Call number: LD2668 .T4 1978 W416 / Master of Science

No description available.

Thesis (MSc)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Two fruit fly species, Ceratitis capitata (Wiedemann) and C. rosa (Karsch) (Diptera: Tephritidae) are known to attack deciduous fruit in the Western Cape Province of South Africa. The relative abundance of these two pests was studied in different kinds of fruit throughout the year. To facilitate field monitoring, using the immature stages, morphological differences between larval instars of C. capitata and C. rosa were investigated. Morphological characters of the larvae, such as the spiracles (anterior and posterior), mouth hooks and oral ridges were used. Many of these characters are only suitable to distinguish between the second and third instar larvae as these structures are not yet developed in the first instar larvae. Anterior spiracles were examined in terms of the number of tubules (papillae) and size or shape of the felt chambers. The number of papillae in both species was similar in the second and third instar larvae, but differed between the larvae of the two species (8-10 for C. capitata and 10-13 for C. rosa). In both species the felt chambers of the second instar larvae were narrow and elongate whilst those of the third instar larvae were broad and short. The major difference between the mouthhooks of the two tephritids was the presence of a sub-apical tooth in the third instar larva of C. rosa, being absent in the third instar of C. capitata. For the morphometric study, both laboratory-reared and field-collected specimens were examined. Measurements of the body dimensions (length and width) and various parts of the cephalopharyngeal skeleton (CPS) (mandible base, mandible length and distance between the tip and notch) were recorded in all three instars of both C. capitata and C. rosa. The data were analysed using finite mixture analysis (FMA-N1) and Levene's test was used to test for homogeneity of variances. The results of these analyses were used to estimate the frequency distributions of the larval measurements. In some cases overlaps in distributions were evident and were resolved using the same program, finite mixture analysis (FMA-N1), based on the probability of the overlapping measurements belonging to the designated instar (i.e. the one with highest probability). Determination of growth ratios suggested an approximate conformation to Dyar's rule thereby disputing the possibility of any hidden instar. However, in most cases measurements of the field samples did not conform to Dyar's rule. For the larval instars of C. capitata and C. rosa with overlapping morphological features, the morphometric approach as a distinguishing tool was demonstrated. In the field survey, the relative abundance of C. rosa at all experimental sites was very low in both orchards and adjacent vines. This suggested that this pest was either not a threat in these sites (crops) or the monitoring procedures applied, should be revised. Trap catches indicated high levels of infestation by C. capitata on some sites and low infestation levels at others. On the site with the highest population levels, activity peaks in the orchards did not co-incide with those in the adjacent vineyards. This suggested that these vineyards could be alternative hosts for fruit fly after the fruit in the orchards have been harvested. Forced oviposition (in vitro) studies indicated that Colombard (grown in Simonsvlei) was the most suitable host for survival of C. capitata. Other wine grape cultivars such as Chardonnay were also suitable for the total larval development of C. capitata. / AFRIKAANSE OPSOMMING: Twee spesies van die vrugtevlieg, Ceratitis capitata (Wiedemann) en C. rosa (Karsch) (Diptera: Tephritidae), val sagtevrugte in die Wes Kaap Provinsie van Suid- Afrika aan. Die groot hoeveelheid van hierdie twee plae op verskillende soorte vrugte is regdeur die jaar bestudeer. Voordat enige insekplaag gemonitor kan word, is dit belangrik dat die identiteit van die besondere plaag, insluitend sy onvolwasse stadiums, bekend moet wees. In hierdie studie word die morfologiese verskille tussen die larwe stadiums van C. capitata en C. rosa ondersoek. Kenmerke soos die spirakels (voor en agter), mondhake en mondriwwe is gebruik. Baie van hierdie morfologiese kenmerke kan net gebruik word om te onderskei tussen larwes in die tweede en derde stadiums omdat hierdie strukture nog nie in die eerste stadium ontwikkel is nie. Die voorste spirakels is ondersoek in terme van die aantal tubules (papillae) en die grootte en vorm van die vilt kamers. In beide spesies is die aantal papillae dieselfde vir die tweede en derde larwe stadiums, maar daar was en verskil tussen die larwes van die twee spesies (8-10 vir C. capitata en 10-13 vir C. rosa). In altwee spesies was die viIt kamers van die twee stadium larwes sma I en verleng, terwyl dit in die derde stadium larwes breed en kort was. Die hoof verskil tussen die mondhake van die twee vrugtevliee was die aanwesigheid van die subapikale tand in die derde stadium larwe van C. rosa, terwyl dit afwesig is in die derde stadium van C. capitata. Vir die morfometriese studie is voorbeelde van laboratorium geteelde vrugtevliee, asook vilee wat in die veld gevind is, ondersoek. Die liggaamsafmetings (Iengte en breedte) is gemeet asook die skelet (mandibel basis, mandibel lengte en die afstand tussen die punt en die kerf) in al drie stadiums van C. capitata en C. rosa. Die data is ontleed deur middel van eindige mengsel analise (FMA-N1) en Levene se toets is gebruik om vir homogeniteit en variansies te toets. Die resultate van die ontleding is gebruik om die frekwensie verspreiding van die larwale metings te skat. In sommige gevalle was daar oorvleueling en dit is opgelos met die gebruik van dieselfde program FMA-N1 baseer op die moontlikheid dat die metings wat oorvleuel, aan die aangeduide stadium (d.w.s die een met die hoogste waarskynlikheid) behoort. Die vasstelling van groei ratios dui aan dat dit naasteby ooreenstem met Dyar se reel en dus die moontlikheid van 'n versteekte stadium betwis. Maar in die meeste gevalle stem die veldmonsters nie ooreen met Dyar se reel nie. Die feit dat die morfometriese benadering die verrnoe het om larwale monsters met oorvleuelende morfologiese kenmerke, beteken dat dit kwalifiseer as In instrument om tussen die larwe stadiums van C. capitata en C. rosa te onderskei. Baie min C. rosa is in vrugteboorde en in nabygelee wingerde gevind. Dit dui of dat die plaag nie 'n bedreiging vir die vrugte inhou nie, of dat die monitor prosedures hersien moet word. Lokvalle dui aan dat daar 'n hoe vlak van infestasie van C. capitata in sommige gebeide is en In lae vlak in ander. Op die plek met die hoogste bevolking van vrugtevliee het die aktiwiteit in die boorde nie ooreengestem met die aktiwiteit in die nabygelee wingerde nie. Dit dui aan dat hierdie wingerde 'n alternatiewe blyplek bied aan die vrugtevliee nadat die vrugte in die boorde geoes is. Gedwonge oviposisie studies dui aan dat C. capitata die beste kan oorleef in Colombard (gekweek te Simonsvlei). Ander wyndruif kultivars is ook geskik vir die ontwikkeling tot by die laaste larwe stadium van C. capitata.

