scholarly journals Molecular Detection and Quantification of the Striga Seedbank in Ethiopian Sorghum Field Soils

2021 ◽  
Author(s):  
Jos Raaijmakers ◽  
Getahun Mitiku ◽  
Desalegn Etalo ◽  
Paulien KleinGunnewiek ◽  
Dominika Rybka ◽  
...  
Keyword(s):  
Agricultural Soils ◽  
Quantitative Polymerase Chain Reaction ◽  
Management Strategies ◽  
Sub Saharan Africa ◽  
Ecological Zones ◽  
Diverse Field ◽  
Field Soils ◽  
Size Based Separation ◽  
The Impact ◽  
Detection And Quantification

Abstract Aims Striga hermonthica is a devastating parasitic weed in Sub-Saharan Africa (SSA) and its persistent soil seedbank is the major contributing factor for its prevalence and persistence. So far, there is little to no information on the Striga seedbank density in agricultural fields in SSA due to the lack of reliable detection and quantification methods. Methods We developed a high-throughput method that combines density- and size-based separation techniques with quantitative polymerase chain reaction (qPCR)-based detection of Striga seeds in soil. The method was optimized and validated on two physicochemically different Striga-free Dutch agricultural soils by introducing increasing numbers of Striga seeds (0, 1, 3, 9, 27, 81 and 243 seeds). Results The results showed that as little as one seed of S. hermonthica per 150 g of soil can be detected. This technique was subsequently tested on soil samples of 48 sorghum fields from different agro-ecological zones in Ethiopia to map the geospatial distribution of the Striga seedbank along a trajectory of more than 1500 km. Considerable variation in Striga seed densities was observed for these soils: in 75% of the field soils, Striga seeds were detectable up to 86 seeds per 150 g of soil. Correlation analyses further revealed a significant non-linear relationship between the seed density and Striga incidence assessed in the same sorghum field soils at the time of soil sampling. Conclusions The method developed allows for high-through-put and accurate mapping of the Striga seedbank in physicochemically diverse field soils and can be used to predict Striga incidence and to assess the impact of management strategies on Striga seedbank dynamics.

scholarly journals Evaluation of Bean Common Mosaic Disease and Associated Aphid Vector, Aphis fabae L., on Common Bean (Phaseolus vulgaris L.) Production in Lower Eastern Kenya

2021 ◽  
pp. 1-18
Author(s):  
Ngela A. Muute ◽  
Benjamin Muli ◽  
Orek Charles
Keyword(s):  
Common Bean ◽  
Management Strategies ◽  
Bean Common Mosaic Virus ◽  
Mosaic Disease ◽  
Aphis Fabae ◽  
Effective Control ◽  
Small Scale ◽  
Ecological Zones ◽  
Aphid Control ◽  
The Impact

Production of common bean in Kenya is constrained by pests and diseases and to improve bean yields amongst majority small-scale farmers, appropriate management strategies should be adopted. Bean common mosaic disease (BCMD) caused by bean common mosaic virus and vectored by bean aphids and infected seeds, substantially inhibit common bean production in Kenya. An extensive and diagnostic field survey was conducted in six agro ecological zones (AEZs) of lower eastern Kenya during the long and short rains of 2018 to determine BCMD incidence (BCMD-I), severity (BCMD-S), bean aphid abundance (BAA), bean aphid incidence (BAI) and the management strategies applied by farmers. Significant (P≤0.001) variations observed for these traits between bean varieties, rainy seasons and AEZs implied that farmers could select and grow a tolerant bean variety or grow a variety either in a season or an AEZ with low BCMD and bean aphid pressure. Such included AEZ-UMSA with least mean BCMD-I (42%), BCMD-S (1.9) and BAI (11%) compared to two AEZs (LHSH & LM4) that showed BCMD-I of >70%, BCMD-S >3.0 and BAI >50%. The AEZs differences could be attributed to variations in altitudes, temperature and humidity that influences vector (aphid) movement.  Of the nine  bean varieties identified during the survey, Selian 14 was the most preferred by farmers (at ~35%) with relatively lower BCMD-I (~49%) and BAI (~35%) compared to the least (<5%) farmer-preferred variety Wairimu that showed higher BCMD-I (56%) and BAI (~68%). Therefore variety Selian 14 was considered tolerant to BCMD and bean aphid. Significant (P≤0.001) and positive correlations (r = 0.67) between BAI and BCMD-I implied an effective control of bean aphids could reduce the impact of BCMD on bean production. On visual diagnostics, >75% of farmers could generally identify diseased or pest-infested bean crops and stage of growth of the crop most affected. None (0%) could however identify BCMD symptoms although ~40% identified the vector bean aphids with ~26% implementing some form of aphid or pest management strategy. On management, season-driven early planting and bean intercropping were the most applied strategies (>80%), crop rotation and weed control accounted for ~71%, certified seeds at 1% and non-chemical or pesticide applications (0%). Both low adoption of certified seeds and no chemical aphid control were attributed to high costs, despite the possibility the two factors could have contributed to higher incidences and severity of BCMD in the study area as the disease is both seed and vector-borne.  In summary, lack of knowledge and training among farmers on diagnosis and management of aphid-pests and BCMD, were cited as the main constraints for low bean cultivation. This study therefore recommends provision of adequate extension services and farmer training in lower eastern Kenya for improved bean yield and subsequent better family livelihoods and income.

