Thesis (M.S.)--Virginia Polytechnic Institute, 1967. / Typescript (photocopy). Vita. Abstract (2 leaves) bound with copy. Includes bibliographical references (leaves 83-89). Also available via the Internet.

Thesis (M.S.)--Oregon State University, 2008. / Printout. Includes bibliographical references (leaves 71-74). Also available on the World Wide Web.

The colour vision of adult citrus psylla, Trioza erytreae, was investigated in the laboratory using the behavioural parameters: alightment and walking. Light green flushing leaves (under which the nymphs develop) were significantly preferred, visually, to dark green mature leaves for alightment. Diffuse reflectance spectroscopy showed (when expressed in the parameters of human colour vision) that flush has a very slightly longer dominant wavelength, and roughly double the reflectance and purity. Alightrnent frequency correlated almost equally well with "purity" (as noted by Moericke, 1952 et seq., in "yellow-sensitive" aphids) as with the aphidological colour parameter "long/short ratio" developed by Kennedy et al. (1961). Elucidation of the mechanism underlying the citrus psylla's alightment colour preference was initially attempted with a printed spectrum and several paint series of measured spectral characteristics. It was clear that T.erytreae belongs to the "yellow-sensitive" group of Homoptera, but it was impossible to distinguish which pararneter(s) of colour the psyllids were responding to. Phototactic (walking) response to the individual parameters of colour was therefore measured using a monochromator. The phototactic action spectrum (against wavelength) was tri-modal, with peaks in the yellow-green (YG), blue (B), and ultra= violet (UV). Rate of phototaxis was not influenced by bandwidth (roughly equivalent to purity), but was proportional to intensity (roughly equivalent to reflectance). To investigate the influence of the above three wavelength regions on alightment, use was made of a very simple flight chamber incorporating a target of coloured light. Yellow-green and UV light both independently stimulated alightment . Their effect was additive. Different thresholds indicated distinct YG and UV receptor systems. Blue light alone did not stimulate alightment, and was strongly alightment-inhibitory in combination both with YG and with UV light. On the basis of the above physiological/behavioural findings, a new alightment formula was drawn up for describing the hamopteran's apparent manner of alightment determining integration of surface reflectance. The flush preference and alightment distributions on the series of artificial surfaces were found to correlate slightly more accurately, on average, as well as more consistently, with the new formula than with previously-available colour parameters. These findings are placed in perspective to the literature, and their possible economic relevance is discussed.

No description available.

L'objectif de la thèse était d'enrichir les connaissances sur les poux de tête et les poux de corps de l'homme. Les poux de tête vivent et pondent leurs œufs à la base des cheveux et sont très répandus chez les enfants dans les écoles. Les poux de corps vivent dans les vêtements et infestent les personnes de milieux sociaux très défavorisés ne permettant pas une hygiène vestimentaire adéquate. Les poux de corps sont vecteurs de trois grandes maladies : le typhus épidémique, la fièvre des tranchées et la fièvre récurrente à poux. Ces insectes hématophages sont étudiés depuis des décennies afin de déterminer si ils constituent deux écotypes de la même espèce ou deux espèces distinctes. Avant l'avènement des techniques de biologie moléculaire, la taxonomie des poux était basée sur leur morphologie et leur biologie. Bien que les différences biologiques décrites entre les poux de tête et les poux de corps ne sont pas toujours cohérentes, il est légitime de penser que leur séparation physique puisse mener à une différenciation spécifique. Certaines études expérimentales ont cependant montré certains cas de migrations de poux de tête vers les vêtements et inversement. Puis, grâce au séquençage du génome du pou, beaucoup de progrès ont été réalisés ces dernières années sur leur phylogénie. Ainsi, sur base de l'ADN mitochondrial, les poux de l'homme sont séparés en trois Clades phylogénétiques : le Clade A qui comprend à fois des poux de tête et des poux de corps et les Clade B et C qui comprennent uniquement des poux de tête. / The objective of this thesis work was to increase the knowledge of human head lice and body lice. Head lice live and lay their eggs at the base of hair shaft and are found frequently in school going children. Body lice live in clothes and are usually associated with low income persons that do not have adequate clothes hygiene. Body lice are the vector of three major diseases: epidemic typhus, trench fever and relapsing fever. These blood feeding insects have been studied over the past decades to determine whether they are two ecotypes of the same species or two distinct species. Before the advent of molecular biology, taxonomical classification of lice was based on their morphology and biological activities. Although described biological differences between head lice and body lice are not always consistent, their physical separation could lead to species differentiation. However, some experimental studies have shown that in certain cases head lice could migrate to the clothes and vice versa. In the recent years many progress were made in the body louse genome sequencing, and further their phylogenetic classification. Thus, on the basis of mitochondrial DNA, human lice are classified into three phylogenetic clades: Clade A that comprise both head lice and body lice and the Clades B and C that comprise only head lice. This phylogenetic organization clustered into three clades surprisingly shows that head lice of Clade A are closer to body lice than to head lice of Clade B or C. Since body lice serve as vectors of several diseases, in view of this, it is crucial to understand human lice epidemiology.

