Dissertations / Theses: 'Host preference'

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Oliveira, Ana L. "Host preference profile in an area of Eastern Equine Encephalitis (EEE) virus transmission in Alabama." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2010. https://www.mhsl.uab.edu/dt/2010p/oliveira.pdf.

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Marriott, Charles. "Host plant location, selection and preference by the wheat bulb fly Delia coarctata Fall. (Diptera: Anthomyiidae)." Thesis, University of Edinburgh, 2001. http://hdl.handle.net/1842/28541.

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The geographical distribution and phenology of WBF are matched more closely with those of couch than with those of other hosts. These factors suggest that couch, and not wheat, is the preferred host. Aspects of this hypothesis were tested in the laboratory, glasshouse and field. In choice test bioassays neonate larvae preferred couch seedlings and their exudates to wheat seedlings and their exudates, and couch rhizome exudates to controls. Couch seedling exudates had attractant properties, whereas wheat exudates had attractant and arrestant properties, when compared with controls. The larvae were photophobic and positively geotactic. In a pot trial, symptoms of infestation appeared earlier in couch than in wheat. At first, larvae encouraged production of extra shoots, especially of couch, which they kill. After 5 weeks, infested plants suffered a relative reduction in number of shoots, but uninfested neighbouring plants, especially wheat, compensated for this by producing more shoots themselves. Larvae raised on couch emerged as adults earlier than those raised on wheat. They thus develop more rapidly, and use more resources, on couch than on wheat, i.e. they are better adapted to couch as a food source. Earlier eclosion in the field would allow adults to make better use of favourable weather conditions, and to live longer, mate more often, and produce more eggs. In the laboratory and the field adult WBF preferred to rest on couch than on wheat. They also preferred taller plants and those nearer the edge of a stand. Buried couch rhizomes did not encourage oviposition by gravid WBF females, either in the laboratory or the field. These findings support the hypothesis that couch is the preferred host of WBF, provide a partial explanation of high larval mortalities on wheat, and suggest that attractants isolated from couch and arrestants isolated from wheat could be used to control WBF larvae if incorporated into buried granules.

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Wong, Kit-man, and 黃潔文. "Diversity, host preference, and vertical distribution of saprobic fungi on grasses and sedges in Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2000. http://hub.hku.hk/bib/B43894409.

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Wong, Kit-man. "Diversity, host preference, and vertical distribution of saprobic fungi on grasses and sedges in Hong Kong." Hong Kong : University of Hong Kong, 2000. http://sunzi.lib.hku.hk/hkuto/record.jsp?B22054078.

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Jefferson, David Kirk. "Euonymus scale, Unaspis euonymi (Comstock) : host preference, and distribution of native and imported natural enemies in Virginia /." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-05092009-040452/.

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Ziani-Hadjhenni, Leila. "Taxonomie integrative des Culicoides (Diptera Ceratopogonidae) de la région Champagne-Ardenne." Thesis, Reims, 2014. http://www.theses.fr/2014REIMS021/document.

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Plusieurs systématiques se côtoient aujourd'hui : la systématique typologique, d'inspiration linnéenne, qui repose sur l'examen morphologique de types porte-nom. Depuis plusieurs années, une systématique phylogénétique conduit également à la création de taxons nouveaux, de niveau spécifique, infra-spécifique et supra-spécifique. Dans ce travail, nous avons cherché une approche globale, qualifiée de taxonomie intégrative couplant les approches morphologiques traditionnelles, la systématique moléculaire et la geomorphométrie alaire, dans le but d'éclairer la notion d'espèce chez les Culicoides avec ses corollaires épidémiologiques, étant donnée l'importance de ces insectes dans des maladies majeures d'intérêt vétérinaire telles que la fièvre catarrhale ovine (FCO) et la maladie causée par le virus de Schmallenberg (SBV). Cette approche nous a permis de mettre en lumière la complexité systématique des espèces affines (C.clastrieri/C.festivipennis, les groupes Obsoletus, Pulicaris et Vexans). De plus, nous nous sommes intéressés aux préférences trophiques des Culicoides de la région Champagne-Ardenne Several systematic coexist today: typological systematic of Linnaean spirit, based on morphological examination of type specimens. For several years, a phylogenetic systematics also led to the creation of new taxa, at specific, sub-specific and supra-specific level.In this study, we have sought a comprehensive approach i.e. an integrative taxonomy that coupling traditional morphological approaches, molecular systematic and wing geometry morphometric in order to clarify the concept of species in the Culicoides with epidemiological corollaries, given the importance of these insects in major diseases of veterinary interest such as bluetongue (BT) and the disease caused by the Schmallenberg virus (SBV). This approach allowed us to highlight the systematic complexity of related species (C.clastrieri / C.festivipennis, the Obsoletus, Pulicaris and Vexans groups). In addition, we investigated the host preference of Culicoides of the Champagne-Ardenne region

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Peterson, Donnie L. "Preference, performance, and selection of historic and novel hosts by emerald ash borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)." Wright State University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=wright15742434948598.

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Egbon, Ikponmwosa Nathaniel. "The performance and preference of a specialist herbivore, Catorhintha schaffneri (Coreidae), on its polytypic host plant, Pereskia aculeata (Cactaceae)." Thesis, Rhodes University, 2019. http://hdl.handle.net/10962/68250.

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Plant species moved beyond their natural ranges may be liberated into enemy-free spaces, where they increase resource allocation to fitness, rather than defence against natural enemies, and become invasive as suggested by the Evolution of Increased Competitive Ability (EICA) Hypothesis. Several cacti are notable invaders and are targeted for biological control. The leafy cactus, Pereskia aculeata Miller, introduced into South Africa from South America, has become a target for biological control after becoming invasive. The absence of natural enemies of P. aculeata in the introduced range may be the reason for its invasiveness. This thesis seeks to investigate the role of the evolution of increased competitive ability (enemy release) as the probable driver of P. aculeata’s success, and ascertain how the plant’s intraspecific variation influences the impact, fitness of, and preference by its biological control agent, Catorhintha schaffneri Brailovsky and Garcia (Coreidae), in South Africa. Enemy release and evolution of traits in P. aculeata were examined by quantifying plant growth parameters of fifteen genotypes of P. aculeata from both the native and invaded distribution of the plant. Ten genotypes of P. aculeata were used in testing the effect of agent herbivory (impact and damage) under similar conditions. These studies indicated that most invaded-range genotypes were more vigorous than the native genotypes. Rapid growth may account for the quick access of invasive genotypes of P. aculeata to tree canopies. Catorhintha schaffneri damage varied between genotypes but differences in the damage and impact from the agent could not be explained by whether the plant originated in the introduced or native distribution. In sum, while the growth of the invasive genotypes largely conforms to the EICA hypothesis, the impact of C. schaffneri did not support the hypothesis. The influence of host variation in P. aculeata on the fitness of C. schaffneri within the context of local adaptation to plant genotypes from different localities was tested using agent survival, stage-specific and total developmental time, and the extent of damage to ten host genotypes. Maw’s Host Suitability Index (HIS) and Dobie’s Susceptibility Index (DSI) showed the preference by and performance of C. schaffneri on the different genotypes of the plant. Catorhintha schaffneri survived to the adult stage on 70% of genotypes tested. Evidence consistent with the assumption that C. schaffneri would be fitter on the native genotypes than the invasive genotypes due to local adaptation was not found. In addition, there was no evidence in support of fitter agents on the invasive genotypes than on the native genotypes as proposed by EICA hypothesis. Catorhintha schaffneri developed equally well on the invasive genotypes of P. aculeata as on the native genotypes. To establish whether host variation would affect diet selection by C. schaffneri, both nymphs and adults were examined in paired-choice and multiple-choice trials. The nymphs and adults chose their hosts regardless of host genotype differences. The agent may be good at selecting good succulent shoots from bad shoots, but is incapable of distinguishing a good host genotype from a poorer one. This thesis shows, therefore, that P. aculeata and its array of genotypes in South Africa could be effectively controlled by C. schaffneri, as it has the potential to suitably utilise and impact the different genotypes of the weed in South Africa with neither any demonstrable preference nor local adaptation for the native genotypes. Consequently, the use of C. schaffneri, as a biological control agent in the weed biological control programme of P. aculeata remains promising, as the agent is insensitive to the intraspecific variation of the invasive host plants.

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Gende, Paul. "The cocoa pod borer, Conopomorpha cramerella (Snellen) (Lepidoptera: Gracillariidae) in Papua New Guinea: its distribution and host plant preference." Thesis, The University of Sydney, 2015. http://hdl.handle.net/2123/13705.

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The Cocoa Pod Borer (CPB) moth, Conopomorpha cramerella (Snellen) (Lepidoptera: Gracillariidae) was first detected attacking cocoa in Papua New Guinea in 2006. Attempts to eradicate were unsuccessful and efforts to promulgate intervention strategies in the cocoa farming communities moved slowly due to various constraints. This provided an opportunity for the pest to spread. The pest, by now, has been in the country for more than six years. However, there is no information and work done on the local biological and ecological interactions of the pest and its distribution. This information is prerequisite to development of an effective location-specific integrated pest management strategy (Ls-IPM) for CPB in Papua New Guinea. This work intends to look into some aspects of the biology and ecology of the pest in its recently established local environment. Two main areas of interest this work intend to investigate are: (1) the spread and distribution of the pest after the incursion, and (2) the host plant preferences. Historical information and literature indicated that CPB is native to Southeast Asia where cocoa was introduced into this region in the 16th century by the Spaniards. Since its detection in 2006, the pest has now spread to nine provinces in Papua New Guinea. Evaluation on host plant preferences using a simple improvised olfactometer indicated a significant difference in orientation responses to Theobroma cacao L. than Nephelium lappaceum L. and Pometia pinnata J.R. Forst. & G. Forst. Egg deposition on host plants offered simultaneously also indicated a strong preference for oviposition on T. cacao. The attention of the pest towards T. cacao is a concern for cocoa cultivation. Also the ability of the adults reared purely from T. cacao to lay eggs and orientate towards N. lappaceum and P. pinnata, though not significant, is a serious concern for T. cacao cultivation in Papua New Guinea as N. lappaceum is gradually gaining momentum as an alternative cash crop and P. pinnata is edible and is a potential alternative cash crop and are seen within the vicinity of many smallholder cocoa farming systems.

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Nguyen, My Land Do. "Understanding the political integration outcomes of enfranchised and high socioeconomic status immigrants in host societies." Doctoral thesis, Universitat Pompeu Fabra, 2020. http://hdl.handle.net/10803/668720.

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The purpose of this dissertation is to systematically investigate the theoretical perspective that political power derives from socioeconomic power—a fundamental tenet of both sociological theories of assimilation and political science theories of participation. Each chapter of this dissertation studies this assumption within the context of the acquisition of socio-racial status, the acquisition of nationality, and the acquisition of assets. This thesis analyses the roles played by political capital obtained from the origin country, social capital built within the communities, and institutional-political context of the host country. This dissertation finds that socioeconomic inclusion does not automatically lead to political inclusion but that much of this process can be facilitated by public policies. L’objectiu d’aquesta tesi és investigar sistemàticament la perspectiva teòrica que el poder polític deriva del poder socioeconòmic, un principi fonamental tant de les teories sociològiques de l’assimilació com de les teories de la ciència política. Cada capítol d'aquesta tesi estudia aquest supòsit en el context de l'adquisició d'estatus socio-racial, l'adquisició de la nacionalitat i l'adquisició de béns. Aquesta tesi analitza els rols jugats pel capital polític obtingut del país d'origen, el capital social construït dins de les comunitats i el context institucional-polític del país amfitrió. Aquesta tesi troba que la inclusió socioeconòmica no condueix automàticament a la inclusió política, però que gran part d’aquest procés pot ser facilitat per les polítiques públiques.

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Muthuthantri, Weerawickramage Sakuntala Nayanatara. "Citrus host utilisation by the Queensland fruit fly, Bactrocera tryoni (Frogatt) (Diptera:Tephritidae) : from individuals to populations." Thesis, Queensland University of Technology, 2013. https://eprints.qut.edu.au/62855/2/Weerawickramage_Muthuthantri_Thesis.pdf.

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Fruit flies are the insects which cause maggots in your backyard fruit and vegetables. They are not just a nuisance to gardeners, but the single greatest insect threat to commercial and subsistence fruit growers throughout Asia, Australia and the Pacific. Queensland fruit fly, the focus of this PhD, costs Australia an estimated $100million per year. I focused specifically on how Queensland fruit fly uses different commercial citrus varieties. I identified specific plant related mechanisms which increase a fruit’s resistance to fruit fly attack. This information can be used by plant breeders to make fruit less prone to fruit fly damage.