Developing a real-time PCR assay for direct detection and quantification of Pratylenchus scribneri in field soil

Nematology ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 733-744
Author(s):  
Deepika Arora ◽  
Guiping Yan ◽  
Richard Baidoo
Keyword(s):  
Real Time ◽  
Quantitative Polymerase Chain Reaction ◽  
Qpcr Assay ◽  
Parasitic Nematodes ◽  
Field Soil ◽  
Accurate Identification ◽  
Soil Dna ◽  
Field Soils ◽  
Pratylenchus Scribneri ◽  
Detection And Quantification

Summary The endomigratory root-lesion nematode, Pratylenchus scribneri, is one of the major plant-parasitic nematodes infecting potato. Accurate identification and quantification of this nematode are essential to develop management strategies but microscopic observations are particularly challenging and time consuming. In this study, a SYBR Green I-based real-time quantitative polymerase chain reaction (qPCR) assay was developed to detect and quantify P. scribneri from field soil DNA extracts. A primer set was designed from the internal transcribed spacer (ITS) region of the P. scribneri rDNA gene. Primer specificity to the target nematode was evaluated by both in silico analysis and qPCR and no detection or non-specific amplification was observed for other non-target nematode species/communities tested in this study. Standard curves were generated using DNA extracts from autoclaved soil infested with varying nematode numbers for calibration. The curves were supported by a high correlation between the P. scribneri numbers artificially added to soil or estimated from naturally infested field soils by traditional methods, and the numbers quantified using the qPCR assay. The assay was able to detect 1 out of 128 (0.0078) equivalents of the DNA of a single nematode in 0.5 g of soil. The qPCR assay developed in this study provides a specific and sensitive detection and quantification of P. scribneri from field soils and a rapid alternative to time-consuming traditional nematode identification and enumeration.

scholarly journals Developing a Real-Time PCR Assay for Detection and Quantification of Pratylenchus neglectus in Soil

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 757-764 ◽  
Author(s):  
Guiping Yan ◽  
Richard W. Smiley ◽  
Patricia A. Okubara ◽  
Andrea M. Skantar ◽  
Catherine L. Reardon
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Management Practices ◽  
Quantitative Polymerase Chain Reaction ◽  
Internal Transcribed Spacer Region ◽  
Pratylenchus Neglectus ◽  
Standard Curve ◽  
Field Soils ◽  
Plant Parasitic ◽  
Detection And Quantification

Pratylenchus neglectus is one of the most widespread and economically important nematodes that invades plant roots and restricts wheat productivity in the Pacific Northwest. It is challenging to quantify P. neglectus using microscopic methods for studies that require large-scale sampling, such as assessment of rotation crops, wheat cultivars, and other management practices. A real-time quantitative polymerase chain reaction (qPCR) assay was developed to detect and quantify P. neglectus from DNA extracts of soil. The primers, designed from the internal transcribed spacer region of rDNA, showed high specificity with a single melt curve peak to DNA from eight isolates of P. neglectus but did not amplify DNA from 28 isolates of other plant-parasitic and non-plant-parasitic nematodes. A standard curve (R2 = 0.96; P < 0.001) was generated by amplifying DNA extracted from soil to which nematodes were added. The soil standard curve was validated using sterilized soil inoculated with lower numbers of P. neglectus. A significant positive relationship (R2 = 0.66; P < 0.001) was observed for nematode numbers quantified from 15 field soils using qPCR and the Whitehead tray and microscopic method but the qPCR generally tended to provide higher estimates. Real-time PCR potentially provides a useful platform for efficient detection and quantification of P. neglectus directly from field soils.

scholarly journals Evaluation of the interaction between insecticide resistance-associated genes and malaria transmission in Anopheles gambiae sensu lato in central Côte d’Ivoire

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Rosine Z. Wolie ◽  
Alphonsine A. Koffi ◽  
Ludovic P. Ahoua Alou ◽  
Eleanore D. Sternberg ◽  
Oulo N’Nan-Alla ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Anopheles Gambiae ◽  
Malaria Transmission ◽  
Vector Competence ◽  
Quantitative Polymerase Chain Reaction ◽  
Sub Saharan Africa ◽  
Human Landing Catch ◽  
Anopheles Coluzzii ◽  
Metabolic Resistance ◽  
The Impact

