Department of Biological Sciences

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Open Access
3D Cranial Morphometry, Sensory Ecology and Climate Change in African Rodents
(2019-05-15) Nengovhela, Aluwani; Taylor,, Peter; Braga, Jose
The order Rodentia is the most speciose group of mammals with muroids being the most diverse superfamily. Since they are represented in arboreal, semiaquatic, subterranean and terrestrial niches, rodents may exhibit morphological traits reflecting their adaptations to such diverse environments. This thesis focuses on the morphology of the endocranium, auditory bulla and cochlea in three tribes (Otomyini, Taterillini and Gerbillini) representing 10 species of African rodents, concentrating on their variability, function and adaptability, using micro-CT imaging and 3D shape comparative methods. Additionally, variations in cranial size were also studied in respective of global warming and climatic variables. Morphological changes/variations are a result of environmental change, therefore each chapter in this study details the effect of environmental change (in space and time) on different morphological traits i.e. general cranial size (chapter 2), cochlea and auditory bulla (chapter 3) and endocranial size and shape (chapter 4). With chapter 2 dealing specifically with climate change in its strict sense and the remaining two chapters looking at different environmental gradients. Chapter 2 tests the applicability of the “third universal response to warming” (i.e. declining body size) and the Resource Rule in two murid subfamilies, Murinae and Gerbillinae. The study shows that the third response is not as universal as only one species conformed to this response. Further, food availability (Resource Rule) was shown to be the more important factor correlated with body size variations in rodent species than Bergmann’s Rule. Chapter 3 looks at the auditory bulla and cochlea, the morphological traits that play a role in hearing capabilities of rodents. I found, with some exceptions, that bulla and cochlea modifications between species could be explained by environment, phylogeny and/or allometry. In addition, I concluded that true desert adapted laminate-toothed rats and gerbils use both bulla and associated cochlea hypertrophy. Chapter 4 shows larger brain size in Taterillini and two species of Otomyini, with life histories and environment being the most probably factors responsible for xiv this. Using a novel method of diffeomorphism (deformation models), there was more variation in endocranial morphology between the gerbils and laminate-toothed rats than within them with olfactory bulb, paraflocculi, and posterior ventral cortex showing the most variability. Overall, this thesis shows that variations in the morphological traits studied are strongly influenced by the environment and function.
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.
Open Access
Animal taxa contrast in their scale-dependent responses to land use change in rural Africa
(2018-05-08) Foord, Stefan Hendrik; Swanepoel, Lourens Hendrik; Evans, Steven Wiiliams; Schoeman, Colin Stephan; Erasmus, Barend Frederik N.; Schoeman, M. Corrie; Keith, Martin; Smith, Alain; Mauda, Evans Vusani; Maree, Naudene; Nembudani, Nkhumeleni; Dippenaar-Schoeman, Anna Sophia; Munyai, Thinandavha Caswell; Taylor, Peter John
Human-dominated landscapes comprise the bulk of the world's terrestrial surface and Africa is predicted to experience the largest relative increase over the next century. A multi-scale approach is required to identify processes that maintain diversity in these landscapes. Here we identify scales at which animal diversity responds by partitioning regional diversity in a rural African agro-ecosystem between one temporal and four spatial scales. Human land use practices are the main driver of diversity in all seven animal assemblages considered, with medium sized mammals and birds most affected. Even the least affected taxa, bats and non-volant small mammals (rodents), responded with increased abundance in settlements and agricultural sites respectively. Regional turnover was important to invertebrate taxa and their response to human land use was intermediate between that of the vertebrate extremes. Local scale (< 300 m) heterogeneity was the next most important level for all taxa, highlighting the importance of fine scale processes for the maintenance of biodiversity. Identifying the triggers of these changes within the context of functional landscapes would provide the context for the long-term sustainability of these rapidly changing landscapes
Open Access
Ant and spider diversity in a rural landscape of the Vhembe Biosphere, South Africa
(2017-09-18) Mauda, Evans Vusani; Foord, S. H.; Munyai, T. C.
