Sammanfattning   Titel: Digitaliserad word of mouth, en betydande faktor för WTA   Nivå: Examensarbete på Grundnivå (kandidatexamen) i ämnet företagsekonomi   Författare: Andreas Ståhl och Markus Westblad   Handledare: Jonas Kågström, Benny Berggren   Datum: 2019 – Juni    Syfte: Syftet med denna studie är att öka förståelsen för hur eWOMs volym och valens påverkar konsumenters WTA i valet av tjänst från säljare. I denna studie har en undersökning av begrepp som WTA och eWOM ställts emot varandra i en experimentell design som sedan genom resultatet delat en förståelse för hur volym och valens påverkar valet av en fastighetsmäklare. Studien har genom tidigare forskning önskats applicerats på andra branscher än tidigare utförda vilket vi anser att denna studie uppfyller genom den replikerade metod som använts.   Metod: Denna studie är utförd genom en kvantitativ forskningsstrategi med en replikerande metod med experimentell design. Den data som samlats in som underlag för studiens resultat och analys har samlats in genom en digital enkät med manipulerade mäklarprofiler genom rekommendationssajten ”Reco”. Datan har sedan analyserats genom programvaran ”Jamovi” genom deskriptiva analyser samt genom en korrelationsanalys.   Resultat & slutsats: Studien har visat resultat som motsäger tidigare forskning med bland annat att volym är mer avgörande i valet av en tjänst i relation till valens.   Detta resultat visar även på att fler bör studera sina branscher för att öka sin förståelse för hur kraftigt vissa faktorer är inom digitaliserad marknadsföring.   Examensarbetets bidrag: Studien presenterar ett teoretiskt såväl som praktiskt bidrag i det avslutande kapitlet som i kort visar på hur volym och valens kan variera i jämförelse med den tidigare forskningen som utförts och vad som bör beaktas och noggrant analyseras för att i framtiden kunna appliceras på företagsnivå inom marknadsföring såväl som rekommendationer.   Förslag till fortsatt forskning: Jämförande studie av de två begreppen eWOM och WOM, vilket är det mer traditionella uttryck för att beskriva en word of mouth effekt. Hur särskiljer sig dessa åt i resultat, och är de skillnader i effektivitet mot den som faktiskt blir rekommenderad.   Studien ger även förslag på att använda sig av demografiska data som underlag för tolkningen utav statistiken, vilket inte gjorts inom denna studie. Vi anser det även intressant med en mer övergripande manipulering av de olika profilerna, såsom att tillägga fabrik eller varumärke och se hur dessa skiljer sig åt.   Nyckelord: WTA, WTP, IRP, eWOM, WOM, Valens och Volym. / Abstract Title: Digitized word of mouth, an important factor for WTA   Level: Student thesis, final assignment for Bachelor Degree in Business Administration   Author: Andreas Ståhl and Markus Westblad   Supervisor: Jonas Kågström, Benny Berggren   Date: 2019 – June   Aim: The purpose of this study is to increase the understanding of how eWOM's volume and valency affects consumers' WTA in the choice of service from sellers. In this paper, a study of concepts such as WTA and eWOM has been compared in an experimental design which then through the result shared an understanding of how volume and valency affects the choice of a real estate agent. Through the previous research, the study has been desired to be applied to other industries previously performed, which we believe this study fulfills through the replicated method used.   Method: This study is conducted through a quantitative research strategy with a replicating method with experimental design. The data collected for the study's results and analysis has been collected through a digital survey with manipulated profiles through the recommendation site "Reco". The data has then been analyzed through the software "Jamovi" through descriptive analyzes and through a correlation matrix.   Result & Conclusions: The study has shown results that contradict previous research, among other things, that volume is more crucial in the choice of a service in relation to valency. This result also shows that companies should study their industries to increase their understanding of how strongly certain factors are within digitalized marketing.   Contribution of the thesis: The study presents a theoretical as well as practical contribution in the final chapter, which briefly shows how volume and valency can vary widely in relation to the previous research carried out and what should be considered and carefully analyzed in order to be able to apply at company level in marketing in the future. as recommendations.   Suggestions for future research: Comparative study of the two terms eWOM and WOM, which is the more traditional expression to describe a word of mouth effect. How do they differentiate in results, and are the differences in efficiency against the one that is actually recommended. The study also proposes to use demographic data as a basis for the interpretation of the statistics, which has not been done in this study. We also consider it interesting with a more general manipulation of the different profiles, such as adding factory or brand and seeing how these differ.   Key words: WTA, WTP, IRP, eWOM, WOM, Valency and Volume.

