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Item Embargo Ecology and Reproductive Biology of Calotropis procera (Aiton) W.T in some parts of Mopani District Limpopo Province(2025-09-05) Ratshibvumo, Rofhiwa; Mokganya, M. G.; Ligavha - Mbelengwa, M. H.Plant species play a crucial role in maintaining the normal functioning of various ecosystems. However, native species often face decline or extinction due to alien species' invasion and its detrimental impact. One such invasive species, the widespread shrub or medium-sized tree Calotropis procera (Aiton) W.T., is encroaching upon several villages and roadside areas in the Limpopo Province of South Africa, where it has been classified as an invasive species. This shrub, ranging from 2.5 to 6 meters in height, has proliferated across various regions of South Africa. This study was conducted in six villages within the Mopani District, Limpopo Province, to investigate the ecology and reproductive biology of Calotropis procera (Aiton) W.T. The findings of this study are critical for devising strategies to manage or eradicate these invasive species in affected areas. Researchers observed and counted the number of Calotropis procera (Aiton) W.T plants alongside roads and villages, measuring the distances between these plants and their nearest neighboring species to assess potential competition. The present study also involved monitoring the phenological patterns of Calotropis procera (Aiton) W.T, including the timing of flower, fruit, and seed production, as well as seed dispersal mechanisms. This information is vital for determining the optimal periods for eradication or control efforts. The distribution pattern of Calotropis procera (Aiton) W.T. was analyzed using the Clark and Evans (1954) method, and phenological data were collected through photographic documentation at each site. The extensive spread of Calotropis procera (Aiton) W.T. is attributed to its prolific seed production, wind-dispersed seeds, and stress tolerance, enabling it to thrive in various environments. The study suggests the best time to remove Calotropis procera (Aiton) W.T. plants is between February and April before they produce fruits. Understanding the impact of Calotropis procera (Aiton) W.T. on the local ecosystem is essential for developing effective management strategies. Overall, this study provides a comprehensive understanding of Calotropis procera (Aiton) W.T.'s ecology and reproductive biology and offers valuable insights into potential strategies for managing and eradicating this invasive plant species.Item Embargo Factors influencing arthropod diversity in the citrus landscape in Tshipise, Limpopo Provincem South Africa(2025-09-05) Manamela, Thakgatso Rosina; Swanepoel, I. H.; Mphephu, T. E.Citrus plants play a crucial role in global food and nutrient supplies. South Africa exported 165.1 million cartons of citrus during the 2023 season and projected growth to 200 million cartons within four years. However, citrus crops are vulnerable to pest infestations, leading to a heavy reliance on chemical pesticides. Different pesticide types and dosages leave varying residue levels on treated citrus, with strict maximum residue limits (MRLs) enforced by global markets. Ongoing shifts in MRL standards and concerns over chemical dependence have pressured Southern African citrus producers to adopt Integrated Pest Management (IPM) approaches that balance effective pest control with minimised chemical use. This study investigated the factors influencing arthropod diversity in citrus agroecosystems, focusing on how landscape heterogeneity influences IPM. Using a landscape context approach, it quantified arthropod diversity within citrus orchards and surrounding habitats and edges to understand how these areas support beneficial arthropods like predators and parasitoids (Chapter 2). Results showed that diverse landscapes supported higher populations of beneficial arthropods in natural habitats, enhancing natural pest control, whereas croplands harboured more pest species. Additionally, the study evaluated the effects of excluding insectivorous vertebrates to assess their roles in pest suppression, crop damage reduction, and the spatial distribution of Thaumatotibia leucotreta (Chapter 3). By elucidating arthropod population dynamics, the role of landscape structure and context, and insectivorous vertebrates, this study highlights the importance of landscape heterogeneity in enhancing natural pest control within citrus agroecosystems. Findings show that maintaining diverse, non-crop habitats near croplands can support natural enemy populations, reducing reliance on chemical pesticides in IPM. The study also reveals that landscape context, especially proximity to natural habitats, influences the distribution and impact of crucial pests like T. leucotreta within citrus orchards. These insights offer practical guidance for optimising IPM approaches, suggesting that incorporating elements of natural habitats within agricultural landscapes can improve pest suppression and align with evolving global standards for pesticide residue limits.Item Embargo Investigating the pollination of African baobab (Adansonia digitata .L) flowers by dayflying insects in South Africa(2025-09-05) Phori, Pabalelo; Swanepoel, L. H.; Venter, S. M.The African baobab (Adansonia digitata L.) is a versatile tree known for its multiple uses in Sub-Saharan Africa. It provides people and animals with food, shelter and other materials. Many people in African countries sell baobab fruit to generate income. Therefore, assessing factors affecting fruit production, such as pollination, is essential. Baobabs has "chiropterophilous" flowers that are adapted to nocturnal pollination. While established research found that fruit bats pollinate baobab flowers in West and East Africa, recent evidence suggests Hawkmoths to be the likely pollinators in Southern Africa. Observations of diurnal insects visiting baobab flowers prompted questions about the effect of these insects on baobab pollination. However, the impact of dayflying insects has yet to be investigated. Therefore, this study specifically focuses on determining if dayflying insects play a role in the pollination of baobab, particularly their foraging behaviour and activity. The study first provides an overall literature review of the significance of pollination in baobabs, the shift of pollination systems, and determining the role of dayflying insects in pollinating baobab flowers in the morning. Secondly, using camera traps, we recorded all floral visitors and their foraging activity on baobab flowers in the morning between 4 am and 7 am. We determined how time, species and temperature affect the activity of dayflying insects. Hand pollination results indicated that the stigmas were still receptive and the pollen was still viable when the dayflying insects visited the flowers in the morning. Open-pollinated flowers showed that dayflying insects do not pollinate baobab flowers. Hymenopterans visit baobab flowers in the morning to collect pollen but do not function as pollinators. We also observed the changing composition of bee species over the 4 am to 7 am period, indicating the difference in the timing of the foraging activity of different insects. Our results support the hypothesis that daytime insects are unlikely to contribute to baobab pollination and that in South Africa, pollination seems to be dominated by hawkmoths. Nonetheless, diurnal insects still benefit from baobab flowers in terms of food.Item Embargo Assessing the genetic diversity and structure of spotted hyena (Crocuta Crocuta) populations across Africa(2025-09-05) Dibakoane, Kagisho; Moodley, Yoshan; Westbury, Michael VincentThe spotted hyena (Crocuta crocuta) is one of the most important species in the savannah ecosystem acting as both a predator and a scavenger yet not a lot is known about this majestic species. This study aims to address the genetic diversity, population structure and gene flow of these species across different regions of the sub-Saharan distribution. 