Lutzomyia longipalpis (Lutz & Neiva) is the vector of Leishmania infantum (Nicolle), the aetiological agent of visceral leishmaniasis in the New World. It has been shown by several authors that Lu. longipalpis represents a complex of at least three species. Adults of this species are known to mediate mating and oviposition using pheromones. This study aimed to investigate an aspect of their behaviour that had previously been neglected, namely the responses of female Lu. longipalpis to human kairomones. It was found that females could be lured by volatiles extracted from skin secretions. Pentane and ether extracts were equally effective in attracting female Lu. longipalpis. Whole pentane extracts were further fractionated by column chromatography into a polar fraction (ether-soluble) and a non-polar fraction (pentane-soluble). Testing both fractions for sandfly activity showed that only the pentane-soluble fraction was attractive to Lu. longipalpis. Host odours not only appeared to explain the variation in attraction of human volunteers, but were also found to be potentially responsible for sandfly biting distributions on a host. Female sandflies exhibited a marked biting preference for the ears of a human volunteer. Cross-mating experiments with putative members of the Lu. longipalpis complex, Jacobina (3-methyl-a-himachelene) and Marajo (Cembrene-producing pheromone type), provided direct evidence of prezygotic isolation between the two studied populations (i. e. by examining insemination rates and pheromone production in FI males). This result explains why two coexisting pheromone types are never detected in single male sandfiies collected in the wild. The cross-mating experiments additionally found partial post-zygotic barriers, with significantly reduced eggs production and egg hatching rates in F1 progeny. A series of independent bioassays provided evidence for innate differences in anthropophily between at least two allopatric populations of Lu. longipalpis. The main behavioural differences detected were in (1) the mean time to bite on a human host during a biting selection trial, (2) the behavioural response to ear washing extracts (landings on impregnated filter papers), and (3) the SAQ (Sandfly Activity Quotient) response (landings) to volatlles deposited onto handled glass Petri dishes (for the two most contrasting sandfly populations: Jacobina and Marajo). Finally, preliminary wind-tunnel studies undertaken with golden hamsters infected with Leishmania infantum suggested a change in the overall body odour composition of the host, making it more attractive to female Lu. longipalpis. Gas chromatography analysis of entrained volatile odours from infected and non-infected hamsters showed a large number of peaks in chromatograms from both animals. A total of 10 extra compounds, eluted from 10 to 16 minutes of retention time, were present in samples from infected hamsters, but were absent in those obtained from non-infected hamsters.

Lygus hesperus is an important pest on different crops including cotton and alfalfa in the western U.S. Anaphes iole is a common parasitoid of Lygus spp. eggs in the U.S. and has potential as a biological control agent against L. hesperus in different crops. Its foraging behavior has been studied to a limited extent, but it is unknown whether A. iole females rely on plant volatiles to locate host habitats. L. hesperus feeding and oviposition are known to induce emission of plant volatiles in cotton and maize, but no studies have addressed the role of plant volatiles in the host searching behavior of A. iole. The objectives of this study were to evaluate the attraction of A. iole females toward volatiles derived from L. hesperus habitats and flight response of A. iole females toward cotton plants harboring L. hesperus eggs or treated with methyl jasmonate. Results from olfactometry bioassays showed that female wasps were attracted to odors emanating from different plant-L. hesperus complexes and from adult L. hesperus, while plants damaged by non-hosts or mechanically-damaged were not attractive. These findings suggested that A. iole females use specific plant volatiles released following L. hesperus feeding and oviposition to locate host habitats. In addition, in flight chamber tests A. iole females discriminated between cotton plants with moderate (41 eggs) and high (98 eggs) levels of L. hesperus infestations relative to uninfested plants, but not between plants with low (7 eggs) infestations compared to uninfested plants. In larger scale experiments conducted in the greenhouse, female wasps responded to L. hesperus-infested plants but not to methyl jasmonate-treated plants under similar conditions. Overall, results from this study revealed that A. iole females employ volatile signals to locate its host’s habitat and that they are attracted to plants damaged by L. hesperus feeding and oviposition. However, further research should seek to identify the chemical elicitors involved in the release of plant volatiles attractive to A. iole females.

