Phosphate rocks (PR), the primary source of phosphorus (P), are often co-composted with organic materials to enhance P availability. However, the mechanisms of P solubilization in PR-enriched composts are not well elucidated. This study investigated such mechanisms by monitoring the changes in P fractions during composting and by determining the relationships between the physicochemical and biological parameters. Sorghum straw residues were composted alone (Comp), or with 10% PR (P-Comp), or with 10% PR and 10% rhizosphere soil (P-Comp-Soil), and samples were collected at 45, 60, and 180 days for analysis. The labile-P composed of H 2 O-and NaHCO 3extractable inorganic P (Pi) and organic P (Po), the moderately labile-P extracted by NaOH (Pi + Po), and the unavailable P formed of the HCl-P and residual-P, increased with the progress of the composting. At 180 days, P-Comp-Soil contained the highest amount of labile-P. There were strong and positive correlations between labile-P and the abundance of total fungi, phosphate-solubilizing fungi (PSF), alkaline phosphatase phoD, phosphonatase phnX, acid phosphatase aphA. Although total fungi were much fewer than total bacteria, the PSF mainly triggered the mineral P solubilization. The alkaline phosphatase phoD was the main enzyme leading the organic P mineralization, while the contribution of phosphonatase phnX, acid phosphatase aphA, and siderophore entA to the organic P solubilization was minor. Besides, the bacterial specific-transporter (pstS) gene increased with the increase of labile-P, allowing for immobilization of little fractions of P in microbial cells. This study highlighted the significant role of PSF and alkaline phosphatase in the P solubilization of PR-enriched composts. Furthermore, it showed the benefit of supplementing the PRenriched composts with rhizosphere soil, a niche of ecologically important source of beneficial microbes.

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The endosymbiont Wolbachia can have major effects on the reproductive fitness, and vectorial capacity of host insects and may provide new avenues to control mosquito‐borne pathogens. Anopheles gambiae s.l is the major vector of malaria in Africa but the use of Wolbachia in this species has been limited by challenges in establishing stable transinfected lines and uncertainty around native infections. High frequencies of infection of Wolbachia have been previously reported in An. gambiae collected from the Valle du Kou region of Burkina Faso in 2011 and 2014. Here, we re‐evaluated the occurrence of Wolbachia in natural samples, collected from Valle du Kou over a 12‐year time span, and in addition, expanded sampling to other sites in Burkina Faso. Our results showed that, in contrast to earlier reports, Wolbachia is present at an extremely low prevalence in natural population of An. gambiae. From 5341 samples analysed, only 29 were positive for Wolbachia by nested PCR representing 0.54% of prevalence. No positive samples were found with regular PCR. Phylogenetic analysis of 16S rRNA gene amplicons clustered across supergroup B, with some having similarity to sequences previously found in Anopheles from Burkina Faso. However, we cannot discount the possibility that the amplicon positive samples we detected were due to environmental contamination or were false positives. Regardless, the lack of a prominent native infection in An. gambiae s.l. is encouraging for applications utilizing Wolbachia transinfected mosquitoes for malaria control.

Low soil available phosphorus (P) severely limits crop production in sub-Saharan Africa. The present study evaluated phosphate rock-enriched composts as locally available low-cost fertilizers for sorghum production. The treatments consisted of sorghum straw, compost (COMP), phosphate rock (BPR), BPR-enriched compost (P-COMP), BPR-rhizosphere soil-enriched compost (P-COMP-SOIL), nitrogen-phosphorus-potassium treatment (NPK, 60–39–25), and control (NK, 60–25). Sorghum straw and compost were applied at 1.34 tons ha−1. N, P, and K in all treatments, excluding the control, were adjusted to 60, 39, and 25 kg ha−1, with urea, BPR, and KCl, respectively. Sorghum vr. kapelga was cultivated and soil samples were collected at the S5, S8, and S9 growth stages. P-COMP-SOIL and NPK yielded better sorghum yields than the other treatments. The rhizosphere soil of P-COMP-SOIL had high abundance of soil bacteria and AMF, and genes involved in P solubilization, such as: acid phosphatase (aphA), phosphonatase (phnX), glucose dehydrogenase (gcd), pyrroloquinoline quinone (pqqE), phosphate-specific transporter (pstS). The superior performance of the P-COMP-SOIL was associated with its higher available P content and microbial abundance. Multivariate analysis also revealed vital contributions of N, carbon, and exchangeable cations to sorghum growth. Soils could be amended with phosphate rock-rhizosphere soil-enriched composts, as an alternative to chemical fertilizers.

To determine the effects of sweet potato feathery mottle virus (SPFMV), Sweet potato chlorotic stunt virus (SPCSV) and their co-infection on sweet potato yield, twelve sweet potato varieties were assessed in a hotspot area in Western Burkina Faso. The experiment was carried out in a randomized complete-block design with the twelve varieties in three replications. Data were collected on plant growth parameters, plant virus symptoms and yield parameters. Additional testing for selected sweet potato viruses was done using a nitrocellulose membrane enzyme-linked immunosorbent assay (NCM-ELISA) and RT-PCR. SPFMV and SPCSV were the viruses detected in this study. Varieties Djakani and Ligri were virus-free and had the highest average yields out of twelve sweet potato varieties assessed. Field monitoring indicated that 58% of plants were found to be virus-infected. The results suggest that severe symptoms were associated with sweet potato virus disease (SPVD) and yield reduction. However, the interaction of SPCSV with other viruses, which may result in synergistic negative effects on sweet potato yield and quality, needs further research.