55 whole genome and restriction site-associated sequences were analysed using Heterozygosity, PCA analysis, Admixture proportions, Phylogenetic analysis and D-statistics. The results showed that the mean heterozygosity of spotted hyena was 0.00094 (RAD-seq) and 0.0011 (WGS) ranging from 0.0006 to 0.0013. Admixture proportions and phylogenetic analyses showed three main populations clusters (western, eastern and southern) but there was also detailed structuring which showed five populations (west, northeast, eastern TanzaniaKenya, westernTanzania and southern) and D-statistics showed that there is gene flow between these populations. The spotted hyena shows highly structured clusters between the western, eastern and southern, this pattern of structure was comparable to other mammals and large carnivores in the same distribution. Although there was evidence of gene flow between these regions the western appeared more differentiation from either the eastern or southern both of which shared considerable genetic material with each other was also the western showed the lowest genetic diversity between these regions, these structures are cause by historical events and anthropogenic factors. We suggest that conservation effects must focus on fostering the exchange of genetic material from the eastern and southern regions to the western regions as a priority to avoid further differentiation.Item Embargo Understanding the thermal biology of macadamia nut borer, Thaumato(bia batrachopa (Meyrick) (Lepidoptera: Tortricidae): a pest of macadamia in South Africa(2025-09-05) Mulateli, Thifhelimbilu; Swanepoel, Lourens; Joubert, Elsje; Muluvhahothe, Mulalo M.Responses and adaptaSon of ThaumatoItem Embargo Exploring the fine line between ecology, conservation and utilisation of a commonly exploited resource: A case study of mopane worms (Gonimbrasia belina) in southern Africa(2025-09-05) Netshanzhe, Mutali Winnie; Swanepoel, L.; Swanepoel, C.; Foord, S.Mopane worms, the larvae of the mopane moth (Gonimbrasia belina), have a wide distribution in south and central Africa. They are valued highly as a food source and thus create local income in rural areas. They also contribute to ecosystem services by being part of the food chain and facilitating nutrient cycling on a landscape level. However, mopane worms are threatened by high harvest rates, habitat loss and the changing climate. Significantly, the existing research focuses on the utilisation of mopane worms, such as nutrient content, for human consumption. Very little research is done on mopane worms' ecology and their ecological contribution and importance. This study aims to determine the extent of mopane worms’ distribution across southern Africa, specifically in relation to protected and non-protected areas, to evaluate to what extent harvesting is restricted or can potentially be addressed, as well as determine the potential ecosystem services of mopane worms by measuring the consumption rate and frass production on a landscape scale and comparing nitrogen release through mineralization from frass and mopane leaves. This was achieved through four main objectives: 1) review current research to evaluate the type of research topics, consolidate current knowledge, and identify gaps and future research directions; 2) quantify the suitable habitat of mopane worms in several southern African countries; estimate the effectiveness of protected areas to capture suitable habitat, and, explore variables affecting the suitable habitat of mopane worms; 3) assess the impact of mopane worms on the mopane veld ecosystem in Mapungubwe National Park through herbivory and 4) compare the N mineralisation rate as indicated by N-NH4 and N-NO3 release from frass from mopane worms and leaves from mopane trees, to establish whether the presence of mopane worms’ frass leads to faster nutrient release for plant uptake. The review found that most studies focus on mopane worm utilisation, such as their importance as a food and income source, while very few research efforts focus on biology or ecology. Although research on mopane worms has drastically increased over the years, these research efforts are not equally distributed among African countries, with most studies being done in South Africa, while other countries have very few or even no studies. Presence-only modelling identified the suitable mopane worm habitat and correlated this with protected and unprotected areas. Most of the harvesting occurs in non- protected areas, where there are relaxed regulations on harvesting. The extent to which mopane worms contribute to defoliations and frass production, was determined by measuring and calculating the consumption rate and frass production for the landscape. Data show that a wide variation exists, which can be due to factors such as weather patterns, type of vegetation, predation, etc. This was followed up with a laboratory incubation trial to determine the difference between nutrient release from mopane worm frass (when a healthy population of mopane worms are present) with the mineralization and nutrient release from mopane leaves (when no mopane worms are present). More nutrients are released from frass compared with leaves, indicating that mopane worms facilitate nutrient cycling in the landscape. This study highlighted the significance of mopane worms in the natural environment and then provided a suitable habitat for the worms that need management to ensure their sustainability.Item Embargo Augmenting black soldier fly (BSF), Hermetia illucens, production on various agricultural waste streams, and the beneficiation of BSF frass(2025-09-05) Kubayi, Consol; Foord, S. H.; Swanepoel, L. H.; Madala, N. E.; Swanepoel, C. M.A sustainable and innovative approach to managing organic waste is presented by Black Soldier Fly Larvae (BSFL), Hermetia illucens, flowing from previously underutilised biological waste streams in agricultural systems. These waste streams are regularly disposed of irresponsibly or recycled inappropriately that lead to environmental problems characterised by emission of greenhouse gases, nutrient leaching, and inefficient waste reduction methods. BSFL’s capacity to convert organic material into valuable protein-rich biomass and nutrient-rich frass have great potential in sustainable waste management systems, especially in handling high moisture organic waste streams and contributing to a circular-loop economy. Thus, the objective of this study was to evaluate