Did the prolonged residual efficacy of clothianidin products lead to a greater reduction in vector populations and subsequent malaria transmission compared to the shorter residual efficacy of pirimiphos-methyl?

BACKGROUND: The residual activity of a clothianidin + deltamethrin mixture and clothianidin alone in IRS covered more than the period of malaria transmission in northern Benin. The aim of this study was to show whether the prolonged residual efficacy of clothianidin-based products resulted in a greater reduction in vector populations and subsequent malaria transmission compared with the shorter residual efficacy of pirimiphos-methyl. METHODS: Human bait mosquito collections by local volunteers and pyrethrum spray collections were used in 6 communes under IRS monitoring and evaluation from 2019 to 2021. ELISA/CSP and species PCR tests were performed on Anopheles gambiae sensu lato (s.l.) to determine the infectivity rate and subspecies by commune and year. The decrease in biting rate, entomological inoculation rate, incidence, inhibition of blood feeding, resting density of An. gambiae s.l. were studied and compared between insecticides per commune. RESULTS: The An. gambiae complex was the major vector throughout the study area, acounting for 98.71% (19,660/19,917) of all Anopheles mosquitoes collected. Anopheles gambiae s.l. collected was lower inside treated houses (45.19%: 4,630/10,245) than outside (54.73%: 5,607/10,245) after IRS (p < 0.001). A significant decrease (p < 0.001) in the biting rate was observed after IRS in all departments except Donga in 2021 after IRS with clothianidin 50 WG. The impact of insecticides on EIR reduction was most noticeable with pirimiphos-methyl 300 CS, followed by the clothianidin + deltamethrin mixture and finally clothianidin 50 WG. A reduction in new cases of malaria was observed in 2020, the year of mass distribution of LLINs and IRS, as well as individual and collective protection measures linked to COVID-19. Anopheles gambiae s.l. blood-feeding rates and parous were high and similar for all insecticides in treated houses. CONCLUSION: To achieve the goal of zero malaria, the optimal choice of vector control tools plays an important role. Compared with pirimiphos-methyl, clothianidin-based insecticides induced a lower reductions in entomological indicators of malaria transmission.

Malaria transmission potential of Anopheles gambiae s.l. in indoor residual spraying areas with clothianidin 50 WG in northern Benin.

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.

The impact of pyrethroid-pyriproxyfen and pyrethroid-chlorfenapyr long-lasting insecticidal nets on density of primary malaria vectors Anopheles gambiae s.s. and Anopheles coluzzii in Benin: a secondary analysis of a cluster randomised controlled trial.

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.

Genotype × environment interaction and stability analysis for seed yield and yield components in sesame (Sesamum indicum L.) in Benin Republic using AMMI, GGE biplot and MTSI.

Increasing production requires the development of high yielding cultivars adapted to various environments. Multi-environment trials (MET) remains the best approach to assess the performance of accessions across environments. The objective of this study was to select the best performing and stable accessions of sesame across different environments in Benin Republic. Nineteen sesame accessions were evaluated across eight environments using a randomized complete block design with four replicates. The accessions were evaluated for three traits: days to 50% flowering (D50F), thousand-seed weight (TSW), and seed yield (SY) during 2020 growing season. The stable and top-performing accessions across environments were determined using AMMI (Additive main effects and multiplicative interaction), GGE (Genotype main effect and genotype × environment interaction), and MTSI (Multi-trait stability index). AMMI analysis of variance showed a significant difference across environments for the three traits. The accessions were affected by environmental conditions for the three traits. The broad-sense heritability estimates were high (>0.60) for all the traits, indicating the improvement is achievable through selection. AMMI1 and AMMI2 biplots identified G10 and G13 as high seed yielding accessions adapted to environments E1, E2. The GGE biplot showed two mega-environments for TSW and three mega-environments for D50F and SY. For SY, G11 and G13 were the best accessions in the first mega-environment, G10 the best accession in the second mega-environment; G3 and G8 were the best accessions in the third mega-environment. AMMI and GGE analyses identified G10, G5, G12 as high seed yielding and stable accessions across environments. GGE biplot revealed that E1 and E2 were the most suitable environments for multi-location trials based on their discriminating ability and representativeness. MTSI indicated G10, G13, G19 as promising germplasm to be recommended for breeding program.

