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Abstract: Invasions of arthropod vectors and viruses are the main factors associated with emerging plant viral diseases. The presence of the Banana bunchy top virus (BBTV, genus Babuvirus), an aphid‐transmitted virus responsible for the banana bunchy top disease (BBTD), was first confirmed in 2008 in the South region of Cameroon. This study reports on surveys over 14 years to determine the status of BBTV spread and virus diversity in Cameroon. A total of 544 fields extending through 81 districts in 7 regions were surveyed in 5 phases: (1) 2009–10, (2) 2012, (3) 2013–14, (4) 2016–17, and (5) 2022. BBTV was detected in 36 sites, all located in the Ambam district in the South region, with an incidence in the virus‐affected fields ranging from 5% to 40%, with an average incidence of 14.8%. The findings indicate BBTV expansion from the location of first detection in 2008 to about 4–25 km in all directions, with the virus spread range of about 700 km2, as of the last survey in 2022. Phylogenetic analysis using complete nucleotide sequences of the BBTV‐R and BBTV‐S gene aligned Cameroon isolates with the sub‐Saharan Africa subgroup of the Pacific‐Indian Oceans (PIO) group of BBTV isolates, suggesting a likely virus invasion from neighbouring central African countries where BBTV presence had been reported in the 1980s. Knowledge of BBTV distribution provided through the detection and delimiting surveys has contributed to the efficient targeting of interventions to limit the expansion of an emerging virus threat to banana production in Cameroon.

The flea beetle Nisotra uniformis Jacoby is a widespread pest of malvaceous crops for which synthetic chemical insecticides remain the principal control tool, particularly in sub-Saharan Africa. With the ultimate aim of developing a microbial alternative for N. uniformis control, we conducted laboratory experiments (25 ± 1°C; 70 - 80% RH) to evaluate the biological attributes of three Cameroonian isolates of the entomopathogenic fungi Beauveria bassiana (Balsamo-Crivelli) Vuillemin and Metarhizium anisopliae sensu lato (Metchnikoff) Sorokin. Spore germination rates of the isolates varied from 0.5% after 4 hrs to 100% after 24 hrs on PDA medium, with MIITAC11.3.4 spores germinating fastest. Pathogenicity tests consisted of dipping adult beetles in conidial suspensions. All isolates were pathogenic to N. uniformis, with corrected mortalities varying between 23.3 - 86.7%. BIITAC-O-2 had the lowest LC50 at 5.17 × 106 conidia/ml, while MIITAC11.3.4 and BIITAC6.2.2 had LC50 at 4.11 × 107 conidia/ml, and 2.00 × 108 conidia/ml, respectively. BIITAC6.2.2 produced the shortest time to the highest mortality rate (1.17 days) and the shortest LT50 of 1.64 days but only at the highest concentration, followed by the two highest concentrations of MIITAC11.3.4 (LT50 at 3.43 and 5.70 days). The c parameter in the Weibull model showed that BIITAC-O-2 caused the highest rate of increase in mortality (2.42) at the highest concentration, followed by MIITAC11.3.4 (1.09) and BIITAC6.2.2 (0.50). The results of our study provide the basis for including N. uniformis in the ongoing development of BIITAC6.2.2 and MIITAC11.3.4 into biopesticide while continuing with further laboratory studies on BIITAC-O-2.

Banana bunchy top disease (BBTD), caused by the banana bunchy top virus (BBTV, genus Babuvirus), is the most destructive viral disease of banana and plantain (Musa spp.). The virus is transmitted persistently by the banana aphid, Pentalonia nigronervosa Coquerel (Hemiptera: Aphididae). While research efforts have focused on screening Musa genotypes for BBTD resistance, comparatively little work has been carried out to identify resistance to banana aphids. This study assessed 44 Musa germplasm of different A and B genome composition for the performance of banana aphids under semicontrolled environmental screenhouse conditions and in a field trial established in a BBTD endemic location. In the screenhouse, the AA diploid Calcutta 4 had the lowest apterous aphid density per plant (9.7 ± 4.6) compared with AAB triploid Waema, which had the highest aphid densities (395.6 ± 20.8). In the field, the highest apterous aphid density per plant (29.2 ± 6.7) occurred on the AAB triploid Batard and the lowest (0.4 ± 0.2) on the AA diploid Pisang Tongat. The AA diploid Tapo was highly susceptible to BBTD (100% infection) compared with the genotypes Balonkawe (ABB), PITA 21 (AAB), Calcutta 4 (AA), and Balbisiana Los Banos (BB), which remained uninfected. The Musa genotypes with apparent resistance to BBTD and least susceptibility to aphid population growth provide options for considering aphid and BBTD resistance in banana and plantain breeding programs.