Abstract Background There is evidence that the knockdown resistance gene (Kdr) L1014F and acetylcholinesterase-1 gene (Ace-1R) G119S mutations involved in pyrethroid and carbamate resistance in Anopheles gambiae influence malaria transmission in sub-Saharan Africa. This is likely due to changes in the behaviour, life history and vector competence and capacity of An. gambiae. In the present study, performed as part of a two-arm cluster randomized controlled trial evaluating the impact of household screening plus a novel insecticide delivery system (In2Care Eave Tubes), we investigated the distribution of insecticide target site mutations and their association with infection status in wild An. gambiae sensu lato (s.l.) populations. Methods Mosquitoes were captured in 40 villages around Bouaké by human landing catch from May 2017 to April 2019. Randomly selected samples of An. gambiae s.l. that were infected or not infected with Plasmodium sp. were identified to species and then genotyped for Kdr L1014F and Ace-1R G119S mutations using quantitative polymerase chain reaction assays. The frequencies of the two alleles were compared between Anopheles coluzzii and Anopheles gambiae and then between infected and uninfected groups for each species. Results The presence of An. gambiae (49%) and An. coluzzii (51%) was confirmed in Bouaké. Individuals of both species infected with Plasmodium parasites were found. Over the study period, the average frequency of the Kdr L1014F and Ace-1R G119S mutations did not vary significantly between study arms. However, the frequencies of the Kdr L1014F and Ace-1R G119S resistance alleles were significantly higher in An. gambiae than in An. coluzzii [odds ratio (95% confidence interval): 59.64 (30.81–131.63) for Kdr, and 2.79 (2.17–3.60) for Ace-1R]. For both species, there were no significant differences in Kdr L1014F or Ace-1R G119S genotypic and allelic frequency distributions between infected and uninfected specimens (P > 0.05). Conclusions Either alone or in combination, Kdr L1014F and Ace-1R G119S showed no significant association with Plasmodium infection in wild An. gambiae and An. coluzzii, demonstrating the similar competence of these species for Plasmodium transmission in Bouaké. Additional factors including behavioural and environmental ones that influence vector competence in natural populations, and those other than allele measurements (metabolic resistance factors) that contribute to resistance, should be considered when establishing the existence of a link between insecticide resistance and vector competence. Graphical Abstract

scholarly journals Multi-criterial analysis for modelling Matengo/Ngolo pits agro-ecological zones using fuzzy logic in Southern Tanzania

2021 ◽  
Vol 911 (1) ◽  
pp. 012080
Author(s):  
S J Nakamo
Keyword(s):  
Fuzzy Logic ◽  
Policy Development ◽  
Sub Saharan Africa ◽  
Agricultural Practice ◽  
Grain Production ◽  
Ecological Zones ◽  
Fuzzy Logic Algorithm ◽  
Sub Saharan ◽  
The Impact ◽  
Agro Ecological Zones

Abstract It has known that grain production is declining globally, leading to food insecurity becoming increasingly apparent in tropical countries, particularly in Sub-Saharan Africa. Countries in Sub-Saharan Africa must concentrate on indigenous agricultural methods to mitigate the impact of climate change on grain production while preserving ecological balances and achieving sustainable goals. Matengo/Ngolo pits, practised on steep slopes in the Matengo highlands, southern Tanzania, are indigenous knowledge invented by local communities over the past 300 years. Despite its effectiveness in increasing agricultural productivity, soil moisture retention, and other environmental advantages, Matengo/Ngolo agricultural technique has resulted in severe land cover changes that substantially influence other producing sectors. Understanding the agro-ecological zones is essential for enhancing policy development for the expansion and restrictive of Matengo/Ngolo pits practice that intercepting by decreasing its influence on the shrinkage of other ecological services, achieving sustainable agricultural practice in the Matengo highlands. Therefore, this study employed the multi-criteria parameters under the fuzzy logic algorithm in ArcGIS 10.8 for modelling the Matengo/Ngolo pits agro-ecological zone to realize sustainable land management in Matengo highlands.

scholarly journals Assessing microscopic and rapid diagnostic tests for malaria among pregnant women with fever in Ondo State, Southwest Nigeria

2020 ◽  
Vol 11 (3) ◽  
pp. 143-153
Author(s):  
Bamgboye M Afolabi ◽  
Waheed Folayan ◽  
Titilola M Afolabi ◽  
Oladipo B Akinmoladun ◽  
Feyijimi Egunjobi ◽  
...  
Keyword(s):  
Pregnant Women ◽  
The State ◽  
Sub Saharan Africa ◽  
P Value ◽  
Ecological Zones ◽  
Significant Difference ◽  
Southwest Nigeria ◽  
Ondo State ◽  
The Impact ◽  
F Statistics

