Recent publications
Maize varieties have specific food processing abilities, with reference to the production of gambari-lifin, lifin, mawe and ogi, four major intermediate products in Benin. Except for the gambari-lifin, these products are widely known in the most of African countries. The recent development of gambari-lifin in relation with the maize grains quality suggests the screening of appropriate maize cultivars for minimizing failure during processing. Panelists comprising 77 maize food processors sorted fifteen maize varieties of which fourteen improved and one local ecotype, and then described each group with their own words. Additionally, 70 maize food processors performed the CATA (Check All That Apply) questions test with a list of sensory terms on the maize varieties. Furthermore, selected physicochemical and rheological parameters were determined on seven representative maize varieties. Multidimensional scaling (MDS) and hierarchical cluster analysis and multiple factorial analyses (MFA) were performed on sensory descriptors and instrumental data. Based on MDS, four groups of maize varieties were identified being specifically appropriate for one or more of these intermediate products. Grains size and weight, endosperm texture and in a lesser extent colour were the major group descriptors of maize varieties. Vitreous character or average size were positively correlated to processing yield as far as gambari-lifin is concerned while floury character was associated to “ability for pasting”. This study confirms that food processors perception is very helpful and useful tools for maize breeders since it early provides consistent information for the end-uses products.
While it is widely acknowledged that the small-sized West African Shorthorn taurine Lagune cattle is being increasingly crossbred with and replaced by large-sized zebus, little is known about the factors that influence farmers’ crossbreeding decisions and selection practices. But this information is necessary for the development of strategies towards a rationale use and conservation of this unique African genetic resource. To fill this knowledge gap, we conducted, between September and November 2016, a questionnaire survey in the belt of this breed in South Benin. One hundred seventy-three cattle farms were surveyed. The binomial logistic regression approach was used to predict the likelihood of a Lagune cattle farmer to be willing to introduce zebus in his herd. The herds were composed of either Lagune only (82.1%), zebu only (4.0%), crossbred Lagune x zebu (1.2%), Lagune and zebu (9.2%) or Lagune and crossbred Lagune x zebu (3.5%). The low productivity of the Lagune cattle and the market demand for large-sized animals were the main farmers’ motivations for crossbreeding. Farmers raising large herds of Lagune cattle under control mating system were more likely to adopt crossbreeding. The risk of dilution of the Lagune breed could be reduced by increasing awareness among farmers, improving their technical skills in herd management and empowering them to develop legal institutions, by-laws and collective actions for sustainable breed management. Farmers who have already adopted crossbreeding should be provided with appropriate services and technical assistance, whereas breed conservation initiatives should mainly focus on small purebred herds kept under control mating.
This paper explores the behavioural drivers of households’ cooking energy decision-making. We empirically examine the effect of time and spatial discounting on cooking energy choices using Generalised Structural Equation Modelling. We rely on the nationally representative household dataset from Benin’s Harmonised Survey on Living Conditions of Households in 2019. The findings highlight that households’ tendencies towards temporal discounting have detrimental effects on cleaner cooking energies, while spatial discounting promotes the adoption of cleaner cooking energy sources. Furthermore, we discern that the influence of time and spatial discounting varies across rural and urban areas, yielding heterogeneous effects. These findings have implications for a better understanding of the non-economic constraints that hinder the promotion of cleaner cooking energies in developing countries.
The Seaport Platform of Environmental Surveillance (PPSE, or Plateforme Portuaire de Surveillance Environnementale in French) was officially inaugurated in Cotonou Seaport (CS), Benin, by the end of 2021. To our knowledge, this platform is the first laboratory dedicated to the monitoring and management of invasive species to be built inside the walls of an African seaport. Its creation has benefitted from a combination of favorable factors, and its existence has resulted from a long-term, multi-stakeholder and still ongoing process that we here describe and analyze. We believe that the PPSE is an innovative science-guided operational initiative that may be useful to replicate in other settings throughout the world.