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Pöykkö, H. (Heikki). "Host range of lichenivorous moths with special reference to nutritional quality and chemical defence in lichens." Doctoral thesis, University of Oulu, 2005. http://urn.fi/urn:isbn:951427959X.

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Abstract Host use and range of herbivorous insects are determined by several factors, of which nutritional quality and secondary chemistry have been shown to play very important roles. For herbivores feeding on lichens these traits are assumed to be more critical than for species feeding on higher plants, since lichens are nutritionally poor and often contain high concentrations of secondary metabolites. I examined the role of lichens' nutritional quality and secondary chemicals on the performance of lichen-feeding Lepidopteran larvae. I also tested whether females of lichenivorous species preferably oviposit on host species of the highest nutritional quality for the growth of larvae. Larvae of Eilema depressum performed best on Melanelia exasperata, which is of the highest nutritional quality, as indicated by the high N concentration and the absence of lichen secondary metabolites compared to the other lichens studied. Host nutritional quality did not promote the production of an additional generation. Larvae of E. depressum needed fewer instars and grew bigger on a high-quality diet than larvae reared on a diet of poorer quality. However, the main factor contributing to the wide variation in the number of larval instars was the question of whether or not larvae overwintered. Growth of Cleorodes lichenaria at the beginning of the larval period matched equally the nutritional quality of the hosts. However, the final larval period was shortest on Ramalina species, which was preferred by both females ovipositing their eggs and larvae searching for a host. In the field, larvae were found almost exclusively on Ramalina species. Larvae of E. depressum were not able to survive on intact thalli of Vulpicida pinastri and Hypogymnia physodes, but after removal of lichen's secondary metabolites, larval survival remained equally high as on other lichens. Larvae also showed a clear preference towards thalli with lowered concentrations of secondary metabolites in Parmelia sulcata, V. pinastri and H. physodes. Parietin in Xanthoria parietina was the only secondary metabolite that had no impact on the survival or host selection of E. depressum larvae. The present results show that the nutritional quality and some lichen secondary chemicals are important factors for the growth, survival and host selection of lichen-feeding Lepidopteran larvae. The preference-performance hypothesis is at least partly able to explain the host range of C. lichenaria, although it seems that there are also other factors, such as larval dispersal and host selection or top-down forces, that might contribute to host range of lichenivorous Lepidopteran larvae. Moreover, lichenivorous larvae seem to be partly responsible for their own host selection.

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Duan, Yanqing. "Genetic structuration and host tree preference of Tomicus piniperda population in southwestern China, with comparison to the French population from scots pine." Orléans, 2003. http://www.theses.fr/2003ORLE2070.

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Tomicus piniperda est un des principaux ravageurs forestiers du monde et cause généralement des pertes de croissance suite à son installation dans les pousses de pins. Les populations du sud-ouest de la Chine sont cependant particulières puisqu'elles causent des mortalités importantes dans les forêts de pin du Yunnan. L'étude visait à comprendre pourquoi des dommages ont lieu au Yunnan alors qu'aucune mortalité n'intervient en Europe. Elle a été focalisée sur la structure génétique des populations et le comportement de sélection des arbres hôtes et a aboutit aux résultats suivants : 1) Des variations des quantités de monoterpènes et de phénols du phloème ont été observées entre espèces de pin et à différentes hauteurs sur le tronc ; 2) L'étude génétique sur les ADN mitocondriaux COI-COII et ITS1 a clairement séparées les populations du Yunnan en 2 groupes d'haplotypes, différant nettement des populations européennes. Un groupe correspond certainement à une espèce nouvelle pour la science alors que l'autre groupe semble en étroite correspondance avec l'espèce T. Brevipilosus ; 3) Pour les insectes chinois, les attaques comme la production ont réussi nettement mieux sur le pin du Yunnan que sur les autres espèces de pin, ainsi que montré dans les tests biologiques, et la composition chimique des hôtes a été considérée comme un facteur essentiel affectant le comportement ; 4) Pour les insectes français, les attaques et la reproduction ont réussi sur toutes les essences testées, mais le pin sylvestre d'Orléans est apparu le plus favorable à la reproduction. Les jeunes émis de P. Nigra et P. Sylvestris ont été les essences préférées, tandis que P. Pinaster du sud-ouest de la France s'est montré le moins attaqué, lors des tests de choix pour la nutrition sur pousses. Les composés chimiques (monoterpènes) émis par les semis pourraient jouer un rôle. Notre étude démontre l'originalité du Tomicus du Yunnan par rapport à l'espèce européenne T. Piniperda.

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Fard, Mohammad Reza Saghari. "Characterisation and host-parasite interaction of the piscine diplomonad Spironucleus salmonis." Doctoral thesis, Humboldt-Universität zu Berlin, Landwirtschaftlich-Gärtnerische Fakultät, 2008. http://dx.doi.org/10.18452/15855.

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Durch Parasiten stellen eine starke Gefährdung für die Aquakultur dar. Die durch diplomonaden Flagellaten bei der Regenbogenforelle Oncorhynchus mykiss verursachte Morbidität und Mortalität wurde bisher in Deutschland noch nicht gründlich untersucht. Ich habe diese Parasiten mittels SEM & TEM charakterisiert und wurde die Art Spironucleus salmonis bestimmt. Erstmals konnten die caudale Projektion, sich entleerende Vakuolen und verformbare Kernloben nachgewiesen werden. Ich untersuchte Mikrohabitatpräferenz von des Parasiten sowie pH-Profile in vier Darmabschnitten der Fische. Das Vorkommen und die Dichte von S. salmonis war in der Pylorusregion wesentlich höher als in anderen Bereichen. Das pH-Profil war bei infizierten und nicht infizierten Fischen gleich. Der optimale pH-Wert für S. salmonis war 7,1-7,5. Ich habe die Lebenszyklus der Diplomonaden mittels LM & SEM unter Kulturbedingungen untersucht. Die Enzystierung begann mit der Anheftung von Trophozoiten mit der Spitze der adhäsiven hinteren Flagellen aneinander oder an Fremdkörper. Die pyriformen Trophozoiten wurden kugelförmig, und die vorderen Flagellen inaktiv. Oberflächenbläschen produzierten eine lichtbrechende Zystenwand. Dies ist der erste Beschreibung der Multifunktionalität von Flagellen bei Diplomonaden. Ich untersuchte pathogene Mechanismen und sezierte die Pylorusregion sowie die Leber mittels H&E, PAS/AB. Bei infizierten Fischen trat eine signifikante Hypertrophie der Becherzellen auf. Zu erkennen war eine Hyperaktivität der Becherzellen, jedoch keine Hyperplasie. Ich entwickelte einen in vitro Plasma-Inkubationstest zur Bestimmung der Suszeptibilität von Regenbogenforelle, Karpfen und Störe. Die unterschiedliche Resistenz von Stör, Karpfen und Regenbogenforelle gegen S. salmonis entsprechend zu den epizootiologischen Daten. Meine Untersuchungen führten zu einem neuen diagnostischen Hilfsmittel, Vorschlägen für neue Behandlungsmethoden, zu verbesserten in vitro-Kulturbedingungen und einem Modellsystem für die Multifunktionalität von Flagellen und flagellaren Signaltransduktion. Parasitic diseases pose a significant threat to aquaculture. Diplomonad flagellates in rainbow trout Oncorhynchus mykiss are associated with morbidity and mortality; but in Germany has not been thoroughly studied. I characterised the species by SEM & TEM, which revealed Spironucleus salmonis, allowed its complete description including newly showing the caudal projection, discharging vacuoles, and deformable nuclear lobes; diagnostic keys were improved. The microhabitat preference of diplomonads was tested by recording occurrence and density of infection, and pH profile in 4 intestinal regions in fish. Occurrence and density of S. salmonis were significant higher in the pyloric region than elsewhere. The pH profile in uninfected and infected fish was similar; a causal relationship between microhabitat preference and pH was unlikely, and the optimal pH was between 7.1 – 7.5. I described life cycle and encystment using light and SEM. Encystment in culture began by trophozoites attaching at tip of adhesive posterior flagella to each other/debris. Pyriform trophozoites became sub-spherical, anterior flagella inactive, surface blebs produced a refractile cyst wall. Cysts clusters may exceed minimum infective dose for new infection; suggesting new treatment target. This is the first report of multi-functionality of flagella in diplomonads. I investigated pathogenic mechanism of diplomonads by sectioning and staining the pyloric region of the intestine and liver with H&E, and PAS/AB. There was significant hypertrophy of goblet cells in infected fish. The hyperactivity of goblet cells was seen, but no hyperplasia. This hyper-production of mucus may decrease nutrient absorption, underlying impaired growth in S. salmonis infected fish. I developed an in vitro plasma incubation test to predict host susceptibility of rainbow trout, carp, and sturgeon. The test showed the hierarchy of resistance of S. salmonis in sturgeon > carp > rainbow trout; this parallels epizootiological data. My research yielded new diagnostic tool, suggested new treatment target, improved in vitro conditions, and new model system for multi-functionality of flagella and flagellar signalling.

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Balagawi, Solomon. "Comparative Ecology of Bactrocera Cucumis (French) and Bactrocera Tryoni (Froggatt) (Diptera: Tephritidae) - Understanding the Life History Consequences of Host Selection and Oviposition Behaviour." Thesis, Griffith University, 2007. http://hdl.handle.net/10072/366527.

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The host use patterns of tephritids (fruit flies) range from those that are highly specific (monophagous, oligophagous) to those that use a wide range of hosts from different plant families (polyphagous). Knowledge of the mechanisms responsible for such host use patterns is critical in understanding the insect-plant relationship and developing successful population management strategies. Several studies have revealed that the behavioural and environmental factors play a significant role in host use. A key theory thought to explain host use patterns of phytophagous insects has been optimality theory (preference-performance hypothesis), however, this has seldom been investigated in fruit flies. In this thesis I compared the host use pattern of the specialist (oligophagous) cucumber fruit fly, Bactrocera cucumis (French), and the generalist (polyphagous) Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae: Dacinae), both serious agricultural pests in Queensland, Australia. I primarily focussed on investigating the role of the preference-performance hypothesis in explaining the host use pattern of these two species at different plant taxonomic levels. I also examined the life history consequences of host use patterns by investigating the demographies of these two dacines on different host plants. The preference-performance hypothesis postulates that the host preference executed by an insect should be positively correlated to its offspring performance. While there were some correlations between preference and performance parameters for both B. cucumis and B. tryoni, these were dependent on the parameter used and were more relevant in explaining host use patterns in B. cucumis than B. tryoni. Both species exhibited significant host discrimination among the different hosts presented to them. More significantly, they preferentially used certain host plants even when hosts of purportedly equivalent status were presented to them simultaneously. The efficiency with which they used their hosts differed even when offered different varieties of a host species from their primary host family. These patterns, observed in both these dacine species, indicated that host use is more plausibly explained by behavioural and physiological factors associated with host use. Key factors affecting host acceptance behaviour and subsequent host use of dacine fruit flies include pre-alighting factors (e.g., host plant structure, fruit colour, shape and size) and post-alighting factors (e.g., pericarp toughness, fruit volatiles and chemical composition of fruit). I investigated the role of fruit size and pericarp toughness in explaining host use patterns. Pericarp toughness appeared to strongly affect host acceptance and subsequent host use in both dacine species. Although some fruit species were readily accepted for oviposition by receiving a high proportion of oviposition attempts from both fly species, very few of these oviposition attempts resulted in pericarp penetration (oviposition event). This behaviour was primarily attributed to the differences in pericarp toughness; fruits with a tougher pericarp provided greater resistance to ovipositor penetration, thus resulting in less use than those with a softer pericarp. In addition to the behavioural aspects of fruit fly-host plant relationships, life history parameters of tephritid species play a significant role in host use. Investigations of the demography of these species on different hosts revealed that the polyphagous B. tryoni has higher fecundity and net reproductive rate, and shorter generation time while the oligophagous B. cucumis has a lower fecundity and net reproductive rate with a longer generation time. While the demographic patterns of the B. cucumis appeared to conform to preference-performance hypothesis, B. tryoni showed some interesting departures from the predictions of the preference-performance hypothesis. For B. tryoni, it was evident that some hosts that may yield lower survival in terms of larval survival (e.g., plum) may still be demographically suitable because of the enhanced reproductive performance of adults emerging from these fruits. This highlights the significance of the quality of adult feeding resource in the demography of this species. Organizing demographic data and analysing them using population projection models also enabled me to identify critical life stages that influence the demography of these two species across different host fruits. This study found that for both the specialist B. cucumis and the generalist B. tryoni, population growth rate is highly sensitive at the adult reproductive stage, indicating that manipulating probability of survival at this life stage would be critical to manage the population of these pest species. This may explain the success of protein bait sprays as a technique to manage these pest species. Predators or pathogens that target the adult reproductive stage may also provide successful biological control of these pest fruit fly populations. In addition to survival of reproductive individuals, pupal survival was also important to the demography of these species, suggesting that biological control targeting pupal stage may also yield population suppression across different fruit production systems. In summary, my studies showed that, while the preference-performance hypothesis may be a useful heuristic tool in explaining comparative host use patterns in the Dacinae, it may be more valuable in understanding primary adaptations of different species that enable them to use different host plants. This understanding combined with the life-history consequences of host use would not only shed light on their ecology, but also prove valuable in designing suitable management strategies for pest dacines. Thesis (PhD Doctorate) Doctor of Philosophy (PhD) Australian School of Environmental Studies Full Text

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Gowacki, William Alan. "Taxonomy, Ecology, and Behavior of the Kleptoplastic Sea Slug Elysia papillosa." Scholar Commons, 2017. http://scholarcommons.usf.edu/etd/6848.