Field performance of three mosquito collection methods for assessing the entomological efficacy of dual-active ingredient long-lasting insecticidal nets.

Selection of mosquito collection methods is of crucial importance to evaluate the impact of vector control tools on entomological outcomes. During a cluster randomised control trial evaluating the relative efficacy of two dual-active ingredient (a.i.) long-lasting insecticidal nets (LLINs) compared to pyrethroid-only LLINs, we assessed the performance of different mosquito collection methods: Human landing catches (HLC), Centers for Disease Control and Prevention (CDC) light traps, and pyrethrum spray catches (PSC). Anopheles mosquitoes were collected using three collection methods in 4 houses, in each of the 60 trial clusters at baseline and every quarter for 24 months using PSCs and HLCs, while CDC light traps were performed during two quarters only. Mean density of vectors collected per method per night was the highest with HLCs (15.9), followed by CDC light traps (6.8); with PSCs (1.1) collecting 10 times less mosquitoes than HLCs. All three collection methods collected fewer mosquitoes in the Interceptor G2® dual a.i. arm, compared to the other trial arms, although only HLCs and PSCs demonstrated strong evidence of this due to a greater number of collection rounds undertaken, than CDC light traps. The broadly similar results regarding the differential impact of the two dual a.i. LLINs showed by the three collection methods suggest that the more ethically acceptable, cheaper, and logistically simpler methods such as CDC light traps could be prioritised for use in large community trials for measuring the efficacy of vector control tools.

What can be learned from the residual efficacy of three formulations of insecticides (pirimiphos-methyl, clothianidin and deltamethrin mixture, and clothianidin alone) in large-scale in community trial in North Benin, West Africa?

BACKGROUND: In Alibori and Donga, two departments of high malaria incidence of Northern Benin, pirimiphos-methyl, mixture deltamethrin + clothianidin, as well as clothianidin were used at large scale for IRS. The present study aimed to assess the residual efficacy of these products. METHODS: Immatures of Anopheles gambiae sensu lato (s.l.) collected in the communes of Kandi and Gogounou (Department of Alibori), Djougou and Copargo (Department of Donga) were reared until adulthood. Females aged 2-5 days were used for susceptibility tube tests following the WHO protocol. The tests were conducted with deltamethrin (0.05%), bendiocarb (0.1%), pirimiphos-methyl (0.25%) and clothianidin (2% weight per volume). For cone tests performed on cement and mud walls, the An. gambiae Kisumu susceptible strain was used. After the quality control of the IRS performed 1-week post-campaign, the evaluation of the residual activity of the different tested insecticides/mixture of insecticides was conducted on a monthly basis. RESULTS: Over the three study years, deltamethrin resistance was observed in all the communes. With bendiocarb, resistance or possible resistance was observed. In 2019 and 2020, full susceptibility to pirimiphos-methyl was observed, while possible resistance to the same product was detected in 2021 in Djougou, Gogounou and Kandi. With clothianidin, full susceptibility was observed 4-6 days post-exposure. The residual activity lasted 4-5 months for pirimiphos-methyl, and 8-10 months for clothianidin and the mixture deltamethrin + clothianidin. A slightly better efficacy of the different tested products was observed on cement walls compared to the mud walls. CONCLUSION: Overall, An. gambiae s.l. was fully susceptible to clothianidin, while resistance/possible resistance was observed the other tested insecticides. In addition, clothianidin-based insecticides showed a better residual activity compared to pirimiphos-methyl, showing thus their ability to provide an improved and prolonged control of pyrethroid resistant vectors.