The basic demographic transition has far-reaching effects on the relative advantages of nations in international trade, including changes in population structure, the increasing participation of women in production, and overall population growth. This research aims to analyze the impact of the demographic structure of nations within the Economic Community of West African States on bilateral trade. Using panel data from 2004 to 2018, this study applies the gravity equation model. The estimation results indicate that variables such as the structure of the youth population, the population size, the fertility rate, and the demographically dependent population have a substantial impact on both bilateral trade and the trade potential of the region. We advise that policymakers take advantage of the demographic benefits offered by the Economic Community of West African States by implementing the measures that will have the greatest impact on the economy. It would be to these countries’ interest to strengthen the variables that raise output magnitude, especially in light of the gap between the two sets of investigated bilateral commerce.
Beam scanning is traditionally achieved with phased arrays, whose application often faces the challenge of high density of antennas and associated electronic components. Metasurfaces (MTS) allow the tailoring of pencil and shaped beams with a low-profile radiator but scanning with MTSs remains difficult, e.g. reconfiguring each sub-wavelength patch of the MTS defeats the initial purpose of simplicity. The present paper proposes a novel design approach to beam scanning with surface-wave (SW) based MTS antennas. Both the feeding as well as the MTS are made periodic at a scale of a few wavelengths. To avoid grating lobes, the unit cell of the periodic MTS is designed such that the embedded element pattern (EEP) has a nearly rectangular shape with proper width. The sparsity of the feeding system enables a drastic reduction of the density of electronics at the expense of a smaller field of view. The resulting antenna, demonstrated here in 2D (uniform antenna versus one space coordinate) has low profile (including the feeder), and enables continuous beam scanning with high gain. With a spacing of two wavelengths between feeds, the scan range is +/-10 degrees. The MTS is first designed at the surface impedance level and the resulting structure has then been validated through full-wave simulation of a MTS implemented with sub-wavelength patches. Numerical analysis versus frequency indicates a pattern bandwidth of the order of 5%.
Background and aims – Climate change induces increasing temperatures and drought, with possible profound shifts in species’ presence and distribution. Ecological niche models are widely used to assess plant species responses to climate change. However, such data are scarce for West Africa, particularly for vulnerable multipurpose species. This study focuses on modelling the ecological niche and the conservation status of the multipurpose tree Detarium senegalense to improve insights into its habitat suitability in West Africa under past, present, and future climatic conditions. This will provide an essential basis for setting up global management plans through efficient conservation and ecological restoration policies.
Material and methods – The potential distribution of D. senegalense under past, current, and future climate scenarios were assessed using four algorithms including generalized additive models (GAM), generalized linear models (GLM), random forest (RF), and Maximum Entropy (MaxEnt). We also assessed the shift direction of suitable habitats and the conservation status of the species based on IUCN criteria. Overall, 220 occurrences were combined with a set of five bioclimatic variables to run the models.
Key results – Models performed well with good values of AUC (0.92) and TSS (0.73). Isothermality (41.10%) and Precipitation of Wettest Month (21.50%) contributed most to the distribution of the species. The distribution of D. senegalense was relatively constant from the past to the present but could decrease in the next decades. In the future, only 17.70% and 13.98% of the areas were predicted to be suitable under respectively ssp245 and ssp585. In protected areas, the suitable areas under ssp245 were estimated at 21.01% with a decrease of 2.50% and 14.60% with a decrease of 8.61% under ssp585 by 2050. The direction of the distribution shifted to the south-east under future climate scenarios. The conservation status assessment of the species is Least Concern (LC).
Conclusion – This study improves our understanding of the past, present-day, and future distribution of the species and provides support to better manage the conservation of D. senegalense in West Africa.
