Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The spatial distribution of animals and plants at different scales is a central theme in ecology. Knowledge of biodiversity distribution is essential, especially with the current threat of climate change and invasion by alien species. Since the impact of climate change and alien species will be, and has already been pronounced in polar regions, information on the current spatial distributions of biota in these regions is critical to predict the consequences of climate change and alien species on the future survival, distribution and abundance of indigenous biota. This study was conducted on the sub- Antarctic Prince Edward Islands (consisting of Marion Island and Prince Edward Island), which have experienced rapid climate changes over the past 50 years. Additionally, a number of alien plant, vertebrate and invertebrate (also microarthropod) species have been introduced to these islands. Since microarthropods (mites and springtails) play an essential role in decomposition and mineralization of plant material on the islands, the loss of microarthropods from decomposer communities might have disastrous results for ecosystem processes. Therefore it is essential to know the current distributions of microarthropods in order to predict future distributions patterns in reaction to climate change and invasive species. In this study, the spatial distribution of mites and springtails inhabiting the cushion plant Azorella selago Hook, were examined at different scales of observation. Firstly, the microarthropod community was examined at a fine scale. The relationship between microarthropod species richness and abundance and plant size, isolation, within-plant variability, grass cover and microclimate variables were investigated. Thereafter, the spatial variability of microarthropod abundances was examined within stands of plants, with statistical methods using varying degrees of locational information to determine if microarthropod abundance is random, regular or aggregated at this scale. Further, the spatial variability of microarthropod communities in A. selago at different altitudes and on different sides of Marion Island, i.e. island-wide scale, was examined. The last scale of observation was the island-wide scale, in which microarthropod assemblages were compared between Marion Island and Prince Edward Island, as well as in different plant species. Microarthropods showed spatial heterogeneity within A. selago plants (higher abundances in eastern and southern sides of plants), island-wide (lower springtail abundance on the eastern side of the island and at high altitudes) and between islands (more alien species on Marion Island). In contrast, microarthropod abundance was not spatially heterogeneous within a stand of plants, i.e. mostly randomly distributed. The possible mechanisms responsible for these patterns differ between scales, and range from temperature and nutrient availability at the within plant and island wide scale to alien species between islands. Climate change is likely to alter these distribution patterns of microarthropods, either directly (unfavourable climate for indigenous species growth, development and dispersal) or indirectly (favouring alien microarthropod species; increase in grass cover on A. selago plants may alter community structure). The information presented here, is essential for predicting the possible impacts of climate change on microarthropods in fellfield ecosystems on sub-Antarctic islands. / AFRIKAANSE OPSOMMING: Die ruimtelike verspreiding van diere en plante op verskillende skale is ‘n sentrale tema in ekologie. Kennis van die verspreiding van biodiversiteit is belangrik, veral met die huidige bedreiging van klimaatsverandering en indringerspesies. Omdat die impak van klimaatsverandering en indringerspesies in die poolstreke alreeds duidelik is en nog meer so sal word, is inligting oor die huidige ruimtelike verspreiding van biota in hierdie streke noodsaaklik. Hierdie studie is op die sub-Antarktiese Prins Edward-eilande (bestaande uit Marion Eiland en Prins Edward Eiland) uitgevoer, waar die klimaat vinnig verander het oor die afeglope 50 jaar. Bykomend is ‘n aantal