scholarly journals Estimates of the population size and dispersal range of Anopheles arabiensis in Northern KwaZulu-Natal, South Africa: implications for a planned pilot programme to release sterile male mosquitoes

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Maria L. Kaiser ◽  
Oliver R. Wood ◽  
David Damiens ◽  
Basil D. Brooke ◽  
Lizette L. Koekemoer ◽  
...  
Keyword(s):  
South Africa ◽  
Vector Control ◽  
Population Size ◽  
Malaria Vector ◽  
Anopheles Arabiensis ◽  
Dispersal Distance ◽  
Successful Implementation ◽  
Sterile Male ◽  
Mark Release Recapture ◽  
The Right

Abstract Background Anopheles arabiensis is a major malaria vector, recently implicated as contributing to ongoing residual malaria transmission in South Africa, which feeds and rests both indoors and outdoors. This species is, therefore, not effectively targeted using core malaria vector control interventions alone. Additionally, increasing resistance to available insecticides necessitates investigations into complementary non-insecticide-based vector control methods for outdoor-resting mosquitoes. The feasibility of the sterile insect technique (SIT) as a complementary vector control intervention is being investigated in South Africa. Successful implementation of an SIT programme largely depends on inundating a target insect population with sterilized laboratory-bred males. Therefore, knowledge of the native population size and dispersal ability of released sterile laboratory-reared males is critical. In this study, we estimated the male An. arabiensis population size and the dispersal of released males in an area targeted for a pilot sterile male release programme. Methods Three separate releases were performed within a 2-year period. Approximately 5000–15,000 laboratory-reared male An. arabiensis (KWAG) were produced and marked for mark–release–recapture experiments. To recapture released mosquitoes, cloth tubes were deployed in widening concentric circles. The average dispersal distance of released males was calculated and the wild male An. arabiensis population size was estimated using two Lincoln index formulae. The natural population was sampled concurrently and Anopheles species diversity examined. Results The Anopheles gambiae complex and An. funestus group species made up the majority of wild collections along with other anophelines. The An. arabiensis population size was estimated to be between 550 and 9500 males per hectare depending on time of year, weather conditions and method used. Average dispersal distance of marked males ranged from 58 to 86 m. Marked males were found in swarms with wild males, indicating that laboratory-reared males are able to locate and participate in mating swarms. Conclusions It was logistically feasible to conduct mark–release–recapture studies at the current scale. The population size estimates obtained may provide a guideline for the initial number of males to use for a pending SIT pilot trial. It is promising for future SIT trials that laboratory-reared marked males participated in natural swarms, appearing at the right place at the right time.

scholarly journals Additional evidence on the efficacy of different Akirin vaccines assessed on Anopheles arabiensis (Diptera: Culicidae)

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Blaženka D. Letinić ◽  
Marinela Contreras ◽  
Yael Dahan-Moss ◽  
Ingrid Linnekugel ◽  
José de la Fuente ◽  
...  
Keyword(s):  
Vector Control ◽  
Aedes Albopictus ◽  
Malaria Vector ◽  
Vaccine Efficacy ◽  
Anopheles Arabiensis ◽  
Vaccine Development ◽  
Target Antigen ◽  
Control Methods ◽  
Protective Response ◽  
Current Vector

Abstract Background Anopheles arabiensis is an opportunistic malaria vector that rests and feeds outdoors, circumventing current indoor vector control methods. Furthermore, this vector will readily feed on both animals and humans. Targeting this vector while feeding on animals can provide an additional intervention for the current vector control activities. Previous results have displayed the efficacy of using Subolesin/Akirin ortholog vaccines for the control of multiple ectoparasite infestations. This made Akirin a potential antigen for vaccine development against An. arabiensis. Methods The efficacy of three antigens, namely recombinant Akirin from An. arabiensis, recombinant Akirin from Aedes albopictus, and recombinant Q38 (Akirin/Subolesin chimera) were evaluated as novel interventions for An. arabiensis vector control. Immunisation trials were conducted based on the concept that mosquitoes feeding on vaccinated balb/c mice would ingest antibodies specific to the target antigen. The antibodies would interact with the target antigen in the arthropod vector, subsequently disrupting its function. Results All three antigens successfully reduced An. arabiensis survival and reproductive capacities, with a vaccine efficacy of 68–73%. Conclusions These results were the first to show that hosts vaccinated with recombinant Akirin vaccines could develop a protective response against this outdoor malaria transmission vector, thus providing a step towards the development of a novel intervention for An. arabiensis vector control. Graphic Abstract

Bionomics of Anopheles Arabiensis from Mamfene in KwaZulu-Natal (South Africa): An Area of High Malaria Transmission in the Province

2020 ◽  
Author(s):  
Rajendra Maharaj ◽  
Vishan Lakan ◽  
Kiash Maharaj
Keyword(s):  
South Africa ◽  
Vector Control ◽  
Anopheles Arabiensis ◽  
Mosquito Control ◽  
Sex Ratios ◽  
Adult Mosquito ◽  
Mosquito Vector ◽  
Larval Control ◽  
Kwazulu Natal ◽  
The Impact