Background
Acaricide resistance in cattle ticks is a significant concern in (sub)tropical regions, particularly Brazil. The Larval Packet Test (LPT) is the standard laboratory bioassay for resistance diagnosis, which requires triplicates of seven acaricidal dilutions plus controls to cover larval mortalities ranging between 0 and 100%. The value of the LPT lies in providing resistance ratios based on the ratio between the LC50 calculated with potentially resistant and susceptible ticks. However, LC50 ratios are difficult to translate into practical advice for farmers. Moreover, LPT requires laboratory facilities to maintain susceptible tick colonies, and it takes 6 weeks to obtain the larvae to be tested by LPT derived from engorged female ticks collected from cattle in the field. Our novel approach was twofold: first, we upgraded the LPT to the Resistance Intensity Test (RIT) by adopting the latest WHO guidelines for resistance detection in mosquitoes, which combines a 1 × recommended dose with 5 × and 10 × concentrated doses to reveal low, moderate and high resistance intensity, respectively. This reduced the number of test papers and tick larvae and, more importantly, provided relevant information on the resistance level. Our second innovative step was to abolish testing larvae entirely and expose partly engorged adult ticks to the same acaricidal doses immediately after removing them from cattle in the field. This resulted in the Rapid Tick exposure Test (RaTexT®), wherein partly engorged adult ticks were exposed to an acaricide-impregnated, specially designed matrix providing test results within 24 h. This approach directly compared resistance detection in tick larvae in the RIT with resistance in adult ticks in RaTexT®.
Methods
Laboratory validation was conducted in Brazil with resistant and susceptible colonies of Rhipicephalus microplus ticks. For field validation, adult R. microplus ticks collected from different cattle farms in Brazil were evaluated for resistance to RaTexT®, and the results regarding their larval progenies were compared with those for the RIT. Partly engorged adult ticks derived from cattle infested with laboratory and field strains of R. microplus were exposed to deltamethrin in RaTexT® containers, which contained six rows of four interconnected compartments, accommodating five to eight semi-engorged female ticks with a preferred size ranging between 5 and 8 mm. The corresponding larvae of each strain were exposed in the RIT to the same deltamethrin concentrations in filter papers.
Results
In RaTexT®, mortality in adult ticks from a resistant strain of R. microplus from Seropédica in Brazil was 38.4%, 54.2% and 75.0% at the 1 ×, 5 × and 10 × doses of deltamethrin, respectively. In RIT, mortality of larvae from the same resistant strain was 2.0%, 4.9% and 19.5% at 1 ×, 5 × and 10 × doses, respectively. The results of RaTexT® and RIT agreed since both tests identified a high level of resistance based on a cut-off of 90% mortality.
In RaTexT®, mortality of adult ticks from a susceptible strain originating from Porto Alegre was 73.8%, 92.9% and 97.6% at the 1 ×, 5 × and 10 × doses, respectively. In RIT, mortality of larvae from the susceptible strain was 95.2%, 95.2% and 96.8% at the 1 ×, 5 × and 10 × doses, respectively. Interestingly, both tests identified a low number of unexpected resistant individuals in the susceptible strain since the mortality of neither larvae nor adults reached 100%. This effect remained unnoticed in the LPT, wherein a resistance ratio of 159.5 was found based on the LC50 of the resistant strain divided by the LC50 of the susceptible strain. Next, RaTexT® was compared with RIT using adult and larval ticks derived from three field strains of R. microplus in Brazil. RaTexT® detected high levels of resistance to deltamethrin in adult ticks in all strains, which was confirmed in larvae tested by the RIT. Both tests agreed on the same resistance level with significantly lower mortality rates in larvae than in adult ticks.
Conclusions
RaTexT® is a novel rapid pen-site test for detecting acaricide resistance in adult livestock ticks. It potentially replaces laborious tests using larval ticks and provides results within 24 h relevant to acaricide resistance management of livestock ticks.
Graphical Abstract
Introduction. Primary liver cancer (PLC) occupied the 6th and 3rd place in the world respectively in terms of incidence and mortality in 2020. The objective of this work was to study the survival and
prognostic factors of primary liver cancer from 2014 to 2020 in Cotonou.
Materials and methods. This retrospective cohort study included 150 patients registered with primary liver
cancer, in the database of the Cotonou Cancer Registry, over a seven-years period from 01/01/2014 to 12/31/2020.
R 3.6.1 software was used for data analysis. The Kaplan-Meier method was used to estimate patient survival.
The comparison of the survival curves was made by the Log-Rank test. The Cox proportional hazard model
was established to identify predictors of mortality. The statistical significance threshold was set at 5%.
