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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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.

Microorganism-mediated behaviour of malaria mosquitoes
Busula, Annette O. - \ 2017
Wageningen University. Promotor(en): Willem Takken, co-promotor(en): Jetske de Boer. - Wageningen : Wageningen University - ISBN 9789463431156 - 199
culicidae - anopheles gambiae - anopheles arabiensis - mosquito-borne diseases - disease vectors - animal behaviour - host-seeking behaviour - plasmodium falciparum - hosts - man - cows - hens - odours - ziekten overgebracht door muskieten - vectoren, ziekten - diergedrag - gedrag bij zoeken van een gastheer - gastheren (dieren, mensen, planten) - mens - koeien - hennen - geurstoffen

Host-seeking is an important component of mosquito vectorial capacity on which the success of the other behavioural determinants depends. Blood-seeking mosquitoes are mainly guided by chemical cues released by their blood hosts. This thesis describes results of a study that determined the effect of microorganisms – host skin bacteria as well as malaria parasites – on host-seeking behaviour of female Anopheles gambiae sensu stricto and An. arabiensis in Homabay county, western Kenya. Semi-field and field experiments were conducted to determine the response of mosquitoes with different host preference to synthetic and natural odour blends from three vertebrate hosts, a human, a cow and a chicken. Screen house experiments were conducted to test whether specific skin bacteria or a mix of skin bacterial volatiles from the three vertebrate hosts mediate mosquito response. A review chapter in this thesis discusses how malaria parasites can manipulate human hosts to enhance their own transmission, by making the hosts more attractive to mosquitoes. Another experiment, using a dual-choice olfactometer, determined whether infection with malaria parasites increases human attractiveness to malaria mosquitoes, and whether the attractiveness of infected humans is Plasmodium falciparum-stage specific. Here, the same children participated in the study during infection with malaria parasites and after treatment with antimalarial drugs, artemisinin lumefantrine. Cage assays were further used to test mechanisms of attractiveness of P. falciparum-infected individuals using body odours or skin bacterial volatiles collected from the children at the two time points. Overall results show that skin bacterial volatiles play an important role in guiding mosquitoes with different host preferences to their specific host. For An. gambiae s.s., high (microscopic) densities of P. falciparum gametocytes (and not parasite-free, submicroscopic gametocytes or asexual stages of Plasmodium parasites) results into higher attractiveness of hosts, and body odours play a role in attractiveness of P. falciparum-infected humans. The results may help to develop more effective health policies and enable targeted interventions towards the most attractive hosts, which could contribute to reductions in malaria transmission. Identification of general or common attractive volatiles produced by the natural hosts as well as those from the gametocyte carriers may contribute to the development of an improved synthetic odour blend that may be used for sampling of mosquitoes with different host preferences. The use of powerful attractive odorants may result in reductions of vector-borne diseases transmitted by mosquitoes.

Natuurkorstkaas ontwikkelt zich goed in proeftuin
Hettinga, Kasper - \ 2016
milk products - cheeses - cheese ripening - cheese mites - odours - pilot farms - ghee - natamycin

De zelfkazer : maandblad voor producenten van boerenkaasDe kazen met natuurkorst ontwikkelen zich goed in de nieuwe rijpingsruimte van boerderij De Groote Voort in Lunteren, al deden zich wel wat problemen voor, onder andere met mijten. De problemen zijn nu onder controle, vertelde Jan Dirk van de Voort op 15 februari bij de presentatie van de tussentijdse resultaten van de ‘Proeftuin Natuurlijke Kaasrijping’.

Impact of odour-baited mosquito traps for malaria control : design and evaluation of a trial using solar-powered mosquito trapping systems in western Kenya
Homan, T. - \ 2016
Wageningen University. Promotor(en): Willem Takken; T.A. Smith. - Wageningen : Wageningen University - ISBN 9789462577435 - 224 p.
016-3935 - culicidae - mosquito-borne diseases - vector control - malaria - bait traps - odours - solar energy - randomized controlled trials - kenya - ziekten overgebracht door muskieten - vectorbestrijding - vallen met lokaas - geurstoffen - zonne-energie - gestuurd experiment met verloting