the BSFL performance in converting three economically abundant organic waste streams in Limpopo, Vhembe district, South Africa (avocado waste, orange waste, and potato peels) and to evaluate the effect of frass from those substrates on agricultural productivity. This was achieved through three main specific objectives:1) to determine the growth and survival of BSFL in response to sawdust as a bulking agent for managing high-moisture potato peels; 2) to investigate the effect of nutrient composition of the three organic wastes on BSFL survival, growth rate, larvae yield, waste reduction and the efficiency to convert waste into useful biomass ; and 3) to evaluate the agronomic potential of BSFL frass as an organic fertiliser for improving the growth and yield of beetroot (Beta vulgaris). This study also contributed to a better understanding of how BSFL performance can be optimised in various organic waste streams, illustrating the potential for sawdust to provide effective bulking more quickly, thus improving larval growth and subsequent management of the high moisture substrates during the bioconversion process. Results showed that sawdust effectively enhanced larval yield and growth rates by maintaining the aeration and moisture balance of the substrates. Moreover, the results of bioconversion in the three waste streams indicated that larval biomass and frass production were highest when potato peels were used, and some wastes were more efficiently reduced than others, which is mainly related to their composition. In agronomic scales, application of frass has improved beetroot growth and yield, thus showing that the frass also serves as a biopesticide that can protect crops. This will advance the knowledge base of BSFL bioconversion systems and allow practical guidance identifying conditions to optimise substrates and possibly render frass to be integrated with agriculture. It highlighted that BSFL not only provides a means for organic waste reduction, but when used as a component of organic fertilisers, increases crop yields and improves soil health, thus presenting an eco-friendly agricultural opportunity. This research contributes to offsetting both ecological and economic problems and creates a step towards broader and more effective application of the insect industry on BSFL for this niche in the waste valorisation system.Item Embargo Population structure and local adaptation in red foxes across an environmental gradient(2025-05-16) Sekhwela, Blessing; Moodley, Yoshan; Prost, StefanThe red fox (Vulpes vulpes) is one of the most successful species across the globe, found on five continents and in diverse habitats across various climatic and environmental conditions. Increasing Arctic warming has allowed the red fox to expand and occupy the Arctic environment. This new environment presents unique selective pressures, characterised by long, dark winters and short, continuous light summers. Arctic animals must endure extended periods of food scarcity, extremely cold conditions, and very short periods of resource abundance. Although red foxes do not exhibit physical adaptations specialized for surviving in the Arctic conditions, they continue to thrive despite these challenges. To investigate whether there are genetic adaptations in the red fox populations in the Arctic region, I used whole genome sequencing to detect signatures of positive selection across the whole genome. To achieve this, I used population branch statistics (PBS). PBS is a three-population test that identifies loci under selection by comparing the pairwise FST between the focal group (here the Arctic population) and a sister population (here Central Europe), controlling for ancestral polymorphisms using an outgroup population (here Israel). The regions found to have unusually high Fst in the focal population are potential candidates for selection. Because only low coverage genomes were available for this project, the test was conducted at two different depths (-setMinDepthInd 1 and -setMinDepthInd 3) to test whether the results were reliable with more or fewer SNPs. The two tests combined identified 123 candidate genes. Among them were genes involved in lipid metabolism, fertility, olfaction, circadian rhythm, response to hypoxia, thermogenesis and some were disease-related. I found that the Arctic population of red foxes exhibited a high genetic diversity and there was clear genetic structuring among populations. However, significant genetic contact remained between the Arctic and Central European populations. Gene-flow analysis also indicated potential signatures of ancient gene-flow between Central Europe and Israel. Despite the relatively low coverage of the available genomes, this study has identified several genes that could play a role in cold adaptation in red foxes. These genes and some of their orthologs, such as those involved in fatty acid metabolism, thermogenesis, circadian rhythm and response to hypoxia, have been identified in other arctic species like polar bears, reindeer, muskox and marmots as adaptive.Item Embargo Green synthesis of copper nanoparticles using Lannea discolor (Sond.) Engl. and evaluation of their biological efficacy(2025-05-16) Rambau, Unarine; Masevhe, N. A.; Samie, A.Worldwide, herbal medicine has become a preferred source of therapy as it contains an array of bioactive phytochemicals, is biologically compatible, and has been used to synthesize nanoparticles with advanced therapeutic potential. Lannea discolor, commonly known as “dikbas,” occurs in southern Africa and is extensively utilized as a traditional medicine. This study explores the phytochemical composition of the plant extracts, identifying potential active compounds. Qualitative and quantitative phytochemical screening and radical scavenging capabilities of the crude extracts of Lannea discolor revealed the presence and abundance of flavonoids, fatty acids, phenolics, and terpenoids and high antioxidant activity. Using LC-MS, several compounds were elucidated by comparing the molecular formulae and retention times with those already published in various chemical databases. The extracts displayed efficient antibacterial activity when evaluated against Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Additionally, the methanolic and acetone extracts were highly toxic against the Caco-2 cancer cell line. The study also focuses on the green synthesis of copper, gold, and silver nanoparticles using Lannea discolor plant extracts as reducing and stabilizing agents. Biosynthesis of copper, gold, and silver nanoparticles was executed using the different extracts at temperatures of 25 °C and 80 °C. The composition of the synthesized nanoparticles (NPs) was confirmed visually by the observation of color change and characterized by UV-Vis, FEGSEM, EDX, HRTEM, FTIR, and Zetasizer. Plasmon resonance peaks confirmed that the particle interfaces were coated with phytochemicals. Evaluation of the zeta potential affirmed the extent of the stability of the NPs, as substantiated by conclusive negative potential values. Elemental mapping revealed particles consisting of copper, gold, and silver among the main elements. The nanoflowers resulting from the reduction of leaf extracts and the nanoparticles acquired from the stem