The nutrient-rich tubers of the greater yam, Dioscorea alata L., provide food and income security for millions of people around the world. Despite its global importance, however, greater yam remains an orphan crop. Here, we address this resource gap by presenting a highly contiguous chromosome-scale genome assembly of D. alata combined with a dense genetic map derived from African breeding populations. The genome sequence reveals an ancient allotetraploidization in the Dioscorea lineage, followed by extensive genome-wide reorganization. Using the genomic tools, we find quantitative trait loci for resistance to anthracnose, a damaging fungal pathogen of yam, and several tuber quality traits. Genomic analysis of breeding lines reveals both extensive inbreeding as well as regions of extensive heterozygosity that may represent interspecific introgression during domestication. These tools and insights will enable yam breeders to unlock the potential of this staple crop and take full advantage of its adaptability to varied environments.

Banana bunchy top disease (BBTD) is the most devasting disease of banana and plantain (Musa spp.). The disease spreads through the use of infected vegetative propagules and the banana aphid (Pentalonia nigronervosa) is the virus vector. This study seeks to understand the gender dimensions and sociocultural aspects of banana seed (vegetative propagule) sourcing and sharing practices among men and women farmers, and its influence on BBTD spread and disease control efforts. Data were collected from 300 banana farmers (187 men and 113 women) in BBTD and non-BBTD areas in southwest Nigeria. The results revealed that seed sharing within the communities is a social responsibility with members expected to share banana seed with the needy mainly as gifts rather than sold for cash. Men farmers mostly sourced seed from old fields, while women sourced seed from relatives. Harvesting of banana seed was predominantly the responsibility of men with women as helpers. Both men and women farmers in the non-BBTD area cultivated larger farm sizes and harvested more banana planting material than farmers in the BBTD area. The existing seed sourcing practices among men and women farmers heighten the risk of BBTD spread. Awareness raising on disease spread through infected seeds should consider gender-differentiated roles and social practices to reduce its spread within communities.

Metarhizium anisopliae (Metschnikoff) Sorokin and Beauveria bassiana (Balsamo) Vuillemin are entomopathogenic fungi commonly used in microbial control of arthropods. In this study, we evaluated the insecticidal potential of six isolates of B. bassiana (BIITAC10.3.3, BIITAC6.2.2, and BIITAC8.1.5) and M. anisopliae (MIITAC11.3.4, MIITAC6.2.2, and MIITAC6.4.2) from Cameroon, against the banana aphid Pentalonia nigronervosa Coquerel, the vector of the banana bunchy top virus (BBTV). Pathogenicity tests were initially conducted using B. bassiana and M. anisopliae isolates at a concentration of 3.2 × 106 conidia/ml on P. nigronervosa adults sourced from four agroecologies in Cameroon. Four isolates (BIITAC6.2.2, BIITAC10.3.3, BIITAC8.1.5, and MIITAC6.2.2) were highly pathogenic, causing greater than 75% aphid mortality in all populations. A significant decrease in aphid fecundity was observed with BIITAC6.2.2, MIITAC6.2.2, and BIITAC10.3.3. These three isolates were in a test of a series of four fungal concentrations (3.2 × 101, 3.2 × 102, 3.2 × 104, and 3.2 × 106 conidia/ml). produced LC50 of 1.31 × 101 and 3.12 × 10−2 for BIITAC10.3.3 and MIITAC6.2.2, respectively. MIITAC6.2.2 had the lowest LC90 (1.55 × 103). Our results strongly support the continued development of biopesticides based on one or more of the three fungal entomopathogens for the control of banana aphids as a component of an Integrated Pest Management (IPM) strategy for the reduction of the prevalence and transmission of BBTV under field conditions. [ABSTRACT FROM AUTHOR]