Results. The mean age of the subjects was 51.7 ± 14.9 years and the sex-ratio 2.7. Half of the deaths occurred
within the first 2 months after diagnosis. The prognostic factors, after multivariate analysis, were: age ≥ 60
(Hazard Ratio adjusted, HRa = 1.7; IC 95% [1.10-2.51]), alcohol consumption (HRa = 3.7; [1.33-9.42]), therapeutic itinerary (HRa = 1. 9; [1.24-3.02]), hepatitis B virus infection (HRa = 7.7; [3.26-12.29]), hepatitis C virus
infection (HRa = 3.6; [1.38-9.43]) and time to consultation ≥4 weeks (HRa = 2.0; [1.01-4.05]).
Conclusion. The mortality of patients with CPF in Cotonou is high with a median survival of 2 months. Factors,
mostly modifiable, are associated with this mortality.
This study evaluated the effectiveness of three plant species (Panicum maximum, Echinochloa pyramidalis, and Typha domingensis), in enhancing the removal of salinity, nitrogen, phosphorus, and chemical oxygen demand during sludge treatment within sludge treatment reed beds (STRBs). The experimental setup consists of 1 m3 tanks composed of sand and gravel, simulating the reed bed configuration. A total of twelve pilot-scale units were used, with each plant species tested in triplicate, while three units were used as non-planted (control) groups. Over a 6-month period, the units received weekly loadings of faecal sludge sourced from a site in southern Benin. Sampling was carried out weekly in order to evaluate the removal efficiency of the assessed parameters. The results showed the superior efficacy of STRBs compared to control beds, attributing this enhancement to the presence of vegetation. At a loading rate of 300 kg TS/m2/year, the system presented good performance. In particular, P. maximum and E. pyramidalis beds demonstrated the highest removal rates (Salinity: 97.95%, PO43−: 97.75%, TP: 98.08%, NH4+: 98.68, NO3−: 98.71%, TKN: 99.53%, TSS: 99.98%, COD: 99.94%). Moreover, the drying rates of E. pyramidalis and P. maximum beds (49.5% and 48.5%, respectively) surpassed those of T. domingensis beds (34.7%). These findings highlight the potential of P. maximum, a newly tested species, for application in STRBs, emphasizing the need for dedicated research on this species.
Gridded climate datasets such as satellite and reanalysis products have biases related to the methods used to develop them. This study aims to improve the hourly rainfall distribution of the WFDE5 reanalysis over all grid boxes in Benin, based on bias adjustment through Quantile Mapping (QM). The bias adjusted product (called NEW) was evaluated on an hourly scale, using the percentage and quantity of precipitation events per modality class ([0–1), [1–2), [2–3), [3–4), [4–5) and ≥ 5 mm/h) and the relative mean absolute error (RMAE). On a daily scale, evaluation was based on Pearson correlation and RMAE values using nine extreme precipitation indices. The mean absolute error (MAE) and Mann Kendall trend are sometimes shown. Our result showed that assimilated rainfall from WFDE5 performed well at seasonal scales (RMAE < 15%) but underperformed at the hourly scale (RMAE sometimes > 400%). NEW offers RMAE values generally < 100%, i.e. an almost four-fold reduction in bias. The QM method improves the rainfall distribution, particularly with regard to the percentage of rainfall between 0 and 1 mm/h (WFDE5 = 95.40%, Obs = 97.87% and NEW = 97.83% at the Nalohou station) and the cumulative rainfall quantity greater than 5 mm/h (WFDE5 = 131 mm/year vs. Obs = 880 mm/year and NEW = 790 mm/year at the Nalohou station). The bias adjustment also significantly improved the description of climate extremes in Benin, particularly in terms of bias. At Cotonou station, WFDE5 was associated with an average RMAE of 61% for the nine indices, compared to 33% for NEW. Finally, NEW presents mean values closer to observation data, and can be used for hydrological impact studies in Benin.
