scholarly journals Toxicity and Oviposition Deterrent Activities of Thyme Essential Oils against Anopheles arabiensis

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Destaw Damtie ◽  
Yalemtsehay Mekonnen
Keyword(s):  
Essential Oils ◽  
Anopheles Arabiensis ◽  
Activity Index ◽  
Lethal Dose ◽  
Environmental Issues ◽  
Field Trials ◽  
Sub Saharan Africa ◽  
Oviposition Deterrent ◽  
Small Doses ◽  
Sub Saharan

Background. Malaria is one of the deadliest mosquito-borne diseases in sub-Saharan Africa and Ethiopia. Owing to their costs and environmental issues, synthetic insecticides are poor choices to control mosquitoes. Plant-based products can be considered as safe and biodegradable alternatives. The present study aimed to test the toxicity and oviposition deterrent activities of Thymus serrulatus and Thymus schimperi essential oils (EOs) against Anopheles arabiensis. Methods. Thyme EOs were extracted by hydrodistillation using the Clevenger-type apparatus. They were named Tar, Ala, and Yil after the areas of thyme collection Tarmaber, Alamata, and Yilmana Densa, respectively. Laboratory-based tests were used to determine the larvicidal, adulticidal, oviposition deterrent, and half lethal dose (LD50) of each EO. Results. The concentrations of 100 μl/L and 50 μl/L resulted in complete mortalities of larvae and adults, respectively, for all the three Eos considered. The EOs exhibited high repellency with oviposition activity index of −1 (OAI = −1) at concentrations of 50 μl/L (Tar), 100 μl/L (Ala), and 200 μl/L (Yil). Conclusions. The EOs of T. serrulatus and T. schimperi were effective against larvae and adult mosquitoes at small doses and resulted in oviposition deterrence at doses from 50 to 200 μl/L. Thus, these EOs are promising mosquitocides and oviposition deterrents. But, further tests both in the presence of already known and effective deterrents and field trials are required.

scholarly journals Molecular typing of bacteria of the genus Asaia in malaria vector Anopheles arabiensis Patton, 1905

2012 ◽  
Vol 44 (2) ◽  
pp. 7 ◽  
Author(s):  
S. Epis ◽  
M. Montagna ◽  
F. Comandatore ◽  
C. Damiani ◽  
A. Diabaté ◽  
...  
Keyword(s):  
Molecular Typing ◽  
Internal Transcribed Spacer ◽  
Anopheles Arabiensis ◽  
Acetic Acid Bacterium ◽  
Sub Saharan Africa ◽  
Randomly Amplified Polymorphic Dna ◽  
Chain Reaction ◽  
Polymerase Chain ◽  
Sub Saharan ◽  
Dna Pcr

The acetic acid bacterium <em>Asaia</em> spp. was successfully detected in <em>Anopheles arabiensis</em> Patton, 1905, one of the major vector of human malaria in Sub-Saharan Africa. A collection of 45 <em>Asaia</em> isolates in cellfree media was established from 20 individuals collected from the field in Burkina Faso. 16S rRNA universal polymerase chain reaction (PCR) and specific qPCR, for the detection of <em>Asaia</em> spp. were performed in order to reveal the presence of different bacterial taxa associated with this insect. The isolates were typed by internal transcribed spacer-PCR, BOX-PCR, and randomly amplified polymorphic DNA-PCR, proved the presence of different <em>Asaia</em> in <em>A. arabiensis</em>.

scholarly journals Efficacy of a cry1Ab Gene for Control of Maruca vitrata (Lepidoptera: Crambidae) in Cowpea (Fabales: Fabaceae)

2020 ◽  
Vol 113 (2) ◽  
pp. 974-979
Author(s):  
Prince C Addae ◽  
Mohammad F Ishiyaku ◽  
Jean-Batiste Tignegre ◽  
Malick N Ba ◽  
Joseph B Bationo ◽  
...  
Keyword(s):  
Insect Pests ◽  
Field Trials ◽  
Genetically Engineered ◽  
Maruca Vitrata ◽  
Sub Saharan Africa ◽  
High Dose ◽  
Cry1ab Protein ◽  
Cry1ab Gene ◽  
Pod Borer ◽  
Sub Saharan

