Epidemiologies de la mosaïque Africaine de manioc et de la striure brune du manioc dans le système semencier paysan en R.D. Congo: tendances et déterminants

peer reviewedi-CARE : Improved Cassava virus resistance mitigation strategies and development of a disease-free seed syste

Facteurs de risque associés à la dissémination de la striure brune du manioc à travers les voies d'acquisition des boutures à l'Est de la R.D. Congo

peer reviewedVegetatively propagated crops are particularly prone to disease dissemination through their seed systems. Strict phytosanitary measures are important to limit the impact of diseases as illustrated by the potato seed system in Europe. Cassava brown streak disease (CBSD) is a devastating disease caused by two viral species collectively named cassava brown streak viruses (CBSVs). CBSD can cause substantial root yield losses of up to 100% in the worst affected areas and is easily transmitted through stem cuttings. In Eastern and Central Africa, the epidemiology of CBSVs in the local socio-economical context of production remains poorly known while a better understanding would be an asset to properly manage the disease. This lack of information explains partially the limited efficiency of current regulatory schemes in increasing the availability of quality seed to smallholders and mitigating the spread of pests and diseases. This study surveyed the epidemiology of CBSVs in Uvira territory, Eastern D.R. Congo, and its drivers using a multivariate approach combining farmer’s interview, field observation, sampling and molecular detection of CBSVs. Investigation on the epidemiology of CBSD revealed that three clusters in the study area could be identified using five most significant factors: (i) symptoms incidence, (ii) number of whiteflies, (iii) types of foliar symptoms, (iv) cutting’s pathways and (v) plant age. Among the three clusters identified, one proved to be potentially interesting for seed multiplication activities since the disease pressure was the lowest. Through risk assessment, we also identified several key socio-economic determinants on disease epidemy: (i) factors related to farmer’s knowledge and awareness (knowledge of cassava pests and diseases, knowledge of management practices, support from extension services and management strategies applied), (ii) factors related to the geographical location of farmer’s fields (proximity to borders, proximity to town, distance to acquire cuttings), as well as (iii) the pathways used to acquire cuttings.2. Zero hunge

First report of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Onion (Allium cepa L.) in South Kivu, Eastern DR Congo

The fall armyworm, Spodoptera frugiperda (J. E. Smith, 1797), has become one of the most devastating pests in the world with diverse host range. To develop effective integrated management strategies against S. frugiperda, it is crucial to know its alternative host plants. In this study, we provide the first information on the occurrence of S. frugiperda in onion crops in Africa. Monitoring was carried out during the 2019 and 2020 growing seasons in onion monoculture and in intercropping with groundnut to detect the presence and assess the incidence of S. frugiperda. The highest average incidence (2.88%) and larval density (0.79 per 9 m2) were observed in onion monoculture. The classification of the onion leaf damage rating scale indicated low S. frugiperda infestation. This suggests that future studies will need to assess this aspect which we consider to be a survival strategy to maintain its population throughout the year, which contributes to sustain the insect in the study area during times when its preferred hosts are not present. Furthermore, genetic studies are needed to provide a better explanation of the ecology of this pest and to find out which of the two existing strain infests onions or whether it is an unknown hybrid population of S. frugiperda

Evaluation of the productivity of seven varieties of wheat (Triticum aestivum) through integrated soil fertility management in Kaziba, South Kivu, DR Congo

Due to high demand for food resources as a result of increasing population, the promotion of large-scale crops such as wheat has become essential. Unfortunately, soil infertility and a lack of improved seed are major constraints on the expansion of this crop in Kaziba, a mountainous rural area in South Kivu. The productivity of seven wheat varieties (Farari, Kayira, Kima, Lokale, Mbega, Nyumbu and Popo) was evaluated under organic and mineral fertilizer during the 2013-2014 crop season on poor soil in South Kivu (DR Congo). NPK 17-17-17, farmyard manure and their combination were applied as fertilizers in a split-plot trial design with three replications. The observations focused on the growth and yield parameters, and the results revealed differences between varieties, treatments and interactions. The NPK + farmyard manure treatment gave the highest mean yield (1317.2 kg), Kayira was the most productive variety (1584.2 kg), and the interaction Kayira X farmyard manure was the most effective (2874.9 kg). The variety Kayira would seem to be indicated, with farmyard manure as the recommended fertilizer, being locally accessible and easily usable for promoting wheat in the region

