Thesis (Ph.D.)--University of Nebraska-Lincoln, 2006. / Title from title screen (site viewed on Nov. 10, 2006). PDF text: xiii, 198 p. : ill. ; 9.99Mb. UMI publication number: AAT 3214778. Includes bibliographical references. Also available in microfilm, microfiche and paper format.

This study has investigated the nature of host derived cues used by parous female <I>C. impunctatus </I>in the location of blood meal hosts. Olfaction has been shown to be a vital part of the process. The responses of antennal receptors of females to a variety of host-derived volatile compounds were assessed using the EAG technique. High antennal sensitivity to olfactory cues was indicated by low thresholds for response and, taking into account the volatility of the compounds, a clear hierarchy of response was obtained in which octenol was the most stimulatory, followed by phenolics, lactic acid and finally ketones. Of particular note with regard to phenolic compounds was the finding that 3-derivatives (3-n-propylphenol & 3-methylphenol) were more stimulatory than their 4-derivatives (eg 4-methylphenol). Behavioural assays conducted within a Y-tube olfactometer showed that attraction to olfactory cues was dose dependent. Supra optimal doses which caused receptor saturation (as demonstrated in the EAG assay), also induced marked changes in behaviour with responses being either no different to random expectation, or the compound appearing to be repellent. Wind tunnel assays corroborated these findings for octenol and acetone when used in conjunction with 0.01% CO<SUB>2</SUB>. Upwind flight was found to be maximal, and significantly different from responses to the CO<SUB>2</SUB> standard, at concentrations within the tunnel of 1.33x10<SUP>-8</SUP> g 1<SUP>-1</SUP> and 1.5x10<SUP>-6</SUP> g 1<SUP>-1</SUP>, respectively. These concentrations are approximately those released by a bovid host for octenol and 1/1000x for acetone. Females exhibited a linear dose dependent response to increases in the concentration of CO<SUB>2</SUB> in the wind tunnel up to 0.09% whether gas was released as a plume or as a lightly turbulent cloud. However, at cloud concentrations above this, CNS mediated habituation is suggested to have arrested upwind flight.

Apanteles rubecula is a solitary insect parasite of Pier is rapae (small cabbage white butterfly, imported cabbageworm). The parasite has been successfully introduced to Australia and Vancouver, Canada but has failed to become established at other North American release sites. This practical problem illustrates a fundamental aspect of insect ecology. The seasonal biology of insects is interpreted here as an interaction of responses to ambient conditions. Emphasis centers on the rates at which life history phenomena occur and the importance of the insect's biological chronometers on the outcome of its ecological relationships with its host and its local climate. Comparisons are made between Canberra, Australia and Vancouver, Canada. The parasite's developmental response to temperature is similar in Canberra and Vancouver but the host response differs. Canberra A. rubecula have a longer generation time relative to the host at low temperatures, but shorter generation times at higher, midseason temperatures. Vancouver parasites always have faster generation times than their hosts but the season is truncated in August by a diapause response to daylengths shorter than I5h. The beginning of the season is delayed until late May by the high thermal requirement to terminate diapause. These local responses to temperature and photoperiod result in different phenologies which, while appropriate locally, are disastrous elsewhere. The failure of North American attempts to establish Vancouver A. rubecula is attributed to the diapause characteristics of the released insects. They entered diapause while ambient temperatures remained warm enough for morphogenesis and were unable to survive the obligatory period to diapause termination. Manipulation of the diapause response is one technique in ecological pest management. A methodology for a breeding program and its analysis is presented. Practical suggestion for biological control efforts are made and the role of individual physiological responses in insect seasonal ecology are discussed. / Land and Food Systems, Faculty of / Graduate

This project is a celebration of an office building in Stockholm from the 1960s, by proposing to preserve the existing and make an addition, to enhance what is already there. A premise of the project was to look upon the extension as a parasite. The existing building is a result of a formulated bureaucratic ideal, a piece of text. By using bureaucracy as a theme, the extension is parasitizing on the existing building. The theme has been explored through the use of bureaucratic tools, letters and numbers. Methods of performing bureaucracy, to do paperwork, its automatization and aesthetics, how forms and documents look. What does the contemporary nomadic office worker need? What props and supplies? How to create a bureaucratic atmosphere? How to relate to the history of office planning and keywords such as flexibility and mobility? How to relate to the actual material of the already existing? How to attach one thing to another?

