Proposition d’une méthode pour le suivi du recul du couvert forestier au Togo : Analyse à partir d’images MODIS et LANDSAT sur la période 2001-2015

International audienceComment réaliser le suivi de l'évolution du couvert forestier dans un contexte de déforestation et de dégradation forestière? Dans cette recherche, il s'agit de mettre en place une méthode simple, basée sur une télédétection peu coûteuse, utilisable à grande échelle, et applicable en routine adaptée à la situation de la forêt au Togo. L'analyse est réalisée à partir d'images satellitaires MODIS et Landsat, dans une zone et sur des sites forestiers. Elle combine étude des changements dans les affectations du sol et dynamique du couvert végétal

Laying Bare: Agamben, Chandler, and The Responsibility to Protect

This paper demonstrates the hidden similarities between Raymond Chandler’s prototypical noir The Big Sleep, and the United Nations Responsibility to Protect (R2P) document. By taking up the work of philosopher Giorgio Agamben, this paper shows that the bare life produces the form of protection embodied by Philip Marlowe in Chandler’s novel and by the United Nations Security Council in R2P. Agamben’s theorizing of the extra-legal status of the sovereign pertains to both texts, in which the protector exists outside of the law. Philip Marlowe, tasked with preventing the distribution of pornographic images, commits breaking-and-entering, withholding evidence, and murder. Analogously, R2P advocates for the Security Council’s ability to trespass laws that safeguard national sovereignty in order to prevent “bare” atrocities against human life. As Agamben demonstrates, the extra-legal position of the protector is made possible by “stripping bare” human life. This paper also gestures towards limitations of Agamben’s thought by indicating, through a comparison of these two texts, that bare life produces states of exception as the object of protection rather than punishment

Caractéristiques Agronomiques et Identification des Facteurs Déterminant la Faible Productivité des Agroforêts à Cacaoyers (Theobroma Cacao L.) au Togo

Les agroforêts à cacaoyers du Togo sont caractérisées par leur faible productivité. L’objectif de cette étude est d’identifier les caractéristiques agronomiques et les facteurs déterminant la faible productivité des cacaoyers. Une enquête a été menée auprès de 385 cacaoculteurs suivie d’une prospection réalisée dans 88 vergers de cacaoyers répartis en quatre tranches d’âge : les jeunes plantations entrant en production (5 à 10 ans), les cacaoyers adultes en pleine production (10 à 20 ans), les cacaoyers vieillissants dont la production est en déclin (21 à 30 ans) et les vieilles plantations (>30 ans). Les résultats ont montré que la tranche d’âge moyenne des vergers est comprise entre 10 et 20 ans. Ces vergers sont essentiellement installés sur les anciens champs de cacaoyers (42,6%) et sur précédent forestier (40,3%) avec du matériel végétal constitué en grande partie d’hybrides sélectionnés (82,9%). Les fréquences de désherbages, des traitements phytosanitaires (insecticides et fongicides) et d’applications de fumure (organique et minérale) sont inférieures aux normes recommandées par la recherche. Les rendements moyens sont faibles et sont compris entre 218,64 kg/ha dans les vieilles plantations (> 30 ans) et 450,77 kg/ha dans les plantations adultes en pleine production (10 à 20 ans). En ce qui concerne les différentes sous zones agroécologiques, les résultats ne révèlent aucune différence significative pour les rendements. Ces rendements varient de 305,76 kg/ha dans la sous zone de plateaux à 376,59 kg/ha dans la sous zone de Kloto-Litimé. Cette faible productivité est liée au faible niveau de gestion et d’entretien des vergers, aux caractéristiques des peuplements cacaoyers et des peuplements associés. Cocoa agroforests in Togo are characterized by their low productivity. The objective of this study is to identify the agronomic characteristics and factors determining the low productivity of cocoa trees. A survey was conducted among 385 cocoa farmers followed by a survey carried out in 88 cocoa orchards and four age groups were considered: young plantations entering production (5 to 10 years), adult cocoa trees in production (10 to 20 years), aging cocoa trees in production (21 to 30 years) and old plantations (>30 years). The results showed that the mean age group of orchards is 10 to 20 years old. These orchards are mainly installed on old cocoa fields (42.6%) and on previous forest (40,3%) with plant material consisting largely of selected hybrids (82,9%). The frequencies of weeding, phytosanitary treatments (insecticides and fungicides) and manure applications (organic and mineral) are below the standards recommended by research. Average yields are low and range between 218,64 kg/ha in old plantations (> 30 years) and 450,77 kg/ha in adult plantations in production (10 to 20 years). With regard to the different agro-ecological sub-zones, the results show that yields vary from 305,76 kg/ha in the plateau sub-zone to 376,59 kg/ha in the Kloto-Litimé sub-zone. This low productivity is linked to the low level of management and maintenance of orchards, to the characteristics of cocoa stands and associated stands. &nbsp