Lygus hesperus is an important pest on different crops including cotton and alfalfa in the western U.S. Anaphes iole is a common parasitoid of Lygus spp. eggs in the U.S. and has potential as a biological control agent against L. hesperus in different crops. Its foraging behavior has been studied to a limited extent, but it is unknown whether A. iole females rely on plant volatiles to locate host habitats. L. hesperus feeding and oviposition are known to induce emission of plant volatiles in cotton and maize, but no studies have addressed the role of plant volatiles in the host searching behavior of A. iole. The objectives of this study were to evaluate the attraction of A. iole females toward volatiles derived from L. hesperus habitats and flight response of A. iole females toward cotton plants harboring L. hesperus eggs or treated with methyl jasmonate. Results from olfactometry bioassays showed that female wasps were attracted to odors emanating from different plant-L. hesperus complexes and from adult L. hesperus, while plants damaged by non-hosts or mechanically-damaged were not attractive. These findings suggested that A. iole females use specific plant volatiles released following L. hesperus feeding and oviposition to locate host habitats. In addition, in flight chamber tests A. iole females discriminated between cotton plants with moderate (41 eggs) and high (98 eggs) levels of L. hesperus infestations relative to uninfested plants, but not between plants with low (7 eggs) infestations compared to uninfested plants. In larger scale experiments conducted in the greenhouse, female wasps responded to L. hesperus-infested plants but not to methyl jasmonate-treated plants under similar conditions. Overall, results from this study revealed that A. iole females employ volatile signals to locate its host’s habitat and that they are attracted to plants damaged by L. hesperus feeding and oviposition. However, further research should seek to identify the chemical elicitors involved in the release of plant volatiles attractive to A. iole females.

Ruminants have a unique ability to acquire protein from non-protein nitrogen (NPN) sources, and to recycle nitrogen back into the rumen, instead of excreting all of it via the urine, faeces and milk. However, a high concentration of blood urea nitrogen (BUN) has a negative influence on conception. Additionally, a high dietary nitrogen intake poses a challenge to the environment in the form of ammonia emissions, eutrophication and bad odours. This calls for strategies to reduce the environmental impact of livestock production. Variation exists in the ability of cattle to recirculate nitrogen between as well as within cattle breeds. The purpose of this study was to investigate the effects of BUN concentration on reproductive performance in beef heifers under different management systems in South Africa. Serum samples from 369 Bonsmara heifers were taken in November and December 2010 to determine the BUN concentrations prior to the onset of the breeding season. Heifers were from five herds with different levels of protein supplementation during the weeks before the commencement of the breeding season. Body mass, age, body condition score (BCS) and reproductive tract score (RTS) were recorded at the same time as BUN concentration. Trans-rectal ultrasound and/or-palpation was performed four to eight weeks after the three-month breeding season to detect and estimate the stage of pregnancy. Days to pregnancy (DTP) was defined as the number of days from the start of the breeding season until a heifer was successfully mated. Logistic regression and Cox proportional hazards survival analysis were performed to estimate the effect of BUN concentration on subsequent pregnancy and DTP respectively, while stratifying by herd and adjusting for potential confounders. The correlations between BUN concentration, BCS and RTS were estimated using Spearman’s rho. Pearson correlations were used for the normally distributed variables of age and body mass. BUN concentration was not a significant predictor of pregnancy status but was a significant (P = 0.007) and independent predictor of DTP in heavily and some moderately supplemented herds. As BUN concentration increased, DTP also increased [hazard ratio (HR) = 0.827; 95% CI: 0.721 – 0.949; P = 0.007], while the chance of becoming pregnant decreased, although this was not statistically significant [odds ratio (OR) = 0.882; 95% CI: 0.772 – 1.007; P = 0.063]. Bonsmara heifers with higher BUN concentration, which suggests a better ability to recirculate nitrogen, might be at a disadvantage when the production system includes high levels of RDP supplementation because of this negative impact on reproductive performance. It is proposed that production systems be adapted to avoid selection against animals with an improved ability to recirculate nitrogen. / Dissertation (MMedVet)--University of Pretoria, 2013. / gm2014 / Production Animal Studies / Unrestricted