indringer plant, vertebraat en invertebraat (ook mikroartropood) spesies op die eilande ingebring. Omdat mikroartropoda (myte en springsterte) ‘n baie belangrike rol in ontbinding en mineralisering van plantmateriaal op hierdie eilande speel, sal die verlies van mikroartropoda uit die ontbindingsgemeenskap rampspoedige gevolge vir die prosesse in die ekosisteem hê. Kennis van die huidige verpreiding van mikroartropoda is dus noodsaaklik om die toekomstige verspreidingspatrone, asook oorlewing en volopheid van inheemse spesies in reaksie op klimaatsveranding en indringerspesies, te voorspel. In hierdie studie is die ruimtelike verspreiding van myte en springsterte wat in die kussingplant Azorella selago Hook voorkom, op verskillende ruimtelike skale ondersoek. Eerstens is die mikroartropood gemeenskap op ‘n klein skaal ondersoek. Die verwantskap tussen mikroartropood spesies rykheid en volopheid en plantgrootte, isolasie, binne-plant variasie, gras bedekking en mikroklimaat faktore is ondersoek. Daarna is die ruimtelike variasie van mikroartropood volopheid binne in ‘n plantstand ondersoek deur gebruik te maak van metodes wat verskillende grade van ligging data gebruik. Dit is gedoen om uit te vind of mikroartropood volopheid lukraak, reëlmatig of versameld verspreid is. Verder is die ruimtelike verspreiding van mikroartropood gemeenskappe in A. selago op verskillende hoogtes bo seespieël en op verskillende kante van Marion Eiland ondersoek. Laastens is die mikroartropood gemeenskap op Marion Eiland en Prins Edward Eiland, asook die gemeenskap in verskillende plant spesies vergelyk. Mikroartropoda is ruimtelik heterogeen verspreid binne-in A. selago (meer individue in die oostelike en suidelike kante van plante), asook regoor Marion Eiland (minder springstert individue aan die ooste kant van die eiland asook minder op hoë hoogtes bo seespieël) en tussen eilande (meer indringerspesies op Marion Eiland). In teenstelling hiermee is mikroartropood volopheid ruimtelik homogeen oor ‘n plantstand, dus meestal lukraak verspreid. Die meganismes wat moontlik vir hierdie patrone verantwoordelik is wissel van temperatuur en voedselbeskikbaarheid op die binne-plant en oor die eiland skaal tot indringerspesies op die tussen-eiland skaal. Klimaatsverandering mag waarskynlik mikroartropood verspreidingspatrone direk (ongunstige klimaat vir inheemse spesies se groei, ontwikkeling en verspreiding), of indirek verander (indringer spesies word begunstig; toename in grasbedekking bo-op A. selago mag die gemeenskapstruktuur van mikroartropoda verander). Hierdie inligting is belangrik vir die voorspelling van die moontlike impak van klimaatsverandering op mikroartropoda in klipveld ekosisteme op sub-Antarktiese eilande.

Thesis (PhD) -- Stellenbosch University, 1989. / ENGLISH ABSTRACT: Arthropod communities of five proteaceous species viz. Protea repens. P. neriifolia. P.cynaroides, Leucospermum cordifolium and Leucadendron /aureolum were studied. A faunal list of the insects was compiled according to the feeding guilds of insects. Six phytophagous guilds were recognized: flower visitors, thrips, endophages, ectophages, sap-suckers, and ants. The guild composition, species packing and seasonal distribution for the free-IMng insects, spiders and other arthropods were investigated on the different plant species. The ants, flower visitors and sap-sucking species found on the plant species, were very similar, but the number of leaf chewing species common to all the plant species was low, suggesting that some species were monophagous. Insect abundance increased during the wet winter months when the plants were in flower. Of the total number of herbivores collected, flower visitors represented 69,5%, leaf feeders 14,5% and sap-suckers 16,1 %. The chewers constituted 60,1% of the total herbivore. biomass. Leaf damage increased with age ; young leaves were practically free of herbivore damage, while older leaves were stm acceptable as food. The degree of insect damage differed amongst the plant species varying from 2% to 15%. The following leaf characteristics were investigated to determine the factors involved in defence against insect herbivory : total phenolic content, protein