. A second laboratory set-up was used to study the influence of non-host herbivores on the host-infochemical-based searching behaviour of the parasitoid. In this on-plant experiment, the behaviour of the parasitoid was observed after landing on the plant. The influence of non-hosts on the combination of plant-volatile-based and host-infochemical-based searching, i.e. the total foraging efficiency of the parasitoid, was investigated using an outdoor tent set-up in an agricultural field. In this semi-field experiment, parasitoids were allowed to parasitize their hosts in a non-host environment for one to three days.

This thesis firstly shows that the feeding guild of non-host herbivores influenced the foraging behaviour of C. glomerata. Leaf-chewing non-hosts negatively impacted the plant-volatile-based searching behaviour of the parasitoid, whereas phloem-feeding non-hosts positively impacted the host-infochemical-based searching. The resulting host-finding efficiency was in general positively affected by phloem-feeding non-hosts. Secondly, the position of host and non-host herbivores on the plant affected the plant-volatile-based and the host-infochemical-based foraging behaviour of the parasitoid, but not the host-finding efficiency. An unnatural distribution of herbivores over the plant (host feeding on old leaf, non-host feeding on young leaf), negatively affected the choice of the parasitoid for a leaf to land on, i.e. the parasitoid more often landed on the non-host infested leaf. Combined feeding by the host and non-host on one leaf positively affected the number of hosts parasitized on that plant compared with the number of hosts parasitized when herbivores were separated. However, the parasitoid was able to compensate for these effects as a result of which the foraging efficiency was unaltered. Thirdly, the density of non-hosts did influence the plant-volatile-based searching of the parasitoid. A high non-host density negatively affected parasitoid preference for host-infested plants. However, the host-infochemical-based foraging and the total foraging efficiency remained unaffected. Fourthly, rather than the species diversity, the species identity of non-host herbivores had an influence on parasitoid host-infochemical-based searching. One of the tested non-host species negatively affected the behaviour of the parasitoid when searching on the plant. However, neither non-host species identity nor diversity affected plant-volatile-based searching of the parasitoid. Fifthly, this thesis investigated if a parasitoid could learn to associate non-host cues with the presence of hosts and if the parasitoid changed the parasitization preference accordingly. After receiving a learning experience, the parasitoid showed an altered landing preference for infested plants according to the learned cues. However, in an outdoor tent set-up, the parasitoid did not show an altered parasitization preference.

The results of this thesis show that non-host herbivore traits can affect the different phases of parasitoid foraging either positively, negatively or neutrally. The non-host effect on the total foraging efficiency is not necessarily a result of the sum of the effects on the first and the second foraging phase. In fact, the results of two out of three outdoor-tent experiments that investigated the foraging efficiency of the parasitoid showed no non-host effect, while the separate foraging phases were affected by non-host presence.

It is concluded that the foraging efficiency of the parasitoid C. glomerata when searching for its host P. brassicae is not strongly affected by non-host herbivore presence. The use of herbivore-induced plant volatiles by C. glomerata during this foraging process is not interrupted by non-host herbivores. It is advised to consider all phases of the foraging process in studies of parasitoid foraging behaviour, preferably in one experiment that covers the whole searching process. Altogether, this thesis gives a clear and comprehensive overview of the impact of non-host presence on a parasitoid-host-food plant complex and it thereby contributes to the fundamental knowledge of insect foraging in a multi-herbivore context.