The eThekwini Municipality is facing two major challenges in controlling odorous emissions by various industries in the South Durban Basin; firstly, getting industry to manage their onsite odorous emissions and, secondly regulating these odorous emissions. This study focused on the Jacobs’s Industrial Complex (JIC) which comprises various industries releasing air emissions which impact on the local air quality. The impact of these emissions is supported by the number of odour complaints reported to the eThekwini Environmental Health Department by the public. Cleaner production (CP) is an integrated approach aimed at continuously reducing environmental impacts of processes, products and services through applying preventive approaches rather than controlling and managing pollution once it has been created. This dissertation has assessed the application of CP as a concept to prevent and reduce emissions of odours by industries in the JIC that are an impacting on the environment and neighbouring communities. Three CP case studies are analysed to demonstrate the applicability of the approach. These are a CP project for drum reprocessing company based in the South Durban Basin and two waste minimisation clubs which operated from 1998 to 2000 in Durban. The key findings, outcomes, experiences and lessons learnt from these case studies underpin the recommendation of an approach that can be applied by eThekwini Municipality to incorporate CP in the scheduled trade (ST) permitting of odour producing industries. This research has applied a multi-case study design implying both qualitative and quantitative approaches. A qualitative approach was used in the detailed analyses of case studies whilst the quantitative one was applied in the graphical analyses of the odour complaints statistics for the JIC. The study concludes by drawing two major recommendations from the lessons leant. Recommendation 1: The general CP strategy that can be applied by eThekwini Municipality in regulating, promoting, enforcing, monitoring and evaluating application of CP practices among stakeholders. The recommended objectives for the general strategy include: · Enforcement of uniform regulatory standards. · Development of a policy or guidelines. · Effective compliance monitoring and enforcement. · Develop a local Cleaner Production Centre (LCPC). · Ensure co-operative governance. · Provide adequate financial resources. · Monitoring and evaluation. Recommendation 2: Strategy for incorporating CP in the ST permitting of odour producing industries. It is recommended that the ST permit holder for an odour producing industry comply with the following: · Prioritisation of odour like the other priority pollutants. · Industry to perform an audit to map odour emitting areas. · Permit holder to development a CP based odour management plan. · Investigate possible CP projects that can be undertaken to prevent and mitigate odour emissions. · Incorporate an odour management plan into a 5 year environmental improvement plan. · Develop and appropriately manage an odour complaints management system. · Set odour management performance indicators and baselines for targets and reporting. · The permit holder should include odour management performance including odour complaints management in the annual report. / Thesis (M.Sc.Eng.)-University of KwaZulu-Natal, Durban, 2011.

<p><!--[if gte mso 10]> <mce:style><! /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Tableau Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin-top:0cm; mso-para-margin-right:0cm; mso-para-margin-bottom:10.0pt; mso-para-margin-left:0cm; text-align:justify; 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:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin;} > <! [endif] ></p><p>The way of consumption has changed. Now, consumers are not only rational when purchasing. They do not buy just for the functionality of the good or service they are looking for. The consumption is more affective and consumers are considered now as poly-sensorial entities that are looking for more emotional and sensorial stimulation during their purchase process. This evolution of consumption is part of the trend that is called "retailtainnment", a mixed of "Retail" and "Entertainment". It is a concept of distribution that combines both of those two activities. Earlier studies have shown the success of using the Sensory Marketing, a concept based on stimulating the five senses in a strategy view. But, if certain senses are heavily used by companies/brands, as the sight and hearing, some are still underused, as the touch, the taste and particularly the smell. Wherefore a study on scent marketing is considered relevant to measure the potential of it. Even if several studies have already explained the important role of smell in a company's strategy, only few of them are using it. Our paper aims to go further on this subject by understanding the scent marketing in stores through the aims, the obstacles, the techniques used, in Umeå, Sweden.