A map of connections between musical features and musical expression have been much sought-after. Unveiling a system behind the musical expression humans achieve and perceive intuitively could benefit a range of human activities including musical composition, therapy, and computer science. The present study featured an experiment in which 50 participants rated the expression of valence on a 9-point scale after listening to 10 music samples. The only difference between the samples was the pitch of one note (occurring at various times, octaves and instruments). Each condition featured the note as forming a different interval in regard to the tonic (the first scale degree, and the tonal focal point). The intervals were: minor second, major second, minor third, major third, augmented fourth (the tritone), perfect fifth, minor sixth, major sixth, minor seventh and major seventh. Participants also rated their musical sophistication by answering the 40 questions of the Gold-MSI self-report inventory and a resulting index variable ranging from 40 to 120 was obtained. Statistically significant finds were made and a pattern emerged where minor/augmented intervals code for negative valence and major/perfect intervals code for positive valence. The expression of the minor and major sevenths appeared neutral, but results lacked statistical significance. The musical sophistication of participant was associated with the ability to perceive musical expression of affect. Finally, the term intervallic semiosis was proposed as a designation for the explained functionality of valence coding.

The recent advances in deep learning have made it state-of-the-art for many different tasks, making its potential usefulness for analyzing electroencephalography (EEG) data appealing. This study aims at automatic feature extraction and classification of likeability, valence, and arousal elicited by auditory stimuli from music by training deep neural networks (DNNs) on  minimally pre-processed multivariate EEG time series. Two data sets were collected, the first containing 840 samples from 21 subjects, the second containing 400 samples from a single subject. Each sample consists of a 30 second EEG stream which was recorded during music playback. Each subject in the multiple subject data set was played 40 different songs from 8 categories, after which they were asked to self-label their opinion of the song and the emotional response it elicited. Different pre- processing and data augmentation methods were tested on the data before it was fed to the DNNs. Three different network architectures were implemented and tested, including a one-dimensional translation of ResNet18, InceptionTime, and a novel architecture built upon from InceptionTime, dubbed EEGNet. The classification tasks were posed both as a binary and a three-class classification problem. The results from the DNNs were compared to three different methods of handcrafted feature extraction. The handcrafted features were used to train LightGBM models, which were used as a baseline. The experiments showed that the DNNs struggled to extract relevant features to discriminate between the different targets, as the results were close to random guessing. The experiments with the baseline models showed generalizability indications in the data, as all 36 experiments performed better than random guessing. The best results were a classification accuracy of 64 % and an AUC of 0.638 for valence on the multiple subject data set. The background study discovered many flaws and unclarities in the published work on the topic. Therefore, future work should not rely too much on these papers and explore other network architectures that can extract the relevant features to classify likeability and emotion from EEG data. / Djupinlärning har visat sig vara effektivt för många olika uppgifter, vilket gör det möjligt att det även kan användas för att analysera data från elektroencefalografi (EEG). Målet med denna studie är att genom två egeninsamlade dataset försöka klassificera huruvida någon gillar en låt eller inte samt vilka känslor låten väcker genom att träna djupa neurala nätverk (DNN) på minimalt pre-processade EEG-tidsserier.  För det första datasettet samlades 840 dataexempel in från 21 deltagare. Dessa fick lyssna på 30-sekunders snuttar av 40 olika låtar från 8 kategorier varvid de fick svara på frågor angående vad de tyckte om låten samt vilka känslor den väckte. Det andra datasettet samlade in 400 dataexempel från endast en deltagare. Datan blev behandlad med flera olika metoder för att öka antalet träningsexempel innan det blev visat för de neurala nätverken. Tre olika nätverksarkitekturer implementerades och testades; en endimensionell variant av ResNet18, InceptionTime samt en egenbyggd arkitektur som byggde vidare på InceptionTime, döpt till EEGNet. Nätverken tränades både för binär och tre-klass klassificering.  Resultaten från nätverken jämfördes med tre olika metoder för att bygga egna prediktorer från EEG-datan. Dessa prediktorer användes för att träna LightGBM modeller, vars resultat användes som baslinje. Experimenten visade att DNNsen hade svårt att extrahera relevanta prediktorer för att kunna diskriminera mellan de olika klasserna, då resultaten var nära till godtyckligt gissande. Experimenten med LightGBM modellerna och de handgjorda prediktorerna visade dock indikationer på att det finns relevant information i datan för att kunna prediktera ett visst utfall, då alla 36 experiment presterade bättre än godyckligt gissande. Det bästa resultatet var 64 % träffsäkerhet för valens och binär klassificering, med en AUC på 0.638, för datasettet med många deltagare. Bakgrundsstudien upptäckte många oklarheter och fel i flera av de artiklar som är publicerade på ämnet. Framtida arbete bör därför inte förlita sig på denna alltför mycket. Den bör fokusera på att utveckla arkitekturer som klarar att extrahera de relevanta prediktorer som behövs för att kunna prediktera huruvida någon tycker om en låt eller inte samt vilka känslor denna väckte.