Efficacy of Pyrethroid-Pyriproxyfen and Pyrethroid-Chlorfenapyr Long-Lasting Insecticidal Nets (LLINs) for the Control of Non-Anopheles Mosquitoes: Secondary Analysis from a Cluster Randomised Controlled Trial (cRCT).

The efficacy of a vector control tool in reducing mosquito biting is crucial for its acceptability. The present study compared the vector density of Culex spp. And Mansonia spp. across clusters, which received two dual-active ingredient (a.i.) long-lasting insecticidal nets (LLINs) and a standard pyrethroid-only LLIN, and assessed the seasonality of these mosquito genera. A total of 85,723 Culex spp. and 144,025 Mansonia spp. were caught over the study period. The density of Culex and Mansonia was reduced in all three arms over the study period. There was no evidence of a significant reduction in the indoor or outdoor density of Culex spp. in either dual-a.i. LLIN arm as compared to the standard pyrethroid-only net arm. A similar trend was observed with Mansonia spp. A high density of Culex spp. was found both in rainy and dry seasons, while for Mansonia spp., this was mainly observed during the rainy season. These results suggest that the novel insecticides in the dual-a.i. LLINs did not have an additional impact on these species and that pyrethroids might still be effective on them. Further work is required to determine whether these species of mosquitoes have resistance to the insecticides tested in this trial.

Problematic Use of Cannabis in Cotonou: Profile of Some Subjects Received in the Laboratory between 2016 and 2021.

Aims: The frequent use of cannabis by certain social strata often induces behavioral changes whose severity deserves to be evaluated. This study aims to describe the profile of some subjects in a situation of cannabis dependence received at the National Laboratory of Narcotics and Toxicology over the period from January 2016 to December 2021. Methodology. The approach of direct interviews with the respondents using a semistructured questionnaire made it possible to collect their sociodemographic characteristics, their experiences, and their reference trajectories. Results: A total of 48 patients, all single, with an average age of 18.13 ± 0.48 years, the majority of whom were male (77.08%) and of Beninese nationality (85.42%), were enrolled. They were pupils (58.34%), students (27.08%), and workers (14.58%). With a prevalence of consumption of 89.58%, the first experimentation of cannabis was done by imitation (83.3%), among friends (81.2%), and in schools (64.58%). The reasons for use include the search for thrills (29.20%) and the improvement of sexual energy performance (27.1%). Subjects between 64.58 and 79.17% reported having received complaints about their behavior after regular consumption of at least 3 joints of cannabis. Conclusion: The knowledge of the typical profile of subjects in a situation of dependence ensures early detection of problematic uses of cannabis and offers the opportunity to intervene a little earlier in front of this phenomenon.

Genetic diversity and population structure of pigeonpea (Cajanus cajan [L.] Millspaugh) landraces grown in Benin revealed by Genotyping-By-Sequencing.

Genetic diversity studies provide important details on target trait availability and its variability, for the success of breeding programs. In this study, GBS approach was used to reveal a new structuration of genetic diversity and population structure of pigeonpea in Benin. We used a total of 688 high-quality Single Nucleotide Polymorphism markers for a total of 44 pigeonpea genotypes. The distribution of SNP markers on the 11 chromosomes ranged from 14 on chromosome 5 to 133 on chromosome 2. The Polymorphism Information Content and gene diversity values were 0.30 and 0.34 respectively. The analysis of population structure revealed four clear subpopulations. The Weighted Neighbor Joining tree agreed with structure analyses by grouping the 44 genotypes into four clusters. The PCoA revealed that genotypes from subpopulations 1, 2 and 3 intermixed among themselves. The Analysis of Molecular Variance showed 7% of the total variation among genotypes while the rest of variation (93%) was within genotypes from subpopulations indicating a high gene exchange (Nm = 7.13) and low genetic differentiation (PhiPT = 0.07) between subpopulations. Subpopulation 2 presented the highest mean values of number of different alleles (Na = 1.57), number of loci with private alleles (Pa = 0.11) and the percentage of polymorphic loci (P = 57.12%). We discuss our findings and demonstrate how the genetic diversity and the population structure of this specie can be used through the Genome Wide Association Studies and Marker-Assisted Selection to enhance genetic gain in pigeonpea breeding programs in Benin.