</p><p> </p><p>For our research, we first had to collect knowledge from scientific articles and previous studies on odours, on smells or perfumes and on scent marketing. Then, we constructed three hypothesises that helped us to conduct our research and made conclusions. Those hypotheses will be discussed by conducting a mixed-method, that is to say by combining two types of researches: a quantitative one, mainly to measure how many stores are using smell as a marketing tool, and then a qualitative one to go deeper into the reasons and how those stores are applying it. The quantitative research, based on a deductive approach, was conducted by using questionnaires. The qualitative research, based on an inductive approach was conducted by making semi-constructed interview. Both types of data collected and analyzed enable us to draw conclusions about scent marketing in Umeå. In this paper we identify the stores in Umeå that have odours or perfumes, those that are using smell as a marketing tool and their reasons to use it or not.</p><p><--></p>

The way of consumption has changed. Now, consumers are not only rational when purchasing. They do not buy just for the functionality of the good or service they are looking for. The consumption is more affective and consumers are considered now as poly-sensorial entities that are looking for more emotional and sensorial stimulation during their purchase process. This evolution of consumption is part of the trend that is called “retailtainnment”, a mixed of “Retail” and “Entertainment”. It is a concept of distribution that combines both of those two activities. Earlier studies have shown the success of using the Sensory Marketing, a concept based on stimulating the five senses in a strategy view. But, if certain senses are heavily used by companies/brands, as the sight and hearing, some are still underused, as the touch, the taste and particularly the smell. Wherefore a study on scent marketing is considered relevant to measure the potential of it. Even if several studies have already explained the important role of smell in a company’s strategy, only few of them are using it. Our paper aims to go further on this subject by understanding the scent marketing in stores through the aims, the obstacles, the techniques used, in Umeå, Sweden. For our research, we first had to collect knowledge from scientific articles and previous studies on odours, on smells or perfumes and on scent marketing. Then, we constructed three hypothesises that helped us to conduct our research and made conclusions. Those hypotheses will be discussed by conducting a mixed-method, that is to say by combining two types of researches: a quantitative one, mainly to measure how many stores are using smell as a marketing tool, and then a qualitative one to go deeper into the reasons and how those stores are applying it. The quantitative research, based on a deductive approach, was conducted by using questionnaires. The qualitative research, based on an inductive approach was conducted by making semi-constructed interview. Both types of data collected and analyzed enable us to draw conclusions about scent marketing in Umeå. In this paper we identify the stores in Umeå that have odours or perfumes, those that are using smell as a marketing tool and their reasons to use it or not.

Cette thèse a pour objectif l’exploration de la dimension sociale des odeurs. Les travaux déjà menés en sciences humaines et sociales montrent que le rapport que les individus et les groupes entretiennent avec les odeurs leur permet de se situer et d’être situés dans un contexte donné. L’intérêt porté à l’ancrage de cet objet sensoriel dans la vie affective des groupes ainsi qu’à sa matérialisation notamment au travers des processus de communication nous conduit à traiter la diversité des connaissances qui en résulte à l’aune de l’approche des représentations sociales. Nous interrogeons les dynamiques inhérentes aux représentations sociales que les groupes ont des odeurs tout autant que les effets que ces dernières ont sur les pratiques et sur les relations sociales. Les liens réciproques existant entre le « senti » d’une