Cacao (Theobroma cacao L.) is a tropical tree species belonging to the Malvaceae, which originated in the lowland rainforests of the Amazon. It is a major agricultural commodity, which contributes towards the Gross Domestic Product of West African countries, where it accounts for about 70% of the world's production. Understanding the genetic diversity of genetic resources in a country, especially for an introduced crop such as cacao, is crucial to their management and effective utilization. However, very little is known about the genetic structure of the cacao germplasm from Sierra Leone and Togo based on molecular information. We assembled cacao germplasm accessions (235 from Sierra Leone and 141 from Togo) from different seed gardens and farmers' fields across the cacao-producing states/regions of these countries for genetic diversity and population structure studies based on single nucleotide polymorphism (SNP) markers using 20 highly informative and reproducible KASP–SNPs markers. Genetic diversity among these accessions was assessed with three complementary clustering methods, including model-based population structure, discriminant analysis of principal components (DAPC), and phylogenetic trees. STRUCTURE and DAPC exhibited some consistency in the allocation of accessions into subpopulations or groups, although some discrepancies in their groupings were noted. Hierarchical clustering analysis grouped all the individuals into two major groups, as well as several sub-clusters. We also conducted a network analysis to elucidate genetic relationships among cacao accessions from Sierra Leone and Togo. Analysis of molecular variance (AMOVA) revealed high genetic diversity (86%) within accessions. A high rate of mislabeling/duplicate genotype names was revealed in both countries, which may be attributed to errors from the sources of introduction, labeling errors, and lost labels. This preliminary study demonstrates the use of KASP–SNPs for fingerprinting that can help identify duplicate/mislabeled accessions and provide strong evidence for improving accuracy and efficiency in cacao germplasm management as well as the distribution of correct materials to farmers. [ABSTRACT FROM AUTHOR]

Banana bunchy top disease (BBTD), an invasive and devastating viral disease, is widespread in banana-producing areas in Sub-Saharan Africa. Recovery of banana production in BBTD-affected areas was undertaken in a research project through the CGIAR Research Program on Roots, Tubers and Bananas (CRP-RTB) in eight countries. Understanding household and community dynamics is vital to recovery because decision-making on banana production and resource allocation occur at household level, while opportunity structures for men and women to engage in such work are influenced by social norms expressed both at household and community levels. Studies were undertaken to understand gender norms, practices and experiences in intra- and inter household and community dynamics related to banana farming in BBTD-affected areas. A standardized methodology was applied in all sites including household survey, gender seasonal calendar, daily activity schedule and a community profile. Results from analysis of four cases studies from Burundi, Gabon, Democratic Republic of Congo (DRC) and Nigeria indicated that banana is an important crop for both female and male farmers in all pilot sites and considered as both a staple food and a source of income. Men, women and male and female children are all involved in different banana production activities at household level; some mostly done by men assisted by male children (land preparation in DRC (95%), Nigeria (83%), Gabon (82.5%) and Burundi (64%)) while others are mostly done by women assisted by female children (watering, weeding in Kisangani (87%)). Men and women have differential use, control and ownership rights to different types of productive resources within the household which have implications for effective BBTD control and the benefits derived. Insights from the study will be used to develop guidelines for the incorporation of gender-responsive strategies into the design and implementation of BBTD control strategies.

Recycling has been the fascinating topic among the researchers for all times. The present study shows the recycling of steel plant's solid wastes as blast furnace flue dust and sludge towards agglomeration and their use in the production of sinter. These wastes consist of metal oxides and coke fines as a valuable material with some alkali oxides. Using these wastes as it is in the form of fines exacerbate the further processing. Pellets of these wastes are prepared with three types of binders as molasses, dextrin and bentonite. The result reveals that properties as compressive strength, shatter strength, are better in the case of bentonite binder having the productivity of the disc pelletizer machine as 75. After that, these macro pellets used for sintering with iron ore and other ingredients in pot type, down draft laboratory grade sintering machine, which shows very high productivity and good mechanical properties of the sinter as well. The microstructural analysis reveals the presence of re-oxidized hematite and a little bit of a magnetite phase with some slag phases, which confirmed later by XRD analysis. Results also show the decrease in coke rate, i.e. coke consumption to produce sinter and at the same time, this process is highly eco-friendly.