Molecular and cellular biology of PCSK9: impact on glucose homeostasis.

Proprotein convertase substilisin/kexin 9 (PCSK9) inhibitors (PCSK9i) revolutionised the lipid-lowering therapy. However, a risk of type 2 diabetes mellitus (T2DM) is evoked under PCSK9i therapy. In this review, we summarise the current knowledge on the link of PCSK9 with T2DM. A significant correlation was found between PCSK9 and insulin, homeostasis model assessment (HOMA) of insulin resistance and glycated haemoglobin. PCSK9 is also involved in inflammation. PCSK9 loss-of-function variants increased T2DM risk by altering insulin secretion. Local pancreatic low PCSK9 regulates ß-cell LDLR expression which in turn promotes intracellular cholesterol accumulation and hampers insulin secretion. Nevertheless, the association of PCSK9 loss-of-function variants and T2DM is inconsistent. InsLeu and R46L polymorphisms were associated with T2DM, low HOMA for ß-cell function and impaired fasting glucose, while the C679X polymorphism was associated with low fasting glucose in Black South African people. Hence, we assume that the impact of these variants on glucose homeostasis may vary depending on the genetic background of the studied populations and the type of effect caused by those genetic variants on the PCSK9 protein. Accordingly, these factors should be considered when choosing a genetic variant of PCSK9 to assess the impact of long-term use of PCSK9i on glucose homeostasis.

Can DNA help trace the local trade of pangolins? Conservation genetics of white-bellied pangolins from the Dahomey Gap (West Africa).

BACKGROUND: African pangolins are currently experiencing unprecedented levels of harvesting, feeding both local demands and the illegal international trade. So far, the lack of knowledge on the population genetics of African pangolins has hampered any attempts at assessing their demographic status and tracing their trade at the local scale. We conducted a pioneer study on the genetic tracing of the African pangolin trade in the Dahomey Gap (DG). We sequenced and genotyped 189 white-bellied pangolins from 18 forests and 12 wildlife markets using one mitochondrial fragment and 20 microsatellite loci. RESULTS: Tree-based assignment procedure showed that the pangolin trade is endemic to the DG region, as it was strictly fed by the the Dahomey Gap lineage (DGL). DGL populations were characterized by low levels of genetic diversity, an overall absence of equilibrium, important inbreeding levels, and lack of geographic structure. We identified a 92-98% decline in DGL effective population size 200-500 ya-concomitant with major political transformations along the 'Slave Coast'-leading to contemporaneous estimates being inferior to minimum viable population size (< 500). Genetic tracing suggested that wildlife markets from the DG sourced pangolins through the entire DGL range. Our loci provided the necessary power to distinguish among all the genotyped pangolins, tracing the dispatch of a same individual on the markets and within local communities. We developed an approach combining rarefaction analysis of private allele frequencies with cross-validation of observed data that traced five traded pangolins to their forest origin, c. 200-300 km away from the markets. CONCLUSIONS: Although the genetic toolkit that we designed from traditional markers can prove helpful to trace the illegal trade in pangolins, our tracing ability was limited by the lack of population structure within the DGL. Given the deleterious combination of genetic, demographic, and trade-related factors affecting DGL populations, the conservation status of white-bellied pangolins in the DG should be urgently re-evaluated.

Pyrethroid Resistance Intensity in Anopheles gambiae s.l. from Different Agricultural Production Zones in Benin, West Africa.