Abstract Background: Although great strides have been made in controlling malaria, the disease is of significant public health importance. Historically, efforts to control the vector has concentrated on adult vector control targeting the female Anopheles mosquitoes. As there is now a focus on eliminating residual malaria from KwaZulu-Natal, new strategies are being investigated to increase the impact of malaria elimination strategies. Greater attention is now being given to larval control, as a complementary measure to indoor residual spraying. However, there is a large gap in knowledge of the bionomics of the larval stages of this mosquito vector of malaria in South Africa. In order to focus on both larval and adult mosquito control methods, larval development and the reproductive stages of the vector were investigated since these variables influences our ability to impact mosquito populations through larval control. This study was therefore conducted to determine the peak eruption times and the emergent sex ratios, as well as the peak egg oviposition time in order to attack the mosquito when it is at its most vulnerable and when control interventions will have the most impact.Results: Oviposition studies showed two peaks corresponding with late evening and again just before dawn. Most eggs were also laid in the first half of the night (18h00 – midnight). Most mosquitoes erupted just after sunset and the sex ratios showed that twice as many females as males emerged. Females readily took a bloodmeal after oviposition or just after erupting. Hatch rate to viable first instar larvae was 74.5%.Conclusions: The results of this study have provided information as to when interventions would be most effective in controlling mosquito populations and have provided information that highlights the value of larval control as a complementary measure to adult mosquito control. The most vulnerable stages of the female Anopheles arabiensis are when they have just emerged or when they have just oviposited. Vector control strategies should be designed to target these vulnerable stages at the breeding sites in order to have maximum impact.

scholarly journals Malaria vector control in South Africa

2013 ◽  
Vol 103 (10) ◽  
pp. 784 ◽  
Author(s):  
B Brooke ◽  
L Koekemoer ◽  
P Kruger ◽  
J Urbach ◽  
E Misiani ◽  
...  
Keyword(s):  
South Africa ◽  
Vector Control ◽  
Malaria Vector ◽  
Malaria Vector Control

scholarly journals DISPUTE RESOLUTION IN THE SOUTH AFRICAN SOCIAL SECURITY SYSTEM: THE NEED FOR MORE APPROPRIATE APPROACHES

Obiter ◽  
2021 ◽  
Vol 33 (1) ◽  
Author(s):  
MAT Nyenti
Keyword(s):  
South Africa ◽  
Social Security ◽  
Dispute Resolution ◽  
South African ◽  
Access To Justice ◽  
Successful Implementation ◽  
Legal Assistance ◽  
The Right ◽  
Resolution Processes ◽  
Social Security Beneficiaries

The right to social security in South Africa is adjudicated and enforced mainly by means of litigation. This article examines litigation as a mechanism for the resolution of social security disputes in South Africa and its impact on both the right to have access to court and to social security. It argues that court-based adjudication may not be the most appropriate means of adjudicating social security claims. This is particularly as South Africa is a country where social security beneficiaries have limited knowledge of the laws and procedures, coupled with a lack of publicly-provided legal assistance/representation for social security cases. Dispute resolution mainly through the courts may contribute to the limitation of their right to seek redress and by implication, their right to have access to social security. Finally, the article proposes the investigation of more appropriate dispute-resolution processes. This is due to the failure of court-based adjudication to ensure access to justice (and to social security); constitutional requirements arising from the protection of the rights of access to justice and to social security; the Constitution’s focus on protecting persons who are particularly vulnerable and desperate; the availability of other (more appropriate) dispute-resolution mechanisms; and the relatively successful implementation of these mechanisms in the resolution of social security disputes in comparative jurisdictions. 

Behavioural variation of Anopheles arabiensis (Diptera: Culicidae) populations in Natal, South Africa

1991 ◽  
Vol 81 (1) ◽  
pp. 107-110 ◽  
Author(s):  
Brian L. Sharp ◽  
David le Sueur
Keyword(s):  
South Africa ◽  
Vector Control ◽  
Human Blood ◽  
Anopheles Arabiensis ◽  
Mosquito Vector ◽  
Human Blood Index ◽  
Blood Index ◽  
Close Proximity ◽  
Exit Trap ◽  
Mosquito Vector Control

AbstractAnopheles arabiensis Patton populations occur in those areas of Natal in which intra-domiciliary DDT is used for mosquito vector control and in the unsprayed areas. Indoor resting collections from the unsprayed area showed a human blood index >90%, in contrast to the indoor collections from the sprayed area where only 31% had fed on man. In exit trap collections from the sprayed area, 66% had fed on man. These trends of a high human blood index in the exit trap collections and a low human blood index in the indoor resting catches were unaffected, despite the close proximity of a cattle kraal to the majority of homesteads.

scholarly journals Evaluation of Larvicidal Activities of Parthenium Hysterophorus L. Against Anopheles Arabiensis (Diptera: Culicidae), the Major Malaria Vector in Ethiopia