The emerging oilseed crop Sesamum indicum enters the “Omics” era

Sesame (Sesamum indicum L.) is one of the oldest oilseed crops widely grown in Africa and Asia for its high-quality nutritional seeds. It is well adapted to harsh environments and constitutes an alternative cash crop for smallholders in developing countries. Despite its economic and nutritional importance, sesame is considered as an orphan crop because it has received very little attention from science. As a consequence, it lags behind the other major oil crops as far as genetic improvement is concerned. In recent years, the scenario has considerably changed with the decoding of the sesame nuclear genome leading to the development of various genomic resources including molecular markers, comprehensive genetic maps, high-quality transcriptome assemblies, web-based functional databases and diverse daft genome sequences. The availability of these tools in association with the discovery of candidate genes and quantitative trait locis for key agronomic traits including high oil content and quality, waterlogging and drought tolerance, disease resistance, cytoplasmic male sterility, high yield, pave the way to the development of some new strategies for sesame genetic improvement. As a result, sesame has graduated from an “orphan crop” to a “genomic resource-rich crop.” With the limited research teams working on sesame worldwide, more synergic efforts are needed to integrate these resources in sesame breeding for productivity upsurge, ensuring food security and improved livelihood in developing countries. This review retraces the evolution of sesame research by highlighting the recent advances in the “Omics” area and also critically discusses the future prospects for a further genetic improvement and a better expansion of this crop. (Résumé d'auteur

Spodoptera frugiperda population structure and influence of farmers’ practices on gut biodiversity for sustainable management of the pest in Kenya

Fall armyworm (FAW), Spodoptera frugiperda, is a highly polyphagous pest that recently invaded Kenya, among other African countries. Information on the pest’s genetic diversity and mechanisms conferring insecticide resistance, in addition to farmers’ knowledge and perceptions on the applicable mitigation measures, inform the development of sustainable management strategies. Therefore, this study collected cross-sectional data from 800 farmers in Kenya and documented their knowledge and perceptions on FAW and factors influencing their choice of FAW control methods. Additionally, we identified the strains present in 8 counties in Kenya using the mitochondrial Cytochrome Oxidase sub-unit I (mt COI) gene, and correlated pesticide use to gut microbiome diversity via 16S rRNA metagenomics to investigate the probable contribution of gut bacteria towards insecticide resistance evolution. All farmers reported FAW infestations, and 24% reported limited and total non-response of FAW to insecticides. Fall armyworm rice-strain and corn-strain were detected ravaging corn fields. However, the corn-strain revealed higher microbial diversity than the rice-strain. Furthermore, pathogenic bacterial genera were elevated in the insect gut in both corn and rice strains after chemical-treatments. Insecticide–endosymbiont interactions should be further explored, and farmers’ training on effective alternative pest control methods is recommended

Integrated Management of Aphis craccivora in Cowpea Using Intercropping and Entomopathogenic Fungi under Field Conditions

Cowpea aphid, Aphis craccivora, is a major cowpea pest. Cowpea–cereal intercrop alone does not effectively manage the pest. Use of pesticides in intercrop leads to health and environmental risks. Fungal-based biopesticides offer a better option because they are environment- and consumer-friendly. This study assessed the combined effect of Metarhizium anisopliae ICIPE 62 and cowpea–maize intercrop against A. craccivora under six treatments: (1) untreated cowpea monocrop, (2) untreated cowpea–maize intercrop, (3) cowpea monocrop + ICIPE 62, (4) cowpea–maize intercrop + ICIPE 62, (5) cowpea monocrop + Duduthrin insecticide, and (6) cowpea–maize intercrop + Duduthrin during three seasons (long rainy/cold and dry/short rainy). In the cold and dry season, cowpea–maize intercrop treated with ICIPE 62 recorded the lowest infestation/cowpea damage, whereas the leaf yield was comparable to cowpea monocrop treated with ICIPE 62. In the short rainy season, the cowpea–maize intercrop treated with ICIPE 62 recorded the lowest infestation/damage, whereas leaf yield was similar to cowpea–maize intercrop treated with ICIPE 62 in the cold and dry season. Duduthrin in monocrop and intercrop did not reduce aphid infestation/cowpea damage levels in all the seasons. Although the efficacy of M. anisopliae ICIPE 62-based biopesticide could be affected by seasons, it successfully controlled aphid population in cowpea–maize intercrop under field conditions without affecting aphid-associated natural enemies.Peer Reviewe

One stone for two birds: Endophytic fungi promote maize seedlings growth and negatively impact the life history parameters of the fall armyworm, Spodoptera frugiperda