and root of Lannea discolor ranged from 30–97 nm and 9–37 nm, respectively, while the copper nanoparticles had sizes of 20–104 nm. Both nanoparticles showed potential for application in biomedicine and conductivity for manufacturing industries. The gold nanoparticles exhibited exceptional antibacterial activity, while the copper nanoparticles had no activities. Furthermore, silver nanoparticles were synthesized to evaluate their antibacterial activity and cytotoxicity against Caco-2 cells. The spherical silver nanoparticles had notable activity against the bacteria Escherichia coli, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, as well as Klebsiella pneumoniae, and were able to inhibit cell proliferation in Caco-2 cells, demonstrating their intrinsic potential as both antibacterial and anticancer agents. Additionally, the nanoparticles showed notable antioxidant activities. As the first study based on phytochemical profiling of L. discolor, this work highlights its potential for unexploited medicinal properties. This was the first study on nanoparticle synthesis of L. discolor, and it contributes positively to the eco-friendly and liberal technique of fabricating nanoparticles for the manufacturing of novel drugs from plants used as alternative medicine.Item Open Access Bioaccumulation and the human health risk of p,p'-DDT, p,p'-DDD, p,p'-DDE in freshwater fish species from the north-eastern Limpopo River valley, Vhembe District, Limpopo Province, South Africa(2024-09-06) Mphephu, Sherron; Barnhoorn, I. E. J.; Bornmann, M. S.Dichloro-diphenyl-trichloroethane (DDT) has been used globally as an agricultural pesticide since the early 1940s, and both the United States and Canada banned its use in 1972. DDT is still used in the malaria-endemic region of South Africa for vector control through indoor residual spraying (IRS). Studies have reported a link between DDT exposure and prostate cancer risk and/or aggressive disease presentation in Italy, Canada, and the United States. Epidemiological analysis of men with prostate cancer (PCa) in South Africa showed an increased PCa risk in Vhavenda people, the predominant population of Vhembe. The Vhembe District municipality falls in the malaria-endemic region, where DDT is used for vector control. The region of interest is fed by three major tributaries of the Limpopo River, which provide communities with agriculture, washing/bathing and portable water as well food (fish). Therefore, environmental levels of p,p-DDT, p,p-dichlorodiphenyldichloroethane (DDD) and p,p- dichlorodiphenyldichloroethylene (DDE) were measured before and after of the 2022 malaria high-transmission period (HTP), through sampling fish, from the Mutale and Mutshindudi rivers, and Thathe Vondo Dam. Fishes were bought from fishermen at the Thathe Vondo Dam and along the Mutale and Mutshindudi rivers. The fish's edible part (muscle), one piece raw and one piece cooked was tested for DDTs. Fish from the Mutshundudi River had higher DDT residuals than all other sites before the IRS. None of the DDTs were present after the yearly IRS. Daily exposure of DDTs for consumers was estimated by comparing estimated daily intake (EDI) with different criteria. The results revealed that the EDIs in our study were all lower than those criteria. Target hazard quotient (THQ) and risk ratio (R) were used to evaluate non-carcinogenic (toxic) and carcinogenic risks. There was no carcinogenic or toxic risk for humans consuming fish from the Mutale and Mutshindudi rivers and Thathe Vondo Dam. This indicates that DDT, DDD, and DDE in fish are not affecting the PCa burden in the Vhavenda men living in remote communities.Item Open Access Compatible components of the integrated pest management of Bathycoelia distincta (Hemiptera: Pentatomidae(2024-09-06) Manzini, Shaun; Foord, S. H.; Joubert, E.Two-spotted stink bug, Bathycoelia distincta Distant (Hemiptera: Pentatomidae), is a major pest of macadamia. It causes damage by directly feeding on macadamia kernel throughout the season and reducing nut quality by inducing nut abscission, premature nut abortion, necrotic lesions, deformed kernels, discoloration, or translucent blemishes on the kernel. Currently, growers rely on chemical insecticides to control stink bug populations. However, with overreliance and extensive use of chemical insecticides, the B. distincta has developed some resistance to certain active ingredients Furthermore, there is no doubt that agricultural intensification is the primary driver of the loss of biodiversity globally. Therefore, there is a need to develop Integrated Pest Management (IPM) strategies to effectively minimize the damage caused by B. distincta and the loss of biodiversity due to agricultural intensification. The goal of this study was to investigate the role of landscape context, elevation, flying vertebrates, and pesticide application in shaping arboreal arthropod assemblages and macadamia nut quality metrics and evaluate the efficacy of alternative pest control measures to control B. distincta, explicitly focusing on entomopathogenic fungi and egg parasitoids Trissolcus basalis (Wollaston, 1858) (Hymenoptera: Platygastridae). Landscape context and elevation were the principal factors that explained species richness and arthropod size. Species richness and insect size decreased with increasing pesticide application rate; however, it was not significant. Insect damage did not vary in response to pesticide application, but the proportion of sound kernels decreased significantly with increasing pesticide application. All entomopathogenic fungal treatments were effective against B. distincta, with chitinase enzyme leading to a 95% mortality rate. Under field conditions, EPFs and a chemical knock-down spray showed no significant difference between the treatments. All parasitoid treatments significantly affected B. distincta egg mortality, with two pairs reaching a 100% parasitism rate. The processes that increase sound kernel recovery seem to be related to an increase in invertebrate community diversity and arthropod size, and although the mechanisms related to this are not always clear, the results suggest that arthropod diversity could be a good proxy for these processes. On the other hand, the study results showed that EPFs and stink bug egg parasitoids, Trissolcus basalis, may be used as biological control agents against B. distincta. Overall, the thesis emphasizes the importance of reducing pesticide application and using biological control agents, promoting more sustainable agricultural practices, and supporting biodiversity to improve ecosystem service provided by pest natural enemies.Item Open Access Assessment of nutraceutical attributes of selected wild edible fruit plants used by Vhavenda people of the Thulamela Local Municipality(2024-09-06) Nephawe, Rinae Lucy; Mokganya, M. G.; Madala, N. E.Wild edible fruit plants are highly valued in many remote rural areas, where they play a significant role in fulfilling the sociocultural and livelihood needs of people. Many of these plants are harvested by local communities to augment and diversify their diets as well as to promote local food security. The decline in the use of wild edible fruit plants may be due to a lack of knowledge of their nutritional