In this study, we reassess the phylogenetic relationships of the genus Sesamia Guenée, 1852 and examine in more detail the members of the nonagrioides species group, for which three distinct species complexes are identified. The calamistis subgroup comprises eight species, of which four new species are described: Sesamia kabirara Le Ru sp. nov., Sesamia kalale Le Ru sp. nov., Sesamia mapalense Le Ru sp. nov. and Sesamia teke Le Ru sp. nov. The incerta subgroup consists of 11 species, of which four new species are described: Sesamia kamba Le Ru sp. nov., Sesamia lalaci Le Ru sp. nov., Sesamia lusese Le Ru sp. nov. and Sesamia msowero Le Ru sp. nov. The nonagrioides subgroup comprises ten species of which two new species are described: Sesamia libode Le Ru sp. nov. and Sesamia satauensis Le Ru sp. nov. Phylogenetic and molecular species delimitation analyses of a multi-marker molecular dataset allow us to investigate and clarify the status of Sesamia species and species complexes. Our results yield a well-supported phylogenetic hypothesis for the genus, which supports the monophyletic nature of all but one species subgroup. The results of 16 distinct molecular species delimitation analyses show some levels of incongruence and, overall, a tendency towards over-splitting. We also present an updated list of species for the genus Sesamia and provide morphological keys based on male and female genitalia to determine the species group of any Sesamia species and to identify all species belonging to the nonagrioides species group.
The coastal environment represents a special site for human and economic activities. The population growth in this area has led to strong urbanization and, therefore, to the establishment of small-scale vegetable farms to feed the growing urban and peri-urban populations. This is an opportunity for youth employment and reduce poverty as this activity generates reliable incomes. However, in recent years, climatic changes and rapid urbanization have influenced agricultural activities in this area. The aim of this study was to characterize market gardening systems along the coastal area of Benin and understand farmers’ perceptions and adaptation strategies in response to the ongoing environmental changes. Data was collected from 130 farms using individual semi-structured questionnaires. A principal component analysis (PCA), K-Mean multivariate classification and statistical inference were used for data analysis. Three farm groups were identified from the hierarchical bottom-up classification: modern coastal farms (MCF, 59.24%), small-scale intra-urban farms (SIF, 35.38%) and traditional co-managed lowland farms (TCF, 5.38%). The perceived environmental changes were mainly temperature increases, strong winds and migration to another farmland. The criteria differentiating the groups were strong winds and variation in the start date of the rains (p < 0.05). According to current strategies farmers in groups 1 and 2 preferred crop diversification, those in group 3 moved their farms. Future strategies range from the early sale of crops to the use of modern watering equipment to the cessation of farming. Thus, sustainable farm management requires the involvement of decentralized structures and local stakeholders to maintain the livelihoods of local populations.
Background
Recently, bacterial endosymbiont, including Wolbachia and Microsporidia were found to limit the infection of Anopheles mosquitoes with Plasmodium falciparum. This study aimed to investigate the natural presence of key transmission-blocking endosymbionts in Anopheles gambiae and Anopheles coluzzii in Southern Benin.
Methods
The present study was conducted in seven communes (Cotonou, Porto-Novo, Aguégués, Ifangni, Pobè Athiémé, and Grand-Popo) of Southern Benin. Anopheles were collected using indoor/outdoor Human Landing Catches (HLCs) and Pyrethrum Spray Catches (PSCs). Following morphological identification, PCR was used to identify An. gambiae sensu lato (s.l.) to species level and to screen for the presence of both Wolbachia and Microsporidia. Plasmodium falciparum sporozoite infection was also assessed using ELISA.
Results
Overall, species composition in An. gambiae s.l. was 53.7% An. coluzzii, while the remainder was An. gambiae sensu stricto (s.s.). Combined data of the two sampling techniques revealed a mean infection prevalence with Wolbachia of 5.1% (95% CI 0.90–18.6) and 1.3% (95% CI 0.07–7.8) in An. gambiae s.s. and An. coluzzii, respectively. The mean infection prevalence with Microsporidia was 41.0% (95% CI 25.9–57.8) for An. gambiae s.s. and 57.0% (95% CI 45.4–67.9) for An. coluzzii. Wolbachia was only observed in Ifangni, Pobè, and Cotonou, while Microsporidia was detected in all study communes. Aggregated data for HLCs and PSCs showed a sporozoite rate (SR) of 0.80% (95% CI 0.09–2.87) and 0.69% (95% CI 0.09–2.87) for An. gambiae and An. coluzzii, respectively, with a mean of 0.74% (95% CI 0.20–1.90). Of the four individual mosquitoes which harboured P. falciparum, none were also infected with Wolbachia and one contained Microsporidia.