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Sacoglossan sea slugs are one of the best known examples of specialist herbivores in the marine environment and can be found strongly associated with their algal hosts and food sources. Perhaps the most intriguing characteristic of many sacoglossans is their ability to sequester functional chloroplasts from their algal food sources in a process called kleptoplasty. Despite this, there continues to be issues regarding taxonomic identification of species. In turn, the ecological characteristics of many of these slugs, such as algal host and food source preference, as well as their behavioral aspects, have received little attention. A prime example of these issues arises in one such kleptoplastic sacoglossan found at Sunset Beach, Tarpon Springs, USA. The slug had previously been identified as Elysia patina based on a recent description, but later evidence suggested this was incorrect. Furthermore, despite the evidence found for the slug’s photosynthetic capabilities, little was known of its ecological relationships and behavior. The purposes of this study were to: 1) correct the uncertain taxonomy of the Tarpon Springs slug previously identified as Elysia patina, and 2) explore the ecological and behavioral characteristics of the slug. First, a comparative study was performed between the Tarpon Springs slug and its original description, as well as descriptions for the superficially-similar congener slug, Elysia papillosa. The gross anatomy, dorsal surface vascular morphology, radular morphology, egg mass morphology, and developmental timeline of the Tarpon Springs slug were used as means of comparison with the previous descriptions. The results of the comparison show that the Tarpon Springs slug was in fact E. papillosa rather than E. patina, and that the most recent description used to identify the slug as E. patina was incorrect and should not be used. Second, a descriptive study of the ecological and behavioral aspects of E. papillosa at the Sunset Beach site were performed. From October 2014 to September 2015, bi-weekly algal collections were made to determine the seasonal abundance of the slug and a possible relationship between slug abundance and algal abundance. Next, a second collection study was performed bi-monthly from April to July 2016 to identify the preferred algal host of E. papillosa between the three most abundant rhizophytic algae at the site, Penicillus capitatus, Penicillus lamourouxii, and Halimeda incrassata, all of which have been previously reported as being hosts of E. papillosa. The results of these studies showed no relationship between slug abundance and algal abundance, however E. papillosa was found to have a seasonal population fluctuation, with the fewest slugs found in winter and summer months and the most slugs found in the spring and fall months, especially in April and May. Elysia papillosa was also found in significantly higher numbers on the alga P. capitatus compared to the other two algal species, although some slugs were found on P. lamourouxii. Only one slug was found on H. incrassata, indicating it is not being used as a host despite previous reports. Further exploration into the genetics of sequestered chloroplasts would provide critical details into E. papillosa’s feeding behavior in situ. Lastly, because of E. papillosa’s photosynthetic abilities, an experiment was performed to determine if E. papillosa exhibited phototactic behavior. Fully-fed slugs were found to have no preference for either light or dark conditions, indicating their behavior was not being influenced by their photosynthetic abilities. This information provides a means of comparison with future studies of the phototactic behavior of kleptoplastic slugs, and could provide insight into how the longevity of functional chloroplasts in each species of slug could influence their behavior.

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Cassell, Meredith Edana. "Bean Leaf Beetle: Impact of Leaf Feeding Injury on Snap Beans, Host Plant Choice and Role as a Vector of Bean Pod Mottle Virus in Virginia." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/76768.

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The bean leaf beetle (BLB), Cerotoma trifurcata (Forster) (Coleoptera: Chrysomelidae), is a pest of commercially produced legumes in eastern Virginia. Field cage and manual-defoliation studies were conducted in Virginia to determine an economic impact of BLB. In the manual-defoliation study, snap bean plants had significant yield loss when > 25% of leaf area was removed. In the field cage experiments, I was unable to establish beetle densities per plant to impact yield. Host plant selection by BLB was done in laboratory and field studies with snap bean, lima bean, and soybeans. Laboratory studies showed that BLB preferred snap bean and lima bean over soybean. Field studies did not showed no preference. A survey was conducted on the Eastern Shore of Virginia determine the epicenter of BPMV. Soybean leaves and beetles were collected and assessed for BPMV by ELISA or TBIA. Beetles at the ESAREC were BPMV-positive upon emergence from overwintering sites, but the virus load was low when tested by ELISA. This suggests acquisition of virus from a source other than infected cultivated legumes. To find the potential inoculum sources of BPMV in eastern Virginia, leguminous weeds and perennial weeds were tested for BPMV. Four weed species gave BPMV-positive tissue blots including: Oxalis stricta, Rumex acetosella, Trifolium pretense, and Trifolium repens. Insecticidal seed treatment of thiamethoxam on soybean seeds was evaluated to test the efficacy. Leaf area eaten and beetle mortality was measured. The thiamethoxam seed treatment protected soybean seedlings from beetle feeding through the V2 stage of growth. Master of Science in Life Sciences

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Santana, Alessandra Figueiredo Kikuda. "Performance e preferência de imaturos selvagens de Ascia monuste (Godart, 1819) (Lepidoptera, Pieridae) na mudança e na privação de hospedeiros alimentares diferentes." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/59/59131/tde-17042008-091705/.

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Lagartas de Ascia monuste (Lepidoptera, Pieridae) são especialistas em Brassicaceae, sendo uma das maiores consumidoras desta família da região Neotropical. No campo, uma grande proporção de lagartas migra para outros hospedeiros e freqüentemente deparam-se com variações nutricionais e espaciais de alimento. O presente trabalho teve como objetivo principal estudar a performance dos imaturos de A. monuste em quatro combinações de alimentações, com hospedeiros alimentares diferentes numa mesma fase ontogenética, utilizando-se três hospedeiros naturais: couve (Brassica oleracea var. acephala) e rúcula (Eruca sativa), e couve e repolho (B. oleracea var. capitata). Estas plantas diferem quanto ao conteúdo de nitrogênio, com couve e rúcula tendo quantidades semelhantes e maiores que o repolho. Além disso, foi avaliado, tanto em campo quanto em laboratório, se a experiência alimentar prévia influencia na escolha de alimento no instar larval subseqüente, e quais seriam os efeitos de um período de privação de 24 horas de alimento, antes da mudança de hospedeiro, sobre a performance do inseto. Apesar de pequenas diferenças digestórias, possivelmente causadas pela adequação às diferenças de nutrientes, o tempo de desenvolvimento não diferiu significativamente entre os tratamentos; houve uma porcentagem de emergência e fecundidade potencial altas. De acordo com os resultados encontrados no presente estudo, rúcula e repolho seriam os hospedeiros de valores nutritivos semelhantes e couve, o hospedeiro de valor nutritivo diferente (e mais adequado para a performance de A. monuste). Pupas originadas de lagartas alimentadas com rúcula e repolho apresentaram, de uma forma geral, menor quantidade de massa e menos oócitos, inclusive quando houve privação alimentar entre os hospedeiros. A preferência alimentar por rúcula, ao invés de couve, e por couve, ao invés de repolho, independente do alimento prévio, mostra que a experiência prévia não determina a escolha por hospedeiros em imaturos em A. monuste. A preferência em campo diferiu daquela encontrada em laboratório. A privação de 24 horas de alimento entre a mudança de hospedeiros não provocou danos adicionais na performance das lagartas alimentadas com couve e rúcula, mas aumentou as taxas de mortalidade dos grupos alimentados com couve e repolho. Ascia monuste (Lepidoptera, Pieridae) caterpillars are Brassicaceae specialists, being one of the most important comsumers of this plant family in the Neotropical region. In the field, a high proportion of immatures migrates to other hosts in order to develop properly, probably facing some variation in terms of nutritional value and location of their hosts. The main objective of this study was to investigate how the feeding of caterpillars of same ontogenetic phase on different hosts [kale (Brassica oleracea L. var. acephala) and rucola (Eruca sativa L.), and kale and cabbage (Brassica olerace L. var. capitata)], affects the corresponding performance of A. monuste. The hosts above mentioned differ in their nitrogen content: kale and rucola have similar nitrogen quantity, and kale has higher quantity than cabbage. In addition, it was evaluated whether the previous host would influence food choice in subsequent larval instar, in the field and in laboratory, as well as the effects of 24 hours of food deprivation on immature performance before switching the host. Beside few differences caused by host switching, possibly by the differences in nutrient levels, all the feeding tests originated similar performances and viable adults. When the preference was determined by the first caterpillar ingestion, previous experience did not influence host choice: caterpillars chose rucola instead of kale, and kale instead of cabbage, independently of previous host. But, when preference was determined by the total amount of ingested food, previous experience acted as a fagoestimulant in kale and rucola as hosts. It was not possible to detect what determine larval preference in the field. All plants tested were attractive for the caterpillars and the migration may occur for hosts that are close and easier to find. The 24 h food deprivation did not increase the effects of host change, but did present some differences. Rucola and cabbage could be less adequate hosts on final instars, because pupae whose larvae ingested these crucifers presented, in general, less pupal mass and also less oocytes, even when food deprivation does not occured.

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Schroder, Michelle L. "Host plant preference of Rhopalosiphum padi (Hemiptera: Aphididae) and its role in selecting crop border plants to reduce Potato virus Y (PVY) in seed potatoes." Diss., University of Pretoria, 2014. http://hdl.handle.net/2263/79775.

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Winged Rhopalosiphum padi in search of good quality host plants transmit the non-persistent Potato virus Y (PVY) to seed potatoes. Planting a non-virus host plant as a border around the main crop can reduce PVY incidence, because aphids tend to land in high numbers at the edge of a field and the crop border acts as a virus sink. Using a trap crop could increase the number of aphids landing in the border. During host-plant searching behaviour, alate (winged) aphids respond to short (UV) and long (green - yellow) wavelength stimuli and plant volatiles. The present study evaluated R. padi preference for maize and wheat cultivars in comparison to potato cultivars to identify a potential crop border plant that is attractive to aphids for landing but does not support a high aphid population density. The study further served to develop selection criteria for potential crop border plants. To this end the landing and settling preference and reproductive rate of R. padi on three cultivars each of maize, potato and wheat were compared in choice and no-choice laboratory trials. The attractiveness of different shades of green, relative to differences in spectral reflectance of the crop cultivars, to R. padi was determined as well as olfactory responses of this species, to the plant cultivars tested. Landing and reproduction of R. padi suggested maize cultivars ‘6Q-121’ and ’78-15B’ are potential crop border plants. In choice and no-choice experiments, R. padi produced the highest number of offspring on wheat than on maize. In contrast, wheat cultivars had the greatest potential to be used as crop border plants based on percentage wavelength reflection in the green-yellow wavelength region. Rhopalosiphum padi preferred to land on yellow and lime colour targets with a maximum wavelength reflectance of 46% and 26%, respectively. The peak light reflectance of the crop plants ranged between 12% and 20%, with wheat reflecting the highest percentage of light. However, olfactory responses of R. padi indicated that maize ‘6Q-121’ may prove to be a suitable crop border plant. The volatiles emitted by maize ‘6Q-121’ did not contain compounds such as -farnasene, (E)-2- hexenal, indole and TMTT which are known to repel R. padi. On the other hand, R. padi did not distinguish between maize and wheat cultivars prior to landing, which indicates that both visual and olfactory cues are important in host plant selection behaviour and thus for selecting crop border plants. The results of the present study suggest that maize ‘6Q-121’ could be used as a crop border plant in seed potato production regions where R. padi is abundant, due to high aphid landing and low reproduction rates. In conclusion, a suitable crop border plant should be a preferred host plant and cultivar of the dominant aphid vector species in a seed potato production region. Potential plant cultivars should reflect a higher percentage of light in the green-yellow wavelength region than the main crop and the volatile profiles should preferably not contain compounds that are known to repel the aphid vector. Thesis (PhD)--University of Pretoria, 2014. Potatoes South Africa (PSA), and the Technology and Human Resources (THRIPP) Zoology and Entomology PhD Unrestricted

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Aguirre-Gil, Oniel Jeremías [UNESP]. "Aspectos biológicos de Microcharops anticarsiae (Hymenoptera: Ichneumonidae) parasitando Anticarsia gemmatalis (Lepidoptera: Erebidae)." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/144687.