En hög personalomsättning råder inom de fyra största revisionsbolagen; Deloitte, EY, KPMG och PWC. Tidigare forskning har visat att det finns en relation mellan personalomsättning och motivation. Det har visat sig vara viktigt för organisationer att förstå medarbetarnas motivation för att besitta en låg personalomsättning. Studiens syfte är därför att öka förståelsen för sambandet mellan revisionsmedarbetares motivation och den höga personalomsättningen. Med hjälp av förväntansteorin har motivationen undersökts utifrån tre variabler; valens, instrumentalitet och förväntan.    För att öka förståelsen kring revisionsmedarbetarnas motivation ansågs intervjuer vara en lämplig datainsamlingsmetod vilket resulterat i en kvalitativ studie. Urvalet bestod av tio respondenter som med olika erfarenhet bidragit med relevant och intressant information för studiens resultat. Dessa respondenter titulerar sig som revisionsmedarbetare och har varit aktiva i upp till fyra år. Det empiriska resultatet sammanvävs i olika teman som kodats fram. Dessa teman är karriärutveckling, kunskap, övertid och familj, feedback och lön, utbildning och förmåner, inställning till yrket samt framtiden inom revisionsbranschen.     Det empiriska resultatet analyserades sedan i relation till det teoretiska ramverket för att besvara studiens syfte. Valens, instrumentalitet och förväntan var därför centrala i analysen där de sammanvävda temana tydligt associerades till respektive variabel. Detta resulterade i en indikation på att den totala motivationen hos revisionsmedarbetare brister. Utifrån de respondenter som deltagit i denna studie är det viktigt att poängtera skillnaden i hur de upplever motivation. En del respondenter kan antas besitta en hög total motivation där det går att förutspå en påtaglig valens, hög instrumentalitet och god förväntan samtidigt som andra kan antas brista på samtliga variabler. / The four largest auditing firms; Deloitte, EY, KPMG and PWC are known for their high staff turnover rate. There is a link between staff turnover and motivation, according to previous studies. Organizations must understand their employees' motivation in order to maintain low staff turnover. The purpose of the research is to better understand the link between audit staff motivation and high staff turnover. The motivation has been explored using the expectation theory on the basis of three variables: valence, instrumentality, and expectancy.    Interviews were chosen as a suitable data collection strategy to analyze the motivation of audit staff, resulting in a qualitative study. The sample consisted of ten respondents with varying levels of experience who supplied useful and intriguing information to the study's findings. These respondents identify themselves as audit staff and have worked up to four years. The empirical results are intertwined with themes that have been coded. Career development, knowledge, overtime and family, feedback and salary, education and benefits, attitude toward the profession, and the future within the industry are among the subjects discussed.   The empirical findings were then compared to the theoretical framework in order to answer the research question. Valence, instrumentality, and expectancy were thus central to the analysis, with each variable clearly related with the empirical themes. As a result, it was determined that the audit staff's overall motivation was low. Based on the respondents who participated in this study, it is important to point out the difference in how they experience motivation. Some respondents can be assumed to have a high total motivation where it is possible to predict a significant valence, high instrumentality and good expectation, while others can be assumed to lack all variables.

The Eurasian spruce bark beetle Dendroctonus micans is a major pest of spruce which is expanding its range in France, Turkey, England and Wales. Its monospecific predator Rhizophagus grandis has followed naturally the bark beetle into most areas and, since the 1960s, has also been mass-produced and successfully released within newly infested locations. In this scope, the development of an effective trapping method would be very useful to assess the bark-beetle presence at previously uninfested sites, or predator establishment after release or natural spread. We demonstrated the efficiency of oxygenated monoterpenes-baited kairomone traps to monitor R. grandis in various epidemiological conditions, including areas localized behind or at the limit of the pest’s distribution, or in areas where artificial releases were performed. Because the predator is strictly species-specific, another exciting possibility offered by the kairomone trapping is the indirect monitoring of the pest itself in areas of unknown status (e.g. areas under colonization, or considered as at risk at medium- term). R. grandis is also considered as one of the most valuable natural enemies to strike aggressive North-American Dendroctonus species. In this respect, R. grandis has been recently applied in a neo-classical biological program against the red turpentine beetle D. valens, which invaded China from North America in the late 1990’s. In laboratory tests conducted on pine logs in the laboratory, or on living pine trees in the field, we demonstrated that R. grandis adults can successfully enter and reproduce into D. valens galleries. In Europe, R. grandis is the only species regularly found in the brood systems of D. micans, where adults and larvae attack the gregarious larvae of their prey. In such enclosed systems, R. grandis’ functional response is therefore influenced by various interrelated components, such as the prey density, the predator density, or the prey distribution. Measuring the predator’s