Search

In June 2023, high populations of Amrasca biguttula were observed in Cotonou, Benin, infected by an entomopathogenic fungus on leaves of Abelmoschus esculentus (okra). This first reporting in Africa could be due to an Entomophthorale. Recommendations are given to better identify the fungus.

Le document est une synthèse qui présente des éléments de biologie des principaux prédateurs des pucerons Aphis gossypii, observés sur le cotonnier, en Afrique sub-saharienne. Des éléments sont donnés sur les ennemis naturels (parasitoïdes) de ces prédateurs. Les références bibliographiques complètent le texte. Quatre planches en couleurs permettent d'identifier les différents stades et les principales espèces rencontrées.

Reducing pesticide use for plant health has become a goal shared by CILSS and ECOWAS countries and a major issue in public policies due to their negative footprint on the environment, human health, and food security in a context of augmentation of phytosanitary risks linked to climate change. In Senegal, a low-income country, where available chemical pesticides are of uncertain origin and quality, the use of unproven quality homemade plant extracts preparations tends to be normalized. Other Biological Control and Biopesticides 564 Surveys conducted in the regions of Fatick, Tamba, and Thies in 2021 and 2022 have shown that chemical pesticides are considered as effective by 97% of respondents. Less than 10% of them use natural products. Regarding organic horticulture, in the vegetable crops and fruits production area in Thiès, 98% of interviewed people were not convinced of the efficacy of homemade plant extracts preparations to control pests, while country and trans-border expertise have capitalized a set of plant species among which Azadirachta indica, Cassia senegalensis, Eucalyptus sp., Allium cepa, Allium sativum, and Capsicum annuum. They invest in the production of biopesticides or source from local input suppliers without enough knowledge on pests, biopesticide preparation techniques and compliance of commercial biopesticide formulations with regulatory requirements. The adoption of the use of plant extracts against crop pest in Senegal where the chemical pesticides use, trade, and availability have reduced traditional local plant protection knowledge transmission in farmers communities, finding alternatives is challenging for producers engaged in organic and those engaged in agroecology.

Negative impacts of chemical pesticide, social demand (healthier food), organic farming organization, rising costs of inputs linked to oil market and their importation (in Africa), and the circular economy approach are a few arguments/opportunities that underlie the roll-out of alternative solutions, including botanicals. Technology readiness levels (TRLs) offer a means to rate relevance of these solutions in the process from plant identification and local knowledge to large-scale use of plant extracts. Options range from do-it-yourself (homemade preparations) - often based on smallholders' traditional know-how - to application of commercial input formulations. The constraints to be overcome vary in scope: technical (biomass availability/sustainability, extraction, chemical analysis, standardization, formulation), societal (grower and consumer perception/acceptability, labour demand, gender issue), and regulatory (adaptation, environmental/ecotoxicological aspects). The following are a few examples of TRL ratings in terrestrial insect management: aqueous extracts of Tephrosia vogelii in Malawi and Tanzania (TRL 4- 5), organic extracts in Brazil (Annonaceae, TRL 3-4), essential oils of Piper borbodense in Réunion (TRL 3-4) and of Piper aduncum in the western Amazon (TRL 5-6). In Brazil, the use of commercial formulations (Orobor, Orange Power, etc.) derived from agroindustrial residue processing (orange oil) is an example of a TRL 9 rating. Potential solutions are presented to foster individual or collective (e.g. in African villages) usage (blends, mixtures with chemical pesticides, quality control) and the pathway towards certification. In particular, the creation of specific regulatory categories (e.g. basic substance) within the framework of the European regulation EC n°1107/2009 could help facilitate the adoption/use of plant-based extracts.

Europe has planned to halve pesticide use by 2030 as part of the Farm to Fork strategy to achieve the European Green Deal. Global warming combined with all year-round availability of host plant for a majority of pests is likely to favor the installation of invasive alien species (IAS) in Europe. The reduction of the range of authorized chemical molecules, initially intended for the control of native species, challenges research to propose sustainable solutions to manage IAS. Plant-based products are an alternative to synthetic products, already adopted in organic agriculture, such as Tanacetum cinerariifolium (natural pyrethrum), formulated as aqueous, organic extracts, or essential oil. The knowledge-based system Knomana has identified, in the scientific literature, 397 plant species used or experimented to protect 64 crop species in Africa against pests and diseases. A knowledge mining software is being developed, based on a method derived from artificial intelligence, i.e. formal concept analysis, to propose to the final user (e.g. producer, technician) potentially usable local plants. As some IAS are coming from the African continent, using Knomana can allow European researchers to identify interesting plant species present in Europe, or plant extracts to be imported from Africa, to control IAS once their official approval is obtained. Examples are given with the Noctuidae species Spodoptera littoralis and Helicoverpa armigera, already present in Europe, or the fall armyworm, Spodoptera frugiperda, that has been observed on maize in many African countries since 2016.