See the attached abstract below
Open Access
Assessing species richness patterns and conservation threats (due to overharvesting and climate change) in South African Cycads, with emphasis on a population of Encephalartos tranvenosus Stapf and Burt Davy from the Soutpansberg Mountain, Limpopo Province
(2018-05-18) Bamigboye, Samuel Oloruntoba; Tshisikhawe, Peter Milingoni; Taylor, Peter John
Cycads are regarded as the oldest living seed plants on earth and they have existed for about 300 million years. Ever since the awareness of the existence of this plant group, they have been facing high extinction risk. Currently they are referred to as the most threatened plant group in the world. Many ecological and anthropological forces are promoting extinction crisis of this taxonomic group. Africa is one of the centres of diversity of this plant group with 70% of the total number of the taxa in this group in Africa found in South Africa. Also South Africa is one of the global hotspots for cycads and it contains the third largest number of cycads after Australia and Mexico. Studies have revealed that there have been high threats and extinction risks among the cycad taxa in South Africa. The Soutpansberg Mountain is a major biodiversity hotspot in Limpopo Province in South Africa with high level of flora and fauna taxa. About 3000 vascular plants species are represented on this mountain. Biodiversity on this mountain has been under threat in recent times and there is need to investigate how cycads are facing risk on this mountain. The main focus of this study is to look at the extinction pattern in South African cycads and cycads endemic to Soupandberg Mountain in Limpopo Province in South Africa. v The first objective evaluated all African cycads over a decade using IUCN red list. Data from IUCN 2014 version was used to calculate the percentages of African cycads in each IUCN categories. The results were compared with those presented by Donaldson 2003. They showed that there have been significant decline and increase in extinction of African cycads over this period. It was also discovered that majority of this extinction crisis were trending in South Africa. The second objective used the IUCN red list to evaluate extinction pattern in South African cycads. The percentages of IUCN threat categories of South African cycads was calculated using IUCN red list. ArcGIS was used to construct distribution map for threatened and extinct South African cycads. The study revealed that the proportion of historically Extinct and Critically Endangered cycads is higher in Limpopo, KwaZulu-Natal and Mpumalanga than the rest of the provinces in South Africa. The third objective of this research investigated extinction pattern of Encephalartos transvenosus Stapf & Burtt Davy (Modjadji cycad) on Soutpansberg Mountain. Indigenous knowledge and population ecology approaches were used to determine current threats Modjadji cycads are facing on Soutpansberg Mountain. The results showed that anthropogenic activities have caused a substantial decline of one important unprotected population of this species on Soutpansberg Mountain.
Embargo
Assessing the genetic diversity and structure of spotted hyena (Crocuta Crocuta) populations across Africa
(2025-09-05) Dibakoane, Kagisho; Moodley, Yoshan; Westbury, Michael Vincent
The 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.
Open Access
Assessment of androstachys johnsonii prain, stem utilization in Matshena Village, Mutale Local Municipality, Limpopo Province
(2016-02-02) Bakali, Mulalo; Tshisikhawe, M. P.; Ligavha-Mbelengwa, M. H.
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.
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.
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.
Open Access
Bioactivity and chromatographic profiles of the selected medicinal plants against candida albicans
(2015-07-17) Mulaudzi, Takalani Millicent; Masevhe, N. A; Mojapelo, P. E. L
Open Access
Comparative in vitro cytotoxic, anti-inflammatory and anti-microbiological activities of two indigenous Venda medicinal plants
(BioMed Central, 2016 December 09) Sigidi, M. T.; Anokwuru, C. P.; Zininga, T.; Tshisikhawe, M. P.; Shonhai, A.; Ramaite, I. D. I.; Traore, A. N.; Potgieter, N.