value, their potential for income generation, and medicinal and cultural uses. This study focused on the documentation of utilisation, conservation, and nutraceutical composition of the wild edible fruit plants of the Thulamela Local Municipality. Information on wild edible fruit plants was gathered through semistructured interviews, fieldwork, and a literature review. A total of 39 wild edible fruit plants of 22 botanical families recorded during the study were used as food, beverage, and additionally as medicine. The number of wild edible fruit plants with medicinal properties was 39 whereas those used to make beverages were 9. Wild edible fruit plants of Thulamela municipality were experiencing challenges due to human activities resulting in declining, endangered, or even extinct. Results of this study also showed the use of wild edible fruit plants as firewood because 10 out of 39 were mentioned for this use. In this study the UHPLC-qTOF-MS/MS-based in source collision induced dissociation method was utilized to generate fragmentation data to assist in the differentiation of closely related isomers. Wild edible fruit plants have been used for centuries in traditional medicine and for nutritional purposes. Strychnos species has not yet been fully decoded, and due to the inherent complexity of plant metabolomes, the characterization of Strychnos photochemistry remains challenging. Thus, in this study, we propose the use of molecular networking to unravel the families using the metabolome analysis of two Strychnos species (Strychnos pungens and Strychnos spinosa) and highlight the relevance of molecular networking in exploring the chemotaxonomy of plants. This allows visualization of chemical classes and the variety of substructures within the molecular families.Item Open Access Role of bats as natural pest control agents of moth pests (false codling moth and carob moth) on citrus orchard(2024-09-06) Khavheli, Thivhileli; Swanepoel, L. H.; Foord,S. H.Over the years, the change in farming practices has caused a tremendous decline in the diversity of flora and fauna within agricultural landscapes through intensification of land use. An increase in agricultural intensification has resulted in increased farm sizes and reduced landscape heterogeneity. In the past two decades, the interest in services that insectivorous bats provide within agricultural landscapes through insect pest suppression has gained recognition globally. Multiple studies have thoroughly examined the vital role played by insectivorous bats within agricultural landscapes as biological control of insect pests for crops such as rice, cotton, pecan, corn, and macadamia. However, little to none is known about the impact insectivorous bats have within citrus landscapes. This study specifically focuses on how insectivorous bats inhabiting different landscapes respond to insect pest outbreaks, especially that of false codling moth (FCM) and carob moth (CM), important pests of citrus. The study first gives a general introduction of the importance of landscape heterogeneity within agricultural landscapes, beneficial effects that insectivorous bats have in agricultural areas, and the use of advanced molecular methods to analyze the diet of insectivorous bats. Secondly, we investigated the influence of land use heterogeneity, temperature, and insect pest activity on bat species richness and different foraging groups. Our results demonstrate higher bat activity in natural areas (wet riparian zones and orchard edges) compared to orchards, and further illustrate that bat species richness and activity were highly influenced by temperature. Lastly, we investigate the moth pest consumption by different bat species of different foraging groups. We found that all bat foraging groups, open-air and clutter-edge foragers, had a high consumption rate of agricultural pests including FCM and CM. The results of this study emphasize how crucial it is to preserve natural habitats and bat populations in citrus landscapes. Including bats in integrated pest management (IPM) programs can benefit both agriculture and biodiversity.Item Open Access Ecology and phenology of Melia Azedarach Linn.on and off the Riverine Areas(2024-09-06) Masia, Khathutshelo Victor; Ligavha-Mbelengwa, M. H.; Mokganya, M. G.Noteworthy, Melia azedarach Linn. is an indispensable tree species that is utilised in various forms. It can be used in craft industries as a substitute for teak wood when the supply is reduced. Simultaneously, its leaves, roots, bark, and flowers are used as medicines and natural pesticides. Melia azedarach Linn. is traditionally used as medicine to treat astringents and furthermore can be used against intestinal worms, skin diseases, stomachaches, uterine illnesses, and as a diuretic and febrifuge. In addition, it has been reported to possess anticancer, antimalarial, analgesic, and anti-inflammatory, antifungal, antibacterial and antioxidant activities. This tree can adapt to different environmental conditions so that it can grow well in extensive areas. Melia azedarach Linn. is a plant that grows both on and off the riparian zones. Communities in South Africa see less value attached to it to the extent that in many places where these trees are found growing, the majority are cut for no good reason. Sometimes, the plant species is cut for the construction of fences, kraals, or firewood. The main reason for this practice is that much is not known about the plant; it could be found de-vegetated anytime. The study was conducted at Ha-Tshikonelo, Thulamela Local Municipality, Limpopo Province, South Africa. Plant phenology and distribution have gained increased interest because climatic change is sensitive to phenological traits and their consequences for ecosystem function. It is made possible to gather information on spatial and ecological scales because of new technologies innovative technologies. Temperature, photoperiod, and winter chilling are examples of plant phenology drivers, and competition is included. A smartphone ( Huawei Nova Y60) camera was used to take pictures of phenological changes when visiting the on and off riparian zones from August 2019 to December 2021. The research aimed to determine the different phenophases and distribution patterns of Melia azedarach in riparian zones. The Nearest-neighbour method of sampling individuals within a population of plants was used for data collection. The collected data was then analysed using Analysis of Variance (ANOVA). It was found that Melia azedarach Linn. is regularly distributed for both on and off-riparian areas. Phenophase occurring off riparian zones was found to be occurring earlier than in riparian zones. It was found that Melia azedarach Linn. is surviving and flourishing in both off and on the riparian zones. On riparian zone individuals were growing bigger than those found off the riparian zones because of the abundant supply of resources such as water and nutrients.Item Open Access An analysis of exposure and slope gradient impact on tree layer profile of Maroelakop vegetation in Nylsvley Nature Reserve, Limpopo Province, South Africa(2024-09-06) Mavhila, Tendani; Tshisikhawe, M. P.; Magwede, K.Since the 1850s, plant ecologists have been eager to investigate challenges in