The parasites belonging to the genus Plasmodium are the cause of the second deadliest infectious disease in the world, malaria. Sub Saharan Africa harbours more than 90% of malaria attributable mortality and morbidity, and most deaths occur in children under 18 years old. Malaria is transmitted to humans by a bite of a Plasmodium infected arthropod vector from the genus Anopheles. Halfway the 20th century malaria was successfully eliminated from most developed countries, nonetheless in the third world effective control remains a laborious challenge. Intensive efforts undertaken to control and eventually eradicate malaria during the past decade have led to substantial reductions in morbidity and mortality. Conversely, scientists became increasingly aware that with the current preventative and curative tools against malaria successful eradication seems unlikely. Not only do current tools not suffice to attain that goal, their efficacy to control malaria as it is, maybe severely threatened. Proper treatment and diagnosis are becoming increasingly less effective because of the adaptive nature of the parasite. Parasites get resistance against drugs and carriers are more often found to have subclinical infections. Likewise prevention of malaria, by vector control, becomes less effective. Malaria vectors become resistant to insecticides and transmission patterns are shifting away from where preventive measures are functional: outside and during the day. It this gap where the SolarMal project experimented with a novel malaria vector control tool, complimentary to existing malaria control methods: odour-baited mosquito traps that mimic human beings to lure and kill mosquitoes to eventually reduce malaria. The ultimate aim of this thesis was to seek proof of principle of the effect of mass trapping of malaria vectors on malaria and mosquito densities by rolling out over 4000 odour-baited mosquito traps at household level on Rusinga Island, Kenya.

Chapter 2 is a study protocol of the SolarMal project and provides a general understanding of how the objectives of the project are translated into a research design. The study comprises of a medical, an entomological and a sociological discipline. A multidisciplinary strategy is presented in which the intervention is explained. Experimental designs of all disciplines are introduced including time frames, participant eligibility, and randomisation. Furthermore, a general overview of the data collected and how it is evaluated and analysed using health and demographic surveillance and monitoring is provided.

In chapter 3 a novel data collection and management platform is presented. The health and demographic surveillance as well as other disciplines in the project are an example of one of the first fully digital data collection systems in a low and middle income country. The development of digital questionnaires and the conducting of these by means of Open Data Kit software enabled the project to efficiently collect data. All residential structures were documented by GPS, and data of individuals attached. Converting the geo-located data to a geodatabase and displayed with Google Earth mobile made navigating from house to house an easy task. By daily uploading of data to the server at the project campus, scientists have access to a near real time database. Once uploaded to the server, data is transferred to the OpenHDS database in which the demography of the study population is updated accordingly. Data quality was further increased by a tool that looked for inconsistencies.

In chapter 4 we explore what experimental design would fit the SolarMal project best. A stepped wedge cluster-randomized trial [SWCRT] design was chosen to make sure that the whole area would cross over from the control to the intervention arm over a period of two years. As elimination was the goal, universal coverage was required. Subsequently, strategies for randomization and crossover of clusters that could measure a possible intervention effect best were simulated with a generic model of disease transmission. Considering sufficient numbers and sizes of clusters a hierarchical SWCRT would best measure a possible effect of OBTs on Rusinga Island. Special care was given to quantifying spill over effects into the control arm. Finally, two new measures of intervention effectiveness are proposed.

Chapter 5 reports on the outcomes of the health and demographic surveillance system on Rusinga Island. Running an HDSS is a thorough but complex method to monitor intervention effects in an area where health surveillance is minimal. As part of the overarching HDSS institution, INDEPTH, data collection methods and reporting are harmonious with many other HDSSs around the world. Demographic parameters are calculated and the HDSS practices are described.

Chapter 6 uses the baseline cross sectional prevalence surveys to elucidate how the epidemiology of malaria on Rusinga Island. Firstly, the malaria distribution and hot spots are identified. Consequently, a standard epidemiological model and a geographically weighted regression are compared, and used to identify risk factors for malaria. The latter model, taking into account non-stationarity, performs better and is able to produce geographically varying risk factors. The strength of the relationship of risk factors for malaria are heterogeneous over the whole island, and for instance social economic status and occupation are strong predictors of malaria in some areas but less in other areas. Considering these risk factor distributions can aid in guiding the implementation of malaria intervention methods.

Chapter 7 presents the main outcomes of the SolarMal project. The impact of OBTs on the prevalence of malaria is pronounced in the contemporaneous comparison between the intervened and the intervened arm. Comparison of baseline data with the intervened clusters does not yield significant effects. A strong decline in cases of clinical malaria was observed starting already in the baseline period, and therefore we cannot attribute this decline to the intervention. Effects on the most prominent malaria vector were large, whereas other vectors did not suffer under the intervention.

Chapter 8 is a general discussion of the work provided. The most important implications of the thesis are discussed underscoring the societal and scientific relevance, and putting the research in a wider perspective. Unaddressed issues are raised and recommendations for further research are provided.

Beyond liking : emotional and physiological responses to food stimuli
He, W. - \ 2016
Wageningen University. Promotor(en): Kees de Graaf, co-promotor(en): Sanne Boesveldt; Rene de Wijk. - Wageningen : Wageningen University - ISBN 9789462576506 - 149 p.
stimuli - food - emotions - autonomic nervous system - odours - taste - beverages - physiological functions - man - human behaviour - expressivity - prikkels - voedsel - emoties - autonome zenuwstelsel - geurstoffen - smaak - dranken - fysiologische functies - mens - menselijk gedrag - expressiviteit

Background and aim

Traditional liking ratings are typically seen as an important determinant in eating behavior. However, in order to better understand eating behavior, we need to first better understand (the dynamic and implicit features underlying) liking appraisal. The aim of this thesis was to investigate the effects of food stimuli varying in sensory modality (smell and taste), pleasantness and intensity, on emotional and physiological responses leading up to liking appraisal.