Background: The Vhembe region of the Limpopo province has a rich tradition of medicinal plants use. Traditionally, boiled roots of Ziziphus mucronata are used in the treatment of boils, general swelling and other skin infections. A combination of leaf paste and root infusion treats measles, dysentery, chest complains, and gland swelling. Pterocarpus angolensis is famous for the treatment of menorrhagia, infertility in women, wounds and pain management. The purpose of the present study was to compare the cytotoxicity, anti-inflammatory potential and anti-microbial activities of Ziziphus mucronata and Pterocarpus angolensis from the Vhembe region. Method: U937, MeWo, Vero and RAW 264.7 cells were treated to various concentrations (50, 100, or 125 or 250 μg/ml depending on assays) of Ziziphus mucronata and Pterocarpus angolensis. Cytotoxicity assay was done using MTT; Antiinflammatory activity was assessed using NO production; Anti-bacterial activity was done using the Micro-Broth dilution method and Anti-mycobacteria activity was determined using the Alamar Blue Method while RT activity was measured by ELISA. Results: Cytotoxicity results showed that Pterocarpus was more toxic than Ziziphus as observed in the Vero and MeWo cells; however both displayed toxicity towards a Human cancer cell line. Both extracts did not inhibit nitrate production but induced significant increase in macrophage activation. The plant extracts have shown anti-tuberculosis activity at concentrations >500 μg/ml and there was moderation inhibition of HIV replication. Conclusions: The results obtained indicated that the extracts have pro-inflammatory properties, and the observed toxicity on malignant cell lines must be investigated further for promising anti-cancer drug therapy.
Open Access
Comparative population ecology of sclerocarya birrea (A. RICH.) HOCHST. Subspecies Caffra (SOND) in two rural villages of Limpopo Province, South Africa
(2018) Mocheki, Tebogo Alison; Ligavha-Mbelengwa, Maanda Hadzhi; Tshisikhawe, Milingoni Peter; Swelankomo, Nonkululeko; Tshivhandekano, Thivhilaeli Robert; Mokganya, Mokgaetji Georgina; Ramovha, Luvhimba Isaac; Masevhe, Ndivhaleni Anox
Sclerocarya birrea (A Rich.) Hochst. subspecies caffra (Sond) is a plant species belonging to the Anacardiaceae family. In South Africa, it is dominant in the Baphalaborwa area in the Limpopo Province. Throughout its distribution range, S. birrea is a keystone species that is highly utilized by herbivores and people. Understanding the utilization pattern assist in determing if the population is not negatively affected. The aim of this study was therefore to compare the distribution patterns and population status of S. birrea in Ga-Makhushane and Tshivhongweni villages in the Limpopo Province. The study will investigate the influence of culture in utilization of S. birrea resources since the study area are made up of communities of people from different cultures. Nearest-neighbour method of sampling individuals within a population of plants was used to collect data on S. birrea populations which was analyzed using Analysis of Variance. It was found that the populations were regularly distributed meaning there is an antagonistic relationship of the species with the users in both villages, and there was also a significant difference in distribution patterns between the two villages. It was concluded that although S. birrea is regularly distributed in both villages, there are differences in terms of interplant distances, heights, stem circumferences and canopy covers. It means that the two culturally different communities have different preferences when they harvest resources form S. birrea species
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.
Open Access
The complete mitochondrial genome of Africa's largest freshwater copepod, Lovenula raynerae
(2018-11-18) Jooste, Candice M.; Emani-Khoyi, Arsalan; Gan, Hang Ming; Wasserman, Ryan J.; Dalu, Tatenda
Lovenula raynerae is the largest known African freshwater copepod. To date, it has only been sampled from ephemeral freshwater ecosystems. This paper reports the complete mitochondrial genome of L. raynerae, which was found to be 14,365 bp long. Base composition of 33.5% base A, 19.3% base G, 34.6% base T, and 12.5% base C was found, with 13 protein-coding genes, 22 tRNAs, and 2 rRNAs. This paper contributes to an improved understanding of phylogenetic relationships in an important crustacean group
Open Access
The complete mitogenome of a South African cryptic species of tadpole shrimp within the Triops granarius (Lucas, 1864) species group
(Taylor & Francis, 2018-11-02) Gan, Han Ming; Wasserman, Ryan John; Dalu, Tatenda; Rogers, D, Christopher
The complete mitochondrial genome of a cryptic species of tadpole shrimp from South Africa (Accession Number: MG770893) was recovered by low coverage shotgun sequencing. The mitogenome consists of 15,216 bp with a GC content of 30.95%. COX1 sequence alignment indicates that this specimen is the most closely related to Triops granarius with a pairwise nucleotide identity of less than 90% (86.6%). Phylogenetic analysis using whole mitogenome dataset supports its affiliation to the genus Triops with moderate support for its relatively basal position within the clade.