Applying the Robson classification to routine facility data to understand the Caesarean section practice in conflict settings of South Kivu, eastern DR Congo

Introduction: Sub-Saharan Africa has low Caesarean (CS) levels, despite a global increase in CS use. In conflict settings, the pattern of CS use is unclear because of scanty data. We aimed to examine the opportunity of using routine facility data to describe the CS use in conflict settings. Methods: We conducted a facility-based cross-sectional study in 8 health zones (HZ) of South Kivu province in eastern DR Congo. We reviewed patient hospital records, maternity registers and operative protocol books, from January to December 2018. Data on direct conflict fatalities were obtained from the Uppsala Conflict Data Program. Based on conflict intensity and chronicity (expressed as a 6-year cumulative conflict death rate), HZ were classified as unstable (higher conflict death rate), intermediate and stable (lower conflict death rate). To describe the Caesarean section practice, we used the Robson classification system. Based on parity, history of previous CS, onset of labour, foetal lie and presentation, number of neonates and gestational age, the Robson classification categorises deliveries into 10 mutually exclusive groups. We performed a descriptive analysis of the relative contribution of each Robson group to the overall CS rate in the conflict stratum. Results: Among the 29,600 deliveries reported by health facilities, 5,520 (18.6%) were by CS; 5,325 (96.5%) records were reviewed, of which 2,883 (54.1%) could be classified. The overall estimated population CS rate was 6.9%. The proportion of health facility deliveries that occurred in secondary hospitals was much smaller in unstable health zones (22.4%) than in intermediate (40.25) or stable health zones (43.0%). Robson groups 5 (previous CS, single cephalic, ≥ 37 weeks), 1 (nulliparous, single cephalic, ≥ 37 weeks, spontaneous labour) and 3 (multiparous, no previous CS, single cephalic, ≥ 37 weeks, spontaneous labour) were the leading contributors to the overall CS rate; and represented 75% of all CS deliveries. In unstable zones, previous CS (27.1%) and abnormal position of the fetus (breech, transverse lie, 3.3%) were much less frequent than in unstable and intermediate (44.3% and 6.0% respectively) and stable (46.7%and 6.2% respectively). Premature delivery and multiple pregnancy were more prominent Robson groups in unstable zones. Conclusion: In South Kivu province, conflict exposure is linked with an uneven estimated CS rate at HZ level with at high-risks women in conflict affected settings likely to have lower access to CS compared to low-risk mothers in stable health zones

Typology of smallholder maize farmers in South-Kivu, Eastern D.R. Congo: implications in improving farming practices and markets

peer reviewedUnderstanding the typology of smallholder maize farmers is crucial to elucidate the diversity in local farming systems, and therefore, devise effective interventions and policies that maximize the impact of agricultural innovations in South-Kivu province, eastern Democratic Republic of Congo (DRC). This study aimed at characterizing maize farmers in South-Kivu province and clustering them based on various socioeconomic and agronomic factors to identify specific production constraints and devise more effective interventions. A household survey among 300 South-Kivu maize farmers allowed to identify four distinct clusters based on farm size, land use, income, and agricultural technology adoption. The clusters ranged from resource-poor smallholder (Types 1 and 2) to medium-resource semi-innovative producers (Type 3) and highly equipped innovative farmers (Type 4). Key discriminative factors included total farm size, maize farm size, farming experience, access to agricultural credit, income, and innovation adoption rate. This study revealed specific constraints for each cluster, including low soil fertility, poor weed management, low market access, and labor scarcity. This study’s findings demonstrate the value of farm typology in guiding targeted interventions to address specific constraints and improve maize productivity, and suggest specific strategic directions for research and development projects in rural areas of the South-Kivu province

Epidémiologie, diversité génétique, distribution et contrôle des virus de la mosaïque africaine du manioc et de son vecteur (Bemisia tabaci) dans la région du Sud-Kivu en République Démocratique du Congo