success in terms of larval survival and growth rates, we demonstrated the time spent by R. grandis larvae to wound and kill their prey to be the main factor limiting their development. This factor may be considerably influenced by the proportions of diseased, wounded or molting prey rise in the brood system, for instance as a result of an increase in prey density, or due to the presence of conspecific adults (which wound their prey but do not consume them entirely). Furthermore, our tests suggest that no cannibalism or noticeable intraspecific competition occurred between R. grandis larvae, whereas some lighter mode of competition probably took place. R. grandis also exhibits a reproductive numerical response to prey density, which mainly relies on the perception of chemical stimuli and inhibitors released in the bark beetle brood system. In the current study, we developed a non-destructive approach to follow the dynamics of volatile compound production, using sequential sample collection on SPME fibers. Our tests demonstrated that the larval activity of D. micans or D. valens strongly influences the release of some oxygenated monoterpenes. However, our attempts to correlate the relative quantities of some identified chemicals to offspring production were less successful as it concerns the identification of potential oviposition stimuli and inhibitors. The problematic rose by the progression of D. micans, as well as detailed results of each of the described above studies are discussed in the two published papers and the three manuscripts forming this thesis. Bringing all these studies together, several perspectives are also presented in the general discussion. / Ravageur des épicéas, Dendroctonus micans est toujours en voie d’extension en France, en Turquie, en Angleterre et au Pays de Galles. Dans la plupart de ces zones, le dendroctone est accompagné de manière naturelle par son prédateur monospécifique, Rhizophagus grandis. Depuis les années 1960, le prédateur a également fait l’objet d’une production de masse et de programmes de lâchers dans les zones d’arrivée récente du scolyte. Dans le cadre de la lutte biologique contre D. micans, les gestionnaires forestiers doivent donc estimer au plus tôt la présence du ravageur dans des zones jusque là indemnes, mais également vérifier l’établissement du prédateur par progression naturelle ou résultant d’introductions délibérées. Dans la présente étude, nous avons démontré l’efficacité de pièges d’interception appatés à l’aide de monoterpènes oxygénés pour la capture de R. grandis. Celle-ci s’est faite dans différentes conditions épidémiologiques, incluant notamment des zones situées en arrière du front de progression du scolyte et des zones où des lâchers artificiels ont été réalisés. Comme R. grandis est strictement inféodé au dendroctone, un autre avantage de la technique est la possibilité de réaliser un dépistage indirect du ravageur dans les zones où son statut est incertain (zones en cours de colonisation, ou considérées comme à risque à moyen terme). Par ailleurs, R. grandis est également considéré comme un des meilleurs ennemis naturels potentiels pour lutter contre d’autres espèces de Dendroctonus aggressifs. Dans cette optique, R. grandis a été récemment utilisé dans un programme de lute biologique contre D. valens, ravageur invasif arrivé en Chine dans la fin des années 1990 en provenance d’Amérique du Nord. Nous avons démontré la capacité de R. grandis à s’introduire et à se reproduire dans les galeries de D. valens lors de tests de laboratoire, mais aussi sur des arbres vivants en pinèdes. En Europe, R. grandis est strictement inféodé aux galeries de D. micans, où larves et adultes du prédateur s’attaquent aux larves grégaires du scolyte. Dans ce système clos, la réponse fonctionelle de R. grandis est influencée par plusieurs facteurs étroitement corrélés, la densité de proies, la densité de prédateurs, et la distribution des proies. En mesurant l’efficacité de prédation de R. grandis en termes de survie des larves et de taux de croissance, nous avons démontré l’influence sur leur développement du temps passé par les larves à blesser et à tuer leurs proies. Ce facteur est par ailleurs fortement dépendant de la proportion de larves malades, blessées ou en cours de mue au sein du système ; une proportion qui peut augmenter en réponse à une augmentation de la densité de proies, ou lorsque des adultes sont présents (ceux-ci blessent les proies mais ne les consomment pas entièrement). Enfin, nos tests suggèrent qu’il n’existe que peu de cannibalisme ou de compétition intraspécifique entre larves de R. grandis, tandis que des modes de compétition moins importants prennent vraisemblablement place. R. grandis présente également une réponse numérique reproductive à la densité de proies disponibles, principalement basée sur la perception de stimuli et d’inhibiteurs présents dans les galeries du scolyte. Par la collecte de composés volatils présents dans ces systèmes à l’aide de fibres SPME, nous avons développé une méthode non-destructive pour suivre la dynamique de production des médiateurs chimiques. Nos tests ont démontré que l’activité des larves de D. micans ou D. valens influence fortement la dynamique de production de certains monoterpènes oxygénés. En revanche, il n’a pas été été possible de corréler les différents composés identifiés au nombre de larves de R. grandis présentes dans le système. La problématique soulevée par la progression de D. micans, de même que les résultats détaillés de chacune des études décrites ci-dessus sont discutés dans les deux papiers publiés et les trois manuscrits formant cette thèse. Les différentes perspectives apportées par ce travail sont également présentées dans la discussion générale.

