Academy of Science of South Africa (ASSAf): Open Journal Systems
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Distribution and impact of the native South African wasp, Megastigmus transvaalensis (Hussey, 1956) (Hymenoptera: Torymidae) on the invasive Schinus terebinthifolia Raddi (Anacardiaceae) in South Africa
No full textSchinus terebinthifolia Raddi (Anacardiaceae) (Brazilian pepper tree) is a tree native to subtropical South America that was introduced into South Africa as an ornamental plant. Globally, it is regarded as one of the world’s worst invasive trees. In South Africa the tree has acquired a native seed-feeding wasp, Megastigmus transvaalensis (Hussey, 1956) (Hymenoptera: Torymidae). The wasp’s native hosts are from the Searsia F.A. Barkley genus (Anacardiaceae), but it has expanded its host range to form a new association with both S. terebinthifolia and its close relative Schinus molle L. (Anacardiaceae). In order to quantify the seed predation by M. transvaalensis on S. terebinthifolia seeds, tree populations were surveyed across the Eastern Cape and KwaZulu-Natal provinces. The wasp was present at 99% of the S. terebinthifolia populations with an average of 22% of the seeds being destroyed. In the Eastern Cape province, the highest seed damage occurred at the start of the winter months, when about 35% of seeds were damaged. This fell to less than 12% in spring and summer when the plants were flowering. Megastigmus transvaalensis was found at nearly all the S. terebinthifolia populations in South Africa, but due to the limited number of predated seeds it is unlikely to reduce population sizes or curb the spread of the invasive alien tree in South Africa
Infection of insects and persistence of Metarhizium (Hypocreales: Clavicipitaceae) species on apple bark
No full textEntomopathogenic fungi (EPF) are cosmopolitan soil borne pathogens that cause epizootics in various insect
orders. EPF isolates of Metarhizium brunneum and M. pinghaense have shown the potential for use as biological
agents of important agricultural insect pests. The aim of the current study was to test for the persistence of
M. brunneum and M. pinghaense on apple bark over a period of three weeks, under laboratory conditions. Apple
bark was sprayed with conidial suspensions of both fungi, at a standard infective conidial concentration of
107 conidia/ml. The persistence, or survival, of the conidia on apple bark was measured using codling moth
larvae (CM) (Cydia pomonella) and females of woolly apple aphid (WAA) (Eriosoma lanigerum) as indicator
species. The results showed that conidia of M. pinghaense can induce mortality of insect pests through contact
with an EPF-treated substrate, with mortality of 39% to 82% for WAA over a period of 10 days post application,
and with mortality of 3% to 68% for CM over a period of 7 days, after application to apple bark. Further
evaluation showed that the conidia of M. pinghaense persisted longer on apple bark, up to 63%, than did
M. brunneum, up to 11%, three weeks post application of the conidial suspensions. The study provides insights
into the potential persistence of fungal isolates on apple bark over time post application. Further evaluation of
the persistence of the isolates on apple bark under both glasshouse and field conditions should be conducted
Is There a Case for Supporting Animal Traction Research, Policy, and Practice in Rural South Africa? - A Review
No full textAppropriate and efficient technology contributes a great deal to smallholder farmer development. This study uses a systematic literature review to debate whether animal traction research and practice should receive support. Firstly, the smallholder farming system is reviewed to contextualise the discussion and present a state-of-the-art review of animal traction in South Africa. After finding the diminishing use of animal traction among smallholder farming systems, the inquiry probes the causes of the rural development policies, basic education curriculum, and higher learning institutions. The results reveal that the technological needs of smallholder farmers can be met with animal traction. However, a lack of support from policies and learning institutions has contributed to the negative attitude toward animal traction. We further note that new animal traction technology is unlikely to be known to smallholders because of poor information dissemination caused by a weak agricultural extension. After realising the benefits of animal traction, it seems worthwhile to revamp animal traction research and practice for subsistence farmers
Baseline Study of Soil Nutrient Status in Smallholder Farms in Limpopo Province of South Africa