part, le « nommé », le « classé » et le « représenté » d’autre part sont ainsi mis à l’étude. Notre plan de recherche se centre sur la conduite de treize focus groups (N=63). Dans ce cadre, nous avons répliqué la technique de la reproduction sérielle (Bartlett, 1932) avec des matériaux odorants. Les groupes ont également collectivement partagé plusieurs expériences olfactives. Enfin, ils ont débattu de leurs rapports aux « odeurs en société ». Les résultats montrent que les groupes reconnaissent et reconstruisent l’odeur par le biais d’une centration collective sur ses sources potentielles. Celles-ci activent à leur tour des attributions, des contextes, et des souvenirs prenant la forme d’un réseau de représentations jugé pertinent par les groupes pour matérialiser l’objet sensoriel. Aussi, une logique de l’ambiguïté caractérise les relations des groupes aux « odeurs sociales ». Ils entretiennent une pluralité de proximités et d’implications à leur encontre, dépendamment des points de perspectives à partir desquels ils se situent. Notre recherche souligne également la négociation collective dont font l’objet les phénomènes représentatifs associés aux odeurs. Elle rend compte des différents visages de ces phénomènes en lien avec les significations qu’ils ont pour les groupes. En s’inscrivant dans la continuité des études menées sur la pensée sociale, cette thèse apporte de nouvelles réflexions s’agissant de l’étude conjointe du social et du sensible. / The present thesis aims to explore the social dimension of odours. Past literature in the field of social and human sciences demonstrated that the relation individuals and groups engage in with odours allow them to self-situate and be situated in a specific context. This work focuses on the diversity of knowledge resulting from the anchoring of this sensorial object in the affective life of groups, as well as from its materialization through the communication processes, with a social representation approach. We investigate the dynamics of groups’ social representations concerning odours, as well as the effects that these have on social practices and relations. The reciprocal connections between the « perceived » on one hand, and the « named », « classed » and « represented » on the other hand are thus central to this study. Thirteen focus groups (N=63) have been carried out for this research, using the technique of serial reproduction (Bartlett, 1932) with odorous stimuli. The groups also shared several olfactory experiences. In the end, participants discussed about their relation to the « odours in society ». Results show that the groups recognized and reconstructed an odour by collectively focusing on its potential sources. These sources activated attributions, contexts and memories structured in a network of representations considered pertinent by the groups to materialise the sensorial object. Moreover, the relations of participants with « social odours » are characterised by an ambiguity. This aspect is indeed defined by a plurality of proximities and implications that the groups have when relating to « social odours », depending on the perspective they adopt when encountering them. The present research highlights the collective negotiation of the representational phenomena associated to odours, and explains the plurality of facets of these phenomena depending on the meaning they have for the groups. In continuity with past studies on social thinking, this manuscript offers new insights concerning the joint study of the social and the sensorial and sensitive.

La pérennité du compostage est cautionnée à une meilleure maîtrise de la qualité des composts ainsi que des émissions gazeuses. Ces deux critères dépendent en partie des conditions de compostage. Néanmoins, le contrôle des émissions gazeuses et des odeurs ne peut se circonscrire à une seule stratégie préventive. L'identification des composés responsables de l'odeur apparaît comme un enjeu permettant d'augmenter l'efficacité des solutions curatives. Cette thèse a eu pour double objectif d'évaluer l'influence des déterminants des procédés de compostage par aération forcée sur la qualité des composts, les émissions gazeuses et les odeurs en compostage et stockage ainsi que d'investiguer les corrélations entre composition chimique (CC) et concentration d'odeur (CO)des gaz émis. Le déchet et le structurant utilisés ont été des boues d'abattoir de porcs et des plaquettes de bois. L'influence des conditions opératoires a été évaluée en réacteur de compostage au regard des critères que sont la stabilisation, l'hygiènisation, le séchage et la conservation de l'azote. Un taux d'aération intermédiaire, un ratio structurant/déchet (S/D) >1 et une granulométrie >10mm semblent être les conditions répondant au mieux aux attentes d'un traitement par compostage. L'étude de l'influence des conditions sur les composés gazeux suspectés les plus contributrices des odeurs a conduit à une caractérisation exhaustive des émissions d'ammoniac, d'hydrogène sulfuré, des mercaptans par piégeage chimique et des COV par TD-GC-MS. L'identification des composés potentiellement contributeurs de l'odeur s'est basée sur le calcul d'unité d'odeur (UO) de chacun des composés i.e. le rapport de leur concentration chimique sur leur seuil olfactif, à leur pic d'émission. Les conditions opératoires générant le moins d'émissions sont un faible taux d'aération, un ratio S/D >1 et une granulométrie >10mm. Le potentiel des conditions opératoire à diminuer les émissions de composés odorants est toutefois limité. Les travaux venant d'être décrits ont été complétés d'une part par des mesures olfactométriques des émissions et leur corrélation à leur CC et d'autre part par la mise en œuvre de simulations de stockage en vue de comparer leurs émissions et odeurs à celles du compostage. Ces caractérisations ont montré que les pics d'odeurs en compostage sont 50 fois supérieurs à ceux du stockage. Deux types de corrélations entre la CC et la CO des gaz issus du compostage et du stockage ont été investiguées. Le premier type présume que la CO correspond à la somme des UO des composés du mélange. Le second suppose que la CO du mélange corresponde à l'UO la plus élevée (UOMAX) parmi l'ensemble des composés du mélange. Une analyse qualitative et quantitative des types de corrélations testés a indiqué qu'UOMAX est plus proche de la CO mesurée. Seuls trois composés, l'hydrogène sulfuré, le méthanethiol et la triméthylamine rendent compte des odeurs mesurées. / Compost sustainability requires a better control of its compost quality and its gaseous emissions. Both were influenced by composting conditions. Nevertheless, controlling gaseous emissions and their odour can’t be assumed by a single preventive approach. The identification of the compounds involved in odour is also a way to improve the efficiency of curatives solutions. This thesis has been the dual objectives to assess the influence of the principal process conditions for the forced aeration composting on compost quality, gaseous emissions and odours during composting and storage, as well as find out a correlation between the chemical composition (CC) and the odour concentration (OC) of the emissions. The waste and the bulking agent used were pig slaughterhouse sludge and wood chips. The influence of the composting process conditions was studied on stabilization, disinfection, drying and nitrogen conservation during composting in pilot reactors. An intermediate rate, a bulking agent/ waste (BA/W) ratio >1 and a particle size >10mm seemed to be the optimal conditions which satisfy composting treatment expectations. The study of the composting process influence on the gaseous compounds supposed as main potential odour contributors led to an gases exhaustive characterizations, including: ammonia, hydrogen sulphide and mercaptans were quantified by chemical traps while TD-GC-MS was used for VOC. Compounds were screened as main odour contributor based on the compute of their odour unit (OU) of each compounds i.e. dividing their chemical concentration by their odour threshold, at their events of peak emission. The composting process conditions which reduced the emissions were, a low aeration rate, a high BA/W ratio and a particle size > 10mm. Composting process conditions had a limited impact on reducing emissions of odorous compounds. Further works were performed for establish a more accurate odour emission evaluation. On a first hand, olfactometric measurements were carried out in order to be correlated with their CC. On a second hand, experiments were designed to simulate storage with a view to compare their emissions and their odours with that in composting. These characterizations showed that the peaks of the odour emissions were found 50 folds higher during composting than during storage. Two types of correlations were investigated between the CC and the OC of gas samples from composting and storage. The first one assumed that, the OC of gas sample was equal to the sum of the OU of every odorous compound. The second one consisted to consider the OC was equal to the highest OU (OUMAX) of the most odorant compound in the sample. Qualitative and quantitative analyses were tested for the both correlation types, indicating that OUMAX is the expression which can provide the most accurate prediction of OC. Only three main odorous compounds were identified: trimethylamine, hydrogen sulphide and methanethiol.