Abstract Cowpea [Vigna unguiculata (L) Walp.] is an important staple legume in the diet of many households in sub-Saharan Africa. Its production, however, is negatively impacted by many insect pests including bean pod borer, Maruca vitrata F., which can cause 20–80% yield loss. Several genetically engineered cowpea events that contain a cry1Ab gene from Bacillus thuringiensis (Bt) for resistance against M. vitrata were evaluated in Nigeria, Burkina Faso, and Ghana (West Africa), where cowpea is commonly grown. As part of the regulatory safety package, these efficacy data were developed and evaluated by in-country scientists. The Bt-cowpea lines were planted in confined field trials under Insect-proof netting and artificially infested with up to 500 M. vitrata larvae per plant during bud formation and flowering periods. Bt-cowpea lines provided nearly complete pod and seed protection and in most cases resulted in significantly increased seed yield over non-Bt control lines. An integrated pest management strategy that includes use of Bt-cowpea augmented with minimal insecticide treatment for protection against other insects is recommended to control pod borer to enhance cowpea production. The insect resistance management plan is based on the high-dose refuge strategy where non-Bt-cowpea and natural refuges are expected to provide M. vitrata susceptible to Cry1Ab protein. In addition, there will be a limited release of this product until a two-toxin cowpea pyramid is released. Other than South African genetically engineered crops, Bt-cowpea is the first genetically engineered food crop developed by the public sector and approved for release in sub-Saharan Africa.

scholarly journals Acaricidal and Repellence of R. appendiculatus, and GC-MS Chemical Content of Essential Oils from Three South African Ethno-Veterinary Plants

2021 ◽  
Vol 33 (6) ◽  
pp. 1370-1378
Author(s):  
N.M. Mkolo ◽  
B.T. Gumede ◽  
S.R. Magano ◽  
O.O. Olaokun
Keyword(s):  
Essential Oils ◽  
South African ◽  
Tick Infestation ◽  
Chemical Compounds ◽  
Sub Saharan Africa ◽  
Tithonia Diversifolia ◽  
Cymbopogon Citratus ◽  
Livestock Farming ◽  
Chemical Content ◽  
Sub Saharan

The advancement of the livestock farming in sub-Saharan Africa is restricted by tick infestation. With conventional pesticides posing a threat to human and the environment, natural products are alternative anti-tick source. This study characterized the essential oils from Tithonia diversifolia, Lavandula angustifolia and Cymbopogon citratus leaves by GC-MS and, for acaricidal and repellence of R. appendiculatus. GC-MS analysis detected various chemical compounds, some of the isolated compounds have anti-tick properties. The repellence of T. diversifolia essential oil at 5% v/v was the weakest against adult ticks. All essential oils at 15% v/v paralysed nymph after 20 mins, with C. citratus after 24 h causing high mortality of nymph and adult ticks. Exposure to L. angustifolia did not achieve 50% mortality after 24 h. All essential oils caused complete inhibition of moulting of engorged larvae. The study demonstrated that the essential oils of the ethno-veterinary plants may be a source of anti-ticks agents.

scholarly journals Microsporidia MB is found predominantly associated with Anopheles gambiae s.s and Anopheles coluzzii in Ghana

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jewelna Akorli ◽  
Esinam Abla Akorli ◽  
Seraphim Naa Afoley Tetteh ◽  
Godwin Kwame Amlalo ◽  
Millicent Opoku ◽  
...  
Keyword(s):  
West Africa ◽  
Malaria Vector ◽  
Sibling Species ◽  
Horizontal Transfer ◽  
Anopheles Arabiensis ◽  
Sub Saharan Africa ◽  
Anopheles Coluzzii ◽  
Vector Species ◽  
Anopheles Gambiae S.S ◽  
Sub Saharan

AbstractA vertically transmitted microsporidian, Microsporidia MB, with the ability to disrupt Plasmodium development was reported in Anopheles arabiensis from Kenya, East Africa. To demonstrate its range of incidence, archived DNA samples from 7575 Anopheles mosquitoes collected from Ghana were screened. MB prevalence was observed at 1.8%. An. gambiae s.s constituted 87% of positive mosquitoes while the remaining were from An. coluzzii. Both sibling species had similar positivity rates (24% and 19%; p = 0.42) despite the significantly higher number of An. gambiae s.s analysed (An. gambiae s.s = 487; An. coluzzii = 94; p = 0.0005). The microsporidian was also more prevalent in emerged adults from field-collected larvae than field-caught adults (p < 0.0001) suggestive of an efficient vertical transmission and/or horizontal transfer among larvae. This is the first report of Microsporidia MB in Anopheles mosquitoes in West Africa. It indicates possible widespread among malaria vector species and warrants investigations into the symbiont’s diversity across sub-Saharan Africa.

