The varroa mite is a primary driver behind periodical losses of honey bee colonies. The mite requires bees for food and reproduction and, in turn, elicits physiological deficiencies and diseases that compromise bee colony health. The mite nervous system is a target site for existing acaricides. These acaricides not only have adverse health effects on bees, but resistance limits their use to reduce mites and diseases in bee colonies. Voltage-gated chloride channels are involved in the maintenance of nerve and muscle excitability in arthropod pests, which suggests that these channels might be exploited as targets for acaricides. Apistan® (the pyrethroid tau-fluvalinate), Checkmite+® (the organophosphate coumaphos), and Apivar® (the formamidine amitraz) are control products for mite management. The effectiveness of these chemistries has diminished as a result of the increasing incidence resistance in mite populations. I report a toxicological analysis of stilbene products against acaricide-susceptible and -resistant mites. My results find a significant increase in metabolic detoxification enzyme activities in acaricide-resistant mites compared to susceptible mites. Acetylcholinesterase of coumaphos-resistant mites was significantly less sensitive to the toxic coumaphos metabolite compared to susceptible mites, which suggests target-site insensitivity as a mechanism of acaricide resistance. The stilbene product DIDS had significantly higher field efficacy to acaricide-resistant mites compared to Apistan®- and CheckMite+®. These data suggest that DIDS, and other stilbene products, might serve as candidate chemistries to continue field efficacy testing of alternative acaricides for Apistan® and CheckMite+® resistant mites. / Master of Science in Life Sciences

Through pollination, bees are responsible for the persistence of many biological systems on our planet. Bees have also been used for thousands of years in agriculture to improve crop quality and yield. Recently, there have been declines in honeybees worldwide. This decline is concerning because it threatens food supplies and global biodiversity. An alternative to alleviating the effect of a honey bee shortage could be to use native bees. Problems with adoption of native bees in agriculture occur because of a lack of large scale analysis methods for native bees, regional species lists and management knowledge. This research explores the use of GIS in modeling native bee habitat to provide a landscape scale analysis method for native bees and develop a systematic sampling method for regional species list development. Raster GIS modeling, incorporating decision support and Poisson statistical methods were used to develop a native bee habitat model. The results show landscape composition is important to bee abundance and diversity. In addition, habitat fragmentation may not be as detrimental to bees as previously thought. Bees are most sensitive to landscape composition at a scale of 250 m, but require large patches of floral resources. GIS proved to be very useful in modeling bee habitat and provides an opportunity to conduct landscape scale bee population analysis. / Master of Science

Much information is available in the field of Apiculture, some technical and some practical. It would appear, however, that there is justification for an attempt to provide information of a practical nature for use in high school Vocational Agricultural classes. Available publications either are too comprehensive or do not contain sufficient material for students of Vocational Agriculture who wish to study beekeeping. It is the intent of this thesis to consolidate and organize factual information for class use by teachers, to suggest a few student problems and activities, and to develop a course calendar of units for study. A detailed discussion of only one type of honey production is presented; but from this type (bulk-comb honey) any other form of honey production may be developed. / M.S.

Yes / The current study was designed to investigate the influence of monofloral Indian mustard bee pollen (MIMBP) and processed monofloral Indian mustard bee pollen (PMIMBP) supplementation on chronic swimming exercise-induced oxidative stress implications in the gastrocnemius muscle of Wistar rats. MIMBP was processed with an edible lipid-surfactant mixture (Captex 355:Tween 80) to increase the extraction of polyphenols and flavonoid aglycones as analyzed by UV spectroscopy and high performance liquid chromatography-photo diode array. Wistar rats in different groups were fed with MIMBP or PMIMBP supplements at a dose of 100 mg/kg, 200 mg/kg and 300 mg/kg individually, while being subjected to chronic swimming exercise for 4 weeks (5 d/wk). Various biochemical [superoxide dismutase (SOD), glutathione (GSH), malonaldehyde (MDA), nitric oxide (NO), and total protein content], mitochondrial (Complex I, II, III, and IV enzyme activity), and molecular (myostatin mRNA expression) parameters were monitored in the gastrocnemius muscle of each group. Administration of both MIMBP (300 mg/kg) and PMIMBP (100 mg/kg, 200 mg/kg, and 300 mg/kg) wielded an antioxidant effect by significantly improving SOD, GSH, MDA, NO, and total protein levels. Further MIMBP (300 mg/kg) and PMIMBP (200 mg/kg and 300 mg/kg) significantly improved impaired mitochondrial Complex I, II, III, and IV enzyme activity. Significant down-regulation of myostatin mRNA expression by MIMBP (300 mg/kg) and PMIMBP (200 mg/kg and 300 mg/kg) indicates a muscle protectant role in oxidative stress conditions. The study establishes the antioxidant, mitochondrial upregulatory, and myostatin inhibitory effects of both MIMBP and PMIMBP in exercise-induced oxidative stress conditions, suggesting their usefulness in effective management of exercise-induced muscular stress. Further, processing of MIMBP with an edible lipid-surfactant mixture was found to improve the therapeutic efficiency of pollen.