Methods

Four studies, using healthy participants, were conducted as part of this thesis. In the first study, responses to pleasant versus unpleasant food odors varying in intensity were measured discretely using pleasantness ratings, intensity ratings and non-verbally reported emotions (PrEmo), as well as continuously using facial expressions and autonomic nervous system (ANS) responses. To further explore how explicit and implicit factors contribute to pleasantness appraisal, the same measures were assessed in response to food odors with a wider range of valence. Next, we focused on facial expressions and ANS responses elicited by single sips of breakfast drinks that were equally liked. In the last study, we investigated changes in pleasantness after consuming semi-liquid meals to (sensory-specific) satiety, combined with measures of facial expressions and ANS responses.

Results

Both non-verbal reported emotions and emotional facial expressions were demonstrated to be able to discriminate between food odors differing in pleasantness and between food odors differing in intensity. In addition to discrete emotional responses, odor valence associated best with facial expressions after 1 second of odor exposure. Furthermore, facial expressions and ANS responses measured continuously were found odor-specific in different rates over time. Results of food odors with a wider range of valence showed that non-verbally reported emotions, facial expressions and ANS responses correlated with each other best in different time windows after odor presentation: facial expressions and ANS responses correlated best with the explicit emotions of the arousal dimension in the 2nd second of odor presentation, whereas later ANS responses correlated best with the explicit emotions of the valence dimension in the 4th second. For food stimuli varying in flavor (breakfast drinks), facial expressions and ANS responses showed strongest associations with liking after 1 second of tasting, as well as with intensity after 2 seconds of tasting. Lastly, we were able to demonstrate that ANS responses, as well as facial expressions of anger and disgust were associated with satiety. Further effects of sensory-specific satiety were also reflected by skin conductance, skin temperature, as well as facial expressions of sadness and anger.

Conclusions

Both non-verbal reported emotions and emotional facial expressions were demonstrated to be able to discriminate between food odors differing in pleasantness and/or intensity. Explicit and implicit emotional responses, as well as physiological patterns are related to liking appraisals involved in smelling foods. Implicit measures such as facial expressions and ANS responses can provide more multidimensional information for both food odors and tastes than explicit measures and prove to be highly dynamic over time with specific time courses. Early implicit facial and ANS responses primarily reflect emotion arousal, whereas later ANS responses reflect emotion valence, suggesting dynamic unfolding of different appraisals of food stimuli. Furthermore, ANS responses and facial expressions can reflect pleasantness, satiety, and a combination of both: sensory-specific satiety. This suggests that implicit processes play an important role in dynamic liking appraisals with respect to eating behavior.