precipitating ability, cyanogenesis, nitrogen content, leaf toughness, woodiness and fibre content lt appears that the plant species use different mechanisms to protect their leaves. The infructescences of Protea repens were exploited by the larvae of four Coleoptera and four Lepidoptera species. The community structure of these phytophagous insects was determined largely by negative interactions. Various strategies are followed (e.g. niche segregation in time and space) to lessen interspecific competition. / AFRIKAANSE OPSOMMING: 'n Studie van die arthropoocl gemeenskap op vyf proteasoorte, naamlik Protea repens. P. neriffolia. P. cynaroides. Leucospennum cordffolium en Leucadendron laureolum is gedoen. 'n Faunalys van insekte volgens hul voedingsgDdes is saamgestel. Die insekte is in ses fitofage gDdes verdeel naamlik blombesoekers, blaaspootjies, endovoeders, ektovoeders, sapsuiers en miere. Die samestelling van die gDdes, spesie-rangskikking en seisoenale verspreiding is bepaal vir die vrylewende insekte, spinnekoppe en ander arthropode. Die miere, blombesoekers en sapsuierspesies wat op die plantsoorte gevind is, is byna dieselfde, maar verslalle in die blaarvoederspesies is gevind wat 'n aanduiding is dat sommige spesies monofaag mag wees. Gedurende die nat wintermaande toon die insekgetalle 'n toename. Blombesoekers verteenwoordig 69,5%, blaarvoeders 14,5% en sapsuiers 16,1% van die aantal insekherbivore wat versamel is. Die kouers vorm 60,1% van die totale herbivoor biomassa Soos die blare verouder, neem die skade op die blare toe; jong blare toon byna geen skade nie, terwyl ouer blare steeds geskik is vir insekvoedsel. Die insekskade op die blare wissel by die verslallende plante tussen 2% en 15%. Om te bepaal watter blaareienskappe moontlik 'n rol kan speel in blaarverdediging teen insekte is die volgende ondersoek: totale fenoliese inhoud, die vermoe om proteiene te presipiteer, sianogenese. stikstofinhoud, blaartaaiheid, houtagtigheid en veselinhoud. Dit wil voorkom asof die plante verskillende meganismes gebruik om die blare te beskerm. Saadkoppe van Protea repens word deur vier Coleoptera en vier Lepidoptera spesies benut Die gemeenskapstruktuur van die boarders word tot 'n groat mate bepaal deur negatiewe interaksies. Verskeie strategiee word gevolg (bv. nissegregasie in ~ en ruimte) om kompetisie tussen spesies te verminder.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Invasive arthropod predators are one of the largest and most diverse groups of invasive insects in the world. Many are generalist predators, with cosmopolitan distributions due to their use as biological control agents in agriculture. Harmonia axyridis (Coleoptera: Coccinellidae), an invasive arthropod predator species native to Asia, which now has a world-wide distribution. It is considered one of the most successful biological control predator species and is generally considered to be economically beneficial. However, negative effects have recently emerged in agricultural and natural systems. Harmonia axyridis poses a threat to biodiversity as it outcompetes native species for food resources. It can also feed directly on native predatory arthropods that disrupt natural ecosystem processes. Their movement in-and-out of agricultural landscapes may depend on food availability with natural vegetation alongside agricultural areas often utilised for refuge and alternative food resources. This beetle has also been recorded in urban areas. The aim of this study was to determine how the invasive H. axyridis beetle uses the local landscape in the Western Cape province, South Africa, and to determine its threat to native species. I sampled urban landscapes, vineyards, natural vegetation/vineyard edge zones and pristine natural areas for arthropods every second month using a suction sampler. Data collected included the abundance and diversity of H. axyridis, herbivores, local predators and non-Harmonia ladybeetles. Most H. axyridis were collected in urban areas during all sampling periods. Highest abundance was recorded in May and July (winter). This indicates that urban areas were the preferred landscape feature and that these act as ovipositing areas, particularly as larval