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Studying the impact of farming systems on soil status is essential in determining the most relevant for a given agroecological zone. A trial was conducted in a West Africa humid savanna, aiming at assessing the short-term effects of farming systems on soil (0-10 cm) organic carbon (SOC) content and some soil microbiological properties. A randomized complete block experimental design with three replications, and the following treatments were used: Mucuna pruriens (Mucuna), Pueraria phaseoloides (Pueraria), Lablab purpureus (Lablab), a combination of these three legumes (Mixed-legumes), maize + urea (Maize-U), maize + triple super phosphate (Maize-Sp), maize + urea + triple super phosphate (Maize-USp), fertilizer-free maize continuous cropping (Maize-Tradi). Results indicated that SOC content was improved over time under legume-based systems. The relative increase was the highest with the legume association and Lablab, where SOC varied from 7.5 to 8.6 g.kg-1 (i.e. 14.7%) and from 7.2 to 8.3 g.kg-1 (i.e. 15.3%) respectively, between the start and the end of the trial. Besides, applying grass and maize residues as mulch on the ground, in association with inorganic fertilizers may be a way of improving SOC content in the short-term. Although legume-based systems exhibited highest values, microbial biomass carbon (MBC) did not show any statistical significant differences between treatments. However, soil C mineralization and soil specific respiration were influenced by the farming systems, with higher mean values under legume-based systems (42 ± 7.6 mg C-CO2.g-1 Corg and 0.4 mg C-CO2.g-1 biomass C, respectively), compared to maize continuous cropping systems (33.1 ± 1.6 mg C-CO2.g-1 Corg and 0.3 mg C-CO2.g-1 biomass C, respectively). Thus, these parameters can be used as sensitive indicators of the early changes in soil organic matter quality. The integration of legumes cover crops in farming systems may contribute to improve soil quality that would lead to sustainable agriculture in Côte d'Ivoire humid savannas.

Soil organic matter (SOM) quality and carbon (C) availability may be major features influencing the effect of earthworms on the aerobic processes in clayey tropical soils. In this study, we assessed the effect of an anecic (Polypheretima elongata), an endogeic (Pontoscolex corethrurus) and an epigeic (Eudrilus eugeniae) earthworm on the aerobic microbial activity of two tropical soils, a calcic Vertisol and an acid Ferralsol, with clay content >70% and very different organic C content and SOM stability. The soil-earthworm interaction was studied in a 6-month mesocosm experiment in a greenhouse using soils with and without (control soil) earthworm addition. Potential C mineralisation, actual net nitrogen (N) mineralisation and dehydrogenase activity (DHA), as indicators of the aerobic activity of the soils, and phosphorus (P) availability were determined during the trial. DHA was used as an indicator of the global aerobic activity. Earthworms had little effect on potential C mineralisation but significantly increased actual net N mineralisation. The increase in N mineralisation in the Vertisol was twice as great as, and longer (6 v. 3 months) than for the Ferralsol. Differences between soils for N mineralisation were associated with a less recalcitrant SOM in the Vertisol. Available P increased 10% in the earthworm treatments. Earthworm activity improved N and P availability. DHA was 15 times higher for the Vertisol than for the Ferralsol, but the positive effect of earthworms on DHA was greater for the Ferralsol. This effect was greater for E. eugeniae, probably because of surface burrows generated by this epigeic earthworm, which favoured oxygen entry into the soil. Differences between the two soils were greater for DHA than for C and N mineralisation, and this was observed for the control soils as well as for the earthworm treatments. This indicates that earthworm activity modified the rate of the aerobic processes but it did not affect the intrinsic biological properties of these tropical soils, which were controlled mainly by SOM quality and C availability. Additional keywords: Eudrilus eugeniae, Ferralsol, Polypheretima elongata, Pontoscolex corethrurus, SOM mineralisation, Vertisol., Introduction Earthworms contribute to many ecosystem services, including water regulation, nutrient cycling, carbon (C) sequestration and primary production (Blouin et al. 2013). Earthworm species and populations vary widely with the [...]