Lokkende werking feromoon vooral bij aanwezigheid van plantengeur : feromoonval beschikbaar voor opsporen behaarde wants
Tol, R.W.H.M. van; Hennekam, M. ; Yang, Daowei - \ 2015
Onder Glas 12 (2015)12. - p. 50 - 51.
tuinbouw - glastuinbouw - gewasbescherming - biologische bestrijding - feromoonvallen - insectenlokstoffen - geurstoffen - hemiptera - afwijkingen, planten - landbouwkundig onderzoek - plantgezondheid - groenten - snijbloemen - aubergines - cucumis - chrysanthemum - horticulture - greenhouse horticulture - plant protection - biological control - pheromone traps - insect attractants - odours - plant disorders - agricultural research - plant health - vegetables - cut flowers
Plaagwantsen zoals behaarde wants en brandnetelwants vormen in teelten als aubergine, komkommer en chrysant een serieus probleem. Ze geven al in kleine aantallen flinke schade: bloemabortie in aubergine, stengel- en vruchtschade in komkommer en splitkoppen in chrysant. Zodra telers wantsen of wantsenschade signaleren zien ze zich al snel genoodzaakt in te grijpen met middelen die schadelijk zijn voor aanwezige biologische bestrijders tegen andere plagen; het begin van het einde van hun biologie.
Emissiereductie door verneveling van probiotica over leefoppervlak : literatuurstudie en metingen bij vleesvarkens
Ellen, H.H. ; Groenestein, K. ; Hol, J.M.G. ; Ogink, N.W.M. ; Pas, L. - \ 2015
Wageningen : Wageningen UR Livestock Research (Livestock Research rapport 809) - 39
varkens - slachtdieren - afmesten - probiotica - ammoniakemissie - geurstoffen - fijn stof - varkenshouderij - pigs - meat animals - finishing - probiotics - ammonia emission - odours - particulate matter - pig farming
In twee identieke afdelingen met vleesvarkens is het effect gemeten van het aanbrengen van probiotica (PIP) via het vernevelen er van in de afdeling. Uit de gemeten waarden blijkt er geen significant effect te zijn van het toepassen van probiotica op de emissies van ammoniak (NH3), geur en fijnstof (PM10) en de concentratie van ammoniak.
Nieuwe mogelijkheden voor de bestrijding van wittevlieg in de sierteelt onder glas : onderzoek aan omnivore roofwantsen en gedragsbeïnvloedende geuren
Messelink, G.J. ; Kruidhof, H.M. ; Elfferich, C. ; Leman, A. - \ 2015
Bleiswijk : Wageningen UR Glastuinbouw (Rapport GTB 1350)
glastuinbouw - sierteelt - organismen ingezet bij biologische bestrijding - reduviidae - thrips - effecten - schade - gerbera - cultivars - limoneen - geurstoffen - greenhouse horticulture - ornamental horticulture - biological control agents - effects - damage - limonene - odours
This study explored new possibilities to control whiteflies in greenhouse ornamental crops with omnivorous predatory bugs and volatiles. Besides the well-known Macrolophus pygmaeus, we tested 4 new species of predatory bugs: Dicyphus errans, Dicyphus eckerleini, Dicyphus maroccanus and Dicyphus tamaninii. We assessed both their potential to control whiteflies and their possible plant damaging effects through plant feeding. The best control of whiteflies was achieved by the species M. pygmaeus, D. tamaninii and D. maroccanus. Significant flower damage was only observed for the predator M. pygmaeus. The degree of flower damage depended strongly on the gerbera cultivar, but damage was observed for both large-flowered and small-flowered types. All 5 species of predatory bugs were able to establish in a winter crop of 2 gerbera cultivars and the exotic plant Lantana camara. The most promising candidate predatory bug for biological control in gerbera is D. maroccanus. This species established well on the 2 tested gerbera cultivars, gave in all cases an excellent control of pests and no significant plant damage was observed. The predatory bugs gave, besides whiteflies, a good control of Echinothrips and in some cases a suppression of aphids and western flower thrips. The volatile limonene showed no significant effect on the oviposition of tobacco and greenhouse whiteflies. Neither did they repel adults of these whiteflies. The mixture of (E)-2-hexenal and 3-hexen-1-ol did not induce a significant attraction response of the adult whiteflies.
Geurdetectie als middel om wolluishaarden op te sporen
Kogel, Willem Jan de - \ 2015
plant protection - horticulture - workshops (programs) - odours - greenhouse experiments - greenhouse horticulture - roses - tetranychidae - pseudococcidae
The appetizing and satiating effects of odours
Ramaekers, M.G. - \ 2014
Wageningen University. Promotor(en): Tiny van Boekel, co-promotor(en): Pieternel Luning; Catriona Lakemond. - Wageningen : Wageningen University - ISBN 9789461739995 - 164
geurstoffen - eetlust - verzadigdheid - sensorische evaluatie - voedingsgewoonten - odours - appetite - satiety - sensory evaluation - feeding habits
Background and aim

Unhealthy eating habits such as unhealthy food choices or overeating increase the prevalence of obesity, diabetes, cancer, cardiovascular and other diseases. Therefore, it is important to understand how separate factors, such as sensory processes, influence our eating behaviour. As one of the sensory modalities, olfaction has a relationship with food intake regulation. Previous research reveals that food odours can induce both appetite and satiation. In this thesis, we split appetite and satiation into a ‘general’ part and a ‘food specific’ part. General appetite and general satiation refer to the desire to eat in general. General satiation measured by subjective ratings (e.g. by using line scales) is also named ‘subjective satiation’. The specific part refers to the desire to eat a specific food: e.g. the appetite for a banana or the appetite for tomato soup.

The main objective of this thesis was to investigate under which circumstances odours are appetizing or satiating in order to identify factors that influence our eating behaviour.Odours arrive at the odour receptors via two routes: the orthonasal route via the nose to perceive the outside world or retronasally via the mouth to ‘taste’ the food. The appetizing and satiating effects of ortho- and retronasally smelled odours were investigated by varying the odour exposure time, the odour concentration(retronasal only), the odour type, passive versus active sniffing (orthonasal only) and by switching between odour types.

Methods

We conducted six within-subject experiments. All participants were healthy normal-weight women (age 18-45 y and BMI 18.5-26 kg/m2). In four experiments (studies 2A, 2B, 3A and 3B), we investigated the appetizing and satiating effects of orthonasal odours, with two experiments addressing odours that were smelled passively in rooms with ambient odours (chapter 2) and two addressing actively smelled odours by sniffing the contents of a cup (chapter 3). In studies 2A (passive, n=21), 2B (passive, n=13) and 3A (active, n=61), we investigated the effects of exposure timeand odour typeon appetite, the appetite for specific foods, food preference and food intake. Differences between passiveand active exposure were investigated by comparing the data from 2A and 3A. In the fourth experiment (n=30) using a similar set-up, sweet and savoury odours were presented directly after each other, to explore the effects of daily encounters with a variety of food odours (i.e. switching). In all orthonasal studies, general appetite and the appetite for specific foods were monitored over time, using visual analogue scales. General appetite comprised hunger and desire-to-eat ratings. The appetite for specific products addressed the appetite for smelled products and the appetites for a set of other products that were congruent and incongruent with the odour (studies 2A, 2B, 3A and 3B). Food preference was assessed using a computerised program offering pairs of food pictures (studies 2A, 2B and 3B).