H. axyridis were also only collected in urban areas. Significantly, vineyards and natural vegetation had very low abundance of H. axyridis, questioning their value as a biological control agent in this region. Harmonia axyridis had a negative effect on the overall local arthropod community, as well as the predator and herbivore guilds, although it was positively correlated with the abundance of non-Harmonia ladybeetles. This suggests that H. axyridis and non-Harmonia ladybeetles are responding to the same resources in these landscapes. A negative correlation found between H. axyridis and the abundance of predators is most likely due to competition for the same resources (e.g. prey items). These negative impacts, along with their negligible value as biological control agents in agriculture, suggest that a programme should be implemented to control this invasive species. More specifically, control should be aimed in urban areas during winter when and where the species aggregates and when larvae are present. / AFRIKAANSE OPSOMMING: Geleedpotige roofdiere is een van die grootste en mees diverse groepe van uitheemse insekte in die wêreld. Die meeste is veelsydige roofdiere, met wêreldwye verspreiding te danke aan hul gebruik as biologiese beheer agente in landbou gebiede. Byvoorbeeld, Harmonia axyridis (Coleoptera: Coccinellidae), 'n indringer geleedpotige roofdier spesies inheems aan Asië, het nou 'n wêreldwye verspreiding. Dit word beskou as die mees suksesvolle roofdier spesies wat gebruik word vir biologiese beheer en word oor die algemeen beskou as ekonomies voordelig. Negatiewe effekte was onlangs aangeteken beide in landbou gebiede en natuurlike areas. Harmonia axyridis hou 'n bedreiging in vir inheemse biodiversiteit as dit inheemse spesies uitkompeteer vir voedsel bronne. Dit kan ook direk voed op plaaslike roofsugtige geleedpotiges wat trofiese vlakke ontwrig en uiteindelik, biodiversiteit. Hulle beweging in-en-uit landbou landskappe kan gekoppel word aan die beskikbaarheid van voedsel, en gebruik natuurlike plantegroei langs landbou gebiede dikwels as 'n toevlugs oord en area vir alternatiewe voedsel bronne. Harmonia axyridis word ook in stedelike gebiede aangeteken. Die doel van hierdie studie was om te bepaal hoe die indringer Harlekynkewer die plaaslike landskap gebruik met die fokus op wingerde in die Wes-Kaap provinsie van Suid-Afrika, en tweedens om die bedreiging wat hierdie kewer moontlik vir inheemse spesies te bepaal. Ek het arthropoda in stedelike landskappe, wingerde, natuurlike plantegroei / wingerd rand sones en ongerepte natuurlike areas elke twee maande met behulp van 'n D-vac versamel. Monsters was ontleed deur gebruik te maak van die getalle van H. axyridis, herbivore, plaaslike roofdiere en nie-Harmonia liewenheers kewers. Die meeste H. axyridis was in stedelike gebiede versamel gedurende al die seisoene, maar meeste individue was gedurende Mei en Julie (winter) versamel. Hierdie toon dat stedelike gebiede die voorkeur-landskappe is vir hierdie kewers en dat hierdie gebiede opgetree as eierleggende gebiede, veral omdat larwes van H. axyridis slegs in hierdie gebiede aangeteken was. Wingerde en die natuurlike plantegroei het baie lae getalle H. axyridis gehuisves wat hul waarde as biobeheermiddel bevraagteken. Harmonia axyridis het 'n negatiewe uitwerking op die algehele plaaslike geleedpotige gemeenskappe gehad, asook op die die roofdier en herbivoor gildes, maar hul getalle was positief gekorreleer met die getalle van nie-Harmonia liewenheerskewers. Dit dui daarop dat H. axyridis en nie-Harmonia liewenheerskewers beide reageer op dieselfde hulpbronne in hierdie landskappe. 'n Negatiewe korrelasie was gevind tussen die getalle van H. axyridis en die getalle van ander predatoriese geleedpotiges at waarskynlik te danke was aan mededinging tussen hierdie groepe vir dieselfde hulpbronne (bv prooi). Hierdie negatiewe invloede, asook hul verminderde waarde as biobeheeragente in die landbou, dui daarop dat 'n program in werking gestel moet word om hierdie indringerspesies te beheer. Meer spesifiek, beheer moet gedurende die winter en in stedelike gebiede geskied, waar en wanneer hierdie spesie op sy volopste is en waar larwes teenwoordig is.