<p>In recent decades, the development of strategies to prevent or slow the loss of biodiversity has become an important task for ecologists. In most terrestrial ecosystems wild-bees play a key role as pollinators of herbs, shrubs and trees. The scope of this thesis was to study 1) pollinator effectiveness of specialist bees vs. generalist flower-visitors, 2) critical floral resources for wild-bees, and 3) methods to estimate the size of wild-bee populations. The wild-bee species <i>Andrena hattorfiana </i>and <i>A. marginata </i>were used as model species. These two species are specialized on pollen from the plant family Dipsacaceae.</p><p>The bee <i>A. hattorfiana </i>was found to be a frequent visitor but a poor pollinator of its preferred food-plant <i>Knautia arvensis</i>. The female bees exert such a strong preference for pollen-producing inflorescences that they likely have deleterious effects on the plant, harvesting valuable pollen that could have been transferred to conspecific stigmas by other flower-visitors. To explore the relationship between wild-bees and their food-plants, the concept of pollen budget was developed. We quantified pollen production in the food-plant population and pollen consumption of wild-bee nests. A survey of the visitation by all flower-visitor taxa indicated that the degree of utilization (the fraction of the total pollen amount that is harvested and utilized by <i>A. hattorfiana</i>) varied from 12% to 80% among <i>K. arvensis</i> populations (N=26). The bee <i>Andrena marginata</i> utilized 44% of the pollen production in a population of <i>Succisa pratensis</i>. The pollen budget suggests that with an average flower-visitor diversity and abundance, 330 individuals of the food-plant <i>K. arvensis </i>are required to sustain a population of 20 <i>A. hattorfiana </i>♀ (the approximate median natural population size). Based on a study of <i>A. hattorfiana</i>, considerable simplifications were proposed for the commonly used mark-recapture design for measuring wild-bee population size. For this species, population size estimated based on mark-recapture data was strongly correlated with the number of observations per survey-walk. The results suggest that large-scale surveys of solitary bee species can be simplified by performing survey-walks.</p><p>The pollen budget and the method proposed for estimating the size of bee populations have the potential to become valuable tools for monitoring and management of wild-bee populations.</p>

In recent decades, the development of strategies to prevent or slow the loss of biodiversity has become an important task for ecologists. In most terrestrial ecosystems wild-bees play a key role as pollinators of herbs, shrubs and trees. The scope of this thesis was to study 1) pollinator effectiveness of specialist bees vs. generalist flower-visitors, 2) critical floral resources for wild-bees, and 3) methods to estimate the size of wild-bee populations. The wild-bee species Andrena hattorfiana and A. marginata were used as model species. These two species are specialized on pollen from the plant family Dipsacaceae. The bee A. hattorfiana was found to be a frequent visitor but a poor pollinator of its preferred food-plant Knautia arvensis. The female bees exert such a strong preference for pollen-producing inflorescences that they likely have deleterious effects on the plant, harvesting valuable pollen that could have been transferred to conspecific stigmas by other flower-visitors. To explore the relationship between wild-bees and their food-plants, the concept of pollen budget was developed. We quantified pollen production in the food-plant population and pollen consumption of wild-bee nests. A survey of the visitation by all flower-visitor taxa indicated that the degree of utilization (the fraction of the total pollen amount that is harvested and utilized by A. hattorfiana) varied from 12% to 80% among K. arvensis populations (N=26). The bee Andrena marginata utilized 44% of the pollen production in a population of Succisa pratensis. The pollen budget suggests that with an average flower-visitor diversity and abundance, 330 individuals of the food-plant K. arvensis are required to sustain a population of 20 A. hattorfiana ♀ (the approximate median natural population size). Based on a study of A. hattorfiana, considerable simplifications were proposed for the commonly used mark-recapture design for measuring wild-bee population size. For this species, population size estimated based on mark-recapture data was strongly correlated with the number of observations per survey-walk. The results suggest that large-scale surveys of solitary bee species can be simplified by performing survey-walks. The pollen budget and the method proposed for estimating the size of bee populations have the potential to become valuable tools for monitoring and management of wild-bee populations.