Agricultural production activities usually occur in Benin with the use of a huge amount of insecticides including pyrethroids for pest control. It is therefore important to regularly monitor pyrethroid resistance intensity in Anopheles gambiae s.l., the main malaria vector. This study was conducted in cereal, cotton, rice growing, and urban market gardening areas throughout the country in 2018 and 2019. Females An. gambiae s.l. field-collected as larvae were exposed to deltamethrin 1 × (0.05%), 2 × (0.1%), 5 × (0.25%), and 10 × (0.5%) and permethrin 1 × (0.75%), 2 × (1.5%), 5 × (3.75%), and 10 × (7.5%). Synergist assays were also performed using World Health Organization articles combining piperonyl butoxide (PBO) (4%) + deltamethrin 1 × and, PBO (4%) + Permethrin 1 × . Molecular species and L1014F kdr mutation were identified using PCR. Expression of metabolic enzymes was also assessed through biochemical tests. After exposure to permethrin and deltamethrin 10 × , An. gambiae s.l. displayed mortality rates <98%. Synergist assays induced significantly higher mortality rates than pyrethroids alone (p < 0.05). An. gambiae s.l. complex was composed of An. gambiae s.s., Anopheles coluzzii, and Anopheles arabiensis, with mean frequency of the L1014F kdr mutation >75%. Overexpression of nonspecific α and ß esterases was observed in the cereal, cotton, and urban market gardening areas, while an overexpression of mixed function oxidases was observed in the cotton and rice growing areas. Overall, An. gambiae s.l. showed high resistance intensity to both deltamethrin and permethrin. The synergist and biochemical tests performed suggest that PBO long-lasting insecticidal nets may provide a greater control of pyrethroid-resistant mosquitoes.

Resistance of Oryza sativa and Oryza glaberrima Genotypes to RBe24 Isolate of Rice Yellow Mottle Virus in Benin and Effects of Silicon on Host Response.

Rice yellow mottle virus (RYMV) is the most harmful virus that affects irrigated and lowland rice in Africa. The RBe24 isolate of the virus is the most pathogenic strain in Benin. A total of 79 genotypes including susceptible IR64 (Oryza sativa) and the resistant TOG5681 (O. glaberrima) as checks were screened for their reactions to RBe24 isolate of RYMV and the effects of silicon on the response of host plants to the virus investigated. The experiment was a three-factor factorial consisting of genotypes, inoculation level (inoculated vs. non-inoculated), and silicon dose (0, 5, and 10 g/plant) applied as CaSiO3 with two replications and carried out twice in the screen house. Significant differences were observed among the rice genotypes. Fifteen highly resistant and eight resistant genotypes were identified, and these were mainly O. glaberrima. Silicon application did not affect disease incidence and severity at 21 and 42 days after inoculation (DAI); it, however, significantly increased plant height of inoculated (3.6% for 5 g CaSiO3/plant and 6.3% for 10 g CaSiO3/plant) and non-inoculated (1.9% for 5 g CaSiO3/plant and 4.9% for 10 g CaSiO3/plant) plants at 42 DAI, with a reduction in the number of tillers (12.3% for both 5 and 10 g CaSiO3/plant) and leaves (26.8% for 5 g CaSiO3/plant and 28% for 10 g CaSiO3/plant) under both inoculation treatments. Our results confirm O. glaberrima germplasm as an important source of resistance to RYMV, and critical in developing a comprehensive strategy for the control of RYMV in West Africa.

Intensity and mechanisms of deltamethrin and permethrin resistance in Anopheles gambiae s.l. populations in southern Benin.