Les poux sont de véritables marqueurs pour l'étude de l'évolution humaine car ils ont été associés à l’homme depuis nos ancêtres et se sont dispersés à travers le monde avec ses différentes migrations. Les poux de tête et les poux de corps ont été étudiés morphologiquement depuis longtemps. Les poux de tête vivent et pondent leurs lentes dans les cheveux tandis que les poux de corps vivent et pondent leurs lentes dans les vêtements. Ces derniers sont associés à une mauvaise hygiène de vie et sont responsables de la transmission du typhus épidémique, de la fièvre des tranchées et de la fièvre récurrente. L’un des objectifs de ma thèse était d'accroître les connaissances sur les poux de tête et les poux de corps de l’homme afin d’assurer un meilleur contrôle. Il est essentiel de déterminer si les poux de tête et les poux de corps sont allopatriques ou s’ils pourraient exister en sympatrie. Ainsi, les études d'ADN mitochondrial ont montré qu'il y a trois clades clairement divergents des poux de tête (A, B et C) et un seul clade des poux de corps qui est partagé avec les poux de tête (clade A). Chaque clade a une répartition géographique bien déterminée. / Lice are effective markers for studying human evolution because they have been parasitizing humans since the emergence of our hominid ancestors and have been dispersed throughout the world by early human migrations. Human head and body lice have been studied morphologically for a long time. Head lice live and lay their eggs in human hair. Body lice live and lay their eggs in clothes, are associated with poor hygiene in clothing and are responsible for the transmission of epidemic typhus, trench fever and relapsing fever. One aim of my thesis was to increase the knowledge of human head lice and body lice for a better control. It is critical to determine if head lice and body lice are allopatric, with distinct epidemiology, or if they might exist in sympatry. Then, mitochondrial DNA studies have shown that there are three clearly divergent clades of head lice (A, B and C) and that only one clade of body lice is shared with head lice (clade A). Each clade has a unique geographic distribution. During the thesis work, extensive literature survey was done to write a review. Then we aimed to establish a molecular tool in order to distinguish between head and body lice. We found that only one gene (Phum_PHUM540560 gene) was able to differentiate the two ecotypes of Pediculus humanus. Moreover, we aimed to estimate the correlation between phenotypes and genotypes among human lice, and we found that the lice phylogeny (based on intergenic spacers) was correlated to the geographic origin of lice, but no correlation between the color and the phylogeny.