<p> The distribution of Eisenia rosea, the main host of P. rudis, is influenced mainly by soil moisture and bulk density. Cluster-fly larvae locate hosts by random locomotion through the soil pores, whereupon penetration is induced by a substance present in the worm slime. Penetration occurs mainly on the upper surface of the worm, with fewer penetrations occurring towards either end of the worm. Several species of earthworm, including some which do not normally act as hosts, were infected in the laboratory. </p> <p> The encystment, surface casting, burrowing and autotomising behaviour of E. rosea varies with soil moisture and bulk density. The penetration rate of P. rudis larvae into E. rosea is affected by this behaviour, as well as by the soil pore morphology. The success of maintenance of infected worms is also affected by the worm behaviour, which in turn depends on the soil conditions. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.

Terminal sire crossbreeding systems which improve growth performance while maintaining parasite resistance have the potential to enhance the profitability of hair sheep enterprises. Katahdin (KT, n = 4), Suffolk (SU, n = 3), and Texel (TX, n = 3) rams were randomly mated to KT ewes over two years (Y1, Y2) at the Virginia Tech Southwest Agricultural Research and Extension Center. Post-lambing until weaning (80 d), pairs were managed on fescue pasture. At weaning, lambs (n = 192) were moved to an ungrazed pasture and provided a concentrate pellet daily for a 90 d grazing trial. During this time, BW, strongylid egg count (FEC), FAMACHA score and packed cell volume (PCV) were collected every 14 d. FAMACHA score - 3 was utilized as the basis for anthelmintic treatment. Post-grazing, lambs were fed to approximately 50 kg BW. Lambs were harvested at the Virginia Tech Meat Center and carcass evaluation performed 1 d post-harvest. Statistical analyses were conducted using SAS (SAS Institute Inc., Cary, NC) with Proc MIXED for repeated measures analysis and Proc GLM with Tukey?s test for mean separation. No differences existed between sire breeds for adjusted number of lambs born or number of lambs weaned. Adjusted birth BW was greater for SU-sired lambs than KT-sired and TX-sired (P < 0.05) in Y2. Adjusted weaning BW was smallest for KT-sired lambs compared to SU- and TX-sired lambs (P < 0.05) in both years. During the grazing trials, BW, ADG, lnFEC, FAMACHA and PCV varied over time (P < 0.001) with lower FAMACHA scores for KT-sired lambs than SU- and TX-sired lambs in Y1 (P < 0.05). A greater proportion of SU-sired lambs tended to require deworming than KT-sired lambs (P = 0.08). Adjusted BW post weaning was greater for TX-sired lambs than KT-sired lambs (P < 0.05) in Y1. Post-grazing, BW and ADG varied over time (P < 0.01) with no sire breed differences for ADG. At harvest, SU-sired lambs were heavier than KT-sired lambs (P < 0.05). TX-sired lambs had greater LM area than KT-sired lambs (P = 0.05). KT-sired lambs had the smallest leg scores (P < 0.05). These results indicate the potential of terminal sires (SU- and TX-sires) to improve lamb growth and carcass merit. TX-sired lambs had more similar parasite resistance characteristics to KT-sired Iambs and may have potential as terminal sires in forage based hair sheep production systems. / Master of Science / Katahdin hair sheep have been developed as an easy-care breed adaptable to forage-based production systems. Their enhanced resistance to gastrointestinal parasites has resulted in their rise in popularity among sheep producers in the southeastern United States. However, their lower cutability (muscle to fat ratio) and lighter carcass weights have resulted in economic concerns. Therefore, other breeds (Texel and Suffolk) have been considered for crossbreeding to increase carcass size and muscle improving the market value of lambs produced. Here, Katahdin, Suffolk and Texel sires were mated to Katahdin ewes over two years at the Southwest Virginia Agriculture Research and Extension Center. Lambs were grazed with their dams until weaning at approximately 70 days of age. Post-weaning, lambs were grazed for approximately 90 days during which time body weights and parasite resistance indicators were recorded every two weeks. Lambs were dewormed based on anemia level measured by mucus membrane color (FAMACHA score). After grazing, lambs were fed until they reached approximately 50 kg. Lambs were harvested at the Virginia Tech Meat Center for carcass evaluation. There were no differences between the sire breeds for number of lambs born or weaned per ewe. Suffolk-sired lambs were heaviest at birth in year 2 and at weaning Suffolk- and Texel-sired lambs were heavier than Katahdin-sired in both years. In year 1, Texel-sired lambs were heaviest at the end of the grazing period. FAMACHA scores tended to be lower for Katahdin-sired lambs and Suffolk-sired lambs tended to require greater deworming. At harvest, Suffolk-sired lambs were heavier than Katahdin-sired lambs while the Texel-sired lambs had greater loin muscle area. These results indicate the potential of terminal-sires (Suffolk and Texel) to improve lamb growth. Texel-sired lambs were more similar to Katahdin-sired lambs for resistance traits while increasing carcass muscling and may be a potential terminal option for forage-based production systems.