Conclusions
The present study is the first report of natural infections of field-collected An. gambiae s.l. populations from Benin with Wolbachia and Microsporidia. Sustained efforts should be made to widen the spectrum of bacteria identified in mosquitoes, with the potential to develop endosymbiont-based control tools; such interventions could be the game-changer in the control of malaria and arboviral disease transmission.
The study objective was to assess the frequency of the kdr-L995F and ace-1 G280S genetic mutations in Anopheles gambiae s.l. mosquitoes and examine their ability to transmit Plasmodium falciparum in areas where indoor residual spraying (IRS) was implemented with Clothianidin 50 WG. The study was conducted in six communes in the Alibori and Donga departments of which four were IRS-treated and two were untreated and served as control. Post-IRS monthly samples of adult mosquitoes were collected in study communes using human landing catches (HLC). An. gambiae s.l. specimens were processed to detect kdr-L995F and ace-1 G280S mutations via PCR as well as Plasmodium falciparum infectivity through CSP ELISA. Our data revealed a high and similar allelic frequency for the kdr-L995F mutation in both treated and control communes (79% vs. 77%, p = 0.14) whilst allelic frequency of the ace-1 G280S mutation was lower across the study area (2–3%, p = 0.58). The sporozoite rate was 2.6% and 2.4% respectively in treated and untreated communes (p = 0.751). No association was found between Plasmodium falciparum infection in Anopheles gambiae s.l. vectors and carriage of kdr-L995F and ace-1 G280S mutations regardless of genotypes. The study findings underline the need for an integrated approach to malaria control, combining different control methods to effectively target transmission. Regular monitoring of insecticide resistance and genetic mutations is essential to guide control strategies.
Background
Malaria remains a major public health problem in sub-Saharan Africa, particularly in Benin. The present study aims to evaluate the different Plasmodium species transmitted by malaria vectors in the communes of Cove, Zagnanado and Ouinhi, Southern Benin.
Methods
The study was conducted between December 2021 and October 2022 in 60 villages spread over the three study communes. Adult mosquitoes were collected from four houses in each village using human landing catches (HLCs). After morphological identification, a subsample of Anopheles gambiae, Anopheles funestus and Anopheles nili was analysed by PCR to test for their infection to the different Plasmodium species.
Results
Anopheles gambiae was collected at higher frequency in all the three study communes, representing 93.5% (95% CI 92.9–94) of all collected mosquitoes (n = 10,465). In total, five molecular species were found, An. gambiae sensu stricto (s.s.) and Anopheles coluzzii of the Gambiae complex, An. funestus and Anopheles leesoni of the Funestus group, and An. nili s.s., the sole species of the Nili group. From the five molecular species, four (An. gambiae s.s., An. coluzzii, An. funestus s.s. and An. nili s.s.) were found to be infected. Plasmodium falciparum was the main Plasmodium species in the study area, followed by Plasmodium vivax and Plasmodium ovale. Only An. gambiae s.s. was infected with all three Plasmodium species, while An. coluzzii was infected with two species, P. falciparum and P. vivax.
Conclusions
Plasmodium falciparum was the only species tested for in malaria vectors in Benin, and remains the only one against which most control tools are directed. It is, therefore, necessary that particular attention be paid to secondary Plasmodium species for an efficient control of the disease. The presence of P. vivax emphasizes the need for an update of case management for malaria.
Background
Long-lasting insecticidal nets (LLINs) may have different impacts on distinct mosquito vector species. We assessed the efficacy of pyrethroid-pyriproxyfen and pyrethroid-chlorfenapyr LLINs on the density of Anopheles gambiae s.s. and An. coluzzii compared to pyrethroid-only nets in a three-arm cluster randomised control trial in Benin.