BACKGROUND: Insecticide resistance is threatening the effectiveness of efforts to control malaria vectors in Benin. This study explores the levels and mechanisms of insecticide resistance in An. gambiae s.l. to pyrethroids. METHODS: Larvae were collected from August 2017 to July 2018 in five communes in southern Benin (Adjohoun, Allada, Bohicon, Cotonou, and Porto-Novo) representing diverse ecological regions, and were reared in Benin's insectary. Two- to five-day-old female mosquitoes from each district were exposed to multiple doses of deltamethrin and permethrin (1×, 2×, 5×, and 10×) using the WHO insecticide resistance intensity bioassay. The effect of pre-exposure to the synergist, piperonyl butoxide (PBO), was also tested at different pyrethroid doses. Molecular allele frequencies of kdr (1014F) and ace-1R (119S) insecticide resistance mutations and levels of detoxification enzymes were determined for mosquitoes sampled from each study area. RESULTS: An. gambiae s.l. were resistant to pyrethroid-only exposure up to 10× the diagnostic doses in all the study sites for both deltamethrin and permethrin. Mortality was significantly higher in An. gambiae s.l. pre-exposed to PBO followed by exposure to deltamethrin or permethrin compared to mosquitoes exposed to deltamethrin or permethrin only (p < 0.001). The difference in mortality between deltamethrin only and PBO plus deltamethrin was the smallest in Cotonou (16-64%) and the greatest in Bohicon (12-93%). The mortality difference between permethrin only and PBO plus permethrin was the smallest in Cotonou (44-75%) and the greatest in Bohicon (22-72%). In all the study sites, the kdr resistance allele (1014F) frequency was high (75-100%), while the ace-1 resistance allele (G119S) frequency was low (0-3%). Analysis of the metabolic enzymatic activity of An. gambiae s.l. showed overexpression of nonspecific esterases and glutathione S-transferases (GST) in all study sites. In contrast to the PBO results, oxidase expression was low and was similar to the susceptible An. gambiae s.s. Kisumu strain in all sites. CONCLUSION: There is high-intensity resistance to pyrethroids in southern Benin. However, pre-exposure to PBO significantly increased susceptibility to the pyrethroids in the different An. gambiae s.l. populations sampled. The use of PBO insecticide-treated bed nets may help maintain the gains in An. gambiae (s.l.) control in southern Benin.

On-farm management and participatory evaluation of pigeonpea (Cajanus cajan [L.] Millspaugh) diversity across the agro-ecological zones of the Republic of Benin.

BACKGROUND: Pigeonpea is a multipurpose food legume crop that contributes to food security in the Republic of Benin. For the establishment of conservation and breeding programs, previous ethnobotanical surveys on pigeonpea were done in Benin but restricted to south and central regions. In previous years, pigeonpea landraces were introduced in northern Benin for soil fertility management; it is therefore important to evaluate the diversity in this legume in this region. Exhaustive documentation of pigeonpea diversity grown in the Republic of Benin will be necessary for effective breeding and conservation programs. Therefore, the aim of this study was to document genetic diversity of pigeonpea, across the agro-ecological zones of the Republic of Benin for its promotion and valorization. METHODS: A total of 500 pigeonpea farmers representing 13 sociolinguistic groups were selected from 50 villages. The data were collected using methods and tools of participatory research appraisal. Folk nomenclatures, taxonomy of pigeonpea and seed system were investigated. The distribution and extent of pigeonpea landraces were evaluated using the Four Square Analysis method. A comparative analysis of pigeonpea use categories production systems, production constraints, famers' preference criteria, and participative evaluation for existing landraces across agro-ecological zones was done. RESULT: Folk nomenclature and taxonomy were mainly based on seed coat color and size. Seven pigeonpea use categories were recorded including sacrifice, grain processing and fertilization. The results showed that the pigeonpea seed system is informal. Based on seed characteristics, fifteen landraces were recorded including seven new landraces. The Sudano-Guinean zone contained the highest number (11) of landraces. The average number of landraces per village was 2.7. A high rate of landraces facing threat of disappearance was observed across the ecological zones. Ten constraints are known to affect pigeonpea production in Benin, with pests and diseases as the most critical in all agro-ecological zones. This study revealed that pigeonpea cultivation is increasing in the Sudanian zone. Varieties to be produced must be selected based on 11 criteria which included precocity and resistance to pests and diseases in the three ecological zones and adaptability to any type of soil in the Sudanian zone. The participatory evaluation revealed the existence of a few performing cultivars. CONCLUSIONS: Our results revealed that implementation of a pigeonpea genetic conservation program in Benin must take into account the diversity, production constraints and varietal preference, which varied according to agro-ecological zones. In situ and ex situ conservation strategies are important to preserve pigeonpea landraces. Morphological and molecular characterizations of identified cultivars are highly recommended to help select suitable varieties for breeding programs.