Pollinators are believed to have played a key role in the radiation of flowering plants. The Grant-Stebbins model of pollinator-mediated speciation, in which evolutionary shifts between pollinators result in phenotypic diversification and enforce reproductive isolation, is one of the most compelling hypotheses for the rapid diversification of angiosperms. A key principle in this model is that plant pollination systems tend towards specialization, resulting in convergent suites of floral traits (syndromes) associated with particular types of pollinators. However, the expectation of pollination system specialization is not always supported by ecological data and has also been questioned on theoretical grounds. In this thesis, I examine pollination by Hemipepsis spider-hunting wasps (Hymenoptera, Pompilidae, Pepsinae) and use this system to address questions about levels and proximal mechanisms of floral specialization, floral shifts and convergent evolution of floral traits. Specialized pollination by Hemipepsis wasps is a newly described pollination system within the angiosperms. I document pollination by these wasps for the first time in 15 South African grassland plant species, including two species of Eucomis (Hyacinthaceae) and 13 asclepiads (Apocynaceae: Asclepiadoideae). In one of the asclepiads, Xysmalobium undulatum, I describe a bimodal pollination system involving both Hemipepsis wasps and a cetoniine beetle. I also describe an unusual and potentially antagonistic pollination mechanism whereby wasps are systematically dismembered during the insertion of pollinia in the two asclepiads Pachycarpus asperifolius and P. appendiculatus. I have used these and previous case studies to establish the existence of a new pollination guild, consisting of at least 21 plant species (across 10 genera and three families), that are reliant on four functionally similar species of Hemipepsis wasp for pollination. Plants in the guild are distributed throughout the moist grasslands of eastern South Africa and flower from September through until early May, peaking in December/January. The Hemipepsis-wasp pollination guild is characterized by high levels of functional specialization (17 of the 21 known guild members are pollinated exclusively by Hemipepsis wasps), despite the absence of morphological adaptations to prevent non-pollinating insects from accessing nectar. I used field and laboratory based experiments to explore the function of floral traits in enforcing specialization. These showed that Hemipepsis wasps primarily use scent, rather than visual cues, to locate flowers, but I was unable to firmly identify specific compounds responsible for the attraction of these wasps (compounds that elicited antennal responses in preliminary GC-EAD experiments did not attract wasps in bioassays). The chemical composition of the floral scents of guild members was examined for 71 individuals representing 14 species in addition to previous studies, and found to comprise complex blends of volatiles (usually containing between 30 and 50 compounds), typically dominated by aliphatics and monoterpenes with small amounts of aromatics. I also showed that the floral colours of guild members are similar to background vegetation, suggesting that floral colours are adapted for crypsis to avoid detection by non-pollinating insects. Palatability choice experiments with honeybees showed that non-pollinating insects find the nectars of at least three of the asclepiad guild members distasteful. Plants in this guild thus appear to achieve specialization through biochemical filters (scent as an attractant and differentially palatable nectar) and cryptic coloration. Pollinator-mediated convergence in floral traits is the fundamental basis for pollination syndromes, but has seldom been rigorously analyzed. Flowers in the Hemipepsis-wasp pollination guild share several qualitative traits, including dull greenish- or brownish-white colour, often with purple blotches, exposed sucrose dominant nectar with a relatively high sugar concentration (typically over 50% sugar by weight) and a sweet/spicy fragrance to the human nose. To test for convergent evolution in guild members, I compared scent, nectar and colour traits of guild members to those of congeners with different pollinators. Although traits often differed between guild members and their congeners, I found little evidence for overall convergence in floral scent profiles and nectar properties, but floral colours in the guild were significantly closer to the colour of background vegetation than those of congeners. At this stage, the lack of knowledge about specific floral volatiles that influence Hemipepsis-wasp behaviour and secondary nectar constituents that limit non-pollinator visits makes it difficult to identify the extent of biochemical convergent evolution within the guild. The directions and functional traits involved in evolutionary transitions between pollination by Hemipepsis wasps and other vectors are currently difficult to ascertain as there is limited phylogenetic data for the plant families concerned. In the genus Eucomis, fly and Hemipepsis-wasp pollinated species are very similar in floral morphology and colour, but differ strongly in floral scent. Using manipulative field experiments in conjunction with detailed analyses of colour, scent and morphology, I was able to show that a shift between wasp and fly pollination could be induced simply by manipulating oligosulphides in the scent emission from inflorescences. When considered in combination with other experiments highlighting the importance of scent as a pollinator attractant for all guild members, this suggests that scent properties may have played a key role in the evolutionary transitions between pollination by Hemipepsis wasps and other vectors. This research has established that pollination by Hemipepsis spider-hunting wasps is more geographically and phylogenetically widespread than was previously known, and has confirmed that these wasps are important and consistent pollinators in southern African grassland ecosystems. I have shown that a distinct guild of plants is specialized for pollination by these wasps. The high levels of specialization within this guild highlight the effectiveness of biochemical filters and cryptic coloration in limiting the spectrum of flower visitors. The major challenge ahead will be to identify the floral volatiles that attract Hemipepsis wasps and the non-sugar constituents that make the nectars of some guild members differentially palatable. These would both contribute greatly to our understanding of floral specialization and the mechanisms involved in the radiation of the angiosperms. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.