Furthermore, two experiments addressed the satiating effects of retronasal odours while consuming tomato soup ad libitum (studies 4A and 4B). The retronasal odour exposure was disconnected from the soup base consumptionby use of a retronasal tube that was connected to an olfactometer. The odours were delivered directly into the nasal cavity at the moment a sip of soup base was swallowed. In study 4A (n=38), the satiating effects of odour exposure time(3 and 18 s) and odour concentration(5x difference) were investigated. In study 4B(n=42),we investigated whether addition of cream odourto tomato soup, in combination with a low or high viscosity, affected satiation. Hunger and appetite ratings were monitored over time during odour exposure, by using 100 mm visual analogue scales (VAS).

Results

The results showed that orthonasalexposure to food odours influenced the appetite for specific foods via a typical pattern: the appetite ratings for the smelled foods increased by +6-20 mm(SSA; all P<0.001), the appetite for congruent sweet and savoury foods increased by +5 mmand the appetite for incongruent sweet and savoury foods decreased by -5 mm (all P<0.01), measured by using 100 mm VAS (studies 2A, 2B, 3A and 3B). This typical pattern was found in all studies, independently of passive or active smelling, exposure time or switching between odours (studies 2A, 2B, 3A and 3B). Results in study 3B showed that the appetite for specific products adjusted to the new odour within one minute after a switch between sweet and savoury odours. Similar results were found with a computerised food preference program, in which participants chose repeatedly between pairs of foods (studies 2A, 2B and 3B). Food preference shifted in circa 20% of the choices. Furthermore, passively smelled food odours had a large effect on the appetite for the smelled foods (+15 mm; P<0.001) and a small effect on general appetite (+4 mm; P=0.01; study 2A). Actively smelled food odours had nosignificant effect on general appetite or food intake (studies 3A and 3B). Non-food odours appeared to suppress general appetite slightly (-2 mm, P=0.01). The appetizing effects did not change over timeduring a twenty-minute odour exposure (studies 2A, 2B, 3A and 3B) and the typical pattern of odour effects on the appetite for specific foods was not affected by switching between sweet and savoury odours (study 3B). The pleasantness of the odour decreased by -4 mmduring active smelling (P=0.005), whereas the appetite for the smelled food remained high (P<0.001; study 3B).

Furthermore, the results from the retronasalstudies showed that an increase in both retronasal odour exposure time and concentration reduced ad libitum intake by 9 % (i.e. 3 sips and 22 kJ; P=0.04) and had no effect on subjective satiation (study 4A). Adding cream odour decreased subjective satiation with circa 5 %between 7 and 13 minutes after the start of consumption (P=0.009), but did not affect ad libitumintake (study 4B). Retronasally smelled odour significantly contributed to the development of sensory-specific satiety (study 4A).

Conclusions

Orthonasally smelled odours affect to a larger extend what you eat, than how much you eat. They influence the appetite for specific foods via a typical pattern: the appetite for the smelled foods and for congruent sweet or savoury foods increases, whereas the appetite for incongruent sweet or savoury foods decreases. This typical pattern is independent of exposure time, passive or active smelling and switchingbetween odours. The reason for this pattern is unknown, however, it may be caused by the preparation of the body for the intake of the smelled food, as food odours may provide information about the nutrient composition of their associated foods. Furthermore, passiveodour exposure may enhance general appetite (how much), whereas activesmelling appears to have no effect. Interestingly,the appetite for the smelled foods remained elevated during the 20-minute smelling, althoughthe pleasantness of the smelled odour decreased a little over time. This shows an earlier assumption from literature incorrect: a decrease in pleasantness of the odour does not lead to less appetite for the smelled food. This seeming contradiction may result from different mechanisms, such as a decrease in hedonic value during prolonged sensory stimulation on the one hand and anticipation of food intake on the other hand. Furthermore, food odours were found to change preference in circa 20% of the cases. Probably, food odours shift food preference, but do not overrule strong initial preferences in circa 80% of the cases.

Moreover, retronasally smelled odours probably have a small influence on satiation, though the evidence is not very strong. An increase in both retronasal odour concentrationand odour exposure timemay enhance satiation. Adding cream odourmay temporarily affect subjective satiation but does not affect food intake. However, the satiating effects that were found in these studies with retronasal odour exposure were borderline significant and data on food intake and subjective appetite ratings were not consistent, which probably reflects thesmall effect size.