Mapping moves on Arabidopsis : from natural variation to single genes affecting aphid behaviour
Kloth, K.J. - \ 2016
Wageningen University. Promotor(en): Marcel Dicke; Harro Bouwmeester, co-promotor(en): Maarten Jongsma. - Wageningen : Wageningen University - ISBN 9789462576483 - 269 p.
016-3933 - arabidopsis thaliana - insect pests - aphidoidea - pest resistance - genetic mapping - gene expression - quantitative traits - functional genomics - feeding behaviour - insect plant relations - insectenplagen - plaagresistentie - genetische kartering - genexpressie - kwantitatieve kenmerken - functionele genomica - voedingsgedrag - insect-plant relaties
Onderzoek Grote Sterns Utopia
Leopold, Mardik - \ 2015
birds - sterna - foraging - feeding behaviour - monitoring - faeces collection - dutch wadden islands
Opfrisbeurt voor de Schijf van Vijf
Ramaker, R. ; Aarts, M.N.C. - \ 2015
Resource: weekblad voor Wageningen UR 10 (2015)7. - ISSN 1874-3625 - p. 12 - 15.
voeding en gezondheid - dieetrichtlijnen - gezondheidsvoedsel - eetpatronen - voedingsgedrag - voedselconsumptie - aanbevolen dagelijkse hoeveelheden - nutrition and health - dietary guidelines - health foods - eating patterns - feeding behaviour - food consumption - recommended dietary allowances
De Schijf van Vijf is een begrip in Nederland. Maar dit iconische beeld lijkt tegenwoordig oubollig naast de snelle foodblogs, gelikte kookboeken en charismatische eetgoeroes. Hoe maken we schijf klaar voor de toekomst?
Waarom kun je door blijven eten terwijl je eigenlijk al vol zit?
Witkamp, R.F. - \ 2015
Universiteit van Nederland
voedselconsumptie - overeten - voedingsgedrag - fysiologie - neurofysiologie - verslaving - biologie - food consumption - overeating - feeding behaviour - physiology - neurophysiology - addiction - biology
Je hebt al een amuse, voorgerecht, hoofdgerecht en toetje op, en dan is-ie daar ineens: de kaasplank. Hoe is het mogelijk dat je door kunt blijven eten terwijl je al vol zit? Renger Witkamp, hoogleraar Voeding en Farmacologie (Wageningen UR), legt je uit wat hier de verklaring voor is en waarom dat ooit nuttig was.
Culturing soles on ragworms: growth and feeding behaviour
Ende, S.S.W. - \ 2015
Wageningen University. Promotor(en): Johan Verreth, co-promotor(en): Johan Schrama. - Wageningen : Wageningen University - ISBN 9789462575622 - 128
solea - soleidae - kweekvis - voeropname - groei - prooi - wormen - foerageren - voedingsgedrag - prestatieniveau - vijverteelt - aquacultuur - farmed fish - feed intake - growth - prey - helminths - foraging - feeding behaviour - performance - pond culture - aquaculture

Ende, S.S.W. (2015). Culturing soles on ragworms: Growth and feeding behaviour. PhD thesis, Wageningen University, The Netherlands.

Despite the high market demand and intensive research efforts since the 1960s commercial culture of common sole (Solea solea L.) has been unsuccessful. Problems related to availability and price of suitable raw materials (invertebrates) and the low tolerance to crowding have hampered the development of intensive sole culture. Alternative extensive pond cultures systems are currently explored where common sole can graze on natural food. The general aim of this study was to get insight into which factors limit growth of common sole foraging on ragworms in ponds. The results did not show any nutritional effects that may hamper the growth of common sole. At non-limiting conditions, i.e. when fed chopped ragworms and when housed in sediment free tanks, common sole showed higher food intake, higher growth rates and higher nutrient utilization efficiencies than when fed mussels or a formulated diet. The results however suggest that growth in a pond with ragworms was limited by reduced foraging capabilities of common sole. To explore this hypothesis, the effect of prey size, predator size and prey density were tested. Overall, intake of buried ragworms was reduced by more than half in contrast to intake of unburied ragworms. Intake of buried ragworms was reduced regardless of ragworm size or common sole size. Increasing ragworm density only resulted in satiation intake values in smaller common sole. Our results additionally indicate that the presence of common sole hampers ragworm performance in a pond. Ragworms reduced their feeding activities when receiving water from tanks which contained common sole and ragworms, i.e. when common sole could graze on ragworms. Results from this PhD study suggest that the growth of common sole in ponds is not limited by nutritional but by their foraging abilities. However, the results of this study are too incomplete to fully predict growth performance of common sole in a pond. Factors such as temperature, oxygen supply or feeding activity need to be investigated to make comprehensive growth predictions.