Idéen att katters spinnande kan emotionellt och fysiologiskt påverka oss verkar resonera med många, och sprids kraftigt av media. Påståendet saknar dock vetenskaplig grund. Syftet med denna studie var att studera spinnandets effekt på människor, genom att undersöka om spinnande ger upphov till någon emotionell respons och/eller pulssänkande effekt. Studien använde en experimentell design och utgick från en dimensionell emotionsteori med skalor över valens och arousal. Deltagarna blev presenterade med isolerade auditiva stimuli innehållandes olika djurläten och ombads sedan notera sin puls och emotionstillstånd. Självskattningsformuläret SAM (The Self-Assessment Manikin) användes som metod för att mäta emotionella förändringar. Resultatet visade att katters spinnljud har en signifikant arousalsänkande effekt hos människor. Ingen signifikant påverkan på valens eller puls hittades. Studien belyser behovet av vidare forskning inom ämnet för att ytterligare förstå och kartlägga spinnandets effekt på människor. / The idea that cats’ purring can affect us emotionally and physiologically seems to resonate with many people and is widely spread by media. However, the claim lacks scientific backing. The purpose of this study was to investigate the effect of purring on people by examining whether purring gives rise to any emotional response and/or pulse-lowering effect. The study used an experimental design and was based on a dimensional emotion theory with scales of valence and arousal. Participants were presented with isolated auditory stimulus containing various animal sounds and was then asked to note their heart rate and emotional state. The self-assessment form SAM (The Self-Assessment Manikin) was used to measure emotional changes. The results showed that the purring sound of cats has a significant arousal-reducing effect in humans. No significant effect on valence or heart rate was found. The study highlights the need for further research on the subject to deepen our understanding of the effect that purring has on humans.

Rhizophagus grandis is one of the rare examples of totally specific predators: it only preys upon the bark beetle Dendroctonus micans in its native range (Europe and Asia). In the course of coevolution in such predator-prey systems, prey are selected for avoidance and resistance mechanisms against predators. Previous laboratory trials suggested that R. grandis could lay more eggs in presence of exotic prey species with an ecology similar to that of D. micans, but which could not evolve resistances against this predator, such as the North American parasitic bark beetles D. punctatus and D. valens. The specificity of the association R. grandis-D. micans is thought to depend on chemical signals (kairomones) used by the predator to find a gallery of its prey and to adjust its oviposition to the number of prey larvae available inside. However, the exact nature of the chemical signals regulating R. grandis’ oviposition is still unknown. While these signals seem specific in nature, stimulation of the predator’s oviposition by exotic prey species suggests that specificity may be constrained by geography. Unlike most bark beetles, which kill living trees or feed on dying trees, D. micans completes its development on healthy trees as a true parasite. This niche is highly defended by tree toxicants (terpenes among others) to which both D. micans and R. grandis are resistant. Insects possess their own detoxification processes, but they may also rely on symbiotic microorganisms (bacteria and fungi) to contend with the specific constraints of their niche. In comparison to other bark beetles, microbial communities of parasitic bark beetles are yet poorly known, as in the case of D. micans and D. punctatus. Apart from detoxification, insect symbionts may provide nutritional supplementation, protection against pathogens, or components of the chemical communication, which affect the hosts as well as partners of the tritrophic relationship tree-bark beetle-natural enemies. The system R. grandis-D. micans is a unique opportunity to study several aspects of this coevolution which are poorly understood to date. The objectives of this thesis were:- (1) the comparison of the oviposition performances of R. grandis on the specific prey D. micans, and on the exotic prey D. punctatus and D. valens, in order to emphasize possible prey resistance mechanisms; - (2) the identification of the chemical signals regulating R. grandis’ oviposition, and the evaluation of their role in the specificity of the association with D. micans, in presence of the exotic prey D. punctatus and D. valens; - (3) the characterization of the bacterial and fungal communities associated with non-aggressive populations of the bark beetles D. micans, D. punctatus and D. valens, and investigating how these microbial symbionts may affect bark beetle hosts in respect of their ecology as well as the tritrophic relationship tree-bark beetle-natural enemies. Our results show that R. grandis laid equivalent numbers of eggs with the native prey D. micans and with the exotic prey D. punctatus and D. valens, which could illustrate that R. grandis’ specificity is constrained by geography but which does not emphasize possible prey resistance mechanisms against the long-standing predator. We identified robust candidates to the stimulation and inhibition of R. grandis’ oviposition which should be confirmed in bioassays. Finally, we report that the bacterial and fungal communities of non-aggressive populations of D. micans, D. punctatus and D. valens are mainly composed of widespread environmental Enterobacteria and yeasts, and we discuss the various ways they may influence bark beetle hosts in respect of their life histories including the attacked trees and their natural enemies. Overall, this thesis