Dissertation (PhD)--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: Within arthropods, inter-individual and inter-population variation is generally poorly explored for physiological parameters. Such physiological variability is important, as it can provide insight into the capacity for evolutionary adaptation and how animals may cope with anthropogenic climate change. Insect vectors of human and animal diseases, such as tsetse flies (Diptera, Glossinidae) which carry trypanosomes, are of particular interest. Predictions of tsetse fly (Glossina spp.) range expansion, possibly paralleled by increased disease occurrence, have been made under future climate scenarios. Moreover, since there are generally strong relationships between abiotic variables (e.g. temperature and moisture availability), population dynamics, distribution and abundance, determining the physiological mechanisms influencing such relationships has utility for predictive modelling of spatial and temporal changes in tsetse fly distributions. I investigated physiological variation among individuals and populations, focusing mainly on Glossina spp. but using other arthropods to address certain issues. Specifically, I show the following: i) metabolic rate is repeatable (intra-class correlation coefficient) within individuals, and may be influenced by several factors such as age, gender, body mass and pregnancy; ii) while metabolic rate is repeatable within individuals, it remains unaltered with acclimation to laboratory conditions from field collection; iii) within a population, metabolic rate-temperature relationships are surprisingly invariant among physiological states such as age, gender, feeding status, pregnancy and temperature acclimation; iv) the magnitude of the effect of temperature acclimation differs among traits, in that upper thermal tolerances respond less than lower thermal tolerances, while metabolic rate responds to heat but not to cold. Water loss rate is relatively unresponsive to either treatment; v) plasticity can account for most inter-population variation in physiological traits related to climatic stress resistance (e.g. thermotolerances and desiccation rates) in the natural environment; vi) adult physiological performance responds differently to developmental and adult acclimation, such that marked traitspecific variation occurs, and combinations of both developmental and adult plasticity can result in further alteration of adult performance. These results have implications for the evolution of stress resistance to abiotic factors in these and other arthropods. I conclude by discussing the potential physiological patterns linking population dynamics and abiotic factors, with particular reference to tsetse flies. / AFRIKAANSE OPSOMMING: Binne arthropoda, is tussen-individu en tussen-bevolking variasie in die algemeen sleg bestudeer vir fisiologiese parameters. Hierdie fisiologiese variasie is belangrik want dit kan insig gee in die mate van evolusionêre aanpassing en hoe diere antropogenies klimaatsverandering kan hanteer. Dit is veral belangrik in die geval van insekte wat mens- en diersiektes kan dra, soos tsetse vlieë (Diptera, Glossinidae) wat trypanosome oordra. In die geval van tsetse vlieë (Glossina spp.) is voorspellings vir verhoogde verspreiding, en gevolglik verhoogde siekte voorkoms, gemaak onder toekomstige voorkoms klimaat senario’s. Verder, aangesien daar in die algemeen sterk verwantskappe tussen abiotiese parameters (bv. temperatuur en water beskikbaarheid), bevolkingsdynamika, verspreiding en voorkoms is, is die bepaling van die fisiologiese meganisme, wat ‘n invloed het op hierdie verwantskappe, nuttig vir die voorspelling van tsetse oor spasie en tyd. Hier, met hoofsaaklik die gebruik van Glossina spp., maar ook ander arthropoda wanneer dit nodig is, word navorsing wat fisiologiese variasie tussen individue en bevolkings aanspreel voorgelê. Spesifiek, word dit gewys dat i) metaboliese tempo is herhaalbaar (intra-klas korrelasie koeffisient) binne individue, alhowel metaboliese tempo kan beinvloed word deur faktore soos ouderdom, geslag, liggaamsmassa en swangerskap, ii) terwyl metaboliese tempo binne individue herhaalbaar is, verander dit nie met akklimasie na laboratorium toestande vanaf versameling in die veld, iii) binne ‘n bevolking metaboliese tempo-temperatuur verwantskappe is verbasend eenders tussen fisiologiese toestande soos ouderdom, geslag, voeding staat, swangerskap en temperatuur akklimasie, iv) die grootte van die effek van temperatuur akklimasie verskil tussen eienskappe, en die boonste termiese limiete reageer minder as laer termiese limiete, terwyl metaboliese tempo reageer op hitte maar nie koue nie, en waterverlies tempo is relatief terughoudend tot enige temperatuur toestand, v) buigbaarheid kan die meeste van inter-bevolkingsvariasie in fisiologiese eienskappe van klimaatstres weerstandsvermoë (termiese toleransie en uitdrogingstempo) in die natuurlike omgewing verklaar, vi) volwasse fisiologiese prestasie reageer verskillend op ontwikkelende en volwasse akklimasie, soveel dat eienskap-spesifieke variasie kan voorkom, en ‘n kombinasie van beide ontwikkelende en volwasse buigbaarheid ‘n verskillende volwasse prestasie tot gevolg kan hê. Hierdie resultate het implikasies vir die evolusie van weerstandsvermoë tot abiotiese faktore in hierdie en ander arthropoda. Hierdie tesis word afgesluit met ‘n bespreeking van die moontlikke fisiologiese patrone wat bevolkingsdinamika en abiotiese faktore kan verbind, met ‘n fokus op tsetse vlieë.

A thesis submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg for the Degree of Doctor of Philosophy. / This thesis reports on the investigation of two genetic aspects of Southern African populations of Drosophila Melanogaster: the " family of transposable elements and the allelic variation present in several enzyme systems. (Abbreviation abstract) / Andrew Chakane 2018

No description available.