vegetation communities that are related to slope. The aspect of the slope is crucial in terms of the diversity and distribution of plants. This research was conducted on Maroelakop Mountain within Nylsvley Nature Reserve located in Mookgopong, Limpopo Province. The investigation aimed to assess and contrast the vegetation composition on the north-facing slope with that of the south-facing slope. The specific goals included ascertaining the density and frequency of dominant tree species on each slope, calculating the importance value indices of trees on both slope gradients and analyzing the population structure of the slope gradient. Point Centred Quarter (PCQ) was used in data collection. Shannon-Weiner diversity index, Simpson diversity index, and Evenness index were used to measure plant species diversity. In this study, a total of 600 trees were discovered and identified by their botanical names. The data represented 21 plant species in 17 genera and 12 families. The tree layer of the north-facing slope was dominated by Diplorhynchus condylocarpon, whereas that on the south-facing slope was dominated by Burkea africana. Both tree species had high-importance value indices. Shannon diversity index of 2.20 was obtained for the North-facing downslope, whereas the South-facing downslope had 1.74. The average Simpson diversity index for the North-facing slope was 0.82 and South-facing slope 0.77. The average Evenness index for the North-facing slope was 0.93 and, on the South-facing slope 0.81. This study concluded that Diplorhynchus condylocarpon is the most prevalent species within Maroelakop Mountain in the Nylsvley Nature Reserve.Item Open Access Effects of anthropogenic factors on the population structure of Pterocarpus angolensis DC in a communal area of Khalavha Village in Vhembe Biosphere(2024-09-06) Ndou, Tshihumbudzo; Tshisikhawe, M. P.; Mashile, S. P.Pterocarpus angolensis DC. is an indigenous species of value across Africa. The species have been identified as having a high utilization rate for different purposes. The purpose of the study was to analyze the population structure of P. angolensis, a species in high demand. Ethnobotanical information was collected with an aid of a questionnaire from fifty-three informants. The informants identified two plant parts preferred by the community. The only preferred parts are stem (67%) and bark (33%). The study identified a lack of indigenous knowledge of the species amongst the youth. Some of the uses reported on P. angolensis were firewood (n=33), medicine (n=43), craftwork (n=35), protection (n=16), and timber (n=4). The transect sampling technique was used to document ecological data on the species to analyze its population structure. Fifty-three transects of 100m x 10m were constructed within the population. Ecological parameters recorded included stem diameter, height, and crown health status. Basal stem diameter data recorded on P. angolensis sampling were grouped into seven size classes and displayed an inverse J-shaped curve when analysed. The study showed that the population had more individuals (n=60) within the seedlings size class (0-5cm) when compared to the bigger size classes (20.1-25cm, 25.1-30cm, and >30.1cm). The majority (37%) of P. angolensis individuals had light crown damage which depicts on average an aspect of healthy crowns. Only 1% of sampled individuals had dead crowns. Monitoring of the P. angolensis population will assist in making sure that it stays healthy and viable.Item Open Access Fruit bat diet, foraging ecology and seed dispersal in the Vhembe Biosphere Reserve.(2024-09-06) Mphethe, Vusani; Swanepoel, L. H.; Taylor, P. J.; Parker, D.; Weiner, S.Agricultural intensification, and a rapid human population growth have resulted in increased human wildlife contact. In the case of fruit bats, conflict with commercial fruit farmers has been a leading contributor to a decline of bat species populations, despite the vital ecosystem service of seed dispersal provided by fruit bats. Conflict between fruit bats and fruit farmers often stems from perceived or actual damage to their crops, especially during the harvest season. Such conflict often leads to the persecution of fruit bats, either legally or illegally. Therefore, a proactive assessment of bats diet in agroecosystems is important. South Africa is one of the major producers of litchi and its litchi industry is well established and continues to grow. This study provides insight into the diet, foraging behavior, and ecosystem service of seed dispersal of fruit bat species in litchi orchards and natural habitats to advise on management strategies on how to reduce crop damage. It also assesses crop raiding by fruit bats and other crop raider animals, and their activity patterns in response to litchi abundance during the harvest season using camera traps. This study also used a vertebrate exclusion experiment to quantify the effect of excluding crop raiders on yield, as well as a questionnaire survey to quantify the perceived damage in litchi orchards. The study was conducted in the subtropical fruit growing area of Levubu and the natural habitats of the Soutpansberg, Limpopo province, South Africa. An introduction to the order Chiroptera and important fruit bats ecosystem service of seed dispersal as well as the disservice of crop depredation in agroecosystems is provided in Chapter One. Chapter Two, bats were captured with mist nest in both agricultural and natural habitats during the litchi pre-harvest and harvest seasons. We sampled the litchi orchards as well as natural habitats from February 2018 to November 2020 and used GIS and R (ggplot2, iNEXT, lme4) to analyse fruit bats diet, their effect on seeds germination and habitat use with respect to litchi fruit abundance. Results show that fruit bat diet was dominated by wild fruit species (95%) during the litchi harvest season (December) when fruit bats are perceived to be feeding on litchi fruits. Ficus (Ficus spp.) seeds collected as fruit bats spit-out seeds had significantly lower germination rates than regular seeds, but a significantly lower germination latency, and a similar pattern was also observed for quinine tree (Rauvolfia caffra). Our results suggested that fruit bats inhabiting litchi orchards and surrounding natural vegetation feed primarily on wild fruits due to the high percentage of natural vegetation in our study area, which support the importance of natural orchard edges in mitigating crop raiding. Chapter Three, we mounted 10 camera traps (from October 2019 to December 2020) on two litchi orchards for assessing fruit bats and other crop raider animal species richness and activity patterns in response to litchi abundance during litchi harvest season. Six time-triggered canopy camera traps were mounted (6m above the ground) to monitor the animals visiting litchi tree canopies during litchi pre-harvest (October/November) and harvest sessions (December). Additionally, four motion-triggered camera traps were mounted 30 cm above the ground to monitor animals visiting the litchi trees at the ground level. We used Digikam software to tag images and R (ggplot2, iNEXT, lme4, overlap, RSQLite) to analyse species richness, Relative abundance Index (RAI), and crop raider activity patterns. We