Eat and be eaten: porpoise diet studies
Leopold, M.F. - \ 2015
Wageningen University. Promotor(en): Peter Reijnders. - Wageningen : Wageningen University - ISBN 9789462575585 - 239
phocoenidae - phocoena - diervoedering - voedingsgedrag - predatoren - voedingsgewoonten - foerageren - zeehonden - noordzee - nederland - animal feeding - feeding behaviour - predators - feeding habits - foraging - seals - north sea - netherlands
Eutrophication, Nile perch and food-web interactions in south-east Lake Victoria
Cornelissen, I.J.M. - \ 2015
Wageningen University. Promotor(en): Johan Verreth, co-promotor(en): Leo Nagelkerke; R. Vijverberg. - Wageningen : Wageningen University - ISBN 9789462575660 - 163
lates niloticus - eutrofiëring - voedselwebben - interacties - visserijbiologie - visstand - dynamica - fytoplankton - distributie - voedingsgedrag - victoriameer - tanzania - eutrophication - food webs - interactions - fishery biology - fish stocks - dynamics - phytoplankton - distribution - feeding behaviour - lake victoria

The increasing eutrophication, the introduction of Nile perch (Lates niloticus) and the increasing fishing pressure has changed Lake Victoria tremendously the last century. Since the 1960s, eutrophication increased primary production, enabling an increase in fish production. However, eutrophication also created hypoxia pockets, which reduced the available habitats for fish. In addition, the endemic haplochromines declined, whereas the introduced Nile perch boomed in the 1980s. The Nile perch boom and increased fish production resulted in the largest freshwater fisheries of the world. However, it is unclear whether fish production can still increase with further eutrophication as maximum primary production rates may have been reached. Fish stocks fluctuate since the 1980s and in order to manage these, it is important to understand how eutrophication and fisheries affect the Nile perch population. The present study investigates the bottom-up effects of eutrophication on the Nile perch and food-web dynamics in south-east Lake Victoria. We analysed the level of eutrophication along an eutrophication gradient in the Mwanza Gulf. Phytoplankton biomass varied spatially and seasonally and was limited by nutrients in deep water and by light in shallow water. Fish distributions were dynamic, with environmental factors depth and temperature influencing Nile perch size structure and distribution patterns similarly on small and large spatial scales. Although prey densities of haplochromines and Caridina nilotica shrimp did not explain Nile perch distributions, ontogenetic diet shifts and composition were related to prey densities, suggesting an opportunistic feeding behaviour of Nile perch. Small Nile perch however, showed some preference to shrimp and Nile perch preferred haplochromines above Dagaa (Rastrineobola argentea) and juvenile Nile perch as fish prey. On a food-web level, the base of the food web was spatially and seasonally highly dynamic. The onset of rains caused a spatial differentiation in littoral/benthic and pelagic carbon sources, affecting the whole food web. Trophic levels of fish were related to the spatial variation in diet compositions. Although a large heterogeneity was found in water quality, fish distributions and food-web structure, bottom-up processes affected the food web similarly. Despite the ongoing nutrient load in Lake Victoria, water quality has improved since the 1990s. Climate forcing through increasing wind speeds increased visibility and oxygen levels. Global climate change will therefore be an important driver of the water quality and fish distributions of Lake Victoria.

Noelle Aarts over The art of dialogue
Aarts, M.N.C. - \ 2015
Luc Dinnissen
communicatietheorie - communicatie - informatieverspreiding - gedragsveranderingen - organisaties - natuurbeheer - voedingsgedrag - communication theory - communication - diffusion of information - behavioural changes - organizations - nature management - feeding behaviour
Communication and change in the field of life sciences. The focus of Noelle Aarts is on inter-human processes and communication with an emphasis on the significance of conversations and stories in change processes.
Gezocht: dé gezonde eter
Ramaker, R. ; Swan, E.C. ; Bouwman, L.I. - \ 2015
Resource: nieuwssite voor studenten en medewerkers van Wageningen UR 9 (2015)14. - ISSN 1389-7756 - p. 10 - 10.
voeding en gezondheid - eetpatronen - voedingsgedrag - voedselconsumptie - nutrition and health - eating patterns - feeding behaviour - food consumption
Wageningse wetenschappers heb- ben een eerste profielschets ge- maakt van dé gezonde eter.
Study of drimane sesquiterpenoids from the Persicaria genus and zigiberene from Callitropsis noorkatensis and their effect on the feeding behaviour of Myzus persicae and Bemisia tabaci
Prota, N. - \ 2015
Wageningen University. Promotor(en): Harro Bouwmeester, co-promotor(en): Maarten Jongsma. - Wageningen : Wageningen University - ISBN 9789462572133 - 191
polygonum - xanthocyparis - sesquiterpenoïden - voedingsgedrag - myzus persicae - bemisia tabaci - vraatremmers - plantensamenstelling - pyrethrinen - chemische samenstelling - verdedigingsmechanismen - sesquiterpenoids - feeding behaviour - antifeedants - plant composition - pyrethrins - chemical composition - defence mechanisms