This study has investigated the interaction between honeybees and their forage plants and the impact of selected climatic variables on honey production in South Africa. Twenty-seven scale-hive records from 25 localities have been used as a measure of colony honey reserves. At least 944 plant species are visited by honeybees in South Africa for their nectar and/or pollen, with more than half providing both rewards. The entire honeybee flora encompasses 532 genera and 137 families. The flowering phenologies of the different reward categories of the indigenous forage plants are all significantly and positively correlated at the 0.05 level. Similarly, species offering both rewards are significantly and positively correlated with the flowering phenology of the null flora. The same results were obtained for correlations between the different reward categories of the exotic forage plants in South Africa. Of the 30 species pairs which fulfilled the criteria for selection, 23 occurred in sympatry, 5 in allopatry and 2 in possible parapatry. There is evidence for both competition and facilitation within different indigenous species pairs. The lack of geographical correlation in the intra-annual variation in honey stores and the near absence of any statistically significant (p < 0.05) honey related intra-annual intracolonial correlations may indicate that the former is more important than the latter for the determination of the level of honey reserves within a colony. Only one statistically significant correlation was found between either scale-hive record from the University of Pretoria Experimental Farm and any of the selected climatic variables. A one month lag period and/or possible seasonal effects were detected for each variable, with the exception of the duration of sunshine, in the autocorrelation analyses. A possible 12 month seasonal period was also identified in the single series fourier analyses for a number of variables. Similarly, 12 months was also the most frequently recurring period in the crossspectral results for the one scale-hive record (H42). Any activities which have an impact on the landscape have the potential to affect honeybees and/or their forage plants. Honeybee crop or plant pollination may also enhance yields for commercial farmers and facilitate rural food security.

Employee share options and Black Economic Empowerment deals are financial instruments found in the South African market. Employee share options (ESOs) are issued as a form of non-cash compensation to the employees of the company in addition to their salaries or bonuses. Its value is linked to the share price and since there is no downside risk for the employee his share option is similar to owning a call option on the stock of his employer. Black economic empowerment (BEE) deals in this report refer to those types of transactions structured by listed South African companies to facilitate the transfer of a portion of their ordinary issued share capital to South African individuals or groups who qualify under the Broad-Based Black Economic Empowerment Act of 2003 (“the Act”). This Act requires a minimum percentage of the company to be black-owned in order to address the disproportionate distribution of wealth amongst racial groups in South Africa due to the legacy of Apartheid. These transactions are usually structured in such a way to allow the BEE partner to participate in the upside of the share price beyond a certain level but not in the downside which replicates a call option on the share price of the issuing company. The cost of both ESOs and BEE deals has to be accounted for on the balance sheet of the issuing company at its fair-value. Neither of these instruments can be traded and their extended option lifetimes are features that distinguish these deals significantly from regular traded options for which liquid markets exist. This makes pricing them a non-trivial exercise. A number of types of mathematical models have been developed to take the unique structure features into account to price them as accurately as possible. Research by Huddart&Lang (1995&1996) has shown that option holders often exercise their vested options long before the maturity of the transactions but are unable to quantify a measure that can be used. The wide variety of factors influencing option holders (recent stock price movements, market-to-strike ratio, proximity of vesting dates, time to maturity, share price volatility and wealth of option holder) as well as little exercise data publicly available prevents the options from being priced in a consistent manner. Various assumptions regarding the exercise behaviour of option holders are used that are not based on empirical observations even though the option prices are sensitive to this input. This dissertation provides an overview of the models, inputs and exercise behaviour assumptions that are recognized in pricing both ESOs and BEE deals under IFRS 2 in South Africa. This puts the reader in a position to evaluate all pricing aspects of these deals. Furthermore, their structuring are also analysed in order to identify the general issues related to them. A number of methods to manage the pricing issue surrounding exercise behaviour on ESOs have been considered for the South African market. The ESO Upper Bound-methodology showed that for each strike there is a threshold at which exercise will occur and the employee can invest the after-tax proceeds in a diversified portfolio with a higher expected return than that of the single equity option. This approach reduces the standard Black-Scholes option value without relying on assumptions about the employee’s exercise behaviour and is a viable alternative for the South African market. The derived option value represents the cost of the option. Seven large listed companies’ BEE transactions are dissected and compared against one another using the fair-value of the transaction as a percentage of the market capitalization of the company. The author shows how this measure is a more equitable way of assigning BEE credits to companies than the current practice which is shareholding-based. The current approach does not reward the effort (read cost) that a company has undertaken to transfer shares to black South Africans but only focuses on the amount that is finally owned by the BEE participants. This leaves the transaction vulnerable to a volatile share price and leads to transactions with extended lock-in periods that do not provide much economic benefit to the BEE participants for many years. Other inefficiencies in the type of BEE transactions that have emerged in reaction to the BEE codes that have been published by the South African government are also considered. Finally the funding model that is often used to facilitate these deals is assessed and the risks involved for the funder (bank) is reflected on. / Dissertation (MSc)--University of Pretoria, 2011. / Mathematics and Applied Mathematics / unrestricted