recorded a significantly higher species richness index during the harvest season (December) compared to litchi pre-harvest season (October/November). Crop raider species richness was lower compared to incidentally observed species during the litchi harvest season. Fruit bats (which could not be assigned to either Epomophorus or Rousettus genus) recorded lower activity (RAI (of 2.49) compared to Dark-capped Bulbul (Pycnonotus tricolor; RAI (43.44)). Lastly, fruit bats did not show/exhibit any change in seasonal activity between the litchi pre-ripe and ripe seasons. As reported in Chapter Four, we collected the litchi yield data on both vertebrate exclusion trees (caged) and paired open control trees during the December/January harvest season between 2019 and 2020, to quantify the effect of excluding crop raider vertebrates, weather, and insect damage on yield. We constructed a total of six vertebrate exclusion cages on two litchi orchards, each enclosing one litchi tree and paired them with open control trees marked with a tapper. Additionally, a questionnaire survey was conducted in Chapter Four from both commercial and small-scale litchi farmers to quantify the perceived damage caused by crop raiders and later compared the results to the total yield for trees inside the exclusion cages and paired open control trees. Our litchi yield results show that open control trees produced significantly higher yield than caged trees, which is contrary to our hypothesis. There was also a weak but non-significant trend towards higher vertebrate damage on control trees compared to caged trees. Questionnaire survey results revealed that weather (sun/rain) and monkeys were the main cause of damage in litchi orchards, when compared to fruit bats, and there was a strong agreement among farmers that the damage varied by vertebrate groups. Farm type (commercial versus small-scale) also show statistically significant difference in the perceived damage caused by bats, birds, insects, monkeys, weather and wild pigs. The results of our study also show lower crop raiding incidence were reported for fruit bats. In summary, Chapter Five concludes that fruit bats prefer to feed on wild fruits over commercially cultivated fruits such as litchi, and potentially provide ecosystem service of seed dispersal, and that remnant natural vegetation at the orchard edges are important food sources, and assist in mitigating crop raiding, and need to be maintained or restored. The study also shows that fruit bats are not crop raiders of litchi fruits, and do not change their seasonal foraging activity in respond to litchi abundance during the litchi harvest season, as believed by farmers. However, further research on fruit bats crop raiding must be conducted in an area with known abundance of colonial species like Rousettus aegyptiacus, a known global pest of litchi crop. Additionally, the use of radio tracking should be considered, and could provide insight into fruit bats habitat use. Our study further revealed that vertebrate exclusions did not increase litchi yield, and that weather and monkeys were the main cause of damage when compared fruit bats. As a result, this study provides information to farmers on fruit bat`s important ecosystem service of seed dispersal and the benefit of maintaining natural orchard edges.Item Open Access The physiology of sprouting and its ecological implications for Savanna woodland and dynamics in the Nylsvley Nature Reserve, Limpopo Province, South Africa(2024-09-06) Ligavha-Mbelengwa, Maanda Hadzhi; Ogola, J. B. Ochanda; Tshisikhawe, M. P.Disturbance in its various forms is an integral component of any ecosystem, and it contributes significantly to the patterning of the vegetation. Many savanna plant species survive disturbance, such as cutting or clipping, through resprouting. Sprouting is important, particularly in situations where chances for the establishment of seedlings is rare. High disturbance intensity suppresses plant recovery, while low disturbance intensity stimulates plant regrowth. Disturbing plants frequently depletes stored carbohydrate reserves which are indispensable for regrowth, while disturbing plants less frequently allows plants space to accumulate root carbohydrate reserves. Savanna plants in game reserves are usually exposed to disturbance in the form of grazing, browsing, accidental fires, and competition. It is necessary to comprehend how savanna plant species respond to the disturbance for the sustenance of the life of the game in those ecosystems. This study assessed how savanna plants (i) respond to cutting, (ii) relate to bark thickness, stem diameter, and fire, and (iii) respond to release from competition. Chapter 3 of the current thesis experimented on juveniles of the two savanna plant species, namely Dichrostachys cinerea (D. cinerea) and Terminalia sericea (T. sericea), and Chapter 4 experimented on seedlings and juveniles of the same two savanna plant species referred to in chapter 3. Juvenile individuals that were utilized for experimentation in chapter 3 were not the same as those utilized in Chapter 4. Dichrostachys cinerea (D. cinerea) and Terminalia sericea (T. sericea), were subjected to clipping. In one instance, a group of juvenile plants per species was cut seasonally during the first year of experimentation for the whole experimental period, while in another instance, seedlings and juveniles were cut; the responses of plants were monitored and compared in both instances. Clipping of individual plant species monthly in the year simulated how seasons differentially affect plants' responses to cutting. The study was carried out for two and half years. The heights of cut plants were compared to establish how the plants responded to clipping. The heights of the plants were measured in both instances only towards the conclusion of the experiments. The bark thickness, and stem diameter of plants of different age groups were measured using Vernier callipers and diameter tapes, respectively. Gaps created between grass plants were measured pre- and post-removal of their potential competitors. All the individual plant species that were clipped anyhow survived clipping throughout the experimental period. Winter-clipped plant species generally outgrew plants that were clipped in other seasons, probably due to ample carbohydrate root reserves during this season of the year. Juveniles grew faster than seedlings in terms of height when both were cut at the same time of the day, presumptively due to more carbohydrates in their roots than in those of the seedlings. More seedlings died than juveniles when both were exposed to the same fire intensity. We found root reserves affected differentially between seasons of the year. The bark thickness increased with plant age and height to about 50 cm in trunk circumference; thereafter, the relationship was inconsistent. Openings that resulted when grass plants competed for resources such as moisture became readily available for invasion by new plant species, mainly alien plants. Managed disturbance is thus important and necessary to maintain ecosystems in balance. Communities should thus be educated on how savanna ecosystems respond to disturbances at different seasons of the year to mitigate situations where our