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Submitted by ONIEL JEREMIAS AGUIRRE GIL null (oaguirretm@outlook.com) on 2016-11-18T19:43:27Z No. of bitstreams: 1 Tese_Versão_definitiva_PDF.pdf: 2376464 bytes, checksum: 98c10cbf6c2dc00d45f713eb74c82f7f (MD5) Approved for entry into archive by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br) on 2016-11-24T15:13:11Z (GMT) No. of bitstreams: 1 gil_oj_dr_jabo.pdf: 2376464 bytes, checksum: 98c10cbf6c2dc00d45f713eb74c82f7f (MD5) Made available in DSpace on 2016-11-24T15:13:11Z (GMT). No. of bitstreams: 1 gil_oj_dr_jabo.pdf: 2376464 bytes, checksum: 98c10cbf6c2dc00d45f713eb74c82f7f (MD5) Previous issue date: 2016-11-04 Outra Microcharops anticarsiae é um eficiente parasitoide da lagarta-dasoja Anticarsia gemmatalis que, também, parasita lagartas de outras espécies como Chrysodeixis includens e Spodoptera eridania. O objetivo do trabalho foi (1) determinar o ínstar larval de A. gemmatalis preferencialmente parasitado por M. anticarsiae a partir de lagartas coletadas em campo, (2) determinar o efeito de criações sucessivas de M. anticarsiae nos parâmetros biológicos do parasitoide e (3) determinar o efeito da soja transgênica sobre a longevidade de adultos do parasitoide. Os experimentos foram conduzidos nos anos agrícolas de 2014/15 e 2015/16 na FCAV/UNESP, Jaboticabal, SP, Brasil. Para a coleta das lagartas em campo, foram semeadas duas áreas de soja transgênica, uma tolerante ao herbicida glifosato e a outra resistente a insetos. Os resultados indicam que (1) M. anticarsiae preferiu parasitar lagartas de A. gemmatalis de primeiro e segundo ínstar em soja tolerante ao glifosato em campo, (2) não houve diferenças nos parâmetros biológicos de M. anticarsiae criado durante três gerações sucessivas em laboratório e (3) a longevidade total de M. anticarsiae e a longevidade de fêmeas foi mais longa em soja tolerante ao glifosato e a longevidade dos machos foi mais curta em ambas as sojas, tolerante ao glifosato e resistente a insetos. Finalmente, conclui-se que M. anticarsiae parasita lagartas de A. gemmatalis de primeiro e segundo ínstar em campo, que os parâmetros biológicos de M. anticarsiae não são afetados quando criados durante três gerações em laboratório e que a soja resistente a insetos afeta negativamente a longevidade dos machos de M. anticarsiae. Microcharops anticarsiae is an efficient parasitoid of Anticarsiagemmatalis and also parasitizes larvae of other species such as Chrysodeixis includens and Spodoptera eridania. This work aimed to (1) determine the larval ínstar of A. gemmatalis preferentially parasitized by M. anticarsiae from larvae collected in the field, (2) determine the effect of successive laboratory rearings of M. anticarsiae in the biological parameters of the parasitoid, and (3) determine the effect of transgenic soybean in the longevity of adults of the parasitoid. the experiments were carried out in the seasons 2014/2015 and 2015/2016 in the FCAV/UNESP, Jaboticabal, SP, Brasil. Two areas were sown with transgenic soybean, the first one tolerant to glyphosate and the second one resistant to insects. The results indicate that (1) M. anticarsiae preferred to parasitize A. gemmatalis larvae on the first and second larval ínstar in soybean tolerant to glyphosate in the field, (2) there were not differences in the biological parameters of M. anticarsiae reared during three successive laboratory rearings, and (3) the longevity total of M. anticarsiae and longevity of females was longer in soybean tolerant to glyphosate and the longevity of males was shorter in soybean tolerant to glyphosate and resistant to insects. Finally, we conclude that M. anticarsiae parasitize first and second ínstar larvae of A. gemmatalis in the field, the biological parameters of M. anticarsiae are not affected when reared during three generations in the laboratory, and the soybean resistant to insects affects negatively the longevity of males M. anticarsiae.

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Hitchner, Erin Marie. "Investigations of the integrated pest management of Colorado potato beetle, Leptinotarsa decemlineata (Say): Host plant preference, development of semiochemical-based strategies, and evaluation of a novel insecticide." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/29562.

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Exploiting the chemical ecology of an insect can unveil novel strategies for its pest management. Though much has been learned about the chemical ecology of Colorado potato beetle (CPB), Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), a major pest of solanaceous crops in the U.S., there has been little use of this knowledge in pest management. To better understand host plant selection by CPB, field and laboratory-choice experiments were conducted in Virginia. In laboratory studies, CPB preferred potato over both tomato and eggplant foliage and eggplant over tomato foliage. However, field studies using counts of live beetles on untreated paired plants and counts of dead beetles on insecticide-treated plants revealed no significant preference for potato over eggplant. Additional studies showed that the presence of adult male CPB on foliage greatly impacted host plant selection, with significantly more adults being attracted to eggplant with male beetles than any other treatment combination. Adult CPB have been shown to be attracted to (S)-3,7-dimethyl-2-oxo-oct-6-ene-1,3-diol [(S)-CPB I], a male-produced aggregation pheromone. Field studies were conducted to determine if the opposite enantiomer of the pheromone, (R)-CPB I had an effect on CPB in the field. Results revealed no differences in counts of all CPB life stages between untreated potato plots with and without rows inundated with (R)-CPB I lures. In addition, the relative attraction of CPB adults to various racemic forms of the (S)- and (R)-enantiomers was also investigated and showed that racemic blends that were less than 97%(S) were not attractive to CPB adults. Combinations of the (S)-CPB I pheromone with synthetic plant volatiles consisting of (Z)-3-hexenyl acetate, (+)-linalool, and methyl salicylate were investigated in a trap crop strategy in potatoes, but failed to reduce CPB numbers in untreated middle rows of potatoes. Combinations of the (S)-CPB I pheromone with synthetic plant volatiles were also used in a novel CPB trap designed to catch colonizing adults in the field. Although the traps caught CPB adults, no differences were observed in traps baited with and without the attractant. Metaflumizone, a novel semicarbazone insecticide, was recently shown to be highly efficacious on CPB. Laboratory studies found the combination of metaflumizone and a low concentration (0.39 ppm) of the pyrethroid esfenvalerate was slightly synergistic on CPB adults and early (1st-2nd) instar larvae. Field trials combining a low rate of esfenvalerate and metaflumizone at one tenth the field rate controlled beetles as well as the full rate of metaflumizone. Ph. D.

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Gonzalez, Javier Garcia. "Interactions of maize bushy stunt phytoplasma with the leafhopper vector, Dalbulus maidis (Delong and Wolcott) (Hemiptera: Cicadellidae) and associated microbiota." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/11/11146/tde-03052016-175553/.

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Phytoplasmas are bacteria with a persistent propagative transmission by insect vectors that generates direct and indirect interactions among them. In order to understand these interactions for maize bushy stunt phytoplasma (MBSP) and the leafhopper vector Dalbulus maidis (Hemiptera: Cicadellidae), two research lines were addressed. The first one aimed to determine the indirect effects of maize infection by MBSP on some biological and behavioral parameters of the vector, whereas a second line investigated direct interactions of the phytoplasma with D. maidis during its movement through the vector body following acquisition from plants, and associated microbiota. Indirect effects were investigated in choice experiments in which alighting and oviposition preferences by D. maidis were compared on healthy vs. MBSP-infected plants with variable incubation time (diseased plants with early and advanced symptoms, or still asymptomatic). Likewise, indirect effect of MBSP on the D. maidis biology was determined in two life table experiments in which the vector was reared on healthy vs. MBSP-infected plants expressing advanced disease symptoms or still asymptomatic. Choice experiments showed that alighting and oviposition preferences of D. maidis on MBSP-infected plants compared to healthy plants depend on the pathogen incubation period in the plant. The leafhopper preferred MBSP-infected plants over healthy ones during the asymptomatic phase of the disease, but rejected infected plants with advanced symptoms. The vector was able to acquire MBSP from asymptomatic infected plants shortly (3 days) after inoculation, but transmission efficiency increased when acquisition occurred at later stages of the pathogen incubation period (≥14 days) in the source plants and the test plants showed disease symptoms faster. These results suggest that MBSP modulates D. maidis preference for asymptomatic infected plants in the early stages of the crop, allowing rapid spread of this pathogen. Maize infection by the phytoplasma had a neutral effect on most life table parameters of D. maidis; a lower net reproductivity rate (Ro) was observed in the cohort reared on MBSP-infected plants with advanced symptoms, which was compensated to some extent by a higher sexual ratio. MBSP acquisition by all vector nymphal stadia was confirmed by PCR, and the pathogen as detected in both male and female reproductive organs. Concerning direct MBSP-vector interactions, transmission electron microscopy analyses showed phytoplasma-like cells in the midgut lumen, microvilli and epithelial cells, suggesting that MBSP enters the epithelium midgut through the microvilli wall. Within the epithelial cells, mitochondria and bacteria-like cells (possibly endosymbionts) were observed together with masses of phythoplasma-like cells. In the hemocoel, phytoplasma-like cells grouped into a matrix were also observed in association with bacteria-like cells similar to those observed in the midgut epithelium. Similar associations were found in the salivary gland. Interestingly, in-situ hybridization (FISH) technique revealed a variation in diversity and abundance of the microbiota in intestine and salivary glands of D. maidis adults over time after MBSP acquisition from plants. Sulcia sp., Cardinium sp. and eubacteria increased their abundance over time, whereas Rickettsia sp. decreased. The frequent association of the vector microbiota with the phytoplasma in some tissues of D. maidis suggests that endosymbiotic bacteria may play some role in MBSP-vector interactions. Fitoplasmas são bactérias transmitidas de forma persistente propagativa por insetos vetores, havendo interações diretas e indiretas envolvendo tais organismos. Para entender algumas dessas interações no caso do enfezamento vermelho do milho, associado ao \'maize bushy stunt phytoplasma\' (MBPS) e à cigarrinha vetora Dalbulus maidis (Hemiptera: Cicadellidae), foram desenvolvidas duas linhas de trabalho. Na primeira determinou-se o efeito indireto de MBSP no comportamento e biologia do vetor, enquanto que na segunda estudaram-se as interações diretas do fitoplasma com o vetor durante sua movimentação através de órgãos internos e associação com a microbiota do inseto. O efeito indireto no comportamento foi demostrado em testes de escolha nos quais se variou o período de incubação de MBSP na planta (plantas com sintomas iniciais ou avançados da doença, e plantas infectadas assintomáticas) sobre a preferência para pouso e oviposição pelo vetor. O efeito indireto na biologia do D. maidis foi estabelecido em dois experimentos de tabela de vida, alimentando o inseto durante seu ciclo de vida em plantas de milho sadias ou plantas infectadas com o fitoplasma em dois tempos de incubação (plantas com sintomas avançados da doença e plantas infectadas assintomáticas). Os testes de escolha mostraram que a preferência de D. maidis para pouso e oviposição em plantas infectadas por MBSP em relação a plantas sadias depende do período de incubação do patógeno na planta. A cigarrinha preferiu plantas infectadas por MBSP na fase assintomática da doença, mas rejeitou plantas com sintomas avançados. Ocorreu aquisição do fitoplasma pelo vetor em plantas assintomáticas a partir de 3 dias após a inoculação, mas a eficiência de transmissão aumentou após 14 dias de incubação do patógeno na planta-fonte, e diminuiu o tempo para expressão de sintomas nas plantas-teste inoculadas. Os resultados sugerem que MBSP modula a preferência do vetor para plantas infectadas no estágio inicial da cultura de modo a permitir sua rápida disseminação. O efeito da infecção de plantas por MBSP na biologia de D. maidis mostrou ser neutro para a maioria dos parâmetros biológicos estimados; houve menor taxa líquida de reprodução (Ro), que foi compensada por maior razão sexual, para insetos criados em plantas com sintomas avançados. Verificou-se, por PCR, aquisição do fitoplasma por todos os estádios ninfais do vetor e sua presença em órgãos reprodutivos dos adultos. Por microscopia eletrônica de transmissão, observaram-se células do tipo fitoplasma no lúmen, microvilosidades e células epiteliais do mesêntero de D. maidis, sugerindo que o MBSP penetra no epitélio através das microvilosidades. No epitélio intestinal, foram observadas massas de células do tipo fitoplasma próximas a mitocôndrias e células bacterianas, possíveis endossimbiontes. Na hemocele, também foram observadas células do tipo fitoplasma agrupadas numa matriz, em associação com bactérias similares às observadas no intestino. Associações semelhantes foram observadas na glândula salivar. A técnica de FISH revelou uma variação na riqueza e abundância das espécies na da microbiota no mesêntero e glândula salivar de D. maidis em função do tempo após a aquisição de MBSP. A abundância de Sulcia sp., Cardinium sp. e eubacteria aumentou, enquanto que a de Rickettsia sp. decresceu. A associação frequente dessas bactérias com fitoplasma em alguns tecidos de D. maidis sugere que endossimbiontes possam ter um papel nas interações fitoplasma-vetor.