Open Access
Conservation Strategies of the Red Listed Brackenridgea zanguebarica Oliv. in Vhembe District Municipality, Limpopo Province, South Africa
(2019-09-20) Tiawoun, Makuete Andre; Tshisikhawe, M. P.; Gwata, E. T.
Brackenridgea zanguebarica Oliv. (Ochnaceae) commonly known as “Yellow Peeling Plane”, is an important medicinal plant species, and one of the most threatened tree species that is endemic to Thengwe village in Vhembe District, South Africa. It is widely harvested for traditional purposes and difficult to propagate sexually and asexually. Nowadays, it has become threatened and this unique plant population is believed to be declining in the Brackenridgea Nature Reserve (BNR). According to the Red List of South African plants, B. zanguebarica is considered a critically endangered medicinal plant. All these facts combined with a lack of knowledge on the conservation of this species prompted this study on its conservation. To ascertain the effective conservation and proper management of this multipurpose tree, this study was conducted with the aim to improve its conservation strategy by investigating current threats to the existence of B. zangueberica, the chemical constituents from the different plant parts, the propagation methods of the species, and the factors delaying the germination of its seeds. In this study, an assessment of the current population threats was important as a first step in conservation; this would update the status of the species in its natural habitat. The current status of Brackenridgea zanguebarica was conducted through an extensive field survey in the Brackenridgea Nature Reserve (BNR), where a belt transect method was deployed to record quantitative information, while the harvesting damage was estimated using a sliding scale from 0 to 5. The structure of the populations in terms of the stem diameter size classes showed a bell shape vi pattern. About 60% of individuals showed some signs of plant parts extraction as the stem bark was reported to be the main plant part harvested. The population structure, however, was dominated by juvenile plants due to the selective harvesting of mature individuals; this hinders fruit production leading to poor or slow seed production. The present study aimed to compare the chemical constituents and the antimicrobial activities of some parts of this plant species. The extracts were screened for phytochemicals using standard methods. Thin-layer chromatography (TLC) was carried out to compare the chemical constituents using various solvent systems of varying polarity. Agar well diffusion and broth microdilution methods were used to evaluate the antimicrobial activity and the minimum inhibitory concentrations (MIC) of plant extracts respectively, against three bacteria and four fungi. The phytochemical analysis revealed a close similarity of various phytoconstituents of the three plant parts (stem bark, twigs and leaves). TLC analysis showed a slight difference in the acetone extract of different plant parts with more bands on the leaves than the stem bark and twigs. Acetone extracts of the three plant parts exhibited varying degrees of antimicrobial activity against Staphylococcus aureus and Candida glabrata, while none of the extracts showed any activity against Escherichia coli, Klebsiella pneumonia, Candida albicans, C. krusei, and C. parapsilosis. However, analysis of the antibacterial activity of various extracts revealed that the best inhibitory activity was produced by the stem bark extract compared to the leaf and twig extract. vii The sustainable way to meet the growing demand of Brackenridgea zanguebarica is to increase its availability through propagation practices. Unfortunately, the conservation of B. zanguebarica is hampered by lack of information on how it can be propagated. Sexual and asexual propagations were conducted to determine an efficient method to increase the number of individuals of this plant species. Seed propagation was carried out to study the effect of various pre-treatments on germination, in order to understand the germination requirements; vegetative propagation was conducted to assess if B. zanguebarica could be successfully propagated via stem cuttings if the appropriate growth hormones and growing media were applied. Brackenridgea zanguebarica seed did not germinate at all under any of the conditions tested. However, the results, showed the potential of propagating this species from stem cutting despite the poor results obtained. Thus B. zanguebarica was found to be difficult to propagate sexually and asexually. Seeds serve as a means of reproduction and a vital element to ensure the survival of plant species. Seed germination is controlled by a number of factors. The propagation of B. zanguebarica via seed is very difficult and research has not been undertaken to understand possible factors that may delay its germination. This study was aimed to investigate and describe both the morphological and anatomical features of B. zanguebarica seed, in order to identify structural features implicated in its poor germination. To achieve this goal, a morphological and anatomical study was conducted based on the observation of seeds under a scanning electron microscope (SEM) and light microscopy (LM). Water uptake potential was assessed by the increase in seed mass. The morpho-anatomical analysis indicated that some structures of the seed, such as seed coat, and the presence of endosperm viii surrounding the embryo that consisted of two prominent cotyledons, seem to greatly hinder the germination of this species. The research findings provided information regarding the seed structure which is one important step in identifying useful techniques to improve seed germination for conservation purposes.