No full textAn assessment of soil nutrient status based on farmers’ samples was carried out in the Capricorn, Sekhukhune, and Waterberg Districts of the Limpopo Province of South Africa. A total of 336 soil samples were collected and analysed for pH, phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg). The results showed that the pH of more than 80% of the submitted soil samples was suitable for the production of most field crops ,while less than 20% required liming to make them productive. Phosphorus levels were very low (<8 mg kg-1), with most soils (≥95%) needing P fertilisation to improve crop yields. Potassium was adequate (>250 mg kg-1) for most districts' crops. Between 70% and 74% of soils from Sekhukhune and Waterberg Districts were deficient in Ca (<200 mg kg-1). Magnesium was adequate (>300 mg kg-1) in more than 60% of the analysed samples. Apart from soil pH, all soil properties showed a high degree of variability across all districts. Further studies are needed to investigate the role of field management, crop rotation, field position in the landscape, lithology, and socioeconomic conditions of the farmer on the observed trends of soil nutrients
Comparison of phosphorus-based extractants on manganese separation from citrate leach solutions for recycling of lithium-ion batteries
No full textThe performance requirements of modern lithium-ion batteries (LIBs) necessitate the use of a number of scarce and strategically sensitive metals such as lithium and cobalt. Recycling end-of-life LIBs reduces the demand on the primary sources of these metals and helps reduce the environmental impact of LIB waste. Citric acid has proven to be an effective environmentally friendly and sustainable lixiviant; however, the formation of metal citrate complexes complicates subsequent metal separation processes such as solvent extraction. This study enhances the understanding of LIB metal separation from citric acid media by comparing the metal separation performance of phosphorus-based liquid-liquid extractants from a citric acid leach. The optimum Mn(II) extraction pH decreases as the extractant’s phosphorus oxidation state increases from phosphinic to phosphonic to phosphoric, due to the oxygen atoms that surround the central phosphorus atom. The maximum Mn(II) separation with Cyanex 272, PC-88A, and D2EHPA was observed at pHs of 6, 3, and 3, respectively. D2EHPA further provided the best separation of Mn(II) over Al, Co, Li, and Ni with separation factors of 137, 191, 118, and 601, respectively. No research is currently available on the metal separation performance of phosphonic (PC-88A) or phosphinic (Cyanex 272) organic extractants from citric acid media.Significance:
This study is the first to investigate the use of phosphonic and phosphinic extractants for metal separation from citric acid leach solutions, towards using citric acid as an environmentally friendly lixiviant.
The phosphoric extractant, D2EHPA, enabled successful and sequential separation and extraction of aluminium, manganese and lithium, making the process technologically feasible and attractive
Immunological interaction during helminth and HIV co-infection: Integrative research needs for sub-Saharan Africa
No full textThe potential of decentralised wastewater treatment in urban and rural sanitation in South Africa: lessons learnt from a demonstration-scale DEWATS within the eThekwini Municipality
No full textThe design principles of decentralised wastewater treatment systems (DEWATS) make them a practical sanitation option for municipalities to adopt in fast-growing cities in South Africa. Since 2014, a demonstration-scale DEWATS with a modular design consisting of a settler, anaerobic baffled reactor (ABR), anaerobic filter (AF), vertical down-flow constructed wetland (VFCW) and horizontal flow constructed wetland (HFCW) has been in operation in eThekwini. A performance evaluation after the long-term operation was undertaken in 2019 by comparing the final effluent with national regulatory requirements. Despite limitations in characterising the raw wastewater, a comparison of the settler and final effluent quality indicated high (≥ 85%) removal efficiencies of total chemical oxygen demand (CODt), ammonium-N (NH4-N) and orthophosphate-P (PO4-P), 75% removal of total suspended solids (TSS) and 83.3% log10 removal of Escherichia coli. Lack of exogenous and endogenous carbon and high dissolved oxygen (DO) concentrations (> 0.5 mg‧L−1) inhibited denitrification in the HFCW, resulting in 12.5% of the effluent samples achieving compliance for nitrate-N (NO3-N). Moreover, mixed aggregate media and low residence times in the HFCW may have also contributed to poor NO3-N removal. During the COVID-19 lockdown, an unexpected shutdown and subsequent resumption of flow to the DEWATS indicated a 16-week recovery time based on achieving full nitrification in the HFCW. Although design modifications are necessary for the HFCW, the installation of urine diversion flushing toilets at the household will reduce the nutrient loading to the DEWATS and potentially achieve fully compliant effluent. Alternatively, the application of two-stage vertical flow constructed wetlands to improve denitrification should also be explored in the South African context. With an improved design, DEWATS has the potential to fill the gap in both urban and rural sanitation in South Africa, where waterborne sanitation is still desired but connections to conventional wastewater treatment works (WWTWs) are not possible