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Petit, Christophe. "Induction des préférences olfactive et gustative chez les lépidoptères foreurs de graminées en Afrique de l'Est : effet des expériences pré-imaginale et imaginale." Thesis, Université Paris-Saclay (ComUE), 2015. http://www.theses.fr/2015SACLS083.

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Chez les insectes phytophages, la sélection de la plante-hôte qui constitue un site de ponte et d'alimentation est cruciale pour la survie et le bon développement de la descendance. Les sens chimiques – olfaction et gustation - sont déterminants pour un insecte lors du choix de sa plante hôte. Ainsi, une expérience olfacto-gustative des signaux chimiques d'une plante permet aux insectes d'optimiser la période de recherche et d'identification de celle-ci. Dans ce travail, nous avons testé l'effet d'une expérience pré-imaginale et imaginale pour un nouveau substrat de développement (enrichi en vanilline) sur l'induction de préférence olfactive et alimentaire à ce substrat chez trois espèces de lépidoptères foreurs de graminées ayant des spectres alimentaires différents, Sesamia nonagrioides (polyphage), Busseola fusca (oligophage) et Busseola nairobica (monophage). Il s'est avéré que la préférence olfactive des femelles pour les odeurs de ce substrat peut être induite par une expérience préalable pré-imaginale et imaginale pour ce nouveau substrat et que cette induction est transmise de façon transgénérationnelle. Elle n'est cependant pas liée à une augmentation de la sensitivité des antennes des femelles à la vanilline. De plus, elle dépend de l'espèce étudiée. Elle se manifeste plus rapidement chez l'espèce la plus polyphage (au bout de deux générations), plus tardivement chez l'espèce monophage (au bout de cinq générations) et est, par contre, absente chez l'espèce oligophage. Même si plusieurs mécanismes peuvent être impliqués dans cette induction, nos résultats valident à la fois la théorie d'Hopkins, le principe néo-Hopkins et l'héritage chimique chez les espèces qui ont présenté cette induction. Concernant les larves, nous avons pu montrer que celles-ci suivent, en général, la préférence olfactive des femelles pour les odeurs d'un nouveau substrat mais que cette préférence n'est pas corrélée avec leurs préférences alimentaires Among herbivorous insects, the selection of the host plant as an egg laying site and food is crucial for the survival and development of the offspring. The chemical senses - olfaction and gustation – of an insect are crucial in host plant selection. An olfactory-gustatory experience of plant chemical signals allows insects to optimize their search period and host identification. In this study, we tested the effect of pre-imaginal and imaginal experience for a new artificial diet (enriched in vanillin) on the induction of olfactory and food preference for this diet in three species of lepidopteran stem borers with different food spectra, namely Sesamia nonagrioides (polyphagous), Busseola fusca (oligophagous) and Busseola nairobica (monophagous). It was shown that the olfactory preference of females for the odor of the new diet could be induced by pre-imaginal and imaginal experience for this new diet and that this induction was transmitted transgenerationally. It was however not linked to an increase in the sensitivity of the female antennae to vanillin. In addition, it depended on the species studied. It occurred after two generations only in the polyphagous species, after five generations in the monophagous species, and it was absent in the oligophagous species. Although several mechanisms may be involved in this induction, our results validate both the theory of Hopkins, neo-Hopkins principle and the chemical legacy in the species in which the induction occurred. The larvae exhibited generally the same olfactory preference than the adult females for the odors of the new diet but this preference was not correlated with their food preferences, indicating in larvae a discrepancy between olfaction and gustation

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Fisher, Makani Layne. "Biogeography and Natural History of Tiger Moths and Spongillaflies of Intermountain North America with Experimental Studies of Host Preference in the Lichen-Feeder Cisthene angelus (Insecta: Lepdioptera: Erebidae: Arctiinae and Neuroptera: Sisyridae)." BYU ScholarsArchive, 2018. https://scholarsarchive.byu.edu/etd/7194.

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The Intermountain West is comprised of impressive land formations, numerous ecoregions, and a unique biota. The area has many flora and fauna that have been investigated, but the region is generally considered undersampled when it comes to insects. However, I propose the matter to be a lack of shared experience in identifying key insect species and the underutilization of professional and personal collections. These impediments are highlighted by two insect groups in the Intermountain West: spongillaflies and tiger moths.Spongillaflies can be difficult to recognize for the general entomologist and have rarely been recorded in the Intermountain West. My colleagues and I recently discovered a large population of spongillaflies in Utah that we present as a substantial additional record. I also followed the population throughout the 2016 field season to make natural history observations. I identified the spongillaflies to be Climacia californica and their associated host to be Ephydatia fluviatilis. During the season, a total of 1,731 specimens were collected, light traps were the most effective sampling technique and the population had one mass emergence event. I hope my work and figures will help investigators as they continue to search the area for spongillaflies. Tiger moths on the other hand have largely been collected in the Intermountain West and are easily recognized, generally being brightly colored. Because of these bright colors, they attract collectors and have been sampled heavily throughout the Intermountain West. However, until now, these records have not been utilized and tucked away in collections. We took the vast amount of records and used them to create predicted models of biogeography for each tiger moth species in the area. We successfully created species level ecological niche models (ENM) analyzing environmental variables such as temperature, precipitation, elevation, and vegetation. Overall, I found tiger moths can be collected almost everywhere and during each month of the year with 93 different species scattered across the region. I anticipate our ENM models to help researchers locate tiger moths of interest to investigate within the Intermountain West.During my studies, I investigated in detail the lichen feeding tiger moths (Lithosiini). Many tiger moths eat toxic plants, but only a few in the area consume lichen, an unusual host because of their secondary defensive chemicals. I investigated how these chemicals impacted Cisthene angelus caterpillars host selection by simultaneously offering them various lichens with differing chemistries. I expected these caterpillars to avoid usnic acid as it deterred other lichen feeding tiger moths. However, these caterpillars surprised me by consistently consuming the acid and being largely polyphagous. Our future work will be directed at how caterpillars balance nutritional needs and the chemicals they sequester.

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Nguyen, Le Thu Ha. "Effet bottom-up du stress hydrique sur la gamme d’hôtes des parasitoïdes de pucerons." Thesis, Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4132/document.

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Le contrôle biologique (C. -B. - l'utilisation d'ennemis naturels pour lutter contre les ravageurs) est durable, écologique et rentable pour contrer la résistance des ravageurs en augmentant l'utilisation des pesticides. Les parasitoïdes des pucerons sont des ennemis naturels communs des pucerons, les principaux ravageurs mondiaux dans l'agriculture. L'étude de la spécificité de l'hôte parasitoïde contribue à (1) comprendre les mécanismes écologiques et évolutifs de l'écosystème et (2) évaluer l'efficacité des agents de lutte biologique et les risques écologiques pour les espèces non ciblées. Cette étude porte sur la spécificité de l'hôte fondamental des parasitoïdes sur les niveaux individuels, en matière de besoins en ressources et dans le contexte des interactions multi trophiques sous stress abiotique environnemental, c'est-à-dire la limitation de l'eau. Aphidius ervi (Hymenoptera: Braconidés: Aphidiinae) a été choisi; ce parasitoïde puceron est largement utilisé comme modèle écologique et comme agent de lutte biologique commercial (BCA). D'une part, l'indice de spécificité de l'hôte A. ervi a été mesuré sur une large gamme d'espèces de pucerons. D'autre part, les impacts indirects de la limitation de l'eau ont été étudiés sur la spécificité de l'hôte du parasitoïde. En outre, les modifications induites par le stress hydrique dans la plante et les traits de vie des pucerons ont été mesurés. A. ervi s'est avéré être une espèce intermédiaire spécialisée qui a attaqué toutes les espèces de pucerons à des taux élevés, mais n'a pas pu se développer correctement sur toutes les espèces. Les quelques espèces qui se développaient bien étaient phylogénétiquement proches et appartenaient à la tribu des Macrosiphini. En outre, une corrélation positive de préférence - performance a été trouvée. Sous stress hydrique, la préférence et la performance des parasitoïdes ont été affectées, causant la perte de la corrélation. La limitation de l'eau a modifié négativement la qualité nutritionnelle de la plante, ce qui a entraîné une faible performance des pucerons sur les plantes hôtes. Ceci à son tour a diminué la convenance des hôtes pucerons pour le parasitoïde. Les effets de la limitation de l'eau n'étaient pas similaires pour toutes les combinaisons plantes-pucerons et dépendaient de plusieurs facteurs, à savoir les mécanismes végétaux adaptés au stress et la spécialisation de l'hôte des pucerons et des parasitoïdes Biological control (BC - the use of natural enemies to control pests) are sustainable, environmentally friendly and cost-effective methods to counteract pest resistance by increasing pesticide use. Aphid parasitoids are common natural enemies of aphids, the major worldwide pests in agriculture. The study of parasitoid host specificity contributes to (1) understanding ecological and evolutionary mechanisms driving the ecosystem and (2) evaluating the efficiency of biocontrol agents and the ecological risks for non-target species. This study focuses on the parasitoids fundamental host specificity on individual levels, in terms of resource requirements and in the context of multi-trophic interactions under environmental abiotic stress, i.e.water limitation. Aphidius ervi (Hymenoptera: Braconidae: Aphidiinae) was chosen; this aphid parasitoid is used widely as an ecological model and commercial biological control agent (BCA). On the one hand, A. ervi host specificity index was measured on a broad range of aphid species. On the other hand, the indirect impacts of water limitation were investigated on the host specificity of the parasitoid. Furthermore, water stress-induced modifications in the plant and the aphid life-history traits were measured. A. ervi was shown to be an intermediate specialist species who attacked all aphid species at high rates but was unable to develop well on all of them. The few that developed well were phylogenetically close and belong to the Macrosiphini tribe. Interestingly, a positive correlation preference – performance was found. Under water stress, both preference and performance of parasitoids were affected causing loss of the correlation. Water limitation negatively altered the plant nutritional quality resulting in low aphid performance on host plants. This in turn decreased the suitability of aphid hosts for the parasitoid. The impacts of water limitation were not similar across all plant-aphid combinations and depended on several factors, namely stress-adapted plant mechanisms and the host specialization of both aphids and parasitoids

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Pritchard, J. "Host specificity in aphid parasitoids (Hymenoptera : Aphidiidae)." Thesis, Bucks New University, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.384680.

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Viennet, Elvina. "Insectes et maladies émergentes : Culicoides en région Paléarctique et leurs implications dans la transmission de la fièvre catarrhale ovine." Thesis, Montpellier 2, 2011. http://www.theses.fr/2011MON20129/document.