The accurate identification of parasites allows for the quick diagnosis and treatment of infections. Current state-of-the-art identification techniques require a trained technician to examine prepared specimens by microscope or other molecular methods. In an effort to automate the process and better facilitate the field identification of parasites, approaches are developed to utilize LabVIEW and MATLAB, which are commercially available image processing software packages, for parasite egg identification. The goal of this project is to investigate different image processing techniques and descriptors for the detection and characterization of the following parasite eggs: Ascaris lumbricoides, Taenia sp., and Paragonimus westermani. One manual approach and four automated approaches are used to locate the parasite eggs and gather parasite characterization data. The manual approach uses manual measurements of the parasite eggs within the digital images. The four automated approaches are LabVIEW Vision Assistant scripts, MATLAB separation code, MATLAB cross-section grayscale analysis, and MATLAB edge signature analysis. Forty-four separate measurements were analyzed through the four different approaches. Two types of statistical tests, single factor global Analysis of Variance (ANOVA) test and Multiple Comparison tests, are used to demonstrate that parasite eggs can be differentiated. Thirty-six of the measurements proved to be statistically significant in the differentiation of at least two of the parasite egg types. Of the thirty-six measurements, seven proved to be statistically significant in the differentiation of all three parasite egg types. These results have shown that it is feasible to develop an automated parasite egg detection and identification algorithm through image processing. The automated image processing techniques have proven successful at differentiating parasite eggs from background material. This initial research will be the foundation for future software structure, image processing techniques, and measurements that should be used for automated parasite egg detection. / Master of Science

Host-parasite interactions are extremely important drivers of evolutionary change, characterised by co-evolutionary dynamics with strong reciprocal selective pressure on both host and parasite genomes. However, little is known about the genomic basis of host-parasite interactions, particularly which genes may affect parasite susceptibility, parasite burden and the ability to resolve energetic life-history trade-offs under chronic parasite insult. This thesis examines the genomic, epigenomic and transcriptomic basis of an avian host's physiological response to chronic parasite infection. The model system throughout is the red grouse (Lagopus lagopus scotica) and its main parasite, the gastrointestinal nematode Trichostrongylus tenuis. T. tenuis is highly prevalent and imposes substantial fitness costs that affect demography and population dynamics through an impact on territorial behaviour, energy balance, fecundity and mortality. Here, the genomic architecture of variation in individual T. tenuis burden is examined via de novo identified candidate genes, genome-wide SNPs and genome-wide cytosine methylation polymorphisms. Further, molecular signatures of natural selection in identified genomic regions are examined across a landscape in northeast Scotland with heterogeneous parasite pressure. Finally, the transcriptomic response of red grouse to experimental T. tenuis infection and manipulation of testosterone titre is harnessed to identify a transcriptomic component in testosterone-driven physiological trade-offs in a sexual selection context.

Saprolegnia is a fresh water fish parasite responsible for significant economic losses in the aquaculture industry worldwide. The disease caused by this organism is termed saprolegniosis, being characterized by a mycosis-like infection of gills and fish skin. Without sustainable treatments available for controlling or preventing saprolegniosis, it has become a significant problem especially for salmon farming, frequently affecting the fish after vaccination. Little is known regarding how the fish immune system responds to infection and such information is vital for developing future treatments and preventive measures to saprolegniosis. To study the immune response of Atlantic salmon to Saprolegnia, a detailed immune profile of experimentally infected presmolts was performed by analyzing the expression levels of several immunity-related genes. Infected fish exhibit a very strong inflammatory response while the majority of genes associate with the adaptive immunity were found to be down regulated. The mechanisms behind this response were then investigated: It was discovered that the cell wall of Saprolegnia can be recognized by fish immune cells, triggering an inflammatory response. A protease secreted by the parasite that has the ability to degrade fish antibodies was identified and, for the first time in an oomycete, the production of prostaglandin E2 was characterized, a molecule that was later shown to potentiate inflammatory responses while suppressing host adaptive immunity genes. Lastly two metabolic pathways of the oomycete were explored as novel targets for control, prostaglandin and sterol metabolism by the use of cyclooxygenase and CYP51 inhibitors, respectively.