An assessment of the epidemiology of cassava pests and diseases in the South Kivu region of the D.R. Congo, and of the molecular diagnosis of cassava mosaic viruses based on their AC2 and AC4 genes, showed that there is a high disease prevalence in the low-altitude areas where cassava is grown intensively. Two virus species (African cassava mosaic virus, ACMV, and East African cassava mosaic virus, EACMV) occur in this region both in cassava plants and in their whitefly vectors (Bemisia tabaci), resulting in severe symptoms and major yield losses. These losses were higher in low-altitude areas where EACMV-UG alone, or in a dual infection with ACMV, was frequent. The incidence of cassava mosaic disease (CMD) ranged from 65 to 100% in low-altitude areas and from 9.5 to 77.7% in high altitude ones. The number of whiteflies per leaf was 8-17.9 and 1-11.3, respectively. The disease severity scores reflected these differences. Based on a phylogenetic study of the partial sequences of their DNA A genome, the ACMV isolates clustered into five distinct groups, whereas the EACMV-UG isolates fell into only two groups, probably due to their more recent history in the region. The whitefly population, which was studied using the sequences of Cytochrome oxydase I of the mitochondrial gene (mtCOI), was homogenous independently of its host plants. Among the 10 major local cassava varieties and five improved genotypes studied, two local varieties (Pharmakina and Cizinduka) and three improved genotypes (MM96/002, MM96/157, MM96/6967) were the most productive and the most tolerant of the disease. The cultivation of cassava in an intercropping system resulted in a reduction of 19% and 33.3% in disease incidence and its vector population, respectively. The study highlighted the differential distribution and impact of cassava mosaic disease depending upon agro-ecosystem characteristics, with factors such as altitude, genotype, virus species and infection period playing a role in the disease epidemic. Under conducive conditions, yield losses ranging from 77.5 to 97.3% have been recorded. Our results indicate that CMD management needs to be considered as more complex than simply managing a viral disease. We propose that an integrative approach should be adopted, taking into account the agro-ecosystem in which cassava is grown, the type of cropping system, varietal adaptation and vector presence and distribution, as well as the incidence of other endemic cassava pests and diseases. It is also very important to ensure the availability of disease-free cassava cuttings and well-adapted cassava varieties.L’épidémiologie et la caractérisation moléculaire des virus de la mosaïque du manioc ont montré une distribution selon les agro-écosystèmes. En basse altitude l’incidence, la sévérité ainsi que la population du vecteur sont plus élevées qu’en moyenne et haute altitude. Des incidences allant de 65-100% et de 9,5 à 77,7% et un nombre de mouches blanches par feuille de 8-17,9 et 1-11,3 sont rapportées dans les zones respectives. La même tendance est observée pour les autres maladies et ravageurs. Les analyses moléculaires révèlent une population du vecteur homogène et seules deux espèces des begomovirus du manioc (ACMV et EACMV). La sévérité est liée à la prédominance des souches EACMV-UG plus virulentes et plus d’infections mixtes en basse altitude qu’en moyenne et haute altitude où prédominent des souches ACMV moins virulentes. Les souches ACMV forment cinq groupes distincts alors que les souches EACMV-UG n’en forment que deux, probablement au vu de leur histoire récente dans la région. Parmi dix variétés locales comparées à cinq variétés améliorées, deux locales (Pharmakina et Cizinduka) et trois améliorées (MM96/002, MM96/157 et MM96/6967) sont plus productives et tolérantes. La culture en association permet de réduire respectivement de 19% et 33,3% les valeurs de l’incidence et de la population du vecteur. Cette étude montre que l’épidémiologie et l’impact de la maladie sont liés à l’adaptation des génotypes dans l’agro-écosystème où ils sont cultivés en interaction avec d’autres facteurs tels que les souches des virus, la période d’infection ainsi que le système de culture. Elle souligne la nécessité d’une approche intégrée qui tienne compte à la fois de tous ces facteurs, du vecteur et de sa distribution, sans oublier les autres maladies et ravageurs.(AGRO 3) -- UCL, 201

Cassava mosaic disease yield loss assessment under various altitude agroecosystems in the sudKivu region, Democratic Republic of Congo