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La découverte du rôle des insectes en tant que vecteurs de pathogènes, établi depuis plus d'un siècle, a été l'élément moteur de la discipline « entomologie médicale et vétérinaire ». Malgré le succès de nombreuses campagnes de prévention et de programmes de lutte, nous assistons depuis une trentaine d'années à l'émergence et à la recrudescence de maladies à transmission vectorielle. Le virus de la fièvre catarrhale ovine (FCO) (Reoviridae : Orbivirus) est un très bon exemple de virus émergent en Europe dont les mécanismes de transmission sont encore peu connus dans cette région. Ce virus est transmis par des moucherons hématophages du genre Culicoides (Diptera : Ceratopogonidae) aux ruminants sauvages et domestiques. En Europe, la FCO a été pendant longtemps considérée comme une maladie exotique. À partir de 1998, plusieurs incursions apparaissent dans l'ouest du bassin méditerranéen en lien avec la remontée vers le nord de populations de Culicoides imicola, le principal vecteur afrotropical. À partir d'août 2006, l'apparition et la transmission du sérotype 8 dans le nord de l'Europe, dans des zones où C. imicola est absent, révèle l'importance des espèces autochtones et la nécessité de comprendre leur rôle vecteur. Ce travail s'intéresse aux mécanismes de transmission du virus de la FCO en Europe non méditerranéenne, en i) présentant un état de l'art de la biologie et l'écologie des Culicoides adultes, ii) en évaluant les conditions possibles d'utilisation de pièges pour estimer le taux de piqûre et iii) en décrivant les comportements trophiques pour les espèces d'intérêt vétérinaire The discovery of insects as pathogens vectors was established for over a century and was the driving force behind the discipline “medical and veterinary entomology”. Despite the success of some prevention and control program campaigns, the emergence and spread of vector-borne diseases occurred dramatically during this last thirty years. Bluetongue virus (BTV) (Reoviridae: Orbivirus) is a good example of emerging virus in Europe, with a little understanding of the epidemiology of this disease. This virus is transmitted by blood-sucking midges of the genus Culicoides (Diptera: Ceratopogonidae) to wild and domestic ruminants. In Europe, BT was considered an exotic disease. In 1998, several incursions appeared in the western Mediterranean Basin in line with the northward progression of C. imicola populations, the main afrotropical vector. From August 2006, the emergence and transmission of serotype 8 in northern Europe, in areas where C. imicola is absent, revealed the importance of autochthonous species and the urgent need to understand their role as vector. This work gives new insights into the understanding of BTV transmission in northern Europe: i) presenting a state of the art review of the biology and ecology of Culicoides adults, ii) assessing different methods to study the biting rate and iii) highlighting trends in host-seeking behavior

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BATISTA, Felipe Colares. "Interação tritrófica de cultivares de repolho, traça-das-crucíferas e do parasitóide Oomyzus sokolowskii (Kurdjumov) (Hymenoptera : Eulophidae)." Universidade Federal Rural de Pernambuco, 2011. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/5972.

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Submitted by (edna.saturno@ufrpe.br) on 2016-11-24T14:16:11Z No. of bitstreams: 1 Felipe Colares Batista.pdf: 401499 bytes, checksum: 66c8054daa99b1513bf4eeb2b13516c0 (MD5) Made available in DSpace on 2016-11-24T14:16:11Z (GMT). No. of bitstreams: 1 Felipe Colares Batista.pdf: 401499 bytes, checksum: 66c8054daa99b1513bf4eeb2b13516c0 (MD5) Previous issue date: 2011-02-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES The diamondback moth (DBM), Plutella xylostella (L.) (Lepidoptera: Plutellidae), is the most important pest of brassicas throughout the world. Prospective results toward DBM manage in cabbage have been achieved using host plant resistance and biological control. However, host plant characteristics conferring resistance against herbivores might also affect their natural enemies. Thus, this work evaluated the influence of red and green (Chato-de-quintal) cabbages on the biology and oviposition preference of P. xylostella and the interaction with the larval-pupal parasitoid Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae). Based on life history parameters for DBM, green cabbage was less favorable compared to red cabbage by delaying larval and pupal stages, and reducing female fecundity. However, under free choice tests for oviposition, DBM females preferred to lay eggs on green than red cabbage. Tests in olfactometer, isolating the color effect of the host plant, however, resulted in similar moth attraction between green and red cabbage. Foraging of O. sokolowskii females was similar on both cabbage cultivars infested with DBM larvae under large cage free choice tests. Furthermore, similar number of parasitized larvae, total number of emerged parasitoids, and adult female parasitoid longevity were found for DBM larvae reared on both cabbage cultivars under laboratory conditions. However, the period from parasitism to adult parasitoid emergence was one day shorter and a higher number of parasitoids produced per parasitized larva was achieved when parasitizing larvae reared on green cabbage. In conclusion, the results indicate a positive association of host plant resistance with the parasitism of O. sokolowskii to manage DBM and suggest that the cabbage color plays an important role on host preference for oviposition by the pest. A traça-das-crucíferas, Plutella xylostella (L.) (Lepidoptera: Plutellidae), é considerada a principal praga das brássicas em todo o mundo. Resultados promissores para o manejo desta praga têm sido alcançados com o uso de cultivares resistentes e controle biológico. Entretanto, sabe-se que características conferindo resistência às plantas não afetam somente os herbívoros, mas também os inimigos naturais associados a eles. Assim, esse trabalho avaliou a influência das cultivares de repolho Roxo e Verde (Chato-de-quintal) na biologia e na preferência para oviposição de P. xylostella, e o efeito no desempenho do parasitóide Oomyzus sokolowskii (Kurdjumov) (Hymenoptera: Eulophidae). Com base nos parâmetros da tabela de vida, a cultivar Chato-de-quintal mostrou-se menos favorável para o desenvolvimento de P. xylostella, por ocasionar maior duração das fases de larva e pupa e redução na fecundidade das fêmeas em relação a cultivar Roxo. Entretanto, a cultivar Chato-de-quintal foi a mais preferida por P. xylostella para oviposição em comparação a cultivar Roxo. Testes de livre escolha das mariposas em olfatômetro, isolando a coloração do hospedeiro, resultaram em semelhança de escolha entre repolho Roxo e Verde. O forrageamento de fêmeas de O. sokolowskii em plantas de ambas as cultivares infestadas com larvas da traça-das-crucíferas em testes de livre escolha foi similar. Também, não houve diferença no número de larvas parasitadas, número total de descendentes produzidos e longevidade média das fêmeas adultas do parasitóide em condições de laboratório. Entretanto, foi observado maior número de descendentes por larva parasitada e, aproximadamente, um dia a menos na duração do período ovo-adulto em larvas da traça-das-crucíferas criadas em repolho Chato-de-quintal. Assim, estes resultados mostram uma associação positiva entre a resistência de cultivares de repolho e o controle biológico com O. sokolowskii visando o manejo da traça-das-crucíferas e sugerem que a cor da cultivar possui papel importante na escolha do hospedeiro para oviposição pela praga.

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Dabee, Vidushi Prema. "Life cycle and host preferences in the Agapanthus borer (Neuranethes spodopterodes)." Bachelor's thesis, University of Cape Town, 2013. http://hdl.handle.net/11427/14123.

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The species Neuranethes spodopterodes is a pest of the Agapanthus species. The larva feeds gregariously on the leaves and rhizomes and cause extensive damage to the plant. This study shows the N.spodopterodes have 6 larval instars. The use of the head capsule width as a morphometric parameter and applying it to Dyar's rule gives significant results which allow for adequate determination of the larval instar. The Agapanthus borer has a life cycle that last approximately 84 days. Some species of Agapanthus are the preferred host plant for oviposition by the female N.spodopterodes. Agapanthus inapertus, Agapanthus caulescens and Agapanthus praecox are the most infested with the Agapanthus borer eggs. Leaf sizes do not appear to be a factor that influences the female choice. There appears to be no preference from the larva during feeding. The larva fed equally on all the six Agapanthus species including A. africanus (p>0.05). This shows that the chemical composition of these species is closely related. Since the larva has no feeding preference, this reinforces the fact that it is the female moth that chooses the host plant and that it abides with preference-performance hypothesis. Since A. africanus is subjected to feeding by the larva under laboratory conditions, it could potential imply that in the event of a range shift by the gravid female, that this species of plant is at risk of extinction. The presence of a parasitoid wasp, Trichogramma in the egg of N. spodopterodes and that the level of parasitism is about 86% suggests that this parasitoid could potentially be used as a biological control agent of the Agapanthus borer.

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Nguyen, Le Thu Ha. "Effet bottom-up du stress hydrique sur la gamme d’hôtes des parasitoïdes de pucerons." Electronic Thesis or Diss., Université Côte d'Azur (ComUE), 2017. http://www.theses.fr/2017AZUR4132.

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Le contrôle biologique (C. -B. - l'utilisation d'ennemis naturels pour lutter contre les ravageurs) est durable, écologique et rentable pour contrer la résistance des ravageurs en augmentant l'utilisation des pesticides. Les parasitoïdes des pucerons sont des ennemis naturels communs des pucerons, les principaux ravageurs mondiaux dans l'agriculture. L'étude de la spécificité de l'hôte parasitoïde contribue à (1) comprendre les mécanismes écologiques et évolutifs de l'écosystème et (2) évaluer l'efficacité des agents de lutte biologique et les risques écologiques pour les espèces non ciblées. Cette étude porte sur la spécificité de l'hôte fondamental des parasitoïdes sur les niveaux individuels, en matière de besoins en ressources et dans le contexte des interactions multi trophiques sous stress abiotique environnemental, c'est-à-dire la limitation de l'eau. Aphidius ervi (Hymenoptera: Braconidés: Aphidiinae) a été choisi; ce parasitoïde puceron est largement utilisé comme modèle écologique et comme agent de lutte biologique commercial (BCA). D'une part, l'indice de spécificité de l'hôte A. ervi a été mesuré sur une large gamme d'espèces de pucerons. D'autre part, les impacts indirects de la limitation de l'eau ont été étudiés sur la spécificité de l'hôte du parasitoïde. En outre, les modifications induites par le stress hydrique dans la plante et les traits de vie des pucerons ont été mesurés. A. ervi s'est avéré être une espèce intermédiaire spécialisée qui a attaqué toutes les espèces de pucerons à des taux élevés, mais n'a pas pu se développer correctement sur toutes les espèces. Les quelques espèces qui se développaient bien étaient phylogénétiquement proches et appartenaient à la tribu des Macrosiphini. En outre, une corrélation positive de préférence - performance a été trouvée. Sous stress hydrique, la préférence et la performance des parasitoïdes ont été affectées, causant la perte de la corrélation. La limitation de l'eau a modifié négativement la qualité nutritionnelle de la plante, ce qui a entraîné une faible performance des pucerons sur les plantes hôtes. Ceci à son tour a diminué la convenance des hôtes pucerons pour le parasitoïde. Les effets de la limitation de l'eau n'étaient pas similaires pour toutes les combinaisons plantes-pucerons et dépendaient de plusieurs facteurs, à savoir les mécanismes végétaux adaptés au stress et la spécialisation de l'hôte des pucerons et des parasitoïdes Biological control (BC - the use of natural enemies to control pests) are sustainable, environmentally friendly and cost-effective methods to counteract pest resistance by increasing pesticide use. Aphid parasitoids are common natural enemies of aphids, the major worldwide pests in agriculture. The study of parasitoid host specificity contributes to (1) understanding ecological and evolutionary mechanisms driving the ecosystem and (2) evaluating the efficiency of biocontrol agents and the ecological risks for non-target species. This study focuses on the parasitoids fundamental host specificity on individual levels, in terms of resource requirements and in the context of multi-trophic interactions under environmental abiotic stress, i.e.water limitation. Aphidius ervi (Hymenoptera: Braconidae: Aphidiinae) was chosen; this aphid parasitoid is used widely as an ecological model and commercial biological control agent (BCA). On the one hand, A. ervi host specificity index was measured on a broad range of aphid species. On the other hand, the indirect impacts of water limitation were investigated on the host specificity of the parasitoid. Furthermore, water stress-induced modifications in the plant and the aphid life-history traits were measured. A. ervi was shown to be an intermediate specialist species who attacked all aphid species at high rates but was unable to develop well on all of them. The few that developed well were phylogenetically close and belong to the Macrosiphini tribe. Interestingly, a positive correlation preference – performance was found. Under water stress, both preference and performance of parasitoids were affected causing loss of the correlation. Water limitation negatively altered the plant nutritional quality resulting in low aphid performance on host plants. This in turn decreased the suitability of aphid hosts for the parasitoid. The impacts of water limitation were not similar across all plant-aphid combinations and depended on several factors, namely stress-adapted plant mechanisms and the host specialization of both aphids and parasitoids

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Moore, Elizabeth Anderson. "Agroforestry Preferences, Identity, and Collaboration Potential Among CAR Refugees and Host Community Cameroonians." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/51259.

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For the past 10 years, thousands of refugees from Central African Republic (CAR) have crossed into Cameroon and settled in villages along the border. Refugee influxes can produce ecological and social challenges to host communities. While conflict is often a result, there is also an opportunity for collaboration and successful integration. Agroforestry, the intentional incorporation and management of trees in agricultural systems, provides a tool that can respond to both social and ecological challenges by providing conservation farming techniques and increasing diversified home production of many needed products. This research sought to understand the needs of community members for specific practices as well as preferences for social implementation of practices, using a frame of identity to help inform on integration and collaboration potential in agricultural projects. The participatory research collected demographic data, employed a 20 point oral questionnaire, and utilized illustrated visual ranking and storytelling tools to gather information on 8 agroforestry practice and implementation preferences, identity, and social arrangement preferences among community members. Agroforestry practices were divided between product-oriented and service-oriented practices. We collected data from 122 individual interviews evenly divided between men and women, and CAR refugees and host community Cameroonians. Results show that there are significant differences in agroforestry practice and implementation preferences across the sample, and between refugees and Cameroonians. Most people felt that refugees and Cameroonians had similar traditions and needs, and that most areas of life should be integrated, however agriculture was an area that the people were more hesitant about mixing, demonstrating that arrangements and implementation of agricultural projects should be carefully designed and executed. Those who preferred mixing of refugees and Cameroonians in fieldwork included members of all demographic groups, signifying the potential for integrated collaboration on community agricultural projects. Results demonstrate that agroforestry projects have the potential to provide important valued resources to communities, create an opportunity for knowledge transfer and improved agricultural systems, and be the scene for positive contact between refugees and Cameroonians, leading to successful integration. Master of Science

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Nygren, Henrietta, and Kristin Unefäldt. "Svinn av grönsaker i primärproduktionen : En inblick hos fyra jordbrukare i Gävleborgs län med kopplingar till påverkande kosmetiska preferenser." Thesis, Högskolan i Gävle, Miljövetenskap, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-32881.