La mission réalisée du 6 au 15 juin 2023 au Bénin a permis, en première semaine, de rencontrer deux doctorants (Joël Lawson et Romaine Assogba) et discuter avec eux de leurs sujets, visiter le laboratoire et les élevages effectuées à Bohicon, participer à une réunion avec des producteurs et productrices de coton biologique dans la commune de Djidja (département du Zou), rencontrer deux promoteurs de biopesticides (entreprises Biophyto et Misericodia Dei). En seconde semaine, une visite d'essais sur cultures maraichères (tomate, gboma, zone de Kpomassé proche de Cotonou) et de l'essai variétal gombo (A. esculentus) à l'INRAB a permis de collecter des adultes et larves de la cicadelle (supposée Amrasca biguttula) signalée sur cotonnier la campagne antérieure. Des cadavres d'individus morts de mycose sur le gombo (épizootie) ont été mis à sporuler sur lames à l'IITA (G. Goergen) et la projection de conidies sphériques a confirmé l'hypothèse d'une espèce du groupe des Entomophthorales. La lecture de la bibliographie a permis d'émettre l'hypothèse de la présence de l'espèce Batkoa amrascae, identification qui reste à vérifier. Une animation scientifique sur le coton biologique a été développée au cours de la matinée du 14 juin avec trois exposés de Professeur S. Vodouhe (Obepab), P. Silvie et A. Lopez (Cirad). Une relecture du plan d'actions de la feuille de route " coton " du Cirad et de la fiche technique Inrab-Obepab sur le coton biologique a été effectuée afin d'actualiser ces documents.

In addition to destroying the leaves, stems, pods, and grains of soybean (Glycine max), Spodoptera frugiperda larvae may also have the cut off behavior in the seedlings close to the ground, harming the establishment of the soybean crop. Therefore, this study aimed to evaluate the consequences of the fall armyworm attack by adopting the cut off behavior, which has been similarly documented for black cutworm (Agrotis ipsilon) in newly emerged soybean plants. The treatments were five levels of infestation with 0, 5, 10, 20 and 40 larvae per m2. Three variables were assessed: (1) stand (relationship between attacked and initial number of plants), (2) types and amounts of injured structures, such as hypocotyl (embryonic shoot), and the cotyledons (seed leaves), and (3) level of defoliation. The variables were collected every 24 hours until the pupal stage. Additionally, the final stand of the seedlings was quantified, with the highest injury intensity observed in the plots that contained the highest number of larvae. In the second experiment, the dynamics of movement and attacks of plants by S. frugiperda larvae at the following times of the day: 07:00, 10:00, 13:00, 16:00, 19:00 and 21:00 were analyzed with supervised machine learning models. The injury caused by S. frugiperda with the behavior of the cut off and the voracity of the larvae were evident in the structures (hypocotyl and cotyledons) of the evaluated plants. The results of the present study emphasize the need to manage S. frugiperda during the preplanting phase of soybean.

One way to reduce the use of synthetic chemical pesticides and antibiotics is to replace them with plants possessing such properties. While many species have been identified for animal, plant and human health, observations show that some species are predominantly used for one or more of these health purposes, such as neem (Azadirachta indica, Meliaceae). As for synthetic products, the excessive or incorrect use of these plants presents a risk of harmful toxicity for humans and their environment. To limit this risk, we create a Knowledge Based System (KBS) named Knomana. This software system allows to explore knowledge bases in order to generate new knowledge, using Artificial Intelligence methods. In September 2021, Knomana contained 46300 descriptions of plant uses in experimental conditions or common practices, related to 81 countries, and extracted from 462 scientific articles. In total, 2540 plant species are listed to protect a hundred organisms (crops, aquatic or terrestrial animals, humans) against 216 species of organisms (Bacteria, Chromista, Eukaryota, Fungi, Insecta, and Viruses). The financial development support of the Artificial Intelligence methods for Knomana is provided by the Digital Agriculture Convergence Lab (https://www.hdigitag.fr/) and the project SmartFCA (ANR-21-CE23- 0023/). The project Santés-Territoires (https://santes-territoires.org), recently launched in Senegal, will build transdisciplinary plant selection criteria considering, among others, active ingredients, toxicity on human being, and impact on biodiversity. Thanks to these criteria, Knomana will propose local plants as alternatives to pesticides, antibiotics, and the most predominantly used plants. This work contributes to the enhancement of the biodiversity. Pestical plant valorization, Knowledge management, Artificial intelligence, Toxicity, Knowledge bases, animal health, plant health, human health.