Species richness, cultural importance, and prioritization of wild spices for conservation in the Sudano-Guinean zone of Benin (West Africa).

BACKGROUND: Spices have always been used for their flavor-enhancement characteristics and for their medicinal properties. In Benin, scientific research on spices is scarce, despite their importance in the local population's daily needs. This study investigated the diversity of wild spices and documented the associated traditional knowledge that can be used for their valuation, domestication, and sustainable management in the Sudano-Guinean Zone of Benin. METHODS: Data were collected during field expeditions using semi-structured interviews in ten localities across the three phytodistricts of the zone. Species richness and Shannon's diversity index were estimated using species accumulation curves. Use report (UR), cultural importance, use value (UV) index, and informant consensus factor (Fic) were used to assess traditional knowledge on wild species, their local importance, and informants' agreement among sociolinguistic groups. Priority wild spices were finally identified using an approach combining eight criteria (native status, economic value, ethnobotanical value, global distribution, national distribution, in-situ and ex-situ conservation status, legislation, and threats assessment) in four prioritization methods (point scoring procedure, point scoring procedure with weighting, compound ranking system, and binomial ranking system). RESULTS: A total of 14 species, belonging to 12 genera and 9 families, were inventoried. The most prominent families were Zingiberaceae (21.43%), Annonaceae (21.43%), and Rutaceae (14.29%). More than 200 specific uses were reported, with the Tchabè people holding the greatest level of knowledge (70 uses; UR = 5.70 ± 0.33). The culturally most important spices differed among sociolinguistic groups. Most of the informants agree on the use of the species among (Fic = 0.72-0.98) and across the considered use categories (Fic = 0.88-0.99). The highest UV were registered for Aframomum alboviolaceum (UV = 0.93), Lippia multiflora (UV = 0.76), and Aframomum angustifolium (UV = 0.18). Overall, people perceived wild spices as declining due to agriculture, grazing, and drought. Five species, A. alboviolaceum, L. multiflora, Monodora tenuifolia, Xylopia aethiopica, and Z. zanthoxyloides, were the most prioritized for conservation. CONCLUSIONS: This study provides information relevant for the implementation of conservation and domestication actions of wild spices in Benin. Priority species could be integrated into traditional agroforestry systems (e.g., home gardens). However, for this to be effective, further research should be undertaken on morphological and genetic diversity and propagation methods of priority wild spices.

Molecular diversity of Scutellonema bradys populations from Benin, based on ITS1 rDNA and COI mtDNA.

In Benin, yam production continues to face numerous production constraints, including yield and quality reduction by Scutellonema bradys. Implementation of efficient management techniques against this pest requires an improved understanding, including at the molecular level, of the pest. The current study aimed at identifying the Scutellonema spp. associated with yam in Benin and investigating the phylogenetic relationships between populations. Nematodes of the genus Scutellonema were obtained from tubers exhibiting external dry rot symptoms. DNA was extracted from nematodes belonging to 138 populations collected from 49 fields from 29 villages. For 51 of these populations, both the ITS1 and COI regions could be amplified via PCR, sequenced, compared with available sequences in the NCBI database and were identified as S. bradys. Maximum likelihood was used to construct 60% consensus phylogenetic trees based on 51 sequences. This phylogenetic analysis did not reveal any genetic separation between populations by cultivar, village, cropping system nor by agroecological zone. Neither could any subgroups within S. bradys be separated, indicating that no subspecies were present. An earlier published species-specific primer set was verified with the DNA of the 51 sequences and was considered a reliable and rapid method for S. bradys identification.

Multi-task Gaussian process for imputing missing data in multi-trait and multi-environment trials.