No presente trabalho procura-se caracterizar biológica e ecologicamente o Aedes albopictus (Skuse) (Diptera: Culicidae) no seu mais recente ambiente geográfico, isto é, nas Américas. São descritos aspectos relacionados com a chegada e dispersão da espécie no Continente Americano. Paralelamente, são discutidos aspectos relativos ao comportamento, biologia, bionomia, ecologia, hematofagia, interação com outras espécies do gênero Aedes, bem como a importância epidemiológica do Ae. albopictus. Esses aspectos foram descritos, por serem considerados importantes pela influência que exercem na competência vetora da espécie, bem como na sua adaptação ao ambiente antrópico. Ressaltando a importância epidemiológica deste vetor para a espécie humana, citam-se dados referentes à potencialidade do Ae. albopictus participar na transmissão de arboviroses. Assim, procura-se caracterizar a importância da possível participação do Ae. albopictus na veiculação do vírus dengue, febre amarela, bem como outros arbovírus que afetam o ser humano nas Américas. Paralelamente, discute-se a possibilidade do Ae. albopictus atuar como vetor da Dirofilaria immitis (Leidy) ao homem. / In the present work, biological and ecological features of Aedes albopictus (Skuse) (Diptera: Culicidae) are discussed based on literature records. The main focus of this study is the epidemiological importance of the presence of this species in Americas. Aspects relative to colonization and dispersion of Ae. albopictus in Americas are discussed. Dispersion, ethology, biology, ecology, haematophagy, bionomics as well as epidemiological importance, and relationships among Ae. albopictus and other members of the genus Aedes are discussed. These aspects are included because of their influence in the vector competence of Ae. albopictus, and also in its adaptation to the human environment. Because of the epidemiological importance of Ae. albopictus to humans, data relative to the potentiality of this species to participate in the transmission of arboviruses are discussed. In this sense, the importance of Ae. albopictus as vector of dengue, yellow fever, and other arboviruses that cause human diseases is described. Besides, it is discussed the potentiality of Ae. albopictus to act as a vector of Dirofilaria immitis (Leidy) to humans.

Doctor of Philosophy / Department of Entomology / C. Michael Smith / The wheat curl mite, Aceria tosichella (Keifer), is an important global pest of bread wheat, Triticum aestivum L. Chronic and often severe reductions of winter wheat yield due to A. tosichella infestations have occurred in North America and all other wheat-production areas for over five decades. Moreover, A. tosichella is the only vector which transmits the three most important wheat viruses in the Great Plains, which are Wheat Streak Mosaic Virus (WSMV), the most economically important wheat virus in North America; Triticum Mosaic Virus (TriMV) and High Plains Wheat Mosaic Virus (HPWMoV). Mite infestation alone causes stunted, chlorotic plants in susceptible wheat varieties. To date, mite resistant wheat cultivars have been the only sufficient method to control A. tosichella. The discovery of new genes for A. tosichella resistance and their introgression into wheat cultivars are essential steps to combat the development of new and/or different A. tosichella biotypes which can develop to overcome resistance genes. Both A. tosichella biotype 1 and 2 exist in U. S. Great Plains wheat producing areas. Elucidating and predicting A. tosichella population composition changes based on climatic and geographic variables is a key to continued effective mite management. Experiments were conducted to: 1) assess A. tosichella virulence in mites collected from 25 sample sites in six states to wheat plants harboring the Cmc2, Cmc3 and Cmc4 mite resistance genes and the Wsm2 WSMV resistance gene in 2014 and 2015, and determine the distribution of WSMV, TriMV and HPWMoV present in mites collected; 2) assess A. tosichella biotype composition using internal transcribed spacer 1 (ITS1) and cytochrome oxidase I (COI) polymorphisms; 3) use generalized additive modeling to capture the spatio-temporal factors contributing to the prevalence of A. tosichella biotypes 1 and 2; and 4) screen Kansas advanced breeding lines for resistance to A. tosichella biotypes 1 and 2. Results indicated that A. tosichella collected from 92% of the sample area were virulent to susceptible Jagger wheat plants with no Cmc resistance genes; that mites from 36% of the sample area were virulent to the Cmc2 gene, and that mites collected from 24% of sample area were virulent to Cmc3. Mite populations from only 8% of the sample sites exhibited virulence to plants containing Cmc4 + Wsm2 or Cmc4. The WSMV virus was predominant and present in 76% of all mites sampled. HPWMoV and TriMV were less apparent and present in 16% and 8% of all mites sampled, respectively. These results will enable breeders to increase the efficiency of wheat production by releasing wheat varieties containing A. tosichella resistance genes that contribute to reducing virus transmission. Results of spatio-temporal factor modeling provide new, more accurate information about the use of ground-cover and precipitation as key predictors of biotype prevalence and ratio. Experiments to determine if Kansas State University advanced breeding lines contain A. tosichella resistance found no resistance to biotype 1, resistance to biotype 2 in breeding lines AYN3-37 and AYN3-34; and moderate resistance to biotype 2 in breeding lines AYN2-28 and AYN2-36. The demonstrated correlation between reduced A. tosichella population size and avirulence; characterization and prediction of the A. tosichella biotype composition; and the identification of new sources of A. tosichella resistance in wheat can help entomologists and wheat breeders increase wheat production efficiency by releasing additional wheat cultivars containing A. tosichella resistance genes.