The fall armyworm (FAW; Spodoptera frugiperda) is one of the major agricultural pest insects. FAW is native to the Americas, and its invasion was first reported in West Africa in 2016. Then it quickly spread through Africa, Asia, and Oceania, becoming one of the main threats to corn production. We analyzed whole genome sequences of 177 FAW individuals from 12 locations on four continents to infer evolutionary processes of invasion. Principal component analysis from the TPI gene and whole genome sequences shows that invasive FAW populations originated from the corn strain. Ancestry coefficient and phylogenetic analyses from the nuclear genome indicate that invasive populations are derived from a single ancestry, distinct from native populations, while the mitochondrial phylogenetic tree supports the hypothesis of multiple introductions. Adaptive evolution specific to invasive populations was observed in detoxification, chemosensory, and digestion genes. We concluded that extant invasive FAW populations originated from the corn strain with potential contributions of adaptive evolution.

Field evolved resistance to insecticides is one of the main challenges in pest control. The fallarmyworm (FAW) is a lepidopteran pest species causing severe crop losses, especially corn. While native to the Americas, the presence of FAW was confirmed in West Africa in 2016. Since then, the FAW has been detected in over 70 countries covering sub-Saharan Africa, the Middle East, North Africa, South Asia, Southeast Asia, and Oceania. In this study, we tested whether this invasion was accompanied by the spread of resistance mutations from native to invasive areas. We observed that mutations causing Bt resistance at ABCC2 genes were observed only in native populations where the mutations were initially reported. Invasive populations were found to have higher gene numbers of cytochrome P450 genes than native populations and a higher proportion of multiple resistance mutations at acetylcholinesterase genes, supporting strong selective pressure for resistanceagainst synthetic insecticides. This result explains the susceptibility to Bt insecticides and resistance to various synthetic insecticides in Chinese populations. These results highlight the necessity of regular and standardized monitoring of insecticide resistance in invasive populations using both genomic approaches and bioassay experiments.

Replacing synthetic pesticides and antimicrobials with plant-based extracts is a current alternative adopted by traditional and family farmers and many organic farming pioneers. A range of natural extracts are already being marketed for agricultural use, but many other plants are prepared and used empirically. A further range of plant species that could be effective in protecting different crops against pests and diseases in Africa could be culled from the large volume of knowledge available in the scientific literature. To meet this challenge, data on plant uses have been compiled in a knowledge base and a software prototype was developed to navigate this trove of information. The present paper introduces this so-called Knomana Knowledge-Based System, while providing outputs related to Spodoptera frugiperda and Tuta absoluta, two invasive insect species in Africa. In early October 2020, the knowledge base hosted data obtained from 342 documents. From these articles, 11,816 uses—experimental or applied by farmers—were identified in the plant health field. In total, 384 crop pest species are currently reported in the knowledge base, in addition to 1547 botanical species used for crop protection. Future prospects for applying this interdisciplinary output to applications under the One Health approach are presented.

Formal Concept Analysis (FCA) comes with a range of rel- evant techniques for knowledge analysis, such as conceptual structures or implications. The Duquenne-Guigues basis of implications provides a cardinality minimal set of non-redundant implications. The concern of a domain expert is to discover new knowledge within this implication set. The objective of this paper is to collect and discuss the di_erent pat- terns of implications extracted from a dataset on plants used in medical care or consumed as food. We identify 16 patterns combining 3 types of knowledge elements (KE). The patterns highlight redundant KEs, in particular, those corresponding to plant taxonomy, as it is familiar knowl- edge for the experts. Removing these KEs from the implications makes them tacit. We suggest a post-process for cleaning up the implications before reporting them to the experts.