Methods
Indoor and outdoor collections of adult mosquitoes took place in 60 clusters using human landing catches at baseline and every 3 months for 2 years. After morphological identification, around 15% of randomly selected samples of An. gambiae s.l. were dissected to determine parity, species (using PCR).
Results
Overall, a total of 46,613 mosquito specimens were collected at baseline and 259,250 in the eight quarterly collections post-net distribution. Post-net distribution, approximately 70% of the specimens of An. gambiae s.l. speciated were An. coluzzii, while the rest were mostly composed of An. gambiae s.s. with a small proportion (< 1%) of hybrids (An. gambiae/coluzzii). There was no evidence of a significant reduction in vector density indoors in either primary vector species [An. coluzzii: DR (density ratio) = 0.62 (95% CI 0.21–1.77), p = 0.3683 for the pyrethroid-pyriproxyfen LLIN and DR = 0.56 (95% CI 0.19–1.62), p = 0.2866 for the pyrethroid-chlorfenapyr LLIN, An. gambiae s.s.: DR = 0.52 (95% CI 0.18–1.46), p = 0.2192 for the pyrethroid-pyriproxyfen LLIN and DR = 0.53 (95% CI 0.19–1.46), p = 0.2222 for the pyrethroid-chlorfenapyr]. The same trend was observed outdoors. Parity rates of An. gambiae s.l. were also similar across study arms.
Conclusions
Compared with pyrethroid-only LLINs, pyrethroid-chlorfenapyr LLINs and pyrethroid-pyriproxyfen LLINs performed similarly against the two primary mosquito species An. gambiae s.s. and An. coluzzii in Benin.
Graphical Abstract
A growing attention in the empirical literature has been paid on the incidence of climate shocks and change on migration decisions. Previous literature leads to different results and uses a multitude of traditional empirical approaches. This paper proposes a tree-based Machine Learning (ML) approach to analyze the role of the weather shocks toward an individual’s intention to migrate in the six agriculture-dependent-economy countries such as Burkina Faso, Ivory Coast, Mali, Mauritania, Niger, and Senegal. We performed several tree-based algorithms (e.g., XGB, Random Forest) using the train-validation-test workflow to build robust and noise-resistant approaches. Then we determine the important features showing in which direction they influence the migration intention. This ML-based estimation accounts for features such as weather shocks captured by the Standardized Precipitation-Evapotranspiration Index (SPEI) for different timescales and various socioeconomic features/covariates. We find that (i) the weather features improve the prediction performance, although socioeconomic characteristics have more influence on migration intentions, (ii) a country-specific model is necessary, and (iii) the international move is influenced more by the longer timescales of SPEIs while general move (which includes internal move) by that of shorter timescales.
The use of decentralized renewable energy systems will continue to play a significant role in electricity generation especially in developing countries where grid expansion to most remote areas is uneconomical. The income levels of these off-grid communities are often low, such that there is a need for the delivery of cost-effective energy solutions through optimum control and sizing of energy system components. This paper aims at minimizing the net present cost (NPC) and the levelised cost of energy (LCOE). The study presents a hybrid power system involving a hydroelectric, solar photovoltaic (PV), and battery system for a rural community in Cameroon. The optimization of the system was done using HOMER Pro and validated using a meta-heuristic algorithm known as genetic algorithm (GA). The GA approach was programmed using the MATLAB software. After the HOMER simulation, the optimal power capacity of 3 kW solar PV, 334.89 Ah battery, and 32.2 kW microhydropower was used to meet the load. The village load profile had a daily energy usage of 431.32 kWh/day and a peak power demand of 38.49 kW. The optimized results showed an NPC and LCOE of /kWh, respectively. The system configuration was tested against an increase in hydropower capacity, and it was observed that increasing the hydropower capacity has the ability to significantly reduce the LCOE as well as the battery and solar PV size. A comparative analysis of the two approaches showed that the optimization using GA was more cost-effective than HOMER Pro with the least LCOE of 0.0344 86,990.94 as well as a loss of power supply probability (LPSP) of 0.99%. In addition, the GA method gave more hydropower generation than HOMER Pro. This supports the fact that stochastic methods are more realistic and economically viable. They also accurately predict system operation than deterministic methods.
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Cotonou, Benin