Summary

Whitefly is an insect pest that has systematically spread into colder latitudes for the past two decades and it poses a serious threat to crops, mainly due to the viruses for which it acts as a vector. As the application of synthetic pesticides is often less effective due to development of resistance or restricted by crop- and country-specific regulations, Integrated Pest Management (IPM) strategies to combat insect pests become attractive. In this thesis, I discuss the potential of the use of secondary metabolites, particularly sesquiterpenoids, of plant origin, both as sprayed repellents or antifeedants and as part of host plant resistance against whitefly.

In Chapter 1, I give a detailed description of the silverleaf whitefly, Bemisia tabaci, its ecology and its effect on crop yield, taking both direct and indirect damage (caused by the viruses the insect transmits) into account. This chapter also provides a detailed account of pest management strategies, both traditional and emergent, with their advantages and disadvantages. The chapter introduces the reader to plant secondary metabolites, and specifically terpenes, discussing their role in plant ecology and their potential as pest management tools with a low environmental impact. Finally, a short overview of the following chapters is given.

Chapter 2 focusses on the antifeedant activity of the drimane sesquiterpene polygodial. This dialdehyde had been described before as antifeedant to a number of insects, such as the Colorado potato beetle, Leptinotarsa decemlineata, the African cotton leafworm, Spodoptera littoralis, and the green peach aphid, Myzus persicae. In this chapter, the effect of polygodial on the feeding preference of whitefly is reported for the first time. The effect of polygodial was benchmarked against that of the more widely used natural pyrethrins, and both were also tested against M. persicae. From the results, we conclude that pyrethrins were effective against whiteflies at 18-fold lower concentrations than polygodial (ED50 of 1.4 and 25 μg gFW-1 respectively), while in the case of aphids this difference in efficacy was only two-fold (ED50 of 28 and 54 μg gFW-1, respectively).

To adopt polygodial as a more persistent and easy to implement pest management strategy, we set out to isolate the genes responsible for its biosynthesis which could then be used to transform crops. As a basis for the selection of the right species and plant tissue to achieve this objective, Chapter 3 describes the chemical composition of one of the sources of polygodial – Persicaria hydropiper (water pepper), as well as of two other congeners (Persicaria minor and Persicaria maculosa). For all three species, GC-MS analysis of extracts of leaves and flowers was performed, which gave insight into the interspecific differences and similarities as well as into the differences between the two tissues. P. hydropiper was the species with the biggest variety and the greatest abundance of secondary metabolites, while P. maculosa had the fewest. The flowers of all species were richer in secondary metabolites compared with the leaves of the same species. Furthermore, the accumulation pattern of the identified compounds throughout the development of flowers and leaves is described. Finally, in this chapter, the possible ecological role of polygodial is also briefly addressed.

Chapter 4 focuses on the discovery and characterization of genes involved in the biosynthesis of drimane sesquiterpenoids. Based on the findings of Chapter 3, we used 454 sequencing of a cDNA library constructed from young flowers of P. hydropiper and P. maculosa, for comparison, to identify a drimenol synthase (PhDS) and a drimenol oxidase (PhDOX1) which can convert farnesyl diphosphate (FPP) into drimenol and an array of other sesquiterpenoids when working in concert. Of the compounds produced in the heterologous systems used (Saccharomyces cerevisiae and Nicotiana benthamiana), two were identified as drimendiol and cinnamolide. The latter was purified and tested against whiteflies and aphids as described for polygodial in Chapter 2. Cinnamolide also displayed antifeedant activity against both insects, although with at slightly lower efficacy than polygodial. In the heterologous hosts used, no polygodial was detected amongst the products of the enzymatic activity of the two genes studied in this chapter. The potential reasons for this are explored in the discussion section of this chapter.