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This study provides an insight into the food waste in primary production of vegetables with links to the influencing cosmetic preferences from the consumer level. To study farmers, a qualitative approach has been chosen and a quantitative approach has been taken for the consumer. To study these complex dependency relationships in the food chain, system theory has enabled a holistic overall picture based on these two approaches. The purpose is to identify the problem to increase the understanding of the causes and origin of food waste in primary production. Furthermore, the goal is that the empirical evidence will identify some possible development potential to reduce food waste in primary production. Sweden is an import-dependent country as well as Gävleborg County where, however, there are good development opportunities seen in the arable land where an increased degree of self-sufficiency can reduce the vulnerability in the food supply chain. From this perspective there is a need for an optimized food supply chain where food waste is minimized, self-sufficiency increases and import dependency decreases. Reducing production waste is an important part of the transition towards a more sustainable food production where system efficiency improvements are required at the macro, meso and micro levels. In order to answer what the study intends to investigate, a qualitative interview survey was conducted at four local farmers in Gävleborg County. A supplementary questionnaire survey with end consumers was also established to elucidate influential cosmetic preferences, such as an oblique carrot or scurf on a potato peel. The interviews and questionnaire survey has since been anchored in a literature study. The results of the interview study of the four farmers show that the main causes of the occurrence of food waste are due to severely affected factors such as weather conditions, pests, diseases / fungal infestation and even a small number of quality quality / cosmetic preferences. None of the farmers had any established measurements methods for food waste, which makes the statistical data more difficult. The results of the survey show that there is a knowledge gap regarding crops and their origin where more information would mean that the consumer considered the product choice. The survey showed that there was a willingness to pay more to meet specific purchasing preferences where information can broaden these preferences and allow for more sustainable choices. Denna studie ger en inblick i uppkommet svinn i primärproduktionen av grönsaker med kopplingar till de påverkande kosmetiska preferenserna från konsumentledet. För att studera jordbrukarna har ett kvalitativ angreppssätt valts och för konsumentledet ett kvantitativt tillvägagångssätt. För att studera dessa komplexa beroenderelationer i livsmedelskedjan har systemteorin möjliggjort en holistisk sammantagen bild utifrån dessa två angreppssätt. Syftet är att identifiera problematiken för att öka förståelsen om svinnets orsaker och uppkomst i primärproduktionen. Vidare är målet att det empiriska underlaget ska leda till att identifiera eventuell utvecklingspotential för att minska svinnet i primärproduktionen. Sverige är ett importberoende land och likaså Gävleborgs län där det också finns goda utvecklingsmöjligheter sett till åkerarealen där en ökad självförsörjningsgrad kan minska sårbarheten i livsmedelskedjan. Utifrån den aspekten finns behov av en optimerad livsmedelskedja där svinn minimeras, självförsörjningsgraden ökar och importberoendet minskar. Att minska produktionssvinnet är en viktig del i omställningen mot en mer hållbar livsmedelsproduktion där systemeffektiviseringar behövs på makro-, meso- och mikronivå. För att besvara det studien ämnar undersöka har en kvalitativ intervjuundersökning genomförts hos fyra lokala jordbrukare i Gävleborgs län. En kompletterande enkätundersökning hos slutkonsument har även upprättats för att belysa påverkande kosmetiska preferenser, till exempel en sned morot eller skorv på potatisskal. Intervju- och enkätundersökningen har sedan förankrats i en litteraturstudie. Resultatet från intervjuundersökningen hos de fyra jordbrukarna visar att huvudorsakerna till uppkommet svinn beror på svårpåverkade faktorer som väderförhållanden, skadedjur, sjukdomar/svampangrepp och även en mindre del kvalitetskrav/kosmetiska preferenser. Ingen av jordbrukarna hade några upprättade mätmetoder för svinnet vilket försvårar den statistiska datan. Resultatet från enkätundersökningen visar att det finns en kunskapslucka om grödor och dess ursprung där mer information skulle innebära att konsumenten övervägde produktvalet. Enkäten visade att det finns vilja att betala mer för att tillgodose specifika inköpspreferenser där information kan utöka dessa preferenser och möjliggöra för mer hållbara val.

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Brugman, Victor. "Host selection and feeding preferences of farm-associated mosquitoes (Diptera: Culicidae) in the United Kingdom." Thesis, London School of Hygiene and Tropical Medicine (University of London), 2016. http://researchonline.lshtm.ac.uk/2548573/.

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Livestock farms sit at the interface between humans, livestock species and wildlife. However, limited data exist on mosquito-vertebrate host interactions on farms in the United Kingdom. This thesis therefore aimed to understand mosquito-vertebrate host interactions on UK livestock farms using a combination of field collections, colony mosquito experiments and molecular techniques for species identification and blood meal analysis. Field collections conducted between 2012 and 2014 yielded a total of 22 693 adult mosquitoes comprising 7 genera and 18 species. Fifteen species displayed human biting activity as assessed by human landing catch, with a maximum observed biting pressure at a single farm of up to 89 bites per 25 minutes at sunset. The avian biting rate, as assessed by the use of chicken-baited traps, was considerably lower than the human biting rate, but demonstrated the ornithophilic activity of three mosquito species, two of which had not previously been collected by such an approach in the UK. Field-caught blood-fed mosquitoes were subjected to a three-stage, targeted analysis, demonstrating that a single DNA extract from an engorged mosquito abdomen provides sufficient DNA for species delineation of Anopheles maculipennis s.l., blood meal identification and detection of myxoma virus. This study implicated Anopheles atroparvus, for the first time, in the transmission of myxomatosis between wild rabbits. The blood meals of over 900 mosquitoes of nine species were identified, revealing feeding on 5 mammalian and 14 avian hosts. Importantly, this study identified key potential vector species Culex pipiens f. pipiens as feeding on both resident and migratory birds. Collectively, these results demonstrate that UK livestock farms support ornithophagic, mammalophagic and anthropophagic mosquito populations which, at certain farms, can lead to a severe nuisance biting pressure on humans. The described feeding of potential vector species, such as newly-established Culex modestus, on farm-associated domestic and wild hosts, suggests that certain mosquito species could play a role in facilitating future pathogen transmission cycles on livestock farms in the case of a novel incursion.

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Rogers, Susan Owen. "Population Biology of the Tan Riffleshell (Epioblasma florentina walkeri) and the Effects of Substratum and Light on Juvenile Propagation." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/36143.

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The federally endangered tan riffleshell (Epioblasma florentina walkeri) is restricted to only one known reproducing population, in Indian Creek, Tazewell County, Virginia. Attempts to recover this species by augmenting relic populations throughout its historic range are aided through knowledge of its population biology and requirements in culture environments. Infestations of host fish (fantail darters, Etheostoma flabellare), obtained from four river drainages, with tan riffleshell glochidia showed that significantly more juveniles transformed per fish from infestations on fantail darters from Indian Creek (mean = 59.22 Â± 10.01) than on fantail darters from the Roanoke River (mean = 9.45 Â± 10.64) (p = 0.024). Number of juveniles from fantail darters collected from Elk Garden and the South Fork Holston River were not significantly different from those of either Indian Creek fish or Roanoke River fish. These results support the hypothesis that mussel-host fish relationships are likely mediated by fish immune responses. Furthermore, this study suggests that this compatibility has resulted from coadaptation between the tan riffleshell and fantail darter populations in Indian Creek. The tan riffleshell population in Indian Creek was estimated to be 1078 adults (95% CI= 760 - 1853), using Schumacher's modification of Schnabel's maximum likelihood estimator. The sex ratio and size distribution of males and females were approximately equal. Specimen ages, determined from thin-sections of shells, showed that mussels aged by external annuli on shells likely underestimates the true ages of individuals. Appropriate culture conditions for this species were examined using juveniles of the wavyrayed lampmussel (Lampsilis fasciola) as a surrogate. In the first experiment, juvenile growth and survival was compared between four substratum types (fine sediment, < 120Î¼m; fine sand, 500 Î¼m-800 Î¼m; coarse sand, 1000 Î¼m-1400 Î¼m; and mixed sediment, < 1400 Î¼m) and two light treatments in open versus covered recirculating troughs (2.8 m). Juveniles in fine sediment substratum and covered troughs fared poorest, with 7% survival and growth to only 0.86 mm in length after 16 wk. Juveniles in mixed sediment and open troughs fared best, with 26% survival and growth to 1.09 mm after 16 wk. Additionally, juveniles in fine sand in covered troughs had significantly higher survival (23.1%) than juveniles in fine sediment (p = 0.04), and juveniles in fine sand survived consistently better between light treatments than in the other substrata. There were no significant differences among the other treatments. A second experiment was performed to determine whether juveniles were responding directly to the presence of light or whether only the increased autochthonous production improved growth and survival. One-half of each of three 2.8 m troughs were covered with 50% shade cloth, while the other sides were left open to ambient light. Additionally, the best and worst sediments from the first experiment (fine sand and fine sediment) were used again to verify the results from the previous experiment. In this case, juveniles in both sides of the troughs grew equally well, but juveniles in the open sides had significantly poorer survival (open mean: 1.78%, sd = 5.01; covered mean: 7.4%, sd = 5.01) (p = 0.046). Fine sediment yielded significantly higher growth of juveniles than fine sand (p = 0.009), with shell lengths of 2.63 mm (sd = 0.075) in fine sediment and 1.94 mm (sd = 0.102) in fine sand. The differences in survival and growth between the two experiments were attributed to differential numbers of chironomids and platyhelminths, which are predators of young juveniles. Additionally, the fine sediment was more tightly packed in the first experiment than in the second, which may have restricted movement and subsequently reduced survival. Light alone likely did not affect juvenile survival and growth; rather, it was seemingly the greater abundance of aufwuchs available as food. This hypothesis was corroborated by a juvenile behavior experiment, which showed that juveniles did not act differently when in tanks not exposed to light versus those open to ambient light. Master of Science

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Ryan, Sean F. "Intraspecific Variation in Natal Plant Secondary Chemistry Leads to Plasticity in Lepidopteran Oviposition Behavior." Bowling Green State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1305253863.

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Johansson, Elin, and Angelica Richardson. "Personlighet och preferens : En kvantitativ studie av gymnasieelevers personlighet och deras preferens för personlighet hos lärare." Thesis, Linnéuniversitetet, Institutionen för psykologi (PSY), 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-40038.

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Stigenberg, Julia. "Hidden Creatures – systematics of the Euphorinae (Hymenoptera)." Doctoral thesis, Stockholms universitet, Zoologiska institutionen, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-87904.

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Parasitic wasps constitute one of the last remaining frontiers in the charting of animal diversity. The Braconidae is the second most species-rich family of parasitic wasps; the world fauna has been estimated at 40 000 species and the Swedish fauna is believed to include a little more than 2 000 species, 1 200 of which are currently documented. This thesis is a contribution to the rapidly increasing knowledge of braconid diversity. In paper I, a new gregarious parasitoid, Meteorus acerbiavorus sp. nov. (Braconidae: Eupohrinae), is described from specimens reared from the cocoons of the butterfly Acerbia alpina (Quensel) (Lepidoptera, Arctiidae) in northwestern Finnish Lapland. Based on a molecular phylogenetic analysis, the new species is shown to belong to the M. rubens species group. In the second paper, the Western Palearctic fauna of the tribe is revised, seven new species are described and a key to the Western Palearctic species is presented. Two molecular markers, 28S and COI, are used to study phylogenetic relationships in the tribe. The molecular results showed that the Meteorini fall into four well supported clades. The results also reveal a considerable cryptic species diversity. The third paper deals with distributional, phenological and in many cases rearing data from nearly 2 500 specimens (44 species) of the Meteorini in the collection of the National Museums of Scotland (NMS), Edinburgh. Patterns in the breadth of host ranges are discussed in relation to a reiterated speciation hypothesis. Paper IV examines the phylogenetic relationships of the entire subfamily Euphorinae based upon four gene regions (18S, CAD, 28S D2, and COI). A revised classification of the Euphorinae is proposed that recognizes 55 genera and 14 tribes. Our study shows that early members of the Euphorinae were parasitoids of coleopteran larvae, with a host shift to larval Lepidoptera, adult or immature hosts in the Hemiptera, Hymenoptera, Neuroptera, Orthoptera and Psocoptera. At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: In press. Paper 4: Manuscript.