Orthonasal odours influence food preference and could potentially be used to encourage healthy eating behaviour. The studies in this thesis were conducted under controlled circumstances and the results possibly deviate from behaviour in daily life. Therefore, it is unclear how strong the influence of odours is on our eating behaviour in daily situations. Finally, we advise product developers not to focus on changing retronasal odour characteristics in order to enhance satiation of products, seen the small effects that were found in this thesis.

Odour-based strategies for surveillance and behavioural disruption of host-seeking malaria and other mosquitoes
Mweresa, C.K. - \ 2014
Wageningen University. Promotor(en): Willem Takken; Marcel Dicke; W.R. Mukabana; Joop van Loon. - Wageningen : Wageningen University - ISBN 9789461739247 - 277
anopheles gambiae - anopheles funestus - anopheles - culicidae - semiochemicals - insectenlokstoffen - lokstoffen - synthetische materialen - geurstoffen - malaria - gedrag bij zoeken van een gastheer - insect attractants - attractants - synthetic materials - odours - host-seeking behaviour
Emissies uit een ligboxenstal voor melkvee met het "vrije keuze" systeem : meetprogramma Integraal Duurzame Stallen
Mosquera Losada, J. ; Hol, J.M.G. ; Huis in 'T Veld, J.W.H. ; Ploegaert, J.P.M. ; Ogink, N.W.M. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 617) - 31
melkveehouderij - ligboxen - roostervloeren - natuurlijke ventilatie - stalklimaat - ammoniakemissie - geurstoffen - fijn stof - methaan - distikstofmonoxide - luchtverontreiniging - dairy farming - cubicles - grid floors - natural ventilation - stall climate - ammonia emission - odours - particulate matter - methane - nitrous oxide - air pollution
In dit rapport worden de emissiemetingen van ammoniak, geur, fijn stof, methaan en lachgas gerapporteerd, die in het kader van het hiervoor genoemde onderzoeksprogramma uitgevoerd zijn op het melkveehouderijbedrijf van Mts. Mensonides te Cornwerd (ligboxenstal met het vrijekeuze systeem). Het beoogde emissiereducerende principe van dit systeem is gebaseerd op 1) het afsluiten van de mestkelder door gebruik te maken van sleufvloer zonder gaatjes in de lange looppaden in de lengterichting van de stal, 2) het versneld afvoeren van de emitterende bron (urine) naar de kelder, het verschuiven van het chemisch evenwicht door het verlagen van de pH van de urine op de roostervloer, en luchtuitwisseling tussen de stal en de kelder beperken door op de verbindingspaden loodrecht op de sleufvloer en de wachtruimte vóór de melkrobots rubber matten op de roostervloer en afdichtflappen in de roosterspleten te plaatsen, en 3) door het ventilatieniveau te beperken door gebruik te maken van Automatically Controlled Natural Ventilation.
Emissies uit een ligboxenstal voor melkvee met het "vrije keuze" systeem : meetprogramma Integraal Duurzame Stallen
Mosquera Losada, J. ; Hol, J.M.G. ; Huis in 'T Veld, J.W.H. ; Ploegaert, J.P.M. ; Ogink, N.W.M. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 616) - 31
melkveehouderij - ligboxen - roostervloeren - natuurlijke ventilatie - stalklimaat - ammoniakemissie - geurstoffen - fijn stof - methaan - distikstofmonoxide - luchtverontreiniging - dairy farming - cubicles - grid floors - natural ventilation - stall climate - ammonia emission - odours - particulate matter - methane - nitrous oxide - air pollution
In dit rapport worden de emissiemetingen van ammoniak, geur, fijn stof, methaan en lachgas gerapporteerd, die in het kader van het hiervoor genoemde onderzoeksprogramma uitgevoerd zijn op het melkveehouderijbedrijf van Mts. Zonderland-Verhoef te Koudum (ligboxenstal met het vrijekeuze systeem). Het beoogde emissiereducerende principe van dit systeem is gebaseerd op 1) het afsluiten van de mestkelder door gebruik te maken van sleufvloer zonder gaatjes in de lange looppaden in de lengterichting van de stal, 2) het versneld afvoeren van de emitterende bron (urine) naar de kelder, het verschuiven van het chemisch evenwicht door het verlagen van de pH van de urine op de roostervloer, en luchtuitwisseling tussen de stal en de kelder beperken door op de verbindingspaden loodrecht op de sleufvloer en de wachtruimte vóór de melkrobots rubber matten op de roostervloer en afdichtflappen in de roosterspleten te plaatsen, en 3) door het ventilatieniveau te beperken door gebruik te maken van Automatically Controlled Natural Ventilation (ACNV).
Emissies uit een ligboxenstal voor melkvee met het "vrije keuze" systeem : meetprogramma Integraal Duurzame Stallen
Mosquera Losada, J. ; Hol, J.M.G. ; Huis in 'T Veld, J.W.H. ; Ploegaert, J.P.M. ; Ogink, N.W.M. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 615) - 31
melkveehouderij - ligboxen - roostervloeren - stalklimaat - natuurlijke ventilatie - ammoniakemissie - geurstoffen - fijn stof - methaan - distikstofmonoxide - luchtverontreiniging - dairy farming - cubicles - grid floors - stall climate - natural ventilation - ammonia emission - odours - particulate matter - methane - nitrous oxide - air pollution