KEY MESSAGE: A method based on a multi-task Gaussian process using self-measuring similarity gave increased accuracy for imputing missing phenotypic data in multi-trait and multi-environment trials. Multi-environmental trial (MET) data often encounter the problem of missing data. Accurate imputation of missing data makes subsequent analysis more effective and the results easier to understand. Moreover, accurate imputation may help to reduce the cost of phenotyping for thinned-out lines tested in METs. METs are generally performed for multiple traits that are correlated to each other. Correlation among traits can be useful information for imputation, but single-trait-based methods cannot utilize information shared by traits that are correlated. In this paper, we propose imputation methods based on a multi-task Gaussian process (MTGP) using self-measuring similarity kernels reflecting relationships among traits, genotypes, and environments. This framework allows us to use genetic correlation among multi-trait multi-environment data and also to combine MET data and marker genotype data. We compared the accuracy of three MTGP methods and iterative regularized PCA using rice MET data. Two scenarios for the generation of missing data at various missing rates were considered. The MTGP performed a better imputation accuracy than regularized PCA, especially at high missing rates. Under the 'uniform' scenario, in which missing data arise randomly, inclusion of marker genotype data in the imputation increased the imputation accuracy at high missing rates. Under the 'fiber' scenario, in which missing data arise in all traits for some combinations between genotypes and environments, the inclusion of marker genotype data decreased the imputation accuracy for most traits while increasing the accuracy in a few traits remarkably. The proposed methods will be useful for solving the missing data problem in MET data.

Genetic divergence in northern Benin sorghum (Sorghum bicolor L. Moench) landraces as revealed by agromorphological traits and selection of candidate genotypes.

Sorghum [Sorghum bicolor (L.) Moench] is an important staple food crop in northern Benin. In order to assess its diversity in Benin, 142 accessions of landraces collected from Northern Benin were grown in Central Benin and characterised using 10 qualitative and 14 quantitative agromorphological traits. High variability among both qualitative and quantitative traits was observed. Grain yield (0.72-10.57 tons/ha), panicle weight (15-215.95 g), days to 50% flowering (57-200 days), and plant height (153.27-636.5 cm) were among traits that exhibited broader variability. Correlations between quantitative traits were determined. Grain yield for instance exhibited highly positive association with panicle weight (r = 0.901, P = 0.000) and 100 seed weight (r = 0.247, P = 0.000). UPGMA cluster analysis classified the 142 accessions into 89 morphotypes. Based on multivariate analysis, twenty promising sorghum genotypes were selected. Among them, AT41, AT14, and AT29 showed early maturity (57 to 66 days to 50% flowering), high grain yields (4.85 to 7.85 tons/ha), and shorter plant height (153.27 to 180.37 cm). The results obtained will help enhancing sorghum production and diversity and developing new varieties that will be better adapted to the current soil and climate conditions in Benin.

Drivers of conservation and utilization of pineapple genetic resources in Benin.

Valuation of farmer knowledge has been seen as a route to promote sustainable use of plant genetic resources. In pineapple production systems in Benin, inadequate knowledge of cultivation practices can lead to a number of inconveniences including abandon of some varieties and cultivars. To understand how farmer's knowledge and cultivation practices impact the sustainable utilization of pineapple genetic resources, we surveyed 177 pineapple farmers in southern Benin. We assessed farmers' knowledge and analyzed the relationship between their knowledge and factors such as age, education, and locality of provenance. Pineapple production system was dominated by men (96% respondents). According to farmers, Smooth cayenne is international market-oriented while Sugarloaf mainly targets domestic and regional markets. All farmers recognized that Smooth cayenne provided more income (USD 5,750/ha) than sugarloaf (USD 3,950/ha) in the production systems of southern Benin. The high value of median scores in comparison with the range of possible score showed that most farmers agreed and shared relatively similar knowledge. Correlation matrix and multiple linear regressions showed a significant relationship between farmers' practices and their knowledge of the plant; their knowledge of pineapple varieties is based on fruits traits. Also, farmer's knowledge was associated with locality of provenance. Constraints and options for genetic resources conservation and utilization in the pineapple production systems in Southern Benin were discussed based on current knowledge.