illustrates the need to encompass all levels of complexity, from prey symbionts and semiochemicals to predators, to study systems like R. grandis-D. micans. / Rhizophagus grandis est un des rares exemples de prédateurs totalement spécifiques :présent en Europe et en Asie, il se nourrit exclusivement du scolyte Dendroctonus micans. Dans de telles associations, la coévolution prédateur-proie mène à la sélection de mécanismes d’évitement ou de résistance chez la proie, contre le prédateur. De précédentes observations en laboratoire ont suggéré que R. grandis pouvait pondre davantage d’œufs en présence de proies exotiques d’écologie comparable à celle de D. micans, mais qui n’auraient pu développer de résistance à l’encontre de ce prédateur, à l’instar des scolytes parasitiques nord-américains D. punctatus et D. valens. Il semble que la spécificité de l’association R. grandis-D. micans repose sur des signaux chimiques (kairomones) qui permettent au prédateur de repérer les galeries de sa proie et d’y ajuster le nombre d’œufs déposé à la quantité de larves de proies disponible. Néanmoins, on ignore encore la nature exacte des signaux régulant l’oviposition de R. grandis. Le fait que l’oviposition soit stimulée par des proies exotiques indique que la spécificité de cette association pourrait être limitée par des barrières géographiques. Contrairement à la plupart des scolytes qui tue des arbres ou s’attaque à des arbres mourants, D. micans se développe intégralement sur des arbres en bonne santé, en véritable parasite. Cette niche est fortement défendue par les composés toxiques de l’arbre (en particulier les terpènes), auxquels à la fois D. micans et R. grandis sont résistants. Certains insectes possèdent leurs propres processus de détoxification, mais ils peuvent également bénéficier de l’aide de microorganismes symbiotiques (bactéries et champignons). En comparaison avec les autres scolytes, les communautés microbiennes associées aux scolytes parasitiques est très peu documentée, comme dans le cas de D. micans et D. punctatus. En dehors de la détoxification, les symbiotes d’insectes peuvent contribuer à leur nutrition, les protéger contre des pathogènes, ou intervenir dans la communication chimique, ce qui affecte leurs hôtes comme les autres acteurs de la relation tritrophique arbre-scolyte-ennemi naturel. L’association R. grandis-D. micans est une opportunité unique d’étudier des aspects méconnus de la coévolution. Les objectifs de cette thèse étaient de :- (1) comparer le nombre d’œufs pondu par R. grandis sur sa proie spécifique, D. micans, et sur les proies exotiques D. punctatus et D. valens, afin de mettre en évidence de possibles résistances ;- (2) identifier les signaux chimiques qui régulent l’oviposition de R. grandis, et évaluer leur rôle dans la spécificité de l’association avec D. micans, en présence des proies exotiques D. punctatus et D. valens ;- (3) caractériser les communautés bactérienne et fongique associées aux populations parasitiques des scolytes D. micans, D. punctatus et D. valens, et investiguer comment ces microorganismes symbiotiques peuvent influencer leurs hôtes, selon leurs contraintes écologiques, ainsi que leurs ennemis naturels et arbres-hôtes. Nos résultats révèlent une oviposition équivalente de R. grandis en présence de la proie native D. micans et des proies exotiques D. punctatus et D. valens, ce qui illustre que la spécificité de cette association pourrait être limitée par des barrières géographiques mais ne met pas en évidence de possibles résistances à l’encontre du prédateur de longue date. Nous avons identifié des candidats robustes à la stimulation et à l’inhibition de la ponte de R. grandis, et leur rôle devrait être confirmé par des bioessais. Enfin, nous rapportons que la communauté microbienne associée aux populations parasitiques des scolytes D. micans, D. punctatus et D. valens est principalement constituée d’Entérobactéries et de levures répandues, et nous discutons des différentes façons dont ces symbiotes peuvent affecter leurs hôtes et autres acteurs de la relation tritrophique arbre-scolyte-ennemi naturel, selon leurs écologies respectives. Dans son ensemble, cette thèse souligne l’importance de considérer tous les niveaux de complexité biologique, des microorganismes associés aux proies jusqu’aux prédateurs, afin d’étudier des systèmes comme R. grandis-D. micans. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

The Eurasian spruce bark beetle Dendroctonus micans is a major pest of spruce which is expanding its range in France, Turkey, England and Wales. Its monospecific predator Rhizophagus grandis has followed naturally the bark beetle into most areas and, since the 1960s, has also been mass-produced and successfully released within newly infested locations. <p>In this scope, the development of an effective trapping method would be very useful to assess the bark-beetle presence at previously uninfested sites, or predator establishment after release or natural spread. We demonstrated the efficiency of oxygenated monoterpenes-baited kairomone traps to monitor R. grandis in various epidemiological conditions, including areas localized behind or at the limit of the pest’s distribution, or in areas where artificial releases were performed. Because the predator is strictly species-specific, another exciting possibility offered by the kairomone trapping is the indirect monitoring of the pest itself in areas of unknown status (e.g. areas under colonization, or considered as at risk at medium- term).