scholarly journals Validation of large-volume batch solar reactors for the treatment of rainwater in field trials in sub-Saharan Africa

2020 ◽  
Vol 717 ◽  
pp. 137223 ◽  
Author(s):  
B. Reyneke ◽  
T. Ndlovu ◽  
M.B. Vincent ◽  
A. Martínez-García ◽  
M.I. Polo-López ◽  
...  
Keyword(s):  
Large Volume ◽  
Field Trials ◽  
Sub Saharan Africa ◽  
Sub Saharan ◽  
Solar Reactors

scholarly journals Development of a cAdVax-Based Bivalent Ebola Virus Vaccine That Induces Immune Responses against both the Sudan and Zaire Species of Ebola Virus

2006 ◽  
Vol 80 (6) ◽  
pp. 2738-2746 ◽  
Author(s):  
Danher Wang ◽  
Nicholas U. Raja ◽  
Charles M. Trubey ◽  
Laure Y. Juompan ◽  
Min Luo ◽  
...  
Keyword(s):  
Immune Responses ◽  
Ebola Virus ◽  
Lethal Dose ◽  
Hemorrhagic Fever ◽  
Sub Saharan Africa ◽  
Potential Efficacy ◽  
Efficient Induction ◽  
Single Complex ◽  
Zaire Ebolavirus ◽  
Sub Saharan

ABSTRACT Ebola virus (EBOV) causes a severe hemorrhagic fever for which there are currently no vaccines or effective treatments. While lethal human outbreaks have so far been restricted to sub-Saharan Africa, the potential exploitation of EBOV as a biological weapon cannot be ignored. Two species of EBOV, Sudan ebolavirus (SEBOV) and Zaire ebolavirus (ZEBOV), have been responsible for all of the deadly human outbreaks resulting from this virus. Therefore, it is important to develop a vaccine that can prevent infection by both lethal species. Here, we describe the bivalent cAdVaxE(GPs/z) vaccine, which includes the SEBOV glycoprotein (GP) and ZEBOV GP genes together in a single complex adenovirus-based vaccine (cAdVax) vector. Vaccination of mice with the bivalent cAdVaxE(GPs/z) vaccine led to efficient induction of EBOV-specific antibody and cell-mediated immune responses to both species of EBOV. In addition, the cAdVax technology demonstrated induction of a 100% protective immune response in mice, as all vaccinated C57BL/6 and BALB/c mice survived challenge with a lethal dose of ZEBOV (30,000 times the 50% lethal dose). This study demonstrates the potential efficacy of a bivalent EBOV vaccine based on a cAdVax vaccine vector design.

scholarly journals Stability of the effect of silencing genes involved in the midgut homeostasis on Anopheles arabiensis mosquito reared under different breeding site conditions

2020 ◽  
Author(s):  
Serkadis Debalke ◽  
Tibebu Habtewold ◽  
George K. Christophides ◽  
Luc Duchateau
Keyword(s):  
Gene Silencing ◽  
Anopheles Arabiensis ◽  
Breeding Site ◽  
Larval Habitat ◽  
Sub Saharan Africa ◽  
Female Adult ◽  
Breeding Sites ◽  
First Instar ◽  
Sub Saharan ◽  
The Stability

Abstract Background: Malaria vector mosquitoes acquire midgut microbiota primarily from their habitat. The homeostasis of these microbial communities plays an essential role in the mosquito longevity, the most essential factor in the mosquito vectorial capacity. Our recent study revealed that silencing genes involved in regulation of the midgut homeostasis including FN3D1, FN3D3, and GPRGr9 reduced the survival of female adult Anopheles arabiensis mosquito. In the present study, we investigate the stability of the gene silencing efficiency of mosquitoes reared in three different breeding conditions representing distinct larval habitat types: town brick pits in Jimma, flood pools in the rural land of Asendabo and roadside pools in Wolkite. Methods: First instar larvae of An. arabiensis mosquitoes were reared separately using water collected from the three breeding sites. The resulting adult females were micro-injected with dsRNA targeting the FN3D1 gene (AARA003032) and their survival was monitored. Control mosquitoes were injected with dsRNA Lacz. In addition, the load of midgut microbiota of these mosquitoes was determined using flow cytometry.Result: Survival of naïve adult female mosquitoes differed between the three sites. Mosquitoes reared using water collected from brick pits and flood pools survived longer than mosquitoes reared using water collected from roadside. However, the FN3D1 gene silencing effect on survival did not differ between the three sites. Conclusion: The present study revealed that the efficacy of FN3D1 gene silencing is not affected by variation in the larval habitat. Thus, silencing this gene using genetic engineering approaches can have a large potential for application throughout sub-Saharan Africa.