Cultivated tomato plants are extremely susceptible to the two-spotted spider mite Tetranychus urticae Koch. Selection for pest resistance is usually a crucial step required to achieve successful genetic resistance transfer from wild into cultivated tomato genotypes. S. habrochaites LA2329, a wild relative of tomato, is highly resistant to arthropods. Its resistance has been attributed to the presence of a high density of type IV and type VI trichomes and abundant production of 7-epi-zingiberene, a sesquiterpene hydrocarbon. The interspecific backcross hybrids used in this research were derived from the cross between the wild relative tomato, S. habrochaites LA2329, and the cultivated tomato, S. lycopersicum ‘Zaofen 2’ (ZH2). This population has been directly selected for type IV trichome density and zingiberene. The arthropod resistance status of the backcross hybrids was unknown when this research was initiated. Thus, the main objective of the research was to verify the transfer of arthropod resistance from S. habrochaites to cultivated tomato. The effects of glandular trichome densities and leaf zingiberene contents on spider mite behavior and biology were also explored. Also, the chemical composition of the trichome secretions in the wild tomato donor is segregating for presence and abundance of sesquiterpenoids related to zingiberene. The bioactivity of these sesquiterpenoids was explored in this research. To evaluate the relative bioactivities of zingiberene alcohol and 7-epizingiberene, extracted from glandular trichomes of Solanum habrochaites accession LA2329, as well as alpha-zingiberene obtained from ginger oil, these were purified by silica gel chromatography and bioassayed with two-spotted spider mites, Tetranychus urticae Koch (Acari: Tetranychidae) using a bean leaf disc bioassay. Zingiberene alcohol was most efficacious and alpha-zingiberene, was least efficacious, while the efficacy of 7-epizingiberene was intermediate. Thus, tomato breeders should consider introgression of the genes responsible for the oxidation of 7-epizingiberene into zingiberene alcohol to potentially improve the spider mite resistance of cultivated tomato. Also, it is possible that this compound may be exploited as eco-biopesticide approach for integrated pest management against a broad spectrum of herbivorous pests. To verify transfer of arthropod resistance, a bioassay utilizing whole leaves was employed. Nine hybrids (BC3F3 and BC3F4) were chosen for this bioassay, based on variation of type IV trichome density and zingiberene concentration among the hybrids. The experiment also included three susceptible and three resistant control plants. Mite responses on some of the hybrids were similar to those on the resistant wild donor parent, S. habrochaites, as indicated by number of leaflet surfaces infested by mites, degree of mite webbing and feeding damage. Egg density on four backcross hybrids was similar to that on the S. habrochaites resistant controls. Based these results, we concluded that resistance had been successfully transferred from the wild accessions to the hybrids by deployment of backcrossing and indirect selection. There was a significant negative correlation of almost all mite behavioral and biological responses with Type IV trichome density and zingiberene content. This bioassay illuminated behavioral variations of mites associated with presence or absence of leaf compounds and glandular trichome densities. Also, the results support the idea that introgression of type IV trichomes and zingiberene has led to effective spider mite resistance. In another bioassay-based experiment to verify transfer of resistance, seven interspecific backcross hybrids (BC3F2), the resistant parent LA2329, and two susceptible cultivated tomato lines, the recurrent parent ZH2 and ‘Small Roma’, were used in thumbtack bioassays. Mite movement was measured by imaging bioassayed leaves at 15, 20, 30, 45, and 60 min intervals. In addition to confirming transfer of spider mite resistance, other objectives included determination of the relative contributions of type IV and VI trichome densities and leaf compounds to mite behavior over time intervals. Our findings confirmed