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Lundberg, Malin. "Habitatpreferenser hos tjockskalig målarmussla (Unio crassus) med avseende på vattendjup och beskuggning." Thesis, Linköpings universitet, Ekologi, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-78961.

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The thick-shelled river mussel (Unio crassus) is a red listed species classified as Endangered (EN) and is also considered within the Habitats Directive. The distribution in Sweden is fragmented and it is mostly occurring in the south eastern parts. We investigated the presence of Unio crassus in a section of the stream Storån, Östergötland County, from Falerum to the inflow into Lake Åkervristen. The environmental parameters investigated were water depth, bottom substrate, shading, water velocity and the slope over the water surface. In this thesis I have focused mainly on water depth and shading, comparing sites with and without mussels. In addition, I used a multivariate PCA analysis to evaluate all parameters together. The water depth was significantly larger in habitats with mussels than in those without. Shading varied from 5 to 80 %, but there was no significant difference between habitats with and without mussels. There was no correlation between water depth and mussel density and not between shading and mussel density either. The multivariate PCA analysis showed that the habitats with and without mussels were different from with regard to the PC1 axis, which included water depth, bottom substrate and water velocity. Alone, the water depth is not enough to predict the presence of Unio crassus in the stream, and it is likely that more parameters need to be considered. Previous work indicate that the more parameters and habitats that are investigated, the more confident results can be stated of which habitats Unio crassus prefer.

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Lagström, Christian. "Födosammansättning hos gråsäl (Halichoerus grypus) samt test av flotte för insamling av sälfekalier." Thesis, University of Kalmar, School of Pure and Applied Natural Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:hik:diva-697.

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During the 1960´s and 1970´s the number of grey seals in the Baltic Sea was decreasing rapidly, mostly due to hunting and toxic substances like DDT and PCB. When hunting became less intense and toxic substances decreased in the environment the grey seal population started to increase. Today grey seals are found common in the Baltic Sea and have started to become a big treat and a problem to the fishing industry. The grey seal destroys and enters fishing traps and consumes large quantities of the fish that have been caught.The knowledge of the grey seal, like abundance and food preferences, is today limited. It is also important to define the position of the grey seal in the ecosystem in the Baltic Sea and to be able to predict changes that could occur if the population would rapidly decrease or increase. This project was therefore started in an attempt to increase the knowledge about the grey seals food preferences. The study was made in tree separate parts. Part one contained analyses of prey remains from stomachs and digestive tract from fourteen individuals put down in two geographically separate areas. The collected material from the seal digestive tract was cleaned and otoliths (hearing stones from fish), scales and back vertebra from fish eaten by the grey seal were sorted out. With the help of hard parts collected from the intestines the food preferences of the seals could be estimated. Eight different species of prey was found. The species were herring (Clupea harengus membras), sprat (Sprattus sprattus), common whitefish (Coregonus spp), perch (Perca fluviatilis), salmon (Salmo salar), trout (Salmo trutta) and roach (Rutilus rutilus). In two of the digestive tracts several individuals of the isopod Saduria entomon were found. No earlier studies describe the isopod as a food source for the grey seals in the Baltic Sea. The findings are therefore unique information. The results showed that during summer the main part of the grey seal diet in the gulf of Sundsvall and in the surrounding coastal area of Hårte was herring and sprat. No significant difference in food preferences was shown between the investigated seals from the gulf of Sundsvall and seals from the surrounding coastal area of Hårte.The second part was made to investigate if it was possible to build a floating platform that would work as a resting place for the grey seal. The surface of the platform was covered by a layer that keeps the seal scats on the platform so that it could be collected. Otoliths from herring and common whitefish were found on the floating platform. Because the platform could not be under surveillance during the whole study some uncertainties about whether the otoliths found came from grey seal or from resting cormorants or other fish eating birds. However, the otolit size is linearly related to the fish size and this relationship can be used to track the predator. Otoliths from herring taken by grey seals and otoliths found on the platform were significantly bigger than the otoliths originating from the prey of cormorants. The results indicated that the common whitefish size was too big for a full grown cormorant bird to consume. The common whitefish size showed that it probably not had been cormorants that had deposited the otoliths on the platform. The platform method was concluded promising but it needs to be modified in order to work more effective in the future.In the third part scats were collected from the area of Österåsen to increase the amount of information about the grey seals food preferences.The knowledge of the grey seals diet in the Baltic Sea is today limited and few similar study’s have earlier been made. The collected scats and otoliths in this project are therefore unique.2008:Bi 2

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Spring, Olivia, and Angelica Svensson. "Hantering av ortsprismetoden utifrån värdepåverkande faktorer hos bostadsrätter : En kvalitativ studie baserad på fastighetsmäklares preferenser." Thesis, Karlstads universitet, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-78866.

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There is not a single object in the world that resembles another object, which is both the delight and the complexity of the residential apartments market. Residential apartments are unique in their kind and possess particular attributes that influence their market values. The comparison method, which is one of the most common methods of residence valuation, is based on previously sold objects with similar characteristics and attributes. One obstacle with the method is that, it is often lacking information about the characteristics and attributes of the comparison objects that may have affected their market values. Residence valuation is a central part of a real estate agents’ profession, but unfortunately, the problems regarding the comparison method have led to an increased risk of incorrect valuations and dissatisfied customers. Customer satisfaction is essential for the professional role, which clarifies the importance of this study. The study examines how real estate agents use the comparison method based on value-affecting factors to maintain customer satisfaction. The empiricism in this paper has been developed through a qualitative method where interviews have been held with real estate agents around Karlstad municipality. In the empirical study, it was found that all respondents experienced some problems with residence valuation through the comparison method, since there is no relevant information about the comparative residential apartments value-affecting. However, the respondents do not feel that the final price in relation to the assessed market value outweighs the real estate agents service work regarding customer satisfaction. The information from the empirical data is linked to the theory in the essay analysis chapter, to elucidate their similarities and differences. The empirical fact presents that the respondents views on the problem of the comparison method are in accordance with the theory. However, their views on what creates customer satisfaction are not consistent with the theory. The theory says that the final price, in comparison with the assessed market value, outweighs the work done by the real estate agent during the process, which the empiricism contradicts. Our conclusion is that there is a certain problem when valuing residential apartments through the comparison method in the form of insufficient information about the comparison objects, which each real estate agent manages in different ways to avoid incorrect valuations. However, should an error evaluation occur, customer satisfaction can still be maintained if the real estate agent does a good service job.

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Lilja, Linda. "Ärlig, glad och omtänksam : Vilka egenskaper är viktiga hos en romantisk partner?" Thesis, Mälardalens högskola, Akademin för hälsa, vård och välfärd, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-42495.

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Sverige toppar listan över singelhushåll i Europa samtidigt som dejtingsajterna blomstrar. Syftet var att undersöka vilka egenskaper som män och kvinnor tyckte var viktiga i val av en potentiell romantisk partner utifrån Sexuell Economics Theory (SET) och positiv psykologi. Deltagarna (50 män, 50 kvinnor) i åldern 21 – 65 från hela Sverige, skattade hur viktiga 30 egenskaper var. Både män och kvinnor ansåg att egenskaper med aspekter från den positiva psykologin var viktigare än de kopplade till sexuella resurser och ekonomiska och omsorgsresurser. I linje med SET värderade män sexuella resurser högre än kvinnorna. Både män och kvinnor ansåg att ärlig, snäll, ville dela livet med dig, varm och omtänksam ochhumor varde viktigaste egenskaperna hos en potentiell romantisk partner.Studien har bidragit med en bättre förståelse kring vad som är viktigt när en livspartner sökes. Vidare forskning förslås undersöka flera egenskaper kopplade till positiv psykologi i jämställda länder.

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Bard, Elin. "Incitament för ökad lövtimmerproduktion : En fallstudie i södra Sverige av preferenser hos säljare och köpare för ökad satsning på inhemskt lövtimmer." Thesis, Linnéuniversitetet, Institutionen för teknik, TEK, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-16378.

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Kvarnsudde, David. "Substratpreferenser hos Crossocalyx hellerianus i svenska barrskogar : är skoglig kontinuitet en viktig faktor?" Thesis, Linköpings universitet, Biologi, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-166982.

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In recent time, forests in Sweden have lost habitat quality in the loss of deadwood due to the practices in productions forestry. This means that substrates for epixylic species has decreased both in quality and quantity. The aim with this study was to find which preferences the epixylic liverwort, Crossocalyx hellerianus has on its substrate and environment. C. hellerianus requires coarse logs with rotten wood, which usually is more available in forests with long forest continuity. This study was performed to see if forest continuity, isolation of habitats and if the substrate was of significance for a demanding species such as C. hellerianus. The study was performed in six sites and in each site several 50x10 meter transects were surveyed for logs. Each log was measured for diameter, sun exposure, ground contact, stage of decay and if the log was colonized by C. hellerianus. The result showed that C. hellerianus preferred coarser logs and that the species only appeared on an intermediate or later stage of decay. A high forest continuity and low habitat isolation turned out to be positive factors for the abundance of C. hellerianus

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Nilsen, Johanna, and Matilda Rydén. "Preferens av spektrala egenskaper hos svepande brus : Hur tonhöjdsförändring och låg-eller högpassfiltrering kan regleras för att anpassa två svepande brus till att upplevas behagliga." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-299333.

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Det finns idag ingen vedertagen teori för hur sonifiering ska utformas för att låta behagligt. Denna studie syftar till att utröna vad som anses vara ett behagligt ljud utifrån två parametrar: tonhöjdsförändring och låg- eller högpassfiltrering. Studien är en del av projektet Sonification of Goods in Stores [19]. För att undersöka denna frågeställning skapades ett webb-baserat test. 41 personer deltog i testet och reglerade parametrarna tonhöjdsförändring och låg-eller högpassfiltrering för att anpassa två olika grundljud till att upplevas så behagligt som möjligt. Testpersonerna fick sedan upprepa proceduren för att anpassa två obehagliga ljud, och slutligen för att anpassa två behagliga ljud ännu en gång. Testpersonerna fick även uppge personliga data som kunde användas för att analysera om det fanns skillnader mellan olika grupper och vad de ansåg vara behagligt. Deltagarna fick utöver detta ange sitt emotionella tillstånd vid ett flertal tillfällen under testets gång för att ljudens påverkan på deltagarna skulle kunna mätas. Resultatet av studien visade att sänkt tonhöjd och applicerat lågpassfilter var gemensamma faktorer för vad som ansågs vara ett behagligt ljud, det vill säga att ljuden spelades med lägre tonhöjd än grundljudet och med dovare klangfärg. Detta i kontrast till vad som ansågs vara obehagliga ljud där applicerat högpassfilter var gemensamt. Resultatet visade ingen korrelation mellan vad som ansågs behagligt och attribut hos deltagarna såsom kön, ålder, musikalisk bakgrund och vilken typ av hörlurar som används. Resultatet förväntas ge användbara insikter för projektet där ett behagligt ljud är önskvärt för en lyckad användning av sonifiering. Today, there is no applied theory for how sonification should be designed to sound pleasant. This report intends to address this and find answers to what is considered a pleasant sound based on the parameters: pitch shift and low-or highpass filtering. The study is part of the project Sonification of Goods in Stores [19]. To investigate this area, a website with a test has been created. 41 persons participated in the test and regulated the parameters pitch shift and low-or highpass filtering to adjust two given original sounds to be experienced as pleasant as possible. The test persons then repeated the procedure to adjust two unpleasant sounds, and finally once more to adjust two pleasant sounds. Furthermore, the test persons provided personal information that could be used to analyze whether there were differences between different groups and what they considered to be pleasant. The participants also stated their emotional state on several occasions during the test so that the impact of the sounds on the participants could be measured. The results of the study showed that lowered pitch and applied lowpass filter were common factors for what was considered a pleasant sound. In other words, the sounds were played with a lower pitch than the original sound and with a duller timbre. This in contrast with what was considered unpleasant sounds where an applied high-pass filter was common. The results showed no correlation between what was considered a pleasant sound and attributes of the participants such as gender, age, musical background and the type of headphones used. The result is expected to provide useful insights for the project where a pleasant sound is desirable for a successful use of sonification.

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Dissertations / Theses on the topic 'Host preference'

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