scholarly journals GC/MS Profiling and Insecticidal Potential of Essential Oils from Thymus vulgaris (Lamiaceae) and Cymbopogon citratus (Poaceae) against tomato borer, Tuta absoluta

2019 ◽  
Author(s):  
Marie Danièle T. Ngongang ◽  
Pierre Eke ◽  
Modeste Lambert Sameza ◽  
Champlain Lordon Djiéto ◽  
Fabrice Fekam Boyom
Keyword(s):  
Essential Oils ◽  
Lethal Dose ◽  
Field Trials ◽  
Tuta Absoluta ◽  
Thymus Vulgaris ◽  
Cymbopogon Citratus ◽  
Alpha Pinene ◽  
Lemongrass Oil ◽  
Recorded Data ◽  
Tomato Borer

This study aimed to determine the Gas Chrommatography (GC)-Mass Spectrometry (MS) profiles and insecticidal activity of essential oils (EOs) from Thymus vulgaris (Thyme) and Cymbopogon citratus (Lemongrass) against the invasive and devastating pest, Tuta absoluta (T. absoluta) through contact and fumigation routes. We found out that thyme oil was predominantly constituted of Thymol (22.16%), &alpha;-Pinene (15.35%) and p-Cymene (13.54%) whilst Neral (21.41%), Geranial (21.36%) and &beta;-Myrcene (9.74%) were the major constituents of lemongrass oil. Lemongrass oil exhibited higher insecticidal efficiency irrespective of application mode with 50% lethal dose (LD50) values of 35.8 and 72.2 &micro;L.L-1air on contact and fumigation routes, respectively. Lemongrass oil also lengthened pupal duration at all tested doses irrespective of application routes. The overall responses of Lemongrass oil surpassed that of the reference insecticide (Lynx&reg;: Lambda-cyhalothrine; Acetamipride). Thus, the recorded data clearly showed the acute and long-term insecticidal effects of the studied EOs, though a greenhouse and open field trials are required prior to the validation of this approach as remediation measure for Integrated Pest Management (IPM) for tomato borer control in Cameroon and elsewhere.

scholarly journals Multiple and complex links between babyWASH and stunting: an evidence synthesis

2020 ◽  
Vol 10 (4) ◽  
pp. 786-805
Author(s):  
Amy Waller ◽  
Monica Lakhanpaul ◽  
Samuel Godfrey ◽  
Priti Parikh
Keyword(s):  
Evidence Synthesis ◽  
Behavioural Change ◽  
Field Trials ◽  
Sub Saharan Africa ◽  
Mixed Data ◽  
Biological Mechanisms ◽  
Transmission Cycle ◽  
Sanitation And Hygiene ◽  
Sub Saharan ◽  
Randomised Controlled

Abstract Studies have shown linkages between water, sanitation and hygiene (WASH) and stunting in children under 2 years in sub-Saharan Africa. WASH interventions have been shown to reduce stunting rates; however, the biological mechanisms and socio-economic influences responsible for this trend remain poorly understood. This paper reviews the literature regarding these links, and the efficacy of both general WASH interventions and those targeted at children in their first 1,000 days, known as babyWASH, for stunting reduction. Fifty-nine papers published between 2008 and 2019 were reviewed, retrieved from Science Direct, Scopus and Web of Science databases, comprising field trials and data analysis, and literature and systematic reviews. Key findings showed that stunting is directly attributed to diarrhoea, environmental enteric dysfunction and undernutrition although a more comprehensive understanding of these biological mechanisms is necessary. Interventions to interrupt the faecal transmission cycle proved to effectively reduce stunting rates, particularly improved sanitation facilities to reduce open defaecation, increased proximity to water and widespread behavioural change. Methodologies should move away from randomised controlled trials towards selected contexts, mixed data collection methods and inclusion of broader social, cultural and environmental conditions. Improved cross-sectoral collaboration is encouraged, particularly to ensure the complexity of social and contextual factors is fully considered.

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