The problem of controlling tsetse flies in Africa is an old one. The tsetse fly transmits the trypanosome parasites which cause sleeping sickness in humans and disease in cattle. Because cattle are a favoured food source for tsetse much work has been done looking at the use of insecticide treated cattle as a control strategy for the tsetse fly. Such treatment methods possess many advantages; they are safe and relatively environmentally benign, they can be applied by individual farmers without the need for logistically demanding and costly traditional control programmes and, in addition to tsetse flies the insecticides are effective against a wide range of other harmful cattle parasites. The cost of the insecticide is however a significant constraint to the number of livestock keepers who can afford to employ the technique and as a result many cattle remain untreated. Following the discovery that tsetse had a significant predilection for feeding on the legs and belly of cattle, it was hypothesised that restricting the insecticide to only those areas could offer comparable protection to treating the whole animal. Such an approach would use up to 80% less drug and thus make the treatment per animal much cheaper. In addition, preferentially targeting areas favoured by tsetse, and leaving the rest of the animal untreated, preserves some important ecological balances between cattle and their parasites which traditional treatment methods destabilise. This thesis describes the design, implementation and analysis of a longitudinal study run over 8 months in south east Uganda that sought to compare the effect of applying insecticide to cattle only on the regions favoured by tsetse flies. Cattle were recruited to the study and assigned one of four treatment groups; a whole body application of deltamethrin insecticide pour-on; a restricted application of deltamethrin spray, applied to the front legs, ears and belly; a prophylactic trypanocide injection of isometamidium chloride, and a control group, that received no further treatments. All animals in the study were however cleared using twin doses of a trypanocide diminazene aceturate at the start of the study.

No description available.