Composting and vermicomposting are interesting options for utilisation in restoration and improvement of weathered and infertile tropical soils. The aim of this study was to assess quality of composts and vermicomposts produced from cattle manure (CM) and green wastes (GW) blended at different ratios under tropical conditions. Chemical, biochemical, and biological indicators were used to idcntify the role of earthworms and the factors affecting organic matter (OM) stability and nutrient balance in the thermophilic (days 0-65) and stabilisation (days 66-183) phases. Total carbon (C) losses averaged 55% and were greater during vermicomposting and for products with a high GW content. One-third of C losses occurred during the stabilisation phase. This phase presented a high level of C mineralisation, which would be linked to high ambient temperatures (~30°C). Although OM content was similar for all of the final products, respiration measurements indicated that OM stability was greater for vermicomposts. These results indicated that humification and OM decomposition occurred simultaneously during vermicomposting. The material source ratio did not affect the OM biodegradability of the final products. No losses were observed for phosphorus (P), calcium (Ca), and magnesium (Mg). However, high potassium (K) (45%) and nitrogen (25%) losses wcre detected and were higher during vermicomposting and for the products with a high GW content. Final vermicomposts were enriched in P, Ca, and Mg, and slightly depleted in K compared with normal composts. Nitrogen content was similar for both composting methods. Plant response to amendment addition was higher for intermediate rates of GW and CM (e.g. 40-60% for CM), with no differences between composts and vermicomposts. The results of this study indicated that vermicomposting was a process that favoured OM stabilisation, which is a key factor for the adoption of this practice in the tropics. Additional keywords: Eudrilus eugeniae, humification, organic matter, respiration, stabilisation, thermophilic., Introduction Waste management and recycling are major environmental concerns in small island states with limited land space and high population density as in the Caribbean region. Recent intensification of the [...]

There is a growing demand for molecules of natural origin for biocontrol and biostimulation, given the current trend away from synthetic chemical products. Leachates extracted from plantain stems were obtained after biodegradation of the plant material. To characterize the leachate, quantitative determinations of nitrogen, carbon, phosphorus, and cations (K + , Ca 2+ , Mg 2+ , Na + ), Q2/4, Q2/6, and Q4/6 absorbance ratios, and metabolomic analysis were carried out. The potential role of plantain leachates as fungicide, elicitor of plant defense, and/or plant biostimulant was evaluated by agar well diffusion method, phenotypic, molecular, and imaging approaches. The plant extracts induced a slight inhibition of fungal growth of an aggressive strain of Colletotrichum gloeosporioides , which causes anthracnose. Organic compounds such as cinnamic, ellagic, quinic, and fulvic acids and indole alkaloid such as ellipticine, along with some minerals such as potassium, calcium, and phosphorus, may be responsible for the inhibition of fungal growth. In addition, jasmonic, benzoic, and salicylic acids, which are known to play a role in plant defense and as biostimulants in tomato, were detected in leachate extract. Indeed, foliar application of banana leachate induced overexpression of LOXD , PPOD , and Worky70-80 genes, which are involved in phenylpropanoid metabolism, jasmonic acid biosynthesis, and salicylic acid metabolism, respectively. Leachate also activated root growth in tomato seedlings. However, the main impact of the leachate was observed on mature plants, where it caused a reduction in leaf area and fresh weight, the remodeling of stem cell wall glycopolymers, and an increase in the expression of proline dehydrogenase.

This study aimed to determine the impact of different agroecological practices on the composition and diversity of edaphic bacterial and fungal communities. We designed two experimental agroecological vegetable cropping systems and analyzed their effects on soil microbial communities by pyrosequencing the 16S and 18S ribosomal RNA genes. Our results highlighted modifications to the Operational Taxonomic Units in both experimental systems compared with bare soil, particularly for the phyla Actinobacteria, Ascomycota, Bacteroidetes, and Mucoromycota. Multidimensional scaling plots based on beta diversity showed a clear distinction between the two experimental systems for fungi, whereas differences were observed between bare soil and the two experimental systems for bacteria. Overall, the agroecological systems enhanced soil microbial diversity. We showed a distinction between the two experimental systems and bare soil, correlated with the high total N and total P contents in the agroecological systems. Both experimental systems promoted soil enrichment with certain essential minerals. The agroecological systems had a positive impact on soil microbial communities, particularly by promoting the development of beneficial soil bacteria like Actinobacteria. In the two experimental systems, changes in the quality and quantity of organic matter (i.e. mulch, vermicompost, plant diversity) could have modified the abundance and diversity of microbial communities., (© The Author(s) 2023. Published by Oxford University Press on behalf of FEMS.)