2020 ◽  
Author(s):  
Mihretu Nigatu Tarekegn ◽  
Yitbarek Wolde-hawariat ◽  
Sisay Dugassa ◽  
Habte Tekie
Keyword(s):  
Petroleum Ether ◽  
Vector Control ◽  
Malaria Vector ◽  
Anopheles Arabiensis ◽  
Larval Mortality ◽  
Indoor Residual Spraying ◽  
Parthenium Hysterophorus ◽  
Mortality Data ◽  
Root Extract ◽  
Larvicidal Activities

Abstract Background: Malaria is a leading public health problem in Ethiopia despite the implementation of effective indoor vector control strategies over several decades. Vector control operations in the country largely depend on the application of Indoor Residual Spraying (IRS) of synthetic insecticides and Long Lasting Insecticidal Nets (LLINs) which resulted in a significant reduction in the malaria burden. The spread of resistance to insecticides in these indoor vector control tools in vector species is a serious challenge. Alternatively, reports indicate that botanicals which are relatively safe possess toxic compounds with high larvicidal activities. However, there are limited evidences on the larvicidal effect of botanicals against the malaria vectors, Anopheles arabiensis . This study aimed to evaluate the larvicidal activities of the extracts of the roots, stems, and leaves of Parthenium hysterophorus against the 4 th instar larvae of An. arabiensis . Methods: Field collected leaves, stems and root parts of P. hysterophorus were dried and separately ground to powder and extracted in petroleum ether, hexane, acetone, and ethanol solvents. The extracts were concentrated using a Rota evaporator, and stock solutions were subject to serial dilutions for use as test concentrations. Laboratory reared 4 th instar larvae of An. arabiensis were used for the larvicidal bioassays. Mortality data were subjected probit analysis to determine LC 50 and LC 90 of the extracts. Results: The results showed that there were significant differences in percentage larval mortalities (P<0.05) among different concentrations of the leaf, stem, and root solvent extracts, respectively. Hexane extracts of leaves and stem of P. hysterophorus at 480ppm caused the highest mortality of 4 th larval instar of An. arabiensis (85% and 96.7%, respectively) compared to those of ethanolic, acetone, and petroleum ether extracts of these plant parts. Petroleum ether extracts of the root of P. hysterophorus were the most effective in causing very high larval mortality at 360ppm and 480ppm (98.3%). The LC 50 value of petroleum ether root extract (10.7ppm) and LC 90 value of petroleum ether root extract (105.5ppm) were significantly lower than those of ethanol, acetone, and hexane root extracts, respectively. Conclusion: Petroleum ether root extract of P. hysterophorus has remarkably high larvicidal potential against 4 th instar larvae of An. arabiensis which could be exploited for malaria vector control. Further studies on the larvicidal efficacy of the extracts under field conditions and identification of the bioactive components in the root parts of this weed plant are recommended.

scholarly journals “Maskandi experience”: exploring the use of a cultural song for community engagement in preparation for a pilot Sterile Insect Technique release programme for malaria vector control in KwaZulu-Natal Province, South Africa 2019

2021 ◽  
Vol 20 (1) ◽  
Author(s):  
Pinky N. Manana ◽  
Sara Jewett ◽  
Jabulani Zikhali ◽  
Dumsani Dlamini ◽  
Nondumiso Mabaso ◽  
...  
Keyword(s):  
South Africa ◽  
Community Engagement ◽  
Vector Control ◽  
Malaria Vector ◽  
Sterile Insect Technique ◽  
Malaria Vector Control ◽  
Community Members ◽  
Kwazulu Natal ◽  
Male Mosquitoes ◽  
Control Tool

Abstract Background An assessment of the Sterile Insect Technique (SIT) as a complementary malaria vector control tool, is at an advanced stage in South Africa. The technique involves the release of laboratory-reared sterilized male mosquitoes of the major malaria vector Anopheles arabiensis, raising social, ethical and regulatory concerns. Therefore, its implementation largely depends on community participation and acceptance. Against this background, it is critical that robust and effective community strategies are developed. This study describes the development of a cultural song to engage the community and increase awareness on SIT and malaria control in KwaZulu-Natal, South Africa. Methods An exploratory concurrent mixed-methods study was conducted to get opinions about the effectiveness of a cultural song developed to engage communities and increase acceptability of the SIT technology. Two self-administered surveys (expert and community) were conducted. Additionally, more in depth opinions of the song and its effectiveness in conveying the intended information were investigated through three community dialogue sessions with community members in the study area. Results A total of 40 experts and 54 community members participated in the survey. Four themes were identified in relation to the appropriateness and effectiveness of the song, with a fifth theme focused on recommendations for adaptations. Overall, the song was well received with the audience finding it entertaining and informative. Responses to unstructured questions posed after the song showed an increase in the knowledge on malaria transmission and SIT technology. In particular, the explanation that male mosquitoes do not bite allayed anxiety and fears about the SIT technology. Conclusion The song was deemed both culturally appropriate and informative in engaging community members about the SIT technology. It proved useful in promoting health messages and conveying SIT technology as a complementary malaria vector control tool. With minor adaptations, the song has potential as an area-wide community engagement tool in areas targeted for sterile male releases.

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