savanna ecosystems could be converted into ecosystems that are not suitable for savanna games.Item Open Access The phenological study of Securidaca longepedunculata, in the Nylsvley Nature Reserve, Limpopo Province, South Africa(2023-10-05) Mukhithi, Aluwani Godfrey; Ligavha-Mbelengwa, M. H.; Magwede, K.Phenological observations were conducted through analysis of phenological phases and stages of 200 sampled S. longepedunculata plant individuals in the sandy soil areas of Nylsvley Nature Reserve, Limpopo Province, South Africa. Phenological stages comprised of onset, peak development and decline; while phenological phase is time spent by those stages for example leaf yellowing (Ruml and Vulic, 2005). Phenological phases patterns were analysed by focussing on vegetative and reproductive phenophases. Vegetative phenophase considered the presence of budding and developmental stages of leaves until they are shed. Reproductive phenophase considered the presence of flowering and developmental stages of fruits until they are shed. Phenological data was mainly collected through direct ground based observation. The results showed that budding, leaf greening and flowering were observed from mid spring in September in response to upcoming summer which is warmer and rainy. Ripe seeds and leaf yellowing were predominantly visible in autumn and winter respectively, as they are in their annual maturity stage. Leaf and seed shedding were observed at their peak development from late winter in June to early spring in August, probably due to the effect of windy conditions on site. Changes in the phenology of S. longepedunculata plant individuals caused by environmental changes resulted in changes at the community level. This shows that thorough phenological pattern monitoring is essential in order to forecast plant species behaviour. Also, it is necessary to provide knowledge on proper management of the reserve and protection of the plant species.Item Open Access Thermal biology of the two-spotted stink bug, Bathycoelia distincta (Hemiptera: Pentatomidae) a major pest of macadamia(2023-10-05) Muluvhahothe, Mulalo Meriam; Foord, S. H.; Joubert, E.The physiological functions of insects are mainly dictated by temperature because they rely on the external environment to regulate their body temperatures. This temperature dependence drives their performance, with profound implications on abundance and distribution. Daily environmental temperature fluctuations may outpace an insect’s thermal tolerance capacity, which requires physiological plastic mechanisms to survive. In the context of global warming, insects may be vulnerable to temperature variations, and may ultimately determine their population dynamics. The two-spotted stink bug, Bathycoelia distincta (Distant) (Hemiptera: Pentatomidae) is an important pest of macadamia in South Africa. It causes damage by direct feeding on the kernel and comprises more than 80 % of the shield bugs in the orchards. Increased crop losses due to stink bug damage threaten macadamia nut production. Modern pest management practices require an understanding of the biology of pests and ecology. An important question to pose is, how does an organism's thermal plastic traits affect its ecological population dynamics? First, this study aimed to quantify the effects of temperature on biological parameters of B. distincta life stages, such as the development rate, development duration, survival, adult longevity, pre-oviposition period, oviposition period, and life table parameters, to determine its thermal requirements and population growth at constant temperatures ranging from 19 to 29 °C. In addition, the effect of diet (macadamia nut and sweetcorn) on development, survival, and sex ratio was investigated at 25 °C (Chapter 2). Second, to quantify the phenotypic plasticity of B. distincta life stages. Two thermal tolerance indices were explored: rapid hardening (rapid heat hardening: RHH and cold hardening: RCH) and acclimation (critical thermal maximum: CTmax and minimum: CTmin). RHH and RCH were determined by exposing B. distincta life stages to extreme temperatures of 41 and -8 °C, respectively. Acclimation effects on CTmax and CTmin were quantified by exposing B. distincta life stages to 48 h at 20, 25, and 30 °C. Temperature was ramped up and down at a rate of 0.2 min-1 to score survival at high (CTmax) and low (CTmin) critical temperature points (Chapter 3). Thirdly, the development rate was monitored (on the host plant) at temperatures ranging from 18 to 40 °C to acquire the total heat required to complete development (degree-days) and thermal requirements of each life stage of B. distincta. iv Lastly, the physiological traits, degree-days, and thermal requirements were used to predict seasonal generation turn-over, heat and cold thermal stress, thermal safety margin (TSM), and relative fitness in macadamia orchards along an elevational gradient (705 - 1493 m a.s.l.) to determine the effects of climatic zones (Cwa climate zone: Monsoon-influenced humid subtropical climate, Cwb: Subtropical highland climate or Monsoon-influenced temperate oceanic climate, and Bsh: Hot semi-arid steppe climate) (Chapter 4). B. distincta developed at a wide range of temperatures on sweetcorn (18 to 29 °C) and macadamia nut (18 to 35 °C). The survival rate was high (51 to 100 %) between temperatures with a monotonic increase of population growth from 19 to 29 °C. The total number of heat units required to complete development was 783 DD. All life stages of B. distincta displayed thermal plasticity, but instar 2 was the most plastic stage except in response to cold acclimation. Response to extremes varied more at low extreme temperatures compared to high extremes. As expected, the number of generations decreased with increasing elevations from the Cwa (Arbor: 2.4 generations) to the Cwb climate zone (Highfield: 1.1 generations). None of the life stages experienced thermal stress. TSM and relative fitness were highest at the Cwb climate zone of the highest elevation. These findings suggest that B. distincta will potentially cause more damage in response to global warming because of its estimated population growth rate at elevated temperatures. Although relative fitness was highest in the Cwb climate zone, damage could be expected in the Cwa zone due to increased number of generations. This study can also help identify macadamia orchards in climate zones vulnerable to climate-related consequences such as outbreaks. Climatic data combined with the DD model can be used to predict the phenology of B. distincta and timing of chemical applications. The impacts of global warming on crop losses due to insect pests are evident worldwide, and this study has shown that macadamia orchards in certain climatic zones (e.g., Cwa climate zone) could be at risk of increased abundance of B. distincta. Thus, integrated pest management strategies should be of priority to macadamia farmers for effective management of B. distincta. Given that South Africa is the largest producer of macadamia globally and its major pest is thermal plastic, linking the physiological traits of B. distincta life stages to climatic conditions of all macadamia growing regions in South Africa will help understand its distribution limits.