Cassava mosaic disease (CMD) is reported as the most important constraint on cassava production in SubSaharan Africa. Yield losses of 2595% are reported. The use of resistant genotypes is one of the components for its integrated management. However its impact on genotypes behavior depends on infection period, age of the infected plants, environment and virus species or strain in cause. This study was carried out to assess its impact in farmers’ fields and the behavior of 14 genotypes under high epidemic pressure in the SudKivu province, at the East of Democratic Republic of Congo (DRC). Early infections have induced 77,5% to 97,3% of yield losses whereas 44,9 to 80% were recorded for cassava plants infected during thirteenth to twentyfourth weeks after planting. The highest yield losses were recorded in low altitude where more EACMVUG and dual infections were reported. Improved resistant genotypes MM96/002, MM96/0157 and MM96/1920 allowed harvesting more than 30 T/ha and didn’t show any symptoms whereas MM96/6967 and Mvuama have developed symptoms at harvest. Local landraces were susceptible to CMD and developed symptoms during the whole season until harvest. However two of them, Pharmakina and Cizinduka yielded more than 50 T/ha of tubers and associated symptoms were moderate. Two improved and two local cassava genotypes are recommended in this area always making sure to use healthy cuttings

Dynamics of customary land rights and its impact on the agronomic choices for small farmers in the South Kivu province, Eastern DR Congo

In Africa, there is still observed a land related legal plurality despite innovations undertaken since colonial times. In DR Congo, while by law land remains the property of the State, it remains difficult to manage rural lands, ignoring customary practices. In fact, alongside the “modern” land administration, the majority of rural lands are covered by customary contracts. Meanwhile, these contracts have evolved due to different socio-political issues in the DRC and particularly in its eastern part. This study aimed at understanding these changes and thus the impact resulted in agricultural activities, especially the small farmers’ technology choice. The study is based on households’ surveys in the Mbinga Sud zone as well as from other stakeholders on land in the Kalehe territory, South Kivu province, eastern DRC. Through this study, it is noted that customary land contracts have sufficiently evolved due to the population growth, innovations taken in land administration in the country, the wars that occurred in the eastern DR Congo, the attractiveness of rural land by elites and rich businessmen leading to land concentration etc. Given this situation, some practices such as purchase and lease of land were thus developed to cope with weak customary land acquisition mechanisms, the land scarcity and / or land depletion and the fear of land grabbing by the strongest. These changes also have an impact on some agricultural practices, including the fertilization of farms, the choice of crops and varieties to grow as well as many other cultivation techniques

Resistance to African swine fever virus among African domestic pigs appears to be associated with a distinct polymorphic signature in the RelA gene and upregulation of RelA transcription

Abstract African swine fever virus (ASFV) is a highly contagious and fatal hemorrhagic disease of domestic pigs, which poses a major threat to the swine industry worldwide. Studies have shown that indigenous African pigs tolerate ASFV infection better than European pigs. The porcine v-rel avian reticuloendotheliosis viral oncogene homolog A (RelA) encoding a p65 kD protein, a major subunit of the NF-kB transcription factor, plays important roles in controlling both innate and adaptive immunity during infection with ASFV. In the present study, RelA genes from ASFV-surviving and symptomatic pigs were sequenced and found to contain polymorphisms revealing two discrete RelA amino acid sequences. One was found in the surviving pigs, and the other in symptomatic pigs. In total, 16 nonsynonymous SNPs (nsSNPs) resulting in codon changes were identified using bioinformatics software (SIFT and Polyphen v2) and web-based tools (MutPre and PredictSNP). Seven nsSNPs (P374-S, T448-S, P462-R, V464-P, Q478-H, L495-E, and P499-Q) were predicted to alter RelA protein function and stability, while 5 of these (P374-S, T448-S, P462-R, L495-E, and Q499-P) were predicted as disease-related SNPs. Additionally, the inflammatory cytokine levels of IFN-α, IL-10, and TNF-α at both the protein and the mRNA transcript levels were measured using ELISA and Real-Time PCR, respectively. The resulting data was used in correlation analysis to assess the association between cytokine levels and the RelA gene expression. Higher levels of IFN-α and detectable levels of IL-10 protein and RelA mRNA were observed in surviving pigs compared to healthy (non-infected). A positive correlation of IFN-α cytokine levels with RelA mRNA expression was also obtained. In conclusion, 7 polymorphic events in the coding region of the RelA gene may contribute to the tolerance of ASFV in pigs