Chapter 5 focuses on the volatile zingiberene, member of the bisabolane family of sesquiterpenes. This compound and its enantiomer, 7-epi-zingiberene have both been previously identified as repellent to whiteflies. In this chapter we used Alaska yellow cedar (Callitropsis nootkatensis) as a possible source of a zingiberene synthase, which we wanted to use a primary line of defence against whitefly next to polygodial, which would be a secondary line of defence. Alaska yellow cedar produces curcumene in some of its tissues, and this metabolite is known to be a dehydrogenation product of zingiberene. An EST from a C. nootkatensis cDNA library with homology to sesquiterpene synthases was cloned and expressed in E. coli. The resulting protein converted FPP to zingiberene as the sole product. This enzyme was therefore named zingiberene synthase (CnZIS). Although no strict correlation was found between the expression levels of CnZIS in Alaska yellow cedar tissues and the accumulation of curcumene in the same tissues, those with high CnZIS expression such as leaves also produced high amounts of curcumene, while heartwood neither expressed the gene nor had detectable levels of curcumene. Subsequently, we tested the effect of transiently expressed CnZIS in tobacco (Nicotiana tabacum) on whiteflies. Except for one time point, the effect of zingiberene on whitefly feeding was negligible, likely due to the fact that only trace amounts of zingiberene were emitted. When genes upstream of CnZIS in the biosynthetic pathway – 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMGR) and farnesyl diphosphate synthase (FPS) – were co-expressed in tobacco, the antifeedant effect on whiteflies became very strong; however, there was still no detectable level of zingiberene emitted. Instead, the emission of the tobacco sesquiterpene, 5-epi-aristolochene, was almost 100-fold higher than in the control, not expressing HMGR and FPS. We discuss potential explanations of this phenomenon, as well as the uncommon outcome of having an endogenous sesquiterpene boosted by the co-expression and redirection to the mitochondria of the three genes of the zingiberene biosynthetic pathway.

Chapter 6 brings all the findings together, discussing their place within a wider scientific perspective and their potential in the frame of IPM. Advantages as well as drawbacks of the use of GM crops are addressed. Finally, the emerging new agricultural paradigm, of a sustainable way of growing crops with less environmental impact compared with the current intensive industrial approach, is brought forth as a broad spectrum solution to most agricultural problems which arose in parallel to the intensification of agriculture that stemmed from the Green revolution.

Terug in het zadel
Bouwman, L.I. - \ 2014
Vork 1 (2014)4. - ISSN 2352-2925 - p. 32 - 36.
food chains - nutrition and health - overweight - obesity - chronic diseases - consumer behaviour - feeding behaviour - eating - eating patterns - voedselketens - voeding en gezondheid - overgewicht - obesitas - chronische ziekten - consumentengedrag - voedingsgedrag - eten - eetpatronen
Dreigende epidemieën van overigens niet besmettelijke aandoeningen als obesitas en diabetes type 2 leiden tot - soms tegenstrijdige - aanbevelingen voor gezond eten. Meer groenten, minder vet maar wel meer vette vis, minder rood vlees, meer koolhydraten of juist minder en een Magnum, passen in een gezond dieet. Dat laatste was overigens een advies van de vorige directeur van Unilever dus dat moeten we met een korreltje zout nemen. Hoewel, zout? Mag dat? Volgens Laura Bouwman zijn we terechtgekomen in een situatie van ‘you are what you are told to eat’, waarbij mensen weten dat ze ongezond eten, er ook iets aan willen doen, maar vandaag nog even niet. Ze pleit voor een andere benadering, gericht op verbinding en het bevorderen van het ‘goede leven’.
Induction of indirect plant defense in the context of multiple herbivory : gene transcription, volatile emission, and predator behavior
Menzel, T.R. - \ 2014
Wageningen University. Promotor(en): Marcel Dicke; Joop van Loon. - Wageningen : Wageningen University - ISBN 9789462571297 - 146
planten - plaagresistentie - geïnduceerde resistentie - verdedigingsmechanismen - multitrofe interacties - phaseolus lunatus - mijten - tetranychus urticae - roofmijten - phytoseiulus persimilis - voedingsgedrag - genen - transcriptie - genexpressie - herbivoor-geinduceerde plantengeuren - plants - pest resistance - induced resistance - defence mechanisms - multitrophic interactions - mites - predatory mites - feeding behaviour - genes - transcription - gene expression - herbivore induced plant volatiles

Abstract

Plants live in complex environments and are under constant threat of being attacked by herbivorous arthropods. Consequently plants possess an arsenal of sophisticated mechanisms in order to defend themselves against their ubiquitous attackers. Induced indirect defenses involve the attraction of natural enemies of herbivores, such as predators and parasitoids. Predators and parasitoids use odors emitted by damaged plants that serve as a “cry for help” to find their respective prey or host herbivore. The aim of this thesis was to use a multidisciplinary approach, with focus on molecular and chemical methods, combined with behavioral investigations, to elucidate the mechanisms of plant responses to multiple herbivory that affect a tritrophic system consisting of a plant, an herbivore and a natural enemy.