the transfer of mite repellency from the wild resistant parent to advanced backcross hybrids. Several backcross hybrids performed similarly to the wild donor parent, displaying shorter distances traveled on the leaves after 15 and 30 min. The type IV and type VI trichome densities as well as zingiberene contents had a significant positive correlation with the number of spider mites remaining on tack. There was a significant negative correlation of type IV density and zingiberene concentration with the total distance travelled by mites for both the abaxial and adaxial surfaces across most time intervals. Stepwise multiple regression analysis showed that the type IV trichome density was the most critical factor, and zingiberene content was a secondary factor across over most time intervals. T. urticae remained longer on the thumbtack heads and traveled shorter distances on the leaf surface of the wild donor parent LA2329 and the interspecific hybrids compared to S. lycopersicum leaves. These results indicated that introgression of genetic resistance, especially repellence, against spider mite from the wild relative into cultivated tomato varieties has been successfully achieved. In conclusion, trichome type IV and/or zingiberene content has been successfully transferred from the wild relative into interspecific tomato hybrids, and the hybrids show significant adverse impact on spider mite behavior and/or biology in whole leaf and thumbtack bioassays. Type IV trichome density is the most crucial factor in mite deterrence while zingiberene seemed to be a second key factor across most of time durations for both surfaces. Collectively, several backcross hybrids had similar leaf characteristics to the S. habrochaites LA2329, also may be a potential source of resistance to other insect pests.

This study identified new compounds with pest control activities. The two sources of candidates that were followed here were the main heartwood extract of Alaska Yellow Cedar (AYC) constituents and several semi-synthetic counterparts. Five compounds were isolated and identified for the first time in AYC heartwood in this research: two monoterpenes, two sesquiterpenes, and one lignan. The two monoterpenes were (1S)-2-oxo-3-p-menthenol (41) and (4R)-4-hydroxy-4-isopropyl-cyclohex-1-enecarboxylic acid (63). The two sesquiterpenes were (5S,7R,10R,11R)-eudesm-4(14)-ene-11,12-diol (46) and (4R,5S,7R)-1(10)- eremohpilen-11,12-diol (59). The lignan was (1R,2S,5R,6S)-2,6-bis-(3,5- dimethoxy-4-hydroxyphenyl)-3,7-dioxabicyclo-[3.3.0]octane,(67). Structures for these compounds were confirmed on the basis of spectroscopic techniques such as 1- and 2-D NMR, high resolution MS and IR. The pest control activity studies of 15 compounds isolated or semi-synthesized from AYC heartwood were conducted at the Centers for Disease Control and Prevention (CDC). Two types of studies were conducted--short-term (24h) and residual (over 1-4 weeks) activity for application against three types of pests related to human health - nymphal I. scapularis ticks, adult X cheopis fleas and adult Ae. eagypti mosquitoes. The 24 h studies revealed that nootkatone, valencene-13-aldehyde and valencene-13-ol were the most active among the studied compounds against the three pests. They exhibited highly improved pest control activities compared to valencene. This suggests that oxidation on both positions C-2 and C-13 of the eremophilane ring structure has an important effect on the activity. For compounds where the conformation of the eremophilane bicyclic ring has been altered, the activity seemed to diminish greatly. The above mentioned three compounds can be good candidates as pest control lead compounds. The residual studies revealed that the most active compounds exhibited activity profiles that generally decreased with time. Although the long-term safety of these compounds has yet to be evaluated, the natural origin and the long history of use of these compounds suggest that they can be promising candidates. This study revealed that the three most promising compounds in the 24 h study exhibited reasonably promising behavior, which makes them even stronger as pest control candidates. / Graduation date: 2004