In dit rapport worden de emissiemetingen van ammoniak, geur, fijn stof, methaan en lachgas gerapporteerd, die zijn uitgevoerd op het melkveehouderijbedrijf van Mts. Van de Streek te Broek (ligboxenstal met het vrijekeuze systeem). Het beoogde emissiereducerende principe van dit systeem is gebaseerd op 1) het afsluiten van de mestkelder door gebruik te maken van sleufvloer zonder gaatjes in de lange looppaden in de lengterichting van de stal, 2) het versneld afvoeren van de emitterende bron (urine) naar de kelder, het verschuiven van het chemisch evenwicht door het verlagen van de pH van de urine op de roostervloer, en luchtuitwisseling tussen de stal en de kelder beperken door op de verbindingspaden loodrecht op de sleufvloer en de wachtruimte vóór de melkrobots rubber matten op de roostervloer en afdichtflappen in de roosterspleten te plaatsen, en 3) door het ventilatieniveau te beperken door gebruik te maken van Automatically Controlled Natural Ventilation (ACNV).
Emissies uit een ligboxenstal voor melkvee met het "vrije keuze" systeem : meetprogramma Integraal Duurzame Stallen
Mosquera Losada, J. ; Hol, J.M.G. ; Huis in 'T Veld, J.W.H. ; Ploegaert, J.P.M. ; Ogink, N.W.M. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 614) - 31
melkveehouderij - ligboxen - roostervloeren - stalklimaat - ammoniakemissie - geurstoffen - fijn stof - methaan - distikstofmonoxide - luchtverontreiniging - dairy farming - cubicles - grid floors - stall climate - ammonia emission - odours - particulate matter - methane - nitrous oxide - air pollution
This study reports the emissions of ammonia, odour, fine dust (PM10 and PM2.5), methane and nitrous oxide from a loose housing dairy cattle barn with cubicles using the "freedom of choice" concept.
Emissies uit een ligboxenstal voor melkvee met roostervloer voorzien van een bolle rubber toplaag en afdichtflappen in de roosterspleten : Meetprogramma Integraal Duurzame Stallen
Mosquera Losada, J. ; Hol, J.M.G. ; Huis in 'T Veld, J.W.H. ; Ploegaert, J.P.M. ; Ogink, N.W.M. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 612) - 27
melkveehouderij - ligboxen - roostervloeren - vloerbedekking - rubber - stalklimaat - ammoniakemissie - geurstoffen - fijn stof - methaan - distikstofmonoxide - luchtverontreiniging - dairy farming - cubicles - grid floors - floor coverings - stall climate - ammonia emission - odours - particulate matter - methane - nitrous oxide - air pollution
This study reports the emissions of ammonia, odour, fine dust (PM10 and PM2.5), methane and nitrous oxide from a loose housing dairy cattle barn with cubicles provided with a slatted floor with a rubber top layer and rubber flaps between the slats.
Emissies uit een ligboxenstal voor melkvee met roostervloer voorzien van een bolle rubber toplaag en afdichtflappen in de roosterspleten : meetprogramma Integraal Duurzame Stallen
Mosquera Losada, J. ; Hol, J.M.G. ; Huis in 'T Veld, J.W.H. ; Ploegaert, J.P.M. ; Ogink, N.W.M. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 610) - 31
melkveehouderij - ligboxen - roostervloeren - vloerbedekking - rubber - stalklimaat - ammoniakemissie - geurstoffen - fijn stof - methaan - distikstofmonoxide - luchtverontreiniging - dairy farming - cubicles - grid floors - floor coverings - stall climate - ammonia emission - odours - particulate matter - methane - nitrous oxide - air pollution
This study reports the emissions of ammonia, odour, fine dust (PM10 and PM2.5), methane and nitrous oxide from a loose housing dairy cattle barn with cubicles provided with a slatted floor with a rubber top layer and rubber flaps between the slats.
Emissies uit een ligboxenstal voor melkvee met roostervloer voorzien van een bolle rubber toplaag : meetprogramma Integraal Duurzame Stallen
Mosquera Losada, J. ; Hol, J.M.G. ; Huis in 'T Veld, J.W.H. ; Ploegaert, J.P.M. ; Ogink, N.W.M. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 598) - 27
melkveehouderij - ligboxen - roostervloeren - vloerbedekking - rubber - stalklimaat - ammoniakemissie - geurstoffen - fijn stof - methaan - distikstofmonoxide - luchtverontreiniging - dairy farming - cubicles - grid floors - floor coverings - stall climate - ammonia emission - odours - particulate matter - methane - nitrous oxide - air pollution
This study reports the emissions of ammonia, odour, fine dust (PM10 and PM2.5), methane and nitrous oxide from a loose housing dairy cattle barn with cubicles provided with a slatted floor with a rubber top layer.
Metingen aan twee luchtwassystemen in een vleeskuikenstal met conditionering van ingaande ventilatielucht = Measurements on two air scrubbing systems on broiler houses with heat exchanger for inlet ventilation air
Melse, R.W. ; Hattum, T.G. van; Huis in 'T Veld, J.W.H. ; Gerrits, F.A. - \ 2012
Lelystad : Wageningen UR Livestock Research (Rapport / Wageningen UR Livestock Research 503) - 22
pluimveehouderij - vleeskuikens - huisvesting van kippen - ventilatie - luchtreinigers - warmtewisselaars - ammoniak - fijn stof - geurstoffen - emissie - luchtverontreiniging - poultry farming - broilers - chicken housing - ventilation - air cleaners - heat exchangers - ammonia - particulate matter - odours - emission - air pollution
The performance of two experimental air scrubber was investigated during 9 months on two broiler houses. The inlet ventilation air of the houses is led through a subsoil heat exchanger. In this report the removal efficiencies of the scrubber are reported for ammonia, odour and fine dust (PM10 and PM2.5).
Modelling the effects of odours and spying parasitoids on fruit fly population dynamics
Lof, M.E. - \ 2012
Wageningen University. Promotor(en): Marcel Dicke, co-promotor(en): Lia Hemerik; Maarten de Gee. - S.l. : s.n. - ISBN 9789461732057 - 146
drosophila melanogaster - parasitoïden - leptopilina heterotoma - aggregatieferomonen - geurstoffen - populatiedynamica - simulatiemodellen - parasitoids - aggregation pheromones - odours - population dynamics - simulation models