Open Access
Detecting threats to Encephalartos transvenosus (Limpopo cycad0 in Limpopo province, South Africa through indigenous knowledge
(2016-08-09) Bamigboye, Samuel O.; Tshisikhawe, Peter M.; Taylor, Peter J.
Indigenous knowledge contains valuable information which is often essential to biodiversity and species conservation. The traditional knowledge of people in local communities can enhance conservation policies and planning and also reveal local perspectives in relation to endangered species. Cycads as a vascular plant group contain the highest percentage of threatened plant species, at global, regional, national and community levels. In this study we focused on Encephalartos transvenosus Stapf & Burtt Davy, a cycad species endemic to Limpopo province in South Africa. Despite every effort to conserve this highly endangered species the threats keep increasing and the population keep decreasing. Through indigenous knowledge, we discovered a location of this species not yet conserved within Vhembe district on the Soutpansberg mountain range in Limpopo province, South Africa. Practices such as bark harvesting, and uprooting of young seedlings were discovered at this population. All these practices noticed at this location are detrimental to in situ conservation of the cycads. This study hereby revealed that indigenous knowledge has a great role in cycads’ conservation. Through the local communities, factors that are threatening cycads existence can be determined and the local community can also be integrated in effective conservation plan that discourage illegal harvesting of cycads.
Open Access
The diet of an invasive crayfish, Cherax quadricarinatus (Von Martens, 1868), in Lake Kariba, inferred using stomach content and stable isotope analyses
(Invasivenet, 2018-01-27) Marufu, Lighthouse T.; Dalu, Tatenda; Phiri, Crispen; Barson, Maxwell; Simango, Rutendo; Utete, Beaven; Nhiwatiwa, Tamuka
The diet of an invasive crayfish, Cherax quadricarinatus (Von Martens 1868), in Lake Kariba, was investigated using stomach content analysis (SCA) and stable isotope analysis (SIA). The frequency of occurrence of macrophytes and detritus ranged between 63.6–97.1% and 20–45.5%, respectively, and the index of relative importance ranked these as the two most important food items across all size classes. Significant differences in the ranking of fish, macroinvertebrates and crayfish were found between size classes 29–37.9, 38–46.9 and 47–55.9 mm. Stomach content analysis showed 16% of crayfish stomachs were empty. Feeding intensity differed significantly between size classes and ranged from 3.46 to 5.21. Stable isotope analysis was done by comparing δ13C, δ15N and C/N ratios in crayfish muscle and potential dietary items in the lake. Macrophytes were the most dominant food item (57%), followed by macroinvertebrates (20%), then detritus, and finally fish and crayfish. Stable isotope analysis revealed that all crayfish size classes analysed were in the same trophic level. Nevertheless, while SCA showed high dietary overlap among all crayfish size classes (>65%), SIA showed that small crayfish (< 28.9mm) had limited overlap with large crayfish (> 56mm), with the former showing a higher proportion of macroinvertebrates in their diet. In Lake Kariba, C. quadricarinatus predominantly feeds on macrophytes, macroinvertebrates and detritus, which may bring about nutrient cycle alterations in the lake. Littoral habitat changes caused by the feeding characteristics of C. quadricarinatus might also lead to competition with, and eventual displacement of, some native littoral fishes in this lake
Open Access
The distribution patterns, utilisation and conservation of Sclerocarya birrea (A. RICH.) HOCHST, SUBSP. CAFFRA in two villages of the Limpopo Province, South Africa
(2016-05) Mocheki, Tebogo Allison; Ligavha- Mbelengwa, M. H.; Tshisikhawe, M. P.
See the attached abstract below