Thesis (MTech (Environmental Health))--Cape Peninsula University of Technology, 2018. / Soil ecosystems in urban, rural and agricultural environments receive chemical input from diverse sources of contamination, such as wastewater, industrial discharge, agricultural and urban runoff, fertilizers, vehicle leakages, landfill seepage, and animal waste overspill. Agricultural activities, transportation and industrial activities are suspected to be the highest sources of metal contamination in Cape Town. Although scientists generally have a good understanding of the toxicity of individual chemical pollutants, there is a great need to bridge the gap between our understanding of the toxic effects of exposure to individual contaminants and those effects from exposure to mixtures of chemicals. Woodlice and other soil detritivores have a particularly important ecosystem function in mineralising organic matter. Woodlice experience stress when exposed to toxic levels of metals in the diet, which can reduce feeding rates and may combine with natural stresses to reduce fitness and lower 'performance', thereby possibly resulting in these organisms being unable to completely fulfil their ecological function. The objectives of this study were: to compare how aluminium and manganese are bioaccumulated in Porcellio scaber in terms of the contribution of the hepatopancreas in metal storage compared to the rest of the body; and to determine whether mixtures of aluminium and manganese affect each other’s bioaccumulation and distribution in Porcellio scaber. Woodlice collected from a clean field site (Kirstenbosch Botanical Garden) were experimentally exposed in the laboratory to a range of environmentally relevant aluminium and manganese concentrations. The woodlice were exposed to these metals in single and mixed metal experiments. Oak leaves, collected from a clean site, were contaminated with aluminium and manganese. Therefore, the woodlice were exposed via their food source. A control experiment, where oak leaves were not contaminated, was also prepared. At week 0 and after five weeks of exposure, a sample of the woodlice (5 per exposure group) were dissected to remove the hepatopancreas. Hepatopancreas and rest of the body samples were acid digested and analysed for the metals by means of the ICP-MS. Contrary to the existing knowledge of metals accumulating in the hepatopancreas of woodlice when ingested, this study showed a higher bioaccumulation of aluminium in the rest of the body of woodlice after 5 weeks of exposure than in the hepatopancreas. This result was interpreted as a possible detoxification mechanism by woodlice through the use of the exoskeleton during the moult cycle. A similar result was found when woodlice were exposed to mixtures of aluminium and manganese. This translated to the fact that woodlice were unable to effectively deal with the toxicity caused by the mixture of aluminium and manganese. In the group of woodlice exposed to manganese alone, it was found that manganese concentrations in the rest of the body of woodlice exposed for 5 weeks were statistically higher than the manganese concentrations in the rest of the body of woodlice at the start of the exposure (week 0). However, in the hepatopancreas, there were no statistical differences between the manganese concentrations in week 0 woodlice and the manganese concentrations in week 5 woodlice. Furthermore, manganese concentrations in the rest of the body of week 5 woodlice were statistically higher than manganese concentrations in the hepatopancreas of week 5 woodlice. This was interpreted as further proof that woodlice would accumulate certain metals (aluminium and manganese in this case) in their exoskeleton so that elimination can follow during the moult cycle.