Background: Malaria as a health burden in sub-Saharan Africa is well-known. Information about access to programs by pregnant women during early antenatal care (ANC) visits and the impact on the burden of malaria is limited. Objective: To evaluate the utilization of malaria control services among pregnant women with fever between 2014 and 2018 in Ondo State, Southwest Nigeria. Materials and methods: Between 2014 and 2018, malaria-related indicators including the proportion of pregnant women with fever who were investigated with microscopy and Rapid Diagnostic Test (RDT) were tracked in Ondo State, Nigeria. Data were captured using the District Health Information Management version 2.0 (DHISv2.0) and analyzed using Stata 13 statistical software. Results: Throughout the study period, the mean (±sd) percentage of pregnant women with fever tested for malaria parasites with microscopy in all the LGAs was 2.71 (4.87) with the lowest and highest means (±sd) occurring in 2016 as 1.20 (1.71) and in 2018 as 5.47 (7.93) respectively with no significant difference (F-statistics=2.25; P-value=0.07).A statistically significant variation (F-statistics=34.90; P-value=0.0000001) was observed in the overall mean (±sd) proportion of pregnant women with fever who were tested for malaria with RDT over the study period with the lowest as 57.0 (15.2) in 2014 and the highest as 96.2 (4.1) in 2017.This level of significance was reflected mostly in the coastal (F-statistics=15.05; P-value=0.0000001) and in the rainforest (F-statistics=12.86; P-value=0.0000001) ecological zones of the state but much less in the Savannah ecological zone (F-statistics=3.23; P-value=0.04).There was no significant correlation (Pearson’s r=0.160, P-value=0.141) between fever cases that tested positive using microscopy and fever cases that tested positive with RDT. A noteworthy variation (F-statistics=3.96, P-value=0.005) was observed in the proportion of fever cases that tested positive with RDT but not with microscopy. Overall mean (±sd) proportion of pregnant women with confirmed fever cases was 76.66 (15.06), mostly in the Savannah ecological system (81.84±21.18) throughout the study period. Conclusion: Data from this study suggests that RDT gradually replaced microscopy in testing for malaria among pregnant women in Ondo State of Nigeria. It also suggests that some ecological zones may be more underserved than others in assessing malaria in pregnancy. More technical and financial assistance are needed for the State Malaria Elimination Program to improve ANC service utilization.

Conflicts in Biafra, Katanga and Cabinda as a result of the geopolitical legacy of colonialism

2020 ◽  
Vol 2020 (10-3) ◽  
pp. 238-246
Author(s):  
Olga Dzhenchakova
Keyword(s):  
Democratic Republic ◽  
Economic Factor ◽  
Colonial Period ◽  
Sub Saharan Africa ◽  
Negative Consequences ◽  
Post Colonial ◽  
Republic Of The Congo ◽  
Sub Saharan ◽  
The Republic ◽  
The Impact

The article considers the impact of the colonial past of some countries in sub-Saharan Africa and its effect on their development during the post-colonial period. The negative consequences of the geopolitical legacy of colonialism are shown on the example of three countries: Nigeria, the Democratic Republic of the Congo and the Republic of Angola, expressed in the emergence of conflicts in these countries based on ethno-cultural, religious and socio-economic contradictions. At the same time, the focus is made on the economic factor and the consequences of the consumer policy of the former metropolises pursuing their mercantile interests were mixed.

The Impact of Biochar on the Soil

2018 ◽  
Vol 69 (8) ◽  
pp. 2197-2208
Author(s):  
Carmen Otilia Rusanescu ◽  
Erol Murad ◽  
Cosmin Jinescu ◽  
Marin Rusanescu
Keyword(s):  
Agricultural Land ◽  
Agricultural Soils ◽  
Biomass Gasification ◽  
High Humidity ◽  
Agricultural Ecosystems ◽  
Productive Potential ◽  
Co2 Balance ◽  
Environmentally Sound ◽  
The Impact ◽  
Organic Resources

In the present paper are presented the experimental results of biomass gasification, the biochair was produced from vineyards by controlled pyrolysis at 750 �C, in order to increase the fertility of soils, it was found the increase of the fertility produced by the development of the vegetables in the soil to which was added biochar. Soil was added to soil 4 g/dm3 biochar, 8 g/dm3 biochar, the soil had no high humidity, was taken at a time when it had not rained for at least one week, the soil pH was 8, in the soil with 8 g/dm3 biochar the plants increased compared to the soil with 4 g/dm3 and the soil without biochar. The biochar resulting from pyrolysis and gasification processes is a valuable amendment to agricultural soils and an efficient and economical way to seize carbon. Using biochar it is possible to increase the diversity of agricultural land in an environmentally sound way in areas with depleted soils, limited organic resources and insufficient water for development. Helps to soil carbon sequestration with negative CO2 balance, increases the productive potential of agricultural ecosystems.

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