ABANDONMENT OF RIGHTS TO MINERALS GRANTED IN TERMS OF THE MINERAL AND PETROLEUM RESOURCES DEVELOPMENT ACT
No full textA peculiar feature of the Mineral and Petroleum Resources Development Act (MPRDA) is the mention of the possibility of abandoning rights granted in terms of its provisions. It has been commented by Van der Schyff that the possibility of abandoning these rights is inconsistent with the Act’s objectives of the MPRDA. In particular, empowering a right-holder to abandon a right granted in terms of the MPRDA fails to take into account that such a right comes with significant responsibilities and obligations. As such, unilateral abandonment should not be possible in terms of the legal framework created by the MPRDA.This article seeks to address this peculiarity in the MPRDA. It considers the legislative context in which such an abandonment (if possible) would operate. The analysis of the possibility of abandoning rights granted in terms of the MPRDA is undertaken in light of theoretical observations in respect of the abandonment of property rights, in particular the seminal article on the subject by Peñalver. The article seeks to answer the question as to whether abandonment, as envisaged by the MPRDA, is possible in the legal framework the Act creates, and outlines the potential consequences thereof for the would-be abandoner
The Practice of Oral Medicine in South Africa
Get PDFOral medicine is a clinical discipline, practiced by periodontists, which concerns itself mostly with the non surgical management of oral mucosal diseases. Many of these diseases are rare and the discipline less well known – making it essential to identify the obstacles this discipline faces. The purpose of this study was to describe the private and academic practice of Oral Medicine. A self-administered, internet-based, questionnaire was distributed to South African periodontists which questioned the clinician’s competency, diseases managed, special investigations performed, referral sources, proportional time and monetary distribution of the discipline, and perceived barriers to the practice. Twenty-six periodontists completed the questionnaire. In comparison to periodontology and implantology, periodontists generally feel less competent, spend less time on, and receive less money from Oral Medicine. Lack of awareness of the speciality (55.6% - 59.3%) was identified as the biggest constraint, with only 11.2% of referrals received from medical doctors. Immune-mediated diseases (29.3%) and benign neoplasms (26.5%) are managed the most, and surgical biopsies (80.2%) are used most regularly to diagnose oral mucosal disease. Oral Medicine is still a lesser-known clinical speciality. Despite the heavy burden of HIV-related oral disease and oral mucosal malignancies, this speciality remains underutilised
MAXILLOFACIAL RADIOLOGY Nevoid Basal Cell Carcinoma Syndrome
Get PDFAn 18-year-old male patient presented at our dental clinic in 2009 for a dental assessment. A panoramic radiograph was taken to evaluate dental crowning (Figure 1). An incidental finding was noted in the right maxilla, presenting as a well-demarcated, round, unilocular, radiolucent lesion with a corticated rim extending from the right maxillary tuberosity area to distal of the 16 causing. impaction of the 18. A biopsy was taken and diagnosed as an odontogenic keratocyst (OKC) that was subsequently enucleated. In 2021 the patient returned, and another panoramic radiograph (Figure 2) and a Waters view was taken where calcification of the falx cerebri was seen (Figure 3). On the panoramic radiograph an additional mandibular lesion was visible that presented as a well-demarcated, round, unilocular, radiolucent lesion with a corticated rim extending from distal of the 46 into the missing 47, 48 area. A CBCT was then. taken to further analyse the lesions (Figure 4). A biopsy was taken in the right posterior mandible and diagnosed as an OKC. In 2023 the patient returned and a CBCT was taken. The right maxilla showed increased bone density adjacent to the enucleated lesion (Figure 5)