The close proximity of net-pen salmon farms and wild Pacific salmon stocks in British Columbia (BC) is an incentive for precautionary management of the environmentally and economically damaging parasites known as sea lice. Bivalves cultured as part of an integrated multi-trophic aquaculture (IMTA) system may contribute natural, preventative louse control through the ingestion of planktonic sea lice larvae. A field trial was conducted to test sea lice mitigation by bivalves at a commercial Atlantic salmon (Salmo salar) farm in BC using Pacific oysters (Crassostrea gigas). Oysters were cultured in trays around one end of the farm and at a reference site approximately 150 m away from August 2013 until August 2014. Parasitic and planktonic sea lice (Lepeophtheirus salmonis and Caligus clemensi) were monitored before and during oyster deployment, beginning in December 2012. Parasite abundance peaked in January 2013 (6.5 lice/fish, >85% C. clemensi), and the following year in February 2014 (3.3 lice/fish, >80% L. salmonis). Larval density within cages peaked in January, both in 2013 (1.28 larvae/m3) and 2014 (0.96 larvae/m3). Parasite abundance was significantly correlated with both surface salinity (r2= 0.28, p=0.04) and sea lice larval density (r2= 0.65, p=0.01). Observed densities were significantly lower (t=3.41, p=0.009) than those calculated for the site based on water temperature and salinity, the number of adult female lice present, and the approximate number of fish. Sea lice mitigation by oysters was assessed by comparing monthly sea lice larval densities inside bivalve and non-bivalve fish cages, and by analyzing preserved oyster digestive tracts from January 2014 (when larval densities were highest) for presence of L. salmonis DNA using PCR. Using these methods, no significant evidence of sea lice mitigation was detected. Oyster growth was monitored by measuring whole wet weight, soft tissue wet, dry, and ash-free dry weight, and shell length, width, and height approximately every four months. Oysters were sampled equally across different sides of the farm and at the reference site (~150 m away from the farm) at three depths: 1, 3, and 6 m. All seven measurements increased significantly over time. Effects of side and depth varied by growth parameter; in general, oysters at 1 and 3 m were significantly larger than those at 6 m, and oysters cultured at the reference site were either significantly smaller or the same size as those cultured around the farm. Oysters from select sides were consistently, significantly larger than those from other sides and from the reference site. Overall, the findings suggest that sea lice larvae quickly dispersed away from the farm after hatching and were not significantly impacted by bivalve presence around the fish cages. Bivalves grew significantly larger over time and size was significantly impacted by both depth and side of the fish cage. While no evidence of larval sea lice reduction/ingestion by cultured bivalves was detected, this study provides information on all sea lice stages present throughout an Atlantic salmon production cycle, as well as the first detailed growth analysis of Pacific oysters cultured alongside farmed Atlantic salmon in BC. / Graduate / 0792 / byrneaa@gmail.com

Skolsköterskor kommer ofta i kontakt med huvudlöss i sin yrkesroll. Hen är ofta en nyckelperson i arbetet med att bekämpa huvudlöss då skolsköterskan kommer i kontakt med både skolan, hemmen och de berörda barnen Studiens syfte var att belysa vilka faktorer i skolsköterskans arbete som är viktiga vid utbrott av löss, bland barn mellan 6 och 9 år. Metod: En kvalitativ intervjustudie genomfördes. Skolsköterskor (n=9) verksamma inom den kommunala skolhälsovården intervjuades om sina erfarenheter av att arbeta med huvudlöss i skolan. Materialet analyserades med kvalitativ innehållsanalys. Resultat: Skolsköterskornas erfarenhet av arbete med huvudlöss i skolan framträdde i två huvudkategorier. Preventivt arbete vid löss utbrott som beskriver skolsköterskans arbete innan det faktiska arbetet börjar med att bekämpa huvudlössen och har tre underkategorier, Ha kunskap om faktorer som främjar löss, Kännedom om förekomst av löss samt Betydelsen av att ha kunskap. Kunna ge råd och stöd vid löss utbrott beskriver skolsköterskans arbete under det faktiska huvudlöss utbrottet och har tre underkategorier Utbildning till barn, föräldrar och personal, Anpassa interaktionen med barn, föräldrar och lärare efter behov samt Användning av olika Omvårdnadsstrategier Slutsats: Arbete mot huvudlöss är en del av skolsköterskans arbete och det kan skapa en stor frustration hos de berörda barnen och dess familjer. Uppsatsen belyste att det finns områden att förbättra i arbetet med huvudlöss utbrott i skolan. / School nurses often come into contact with head lice in their professional capacity. The school nurse is often a key figure in efforts to combat head lice when the school nurse comes in contact with both persons in the school, in the home and the children concerned. The study's purpose was to illustrate which factors in the school nurse's work that are important to the outbreak of lice among children between 6 and 9 years. Methods: A qualitative study was carried out. School nurses (n = 9) active in the municipal school health were interviewed about their experiences of working with head lice at school. The material was analyzed using qualitative content analysis. Results: School nurses' experience of working with head lice in the school appeared in two main categories. Preventive work for lice outbreaks that describes the school nurse's work before the actual work begins with combat head lice, and has three sub-categories, Have knowledge of factors that promote lice, Knowledge of the outbreak and The importance of having knowledge. To give advice and support during lice outbreaks describes the school nurse's work during the actual head lice outbreak and has three subcategories Education to children, parents and personal, adapting the interaction with the children, parents and teachers as needed and have different caring strategies. Conclusion: Work against head lice is part of the school nurse's work and it can create a big frustration for the affected children and their families. The paper highlighted that there are areas to improve the work of head lice outbreak in school.