<p>R. grandis is also considered as one of the most valuable natural enemies to strike aggressive North-American Dendroctonus species. In this respect, R. grandis has been recently applied in a neo-classical biological program against the red turpentine beetle D. valens, which invaded China from North America in the late 1990’s. In laboratory tests conducted on pine logs in the laboratory, or on living pine trees in the field, we demonstrated that R. grandis adults can successfully enter and reproduce into D. valens galleries. <p>In Europe, R. grandis is the only species regularly found in the brood systems of D. micans, where adults and larvae attack the gregarious larvae of their prey. In such enclosed systems, R. grandis’ functional response is therefore influenced by various interrelated components, such as the prey density, the predator density, or the prey distribution. Measuring the predator’s success in terms of larval survival and growth rates, we demonstrated the time spent by R. grandis larvae to wound and kill their prey to be the main factor limiting their development. This factor may be considerably influenced by the proportions of diseased, wounded or molting prey rise in the brood system, for instance as a result of an increase in prey density, or due to the presence of conspecific adults (which wound their prey but do not consume them entirely). Furthermore, our tests suggest that no cannibalism or noticeable intraspecific competition occurred between R. grandis larvae, whereas some lighter mode of competition probably took place. <p>R. grandis also exhibits a reproductive numerical response to prey density, which mainly relies on the perception of chemical stimuli and inhibitors released in the bark beetle brood system. In the current study, we developed a non-destructive approach to follow the dynamics of volatile compound production, using sequential sample collection on SPME fibers. Our tests demonstrated that the larval activity of D. micans or D. valens strongly influences the release of some oxygenated monoterpenes. However, our attempts to correlate the relative quantities of some identified chemicals to offspring production were less successful as it concerns the identification of potential oviposition stimuli and inhibitors. <p>The problematic rose by the progression of D. micans, as well as detailed results of each of the described above studies are discussed in the two published papers and the three manuscripts forming this thesis. Bringing all these studies together, several perspectives are also presented in the general discussion. <p>/<p>Ravageur des épicéas, Dendroctonus micans est toujours en voie d’extension en France, en Turquie, en Angleterre et au Pays de Galles. Dans la plupart de ces zones, le dendroctone est accompagné de manière naturelle par son prédateur monospécifique, Rhizophagus grandis. Depuis les années 1960, le prédateur a également fait l’objet d’une production de masse et de programmes de lâchers dans les zones d’arrivée récente du scolyte.<p>Dans le cadre de la lutte biologique contre D. micans, les gestionnaires forestiers doivent donc estimer au plus tôt la présence du ravageur dans des zones jusque là indemnes, mais également vérifier l’établissement du prédateur par progression naturelle ou résultant d’introductions délibérées. Dans la présente étude, nous avons démontré l’efficacité de pièges d’interception appatés à l’aide de monoterpènes oxygénés pour la capture de R. grandis. Celle-ci s’est faite dans différentes conditions épidémiologiques, incluant notamment des zones situées en arrière du front de progression du scolyte et des zones où des lâchers artificiels ont été réalisés. Comme R. grandis est strictement inféodé au dendroctone, un autre avantage de la technique est la possibilité de réaliser un dépistage indirect du ravageur dans les zones où son statut est incertain (zones en cours de colonisation, ou considérées comme à risque à moyen terme).<p>Par ailleurs, R. grandis est également considéré comme un des meilleurs ennemis naturels potentiels pour lutter contre d’autres espèces de Dendroctonus aggressifs. Dans cette optique, R. grandis a été récemment utilisé dans un programme de lute biologique contre D. valens, ravageur invasif arrivé en Chine dans la fin des années 1990 en provenance d’Amérique du Nord. Nous avons démontré la capacité de R. grandis à s’introduire et à se reproduire dans les galeries de D. valens lors de tests de laboratoire, mais aussi sur des arbres vivants en pinèdes. <p>En Europe, R. grandis est strictement inféodé aux galeries de D. micans, où larves et adultes du prédateur s’attaquent aux larves grégaires du scolyte. Dans ce système clos, la réponse fonctionelle de R. grandis est influencée par plusieurs facteurs étroitement corrélés, la densité de proies, la densité de prédateurs, et la distribution des proies. En mesurant l’efficacité de prédation de R. grandis en termes de survie des larves et de taux de croissance, nous avons démontré l’influence sur leur développement du temps passé par les larves à blesser et à tuer leurs proies. Ce facteur est par ailleurs fortement dépendant de la proportion de larves malades, blessées ou en cours de mue au sein du système ;une proportion qui peut augmenter en réponse à une augmentation de la densité de proies, ou lorsque des adultes sont présents (ceux-ci blessent les proies mais ne les consomment pas entièrement). Enfin, nos tests suggèrent qu’il n’existe que peu de cannibalisme ou de compétition intraspécifique entre larves de R. grandis, tandis que des modes de compétition moins importants prennent vraisemblablement place.<p>R. grandis présente également une réponse numérique reproductive à la densité de proies disponibles, principalement basée sur la perception de stimuli et d’inhibiteurs présents dans les galeries du scolyte. Par la collecte de composés volatils présents dans ces systèmes à l’aide de fibres SPME, nous avons développé une méthode non-destructive pour suivre la dynamique de production des médiateurs chimiques. Nos tests ont démontré que l’activité des larves de D. micans ou D. valens influence fortement la dynamique de production de certains monoterpènes oxygénés. En revanche, il n’a pas été été possible de corréler les différents composés identifiés au nombre de larves de R. grandis présentes dans le système. <p>La problématique soulevée par la progression de D. micans, de même que les résultats détaillés de chacune des études décrites ci-dessus sont discutés dans les deux papiers publiés et les trois manuscrits formant cette thèse. Les différentes perspectives apportées par ce travail sont également présentées dans la discussion générale.<p> / Doctorat en Sciences agronomiques et ingénierie biologique / info:eu-repo/semantics/nonPublished