Induced plant defenses are regulated by a network of defense signaling pathways in which phytohormones act as signaling molecules. Accordingly, simulation of herbivory by exogenous application of phytohormones and actual herbivory by the two-spotted spider mite Tetranychus urticae affected transcript levels of a defense gene involved in indirect defense in Lima bean. However, two other genes involved in defense were not affected at the time point investigated. Moreover, application of a low dose of JA followed by minor herbivory by T. urticae spider mites affected gene transcript levels and emissions of plant volatiles commonly associated with herbivory. Only endogenous phytohormone levels of jasmonic acid (JA), but not salicylic acid (SA), were affected by treatments. Nevertheless, the low-dose JA application resulted in a synergistic effect on gene transcription and an increased emission of a volatile compound involved in indirect defense after herbivore infestation.

Caterpillar feeding as well as application of caterpillar oral secretion on mechanically inflicted wounds are frequently used to induce plant defense against biting-chewing insects, which is JA-related. Feeding damage by two caterpillar species caused mostly identical induction of gene transcription, but combination of mechanical damage and oral secretions of caterpillars caused differential induction of the transcription of defense genes. Nevertheless, gene transcript levels for plants that subsequently experienced an infestation by T. urticae were only different for a gene potentially involved in direct defense of plants that experienced a single event of herbivory by T. urticae. Indirect defense was not affected. Also sequential induction of plant defense by caterpillar oral secretion and an infestation by T. urticae spider mites did not interfere with attraction of the specialist predatory mite P. persimilis in olfactometer assays. The predator did distinguish between plants induced by spider mites and plants induced by the combination of mechanical damage and caterpillar oral secretion but not between plants with single spider mite infestation and plants induced by caterpillar oral secretion prior to spider mite infestation. The composition of the volatile blends emitted by plants induced by spider mites only or by the sequential induction treatment of caterpillar oral secretion followed by spider mite infestation were similar. Consequently, the induction of plant indirect defense as applied in these experiments was not affected by previous treatment with oral secretion of caterpillars. Moreover, herbivory by conspecific T. urticae mites did not affect gene transcript levels or emission of volatiles of plants that experienced two bouts of herbivore attack by conspecific spider mites compared to plants that experienced only one bout of spider mite attack. This suggests that Lima bean plants do no increase defense in response to sequential herbivory by T. urticae.

In conclusion, using a multidisciplinary approach new insights were obtained in the mechanisms of induction of indirect plant defense and tritrophic interactions in a multiple herbivore context, providing helpful leads for future research on plant responses to multiple stresses.

The Dutch Healthy Diet Index : development, evaluation, and application
Lee, L. van - \ 2014
Wageningen University. Promotor(en): Edith Feskens, co-promotor(en): Anouk Geelen. - Wageningen : Wageningen University - ISBN 9789462570962 - 169
dieet - dieetrichtlijnen - gezondheid - gezondheidsindicatoren - dieetonderzoeken - voedselconsumptie - voedingsgedrag - diet - dietary guidelines - health - health indicators - dietary surveys - food consumption - feeding behaviour

The Dutch Healthy Diet index – Development, Evaluation, and Application

Linde van Lee

Abstract

Background: Dietary indices evaluate the conformity of an individual’s diet with pre-defined standards. Generally, dietary guidelines are used for this purpose. As no index based on the current dietary guidelines was available in the Netherlands, the aim of the present thesis was to develop, evaluate, and apply a dietary index for use in the country.