The study of the role of chemical information in species interactions has been mostly restricted to studies at the level of individual organisms. The central question in this thesis is how intraspecific chemical information conveyance and exploitation thereof by a natural enemy affects the spatial population dynamics of a species. To answer this question, I developed a spatio-temporal model where both host and parasitoid can respond to infochemicals. Our model system consists of the fruit fly Drosophila melanogaster, and its natural enemy, the larval parasitoid Leptopilina heterotoma. D. melanogaster uses its aggregation pheromone in combination with odours from fermenting fruits to localise suitable resources for reproduction. L. heterotoma uses these same odours to localise its host. For D. melanogaster, aggregation on a resource can be beneficial when a population is small and has to overcome negative effects associated with low population densities. Such negative effects, known as the Allee effect, can for instance be caused by difficulties in resource exploitation or in finding a mate. Aggregation also involves costs. Individuals within an aggregation frequently experience more severe competition for food, space and mates than they would experience when being on their own. Furthermore, I investigated which behavioural decisions enhance the ability to find - and distinguish between – odour sources that differ in their suitability for reproduction.

On the individual level, this research showed that, like real fruit flies, the modelled fruit flies need to have a preference for the presence of both aggregation pheromone and food odours, over food odours alone, to be able to distinguish between the two types of odour sources. The results show that this stronger preference does not have to be innate. As long as fruit flies are able to remember and adjust their current preference based on the odour concentrations that they perceive, more fruit flies find the more attractive odour source.

On a population level, this thesis shows that the use of chemical information by D. melanogaster affects its population dynamics. In the absence of its natural enemy, and when the Drosphila population is small, the use of food odours and aggregation pheromone has a positive effect on population growth and enhances the fruit fly’s colonization ability. When the population becomes larger, however, the negative effects of larval competition are stronger than the positive effects of reduced mortality due to the Allee effect. The use of chemical information was crucial to colonize an area from the boundaries. A fruit fly population that was unable to use chemical information could not colonize the area and went extinct. When parasitoids can use chemical information, parasitism rates are higher, resulting in a slower population growth of their host. No difference was recorded in fruit fly population size and in larval mortality due to parasitism, when parasitoids exploited the aggregation pheromone of the fruit fly adults as compared with the simulations where the parasitoids could only respond to chemicals emitted by the host habitat. In contrast, the use of chemical information by the host enhanced its population growth and enabled it to survive, even at higher parasitoid densities. This research showed that mortality when the population was small had a greater impact on population size than mortality due to competition or parsitism. Food patches are not always abundant in nature. Thus, the reproductive success of fruit flies is mainly determined by their opportunities of producing clutches (i.e. locating patches) rather than by preventing over-aggregation or parasitism. As a result, the use of chemical information has a net positive effect on fruit fly population dynamics, despite the fact that L. heterotoma is able to exploit it.

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