Os prefixos germânicos de alguns verbos suecos serão comparados numa análise contrastiva com as relativas equivalências em português e em italiano num corpus paralelo escrito composto por um romance de língua sueca, um de língua portuguesa e um de língua italiana e pelas suas respectivas traduções. As funções desenvolvidas pelos prefixos germânicos dos verbos suecos analisados serão examinadas e depois confrontadas com as relativas equivalências, com o resultado que também nas duas línguas românicas relevam-se, de maneira bastante constante, procedimentos gramaticais parecidos aos desenvolvidos pelos prefixos germânicos. / Germanic prefixes of which some Swedish verbs are composed are going to be compared in acontrastive analysis with their relative equivalences in Portuguese and Italian in a parallel written corpus characterized by a Swedish-language romance, a Portuguese-language romance and an Italian language romance, and by their relative translations. The functions executed by the German prefixes of the analysed Swedish verbs are going to be examined and then compared with their relative equivalences, with the result that even in the Romance languages it is possible to find in a quite constant way grammatical processes which are similar to those executed by the Germanic prefixes. / I prefissi germanici di alcuni verbi svedesi saranno comparati in un'analisi contrastiva con le relative equivalenze in portoghese e in italiano in un corpus parallelo scritto composto da un romanzo di lingua svedese, uno di lingua portoghese e uno di lingua italiana e dalle rispettive traduzioni. Le funzioni svolte dai prefissi germanici dei verbi svedesi analizzati saranno esaminate e poi confrontate con le relative equivalenze, con il risultato che anche nelle due lingue romanze si riscontrano in maniera abbastanza costante processi grammaticali simili a quelli svolti dai prefissi germanici. / De germanska prefix som återfinns i vissa svenska verb kommer att jämföras med sina motsvarigheter på portugisiska och italienska. Detta görs med hjälp av en skriven korpus bestående av en roman ursprungligen skriven på svenska, en skriven på portugisiska och en skriven på italienska samt översättningar av dessa romaner till de två andra språken. Funktionen hos de svenska verben med germanska prefix kommer att analyseras och sedan jämföras med verbens motsvarigheter. Resultatet av analysen visar att det är möjligt att finna systematiskt återkommande grammatiska processer i de romanska språken, som liknar de som förekommer i samband med de germanska prefixen på svenska.

Os prefixos germânicos de alguns verbos suecos serão comparados numa análise contrastiva com as relativas equivalências em português e em italiano num corpus paralelo escrito composto por um romance de língua sueca, um de língua portuguesa e um de língua italiana e pelas suas respectivas traduções. As funções desenvolvidas pelos prefixos germânicos dos verbos suecos analisados serão examinadas e depois confrontadas com as relativas equivalências, com o resultado que também nas duas línguas românicas relevam-se, de maneira bastante constante, procedimentos gramaticais parecidos aos desenvolvidos pelos prefixos germânicos. / Germanic prefixes of which some Swedish verbs are composed are going to be compared in a contrastive analysis with their relative equivalences in Portuguese and Italian in a parallel written corpus characterized by a Swedish-language romance, a Portuguese-language romance and an Italian-language romance, and by their relative translations. The functions executed by the German prefixes of the analysed Swedish verbs are going to be examined and then compared with their relative equivalences, with the result that even in the Romance languages it is possible to find in a quite constant way grammatical processes which are similar to those executed by the Germanic prefixes. / I prefissi germanici di alcuni verbi svedesi saranno comparati in un’analisi contrastiva con le relative equivalenze in portoghese e in italiano in un corpus parallelo scritto composto da un romanzo di lingua svedese, uno di lingua portoghese e uno di lingua italiana e dalle rispettive traduzioni. Le funzioni svolte dai prefissi germanici dei verbi svedesi analizzati saranno esaminate e poi confrontate con le relative equivalenze, con il risultato che anche nelle due lingue romanze si riscontrano in maniera abbastanza costante processi grammaticali simili a quelli svolti dai prefissi germanici. / De germanska prefix som återfinns i vissa svenska verb kommer att jämföras med sina motsvarigheter på portugisiska och italienska. Detta görs med hjälp av en skriven korpus bestående av en roman ursprungligen skriven på svenska, en skriven på portugisiska och en skriven på italienska samt översättningar av dessa romaner till de två andra språken. Funktionen hos de svenska verben med germanska prefix kommer att analyseras och sedan jämföras med verbens motsvarigheter. Resultatet av analysen visar att det är möjligt att finna systematiskt återkommande grammatiska processer i de romanska språken, som liknar de som förekommer i samband med de germanska prefixen på svenska.