Methods and results: The Dutch Healthy Diet index (DHD-index) was developed on the basis of the 2006 Dutch dietary guidelines using data relating to 749 young adults who completed two 24-hour recalls in the Dutch national food consumption survey 2003. The index comprises ten components on physical activity, vegetables, fruit, dietary fibre, saturated fatty acids, trans fatty acids, consumption occasions with acidic drinks and foods, sodium, and alcohol. Scores for each component range between 0 (no adherence) and 10 (complete adherence) points. The DHD-index was inversely associated with energy intake and positively associated with most micronutrient intakes when adjusted for energy intake. We compared the DHD-index score based on two 24-hour recalls with the index based on the food frequency questionnaires (FFQ) of 121 adults from the European Food Consumption Validation study. We revealed an acceptable correlation (r=0.48) and absolute agreement between the indices based on the two methods. The prospective relationship with mortality outcomes was studied in 3593 of the Rotterdam Study participants who were followed for 20 years. The DHD-index per 10 points increment was associated with a 9% (95% CI 0.87-0.96) risk reduction for all-cause mortality, and non-significantly associated with risk reductions for cardiovascular disease, coronary heart disease, and stroke mortality. Among women, shared dinners were associated with lower DHD-index scores for that day than solo dinners in 1740 participants who contributed multiple 24-hour recalls in the Nutrition Questionnaires plus study. Among men and women, dinners shared with family members were associated with a higher DHD-index score on that day than dinners shared with others. Furthermore, in a subsample of 1235 participants in the Nutrition Questionnaires plus study, we evaluated the DHD-index based on the newly developed 34-item DHD-FFQ, a short questionnaire to assess diet quality in time-limited settings. The DHD-index based on the DHD-FFQ showed an acceptable correlation (r=0.56) with the index based on a 180-item FFQ, but showed a large variation in bias at individual level.

Conclusions: The DHD-index based on an FFQ, on multiple 24-hour recalls, or on the DHD-FFQ was considered a valid tool to rank participants according to their diet quality. The DHD-index was therefore considered useful to monitor populations, study diet–disease associations, and identify subpopulations at risk of poor diet quality.

Towards healthy diets for parents: effectiveness of a counselling intervention
Hooft Van Huysduynen, E.J.C. - \ 2014
Wageningen University. Promotor(en): Cees van Woerkum, co-promotor(en): Jeanne de Vries. - Wageningen : Wageningen University - ISBN 9789462571532 - 114
ouders - gezondheid - voeding en gezondheid - voeding - dieetadvisering - dieet - counseling - voedingsgedrag - parents - health - nutrition and health - nutrition - diet counseling - diet - counselling - feeding behaviour

Towards Healthy Diets for parents: efectiveness of a counselling intervention

Eveline J.C. Hooft van Huysduynen

Abstract

Introduction and Objective: As parents’ modelling of dietary behaviour is one of the factors influencing children’s diets, improving parents’ diets is expected to result in improved dietary intake of their children. This thesis describes research that was conducted to develop and evaluate a counselling intervention to improve parental adherence to the Dutch dietary guidelines.

Methods: A counselling intervention was developed, which was underpinned with the theory of planned behaviour and the transtheoretical model. In 20 weeks, five face-to-face counselling sessions were provided by a registered dietician who used motivational interviewing to improve parental adherence to the Dutch dietary guidelines. In addition, parents received three individually tailored email messages. During the counselling, the dietary guidelines and additional eating behaviours, that were hypothesized to affect diet quality, were addressed. The intervention was evaluated in a randomised controlled trial with 92 parents receiving the counselling and 94 parents as controls. Effects on dietary intake, biomarkers, intermediate markers of health and children’s dietary intake were evaluated. With mediation analyses, it was investigated if changes in dietary intake were established via changes in behavioural determinants. Thereby, it was also examined if spot urine samples could be used to replace 24 h urine samples for evaluating changes in sodium and potassium intake.

Results: The intervention group increased their adherence to the dietary guidelines, as assessed with the Dutch Healthy Diet-index (ranging from 0 to 100 points), by 6.7 points more than the control group did. This improvement was achieved by small increases in the scores of seven out of ten index components. The most substantial changes were shown in fruit and fish intakes of which increases in fish intake were reflected in changes in fatty acid profiles derived from blood plasma. Also a small decrease in waist circumference was observed. Based on parental reports, the children in the intervention group increased their intakes of fruit, vegetables and fish more than the children in the control group. Improvements in parental fruit intake were mediated by changes in the behavioural determinants attitude and habit strength. Decreases in snack intake were mediated by changes in self-identity as a healthy eater. Although the results of a study in young Caucasian women showed that spot urine can be used to rank individuals for their ratios of sodium to potassium, no intervention effects on these ratios were observed.

Conclusion: This thesis provides empirical knowledge on potential effective elements for counselling interventions aiming at improving the dietary pattern as a whole of parents and provides knowledge on methods to evaluate changes in dietary intake.

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