Honey bees, Apis mellifera, play an important role in many ecosystems, pollinating a wide variety of native, agricultural, and exotic plants. The recent decline in the number of feral and managed honey bee colonies in North America, as well as the arrival of Africanized honey bees, have caused concern about adequate pollination for agricultural crops and natural plant communities. However, little is known about feral colonies, and the feral population is the source for Africanized honey bees as they spread and infiltrate managed populations. The goal of my dissertation was to examine the ecology of feral honey bee colonies, adding the spatial context necessary to understand the population ecology and patterns of resource use by feral honey bees on the Welder Wildlife Refuge. I defined the functional heterogeneity of feral honey bee habitat by identifying the suitability of different habitats for feral colonies based on the distribution and abundance of important resources (cavities, nectar, and pollen). I evaluated the distribution and abundance of feral colonies by examining nest site characteristics, population trends, and spatial and temporal patterns in cavity use. Lastly, I examined resource use by evaluating patterns in pollen collection and identifying where and when honey bees searched for resources. Overall, the Welder Wildlife Refuge provided excellent habitat for feral honey bees, supporting a high density of feral colonies. The dense live oak habitat was the best overall source for cavities, nectar, and pollen. Nectar and pollen were abundant throughout the year, with the exception of December and January, when a large number of honey bees searched for resources. Cavities did not appear to vary in their suitability for feral colonies based on measured structural and environmental attributes, since no cavity attributes were correlated with indices of cavity quality. However, the cavity quality indices varied between cavities, suggesting some cavities were more suitable for feral honey bees than others. Colonies were aggregated within the study area, probably due to the distribution of resources. The invasion of Africanized honey bees appeared to fragment the existing European population, with Africanized colonies aggregated in distribution and European colonies random in distribution.

Le virus de la paralysie chronique de l'abeille (Chronic bee paralysis virus, CBPV) est l'agent étiologique d'une maladie infectieuse et contagieuse des abeilles adultes (Apis mellifera L.), appelée la paralysie chronique. Le CBPV est un virus à ARN simple brin positif qui contient 2 fragments d'ARN majoritaires. L'ARN 1 (3674 nt) et l'ARN 2 (2305 nt) codent respectivement 3 et 4 cadres ouverts de lecture (ORF). La séquence d'acides aminés de l'ORF 3 de l'ARN 1 partage des similitudes avec l'ARN polymérase ARN dépendante (RdRp) des virus des familles Nodaviridae et Tombusviridae. Par analogie avec ces familles virales, il a été suggéré que l'ARN 1 coderait les protéines non-structurales tandis que l'ARN 2 coderait les protéines structurales. Cependant, la réalité de ces protéines virales doit être démontrée expérimentalement afin d'étudier leurs fonctions, de mieux décrire ce virus et sa position taxonomique ainsi que d'améliorer les outils de diagnostic. Dans ce but, différentes approches expérimentales ont été utilisées. Une comparaison des protéomes d'hémolymphe d'abeilles non-infectées et infectées par le CBPV a été effectuée. Les protéines différentiellement exprimées ont été identifiées par empreinte peptidique massique (peptide mass fingerprint, PMF). Cette étude a permis d'identifier des protéines de l'abeille dont certaines contribueraient à une réponse immunitaire antivirale, mais aucune protéine virale n'a été identifiée par cette approche. Les ARN extraits du CBPV ont été utilisés dans des expériences de traduction in vitro. Malgré plusieurs essais réalisés en faisant varier les conditions expérimentales, cette approche s'est révélée infructueuse. / Chronic bee paralysis virus (CBPV) is the etiological agent that causes an infectious and contagious disease in adult bees (Apis mellifera L.), called chronic paralysis. CBPV is a positive single-stranded fragmented RNA virus which contains 2 major viral RNA fragments. RNA 1 (3674 nt) and RNA 2 (2305 nt) encode 3 and 4 putative open reading frames (ORFs), respectively. The amino acid sequence of ORF 3 on RNA 1 shares similarities with the RNA-dependent RNA polymerase (RdRp) of virus families Nodaviridae and Tombusviridae. By analogy with these viral families, it has been suggested that RNA 1 encodes non-structural proteins and RNA 2 encodes structural proteins. However, the reality of viral proteins needs to be experimentally demonstrated in order to study theirs functions, to describe CBPV biology and its taxonomic position and to improve diagnostic tools. With this aim, different experimental strategies have been used.A comparison of hemolymph proteomes between uninfected bees and bees infected with CBPV was performed. Differentially expressed proteins have been identified using peptide mass fingerprint method (PMF). This study allowed only identifying proteins of bees which could contribute to an antiviral immune response but viral proteins were not identified using this approach. Extracted CBPV RNAs were used for in vitro translation experiments. Despite several assays in varying experimental conditions, this approach has been unsuccessful. Another approach was to generate antibodies directed against different proteins or parts of viral proteins.