Call number: LD2668 .T4 1986 H32 / Master of Science / Entomology

Orientador: Katia Denise Saraiva Bresciani / Resumo: A Leishmaniose Visceral (LV) apresenta uma ampla distribuição geográfica em todos os continentes, representando um sério problema de Saúde Pública. Os flebotomíneos (Diptera, Psychodidae, Phlebotominae) são importantes insetos vetores de microrganismos patogênicos como Leishmania spp., Bartonella spp. e arbovírus (Vesiculovirus, Phlebovirus, Orbivirus), porém, estes insetos apresentam grande importância para a transmissão das leishmanioses em várias regiões do mundo, incluindo as Américas do Sul e Central. No Brasil, há duas espécies, até o momento, relacionadas com a transmissão da Leishmania infantum: a Lutzomyia longipalpis e a Lutzomyia cruzi. Infecções por Leishmania spp. são potencialmente zoonóticas e acometem homens e diversas espécies de animais silvestres e domésticos. Os cães são importantes hospedeiros, fontes de infecções e potenciais reservatórios, não só pelo estreito relacionamento ou convívio com os seres humanos, mas também por sua incapacidade imunológica em responder à doença com sucesso. O Ministério da Saúde no Brasil, preconiza para o diagnóstico da Leishmaniose Visceral Canina (LVC), o teste imunocromatográfico, como exame de triagem e o ensaio imunoenzimático, como confirmatório. Também recomenda o diagnóstico precoce e tratamento adequado dos casos humanos, o controle dos vetores, a eutanásia dos cães e atividades de educação em saúde nas áreas endêmicas para esta doença. Por tanto, foram instituídas ações de prevenção e controle da LV canina, na áre... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Visceral leishmaniasis (VL) has a wide geographical distribution on all continents, representing a serious Public Health problem. Sand flies (Diptera, Psychodidae, Phlebotominae) are important insect vectors of pathogenic microorganisms such as Leishmania spp., Bartonella spp. and arboviruses (Vesiculovirus, Phlebovirus, Orbivirus), however, these insects are of great importance for leishmaniasis transmission in various regions of the world, including South and Central America. In Brazil, there are two species related to the transmission of Leishmania infantum: Lutzomyia longipalpis and Lutzomyia cruzi. Leishmania spp. infections are potentially zoonotic and affect men and various species of wild and domestic animals. Dogs are important hosts, sources of infections and potential reservoirs, not only for their close relationship or contact with humans, but also for their immunological inability to successfully respond to the disease. The Health Ministry of Brazil recommends for the diagnosis of canine visceral leishmaniasis (CVL), the immunochromatographic test as a screening test and the enzyme immunoassay as confirmatory. It also recommends early diagnosis and appropriate treatment of human cases, vector control, dog euthanasia and health education activities in endemic areas for this disease. Therefore, prevention and control actions of canine VL were instituted in the urban area of municipality of Araçatuba, São Paulo, Brazil. / Doutor

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In this work, I seek to model swarms of fruit flies, drosophila melanogaster, whose flights are characterized by straight flight segments interrupted by rapid turns called saccades. These flights are reminiscent of Levy-distributed random walks which are known to lead to efficient search behavior. I build two types of model for swarms of foraging fruit flies, whose behavior depends on swarm density and chemoattractant concentration, using rules inspired by experimentally observed flight patterns. First I will present a Lagrangian model where the path of each individual fly is tracked. I will also consider an Eulerian model where the fruit fly density evolves as a function of time and position in space. I will discuss the advantages and disadvantages of the two models and the relationship between them.

<p><!-- /* Font Definitions */ @font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4; mso-font-charset:1; mso-generic-font-family:roman; mso-font-format:other; mso-font-pitch:variable; mso-font-signature:0 0 0 0 0 0;} @font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4; mso-font-charset:0; mso-generic-font-family:swiss; mso-font-pitch:variable; mso-font-signature:-1610611985 1073750139 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-unhide:no; mso-style-qformat:yes; mso-style-parent:""; margin-top:0cm; margin-right:0cm; margin-bottom:10.0pt; margin-left:0cm; line-height:150%; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;} .MsoChpDefault {mso-style-type:export-only; mso-default-props:yes; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:Calibri; mso-fareast-theme-font:minor-latin; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi; mso-fareast-language:EN-US;} .MsoPapDefault {mso-style-type:export-only; margin-bottom:10.0pt; line-height:115%;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 70.85pt 70.85pt 70.85pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --><p><strong>The Symbolism of Power in William Golding’s <em>Lord of the Flies</em></strong></p><p> </p><p>An important theme in William Golding’s novel <em>Lord of the Flies</em> is social power relations.  These power relations are everywhere on the island, and are shown at different levels throughout the novel. These power relations are illustrated by symbols in the novel, which center on two different power systems, a democratic system, with Ralph as the head, and a dictatorial system with Jack as the leader. Sometimes these symbols are tied so closely together to both power systems that they mean different things for each of them. The aim of this essay is to investigate the different kinds of symbols that are used in the novel, and to show how they are tied to its social power relations. Those symbols that I have found are always important items that either Ralph or Jack use intentionally or unintentionally. The use of symbols is crucial to this novel, thus Golding shows us that an item is more powerful than it first seems.</p></p>