Leaf-cutting ants, Acromyrmex octospinosus (Reich), are considering among the most important pest species of the New World. Until now, the main insecticides used for controlling these ants were synthetic chemicals. Leaf-cutting ants live in obligate symbiosis with abasidiomycete fungus, Leucocoprinus gongylophorus (Heim) Moeller. The crucial role of this symbiotic partner in the nest of leaf-cutting ants has prompted us to focus on A. octospinosus management through the use of fungicides in our study. Five parts of plants identified for their antifungal potential through TRAMIL ethnopharmacological surveys were tested: 1) bulbs of Allium cepa L.; 2) seed pods of Allium sativum L.; 3) green fruits of Lycopersicon esculentum L.; 4) leaves of Manihot esculenta Crantz; and 5) leaves of Senna alata (L.) Roxburgh. One plant extract with strong fungicidal activity (S. alata) against L. gongylophorus was found. The other extracts had lesser fungistatic or fungicidal effects depending on the concentrations used. The data presented in this study showed that TRAMILs fungicidal plant extracts have potential to control the symbiotic fungus of leaf cutting ants, in particular a foliage extract of S. alata.

Background: Leaf-cutting ants are considered to be one of the most important pest species of the New World. Until now, control strategies against these leaf-cutting ants have mainly been synthetic chemicals. The aim of the present study was to test the action of several plant extracts quoted as an example by TRAMIL participative surveys for their insecticidal properties on adult major workers of Acromyrmex octospinosus. Three tests were used to that end: contact toxicity, repellent test and ingestion bioassay. Six traditional plant uses recommended by interviewed people in surveys were tested: (1) maceration of Mammea americana fresh crushed seeds; (2) decoction of Nerium oleander fresh leaves; (3) Nerium oleander dried leaf water juice; (4) decoction of Nicotiana tabacum dried leaves; (5) Trichillia pallida dried leaf water juice; (6) decoction of Rollinia mucosa dried seeds., Results: Two plant extracts with contact toxicity (Mammea americana and Nicotiana tabacum), six plant extracts with repellent activity and four plant extracts with ingestion toxicity (Mammea americana, Nicotiana tabacum and both extracts of Nerium oleander) were found., Conclusion: The data presented in this study showed that plant extracts cited by TRAMIL ethnopharmacological surveys have the potential to control the leaf-cutting ant, Acromyrmex octospinosus. In particular, the Mammea americana extract, with its natural low repellent effect and its high toxicity by ingestion, and Nerium oleander extracts, with their natural delay action, are possibly the best extracts for the control of these ants., (Copyright © 2011 Society of Chemical Industry.)

Aim of the Study: The aim of this study was a comparison of popular household remedies in primary health care in the communities of Terre-de-Haut and Terre-de-Bas, the inhabited islands of 'Les Saintes' archipelago (Guadeloupe, French West Indies)., Methods: Twelve ailments, with higher prevalence, were chosen in each island and a total of 216 families were interviewed using TRAMIL participative ethnopharmacological interviews., Results: According to TRAMIL methodology (frequency over 20%), twenty-two plants uses were recorded for Terre-de-Haut and eighteen for Terre-de-Bas. The islands share only ten significant plants uses and four of them have notable different frequencies. The informant consensus factor in the use of many specific remedies was fairly high, that gave an additional validity to these popular medicines., Conclusion: The data presented in this study show that popular knowledge on medicinal plants uses is still alive in the studied area. The difference between the two nearby islands is very narrow but on the other hand, there exist some differences possibly due to a probable declining of plant resources and a more important flux of migration and its provision of other practices of healthcare in Terre-de-Haut., (Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.)

With the important infection of small ruminants by gastrointestinal nematodes, and in the face of reduced efficacy of anthelminthic treatments, a search for other biological options is necessary. The effect of earthworms on the free-living stages of Haemonchus contortus and Trichostrongylus colubriformis in faeces from goats naturally infected in tropical pastures was evaluated. Two levels (0 vs 14 individuals per container) of indigenous earthworms (50% Pontoscolex corethrus and 50% Perionyx excavatus) were added to containers filled with soil and faeces collected from 20 grazing goats. After 1 week, the numbers of free-living stages of each infective larvae species was measured. The addition of earthworms reduced by 34% (P<0.006) the number of infective larvae recovered in the faeces of goats. The reduction was significant for both larvae species, 29% and 33% for H. contortus and T. colubriformis, respectively. The ratio of the two species of larvae, without or with earthworms, did not vary significantly (P>0.21). These results must be confirmed in experiments on pasture, with other ratios and combinations of earthworms.