Pacific salmon (Oncorhynchus spp.) are key elements of ecological systems, and play an important role in the cultural foundation of human societies. All species of wild salmon face multiple, simultaneous threats, with habitat degradation likely playing a key role in survival. Open net-pen salmon farms can degrade important nursery marine habitat for wild juvenile salmon by disrupting natural salmonid host-parasite dynamics. The first two chapters in this thesis examine louse parasitism of wild juvenile chum (Oncorhynchus keta), pink (O. gorbuscha), and sockeye salmon (O. nerka) in relation to their marine migration past salmon farms. I compare sites of low and high exposure to salmon farms, and include two areas without farms on British Columbia’s central and north coasts to assess baseline infection levels. Louse prevalence and abundance were lowest and most similar to natural baseline levels at low exposure sites, and highest at high exposure sites in all farm regions. A significantly greater proportion of the lice infecting juvenile chum and pink salmon were Lepeophtheirus salmonis at high exposure sites. Caligus clemensi was the principal louse species infecting all juveniles in areas without salmon farms, and at low exposure sites within salmon farm regions; C. clemensi was also the dominant louse to infect juvenile sockeye that migrated past farms. Mixed-effects modelling results showed that exposure to salmon farms was the most consistent factor to explain the variation in louse infection levels, and support my hypothesis that salmon farms are a major source of sea lice on juvenile wild salmon in regions with salmon farms. I discovered that juvenile sockeye at one particular location within the Georgia Strait hosted unusually high lice levels; this location was situated at a distance from salmon farms, but near a farm salmon processing facility. Upon further investigation, I found live sea lice, Lepeophtheirus salmonis, mucus, and fish tissue in effluent discharged from the processing facility. Sea lice transmitted from this source may pose a threat to wild salmon populations, and the release of potentially untreated offal, including blood water, is of considerable concern. These results form the third chapter in my thesis. Given the challenges facing juvenile salmon in general, and sockeye from the Fraser River in particular (i.e., 2009 was the lowest return on record), and because poor habitat conditions within Georgia Strait are considered the major cause of the recent decline in Fraser River sockeye, this raises the question as to whether food limitations are a factor. The final chapter in my thesis examines the prey assemblage, diet composition, and foraging selectivity of juvenile sockeye, and investigates whether food limitations can be detected during early migration through Georgia Strait. Juvenile sockeye demonstrated high prey diversity, with preference for particular prey. Prey were more concentrated in the north, which may help explain migratory behavior of juveniles through the study region, and temporal similarities in sockeye foraging success may reflect short-term food resource stability. Moreover, I could not find evidence of food limitations that might suggest juvenile sockeye were strongly food deprived during the years of this study. Finally, my thesis explores how best to conserve salmon populations given the multitude of stressors. Because stressors often interact to produce compound effects and unpredictable results, ranking the overall threats in order of severity may not be useful. Instead, the most successful ranking system may be in terms of reducing harm where possible. For juvenile salmon during their early marine migration, risks posed by salmon farms can be more easily mitigated than the far-reaching effects on ocean productivity of climate change and ocean acidification, or predator removal. I recommend we begin here. / Graduate