The fall armyworm (FAW) Spodoptera frugiperda, is a voracious pest of cereals native to the Americas and which invaded Africa in 2016. Chemical control is the main management option, which however remains ineffective and unsustainable. Fungal endophytes are increasingly used as alternative for the management of insect pests of economic importance. This study assessed the potential of eight endophytic fungal isolates to colonize maize plant and their ability to promote seedlings growth through seed and foliar inoculations, as well as their suppressive effects on FAW. Fungal colonization rates of different plant parts by the endophytes varied as per the inoculation methods. Beauveria bassiana ICIPE 279 colonized more than 60% of all the seedling parts while B. bassiana G1LU3 only colonized stem (25%) and leaf (5%) tissues through foliar inoculation. Trichoderma atroviride F2S21, T. asperellum M2RT4, T. harzianum F2R41, Trichoderma sp. F2L41, Hypocrea lixii F3ST1 and Fusarium proliferatum F2S51 successfully colonized all the plant parts and therefore were selected and further evaluated through seed inoculation for their endophytic persistence, effect on plant growth, and pathogenicity to Spodoptera frugiperda immature and adult stages. Weekly assessment showed varied effect of the endophytes on maize plant growth parameters compared to the control. During the first week, percentage colonization of the plant parts ranges between 90%–100%, 65%–100%, and 60%–100%, in the roots, stems, and leaves, respectively for all the five tested isolates. However, the colonization pattern/rates significantly decreased over time for H. lixii F3ST1 in the stems and leaves, and for T. harzianum F2R41 in the leaves and for T. asperellum M2RT4 in the roots. In addition, T. harzianum F2R41 outperformed all the other isolates in boosting the plant height, whereas H. lixii F3ST1 and T. asperellum M2RT4 outperformed all the other isolates in increasing the wet and dry shoots weight. Furthermore, the number of egg masses laid on endophytically-colonized maize plants varied among the treatments. Trichoderma asperellum M2RT4 and H. lixii F3ST1 endophytically-colonized maize plants significantly reduced the number of egg masses and the defoliation/feeding rates of the pest compared to the control. Additionally, T. harzianum F2R41 had the highest negative impact on the pupation and adult emergence of S. frugiperda with a female-biased sex ratio. Our findings indicate that T. asperellum M2RT4, T. harzianum F2R41, and H. lixii F3ST1 hold a potential to be developed as endophytic-fungal-based biopesticides for sustainable management of S. frugiperda and as plant growth promoters

The Endophyte Trichoderma asperellum M2RT4 induces the systemic release of methyl Salicylate and (Z)-jasmone in tomato plant affecting host location and herbivory of Tuta absoluta

The use of endophytic fungi has dramatically increased plant performance through the enhancement of plant protection against abiotic and biotic stressors. We previously demonstrated that the endophytic fungus Trichoderma asperellum M2RT4 improves tomato defenses against the tomato leafminer Tuta absoluta through the reduction of oviposition, leafmining, pupation, and adult emergence. However, the underlying mechanism by which the presence of this endophytic fungus within tomato host plant affects T. absoluta host selection and life-history traits is unknown. We tested the behavioral responses of T. absoluta in Y-tube olfactometer bioassays and found that females preferred non-inoculated tomato plants against those inoculated by endophytes. Additionally, T. absoluta females were not attracted to non-inoculated infested nor to inoculated-infested tomato plants. Chemical analysis revealed the emission of methyl salicylate in inoculated tomato plant and an increase in the amounts of monoterpenes emitted from non-inoculated infested plants. Additionally, we found that upon herbivory, T. asperellum M2RT4 modulates tomato plant chemistry through the production of (Z)-jasmone thus activating both salicylic and jasmonic acid defense pathways. Further, T. absoluta females were attracted to monoterpernes including α-pinene, 2-carene, and β-phellandrene but repelled by methyl salicylate. Methyl salicylate could therefore be considered as a good semiochemical-based candidate for sustainable T. absoluta management using a “push-pull” approach. However, in dose-response bioassays, females of T. absoluta did not show any preference to the four component-blend (α-pinene, 2-carene, β-phellandrene, and methyl salicylate). (Z)-jasmone-treated tomato leaflets significantly reduced the leafmining activity of the pest at the concentration of 10 ng/µL and causing the highest larval mortality rate (83%) with the shortest LT50 (1.73 days) 7 days post-treatment. T. asperellum M2RT4 effect on herbivore performance was then (Z)-jasmone-mediated. These findings expand our understanding of how the endophytic fungus T. asperellum M2RT4 could mediate chemical interactions between T. absoluta and its host plant which are potentially important for development of environmentally friendly T. absoluta management programs.https://www.frontiersin.org/journals/plant-sciencedm2022Forestry and Agricultural Biotechnology Institute (FABI)Zoology and Entomolog

Insight into the AP2/ERF transcription factor superfamily in sesame and expression profiling of DREB subfamily under drought stress

Background. Sesame is an important oilseed crop mainly grown in inclement areas with high temperatures and frequent drought. Thus, drought constitutes one of the major constraints of its production. The AP2/ERF is a large family of transcription factors known to play significant roles in various plant processes including biotic and abiotic stress responses. Despite their importance, little is known about sesame AP2/ERF genes. This constitutes a limitation for drought-tolerance candidate genes discovery and breeding for tolerance to water deficit. Results. One hundred thirty-two AP2/ERF genes were identified in the sesame genome. Based on the number of domains, conserved motifs, genes structure and phylogenetic analysis including 5 relatives species, they were classified into 24 AP2, 41 DREB, 61 ERF, 4 RAV and 2 Soloist. The number of sesame AP2/ERF genes was relatively few compared to that of other relatives, probably due to gene loss in ERF and DREB subfamilies during evolutionary process. In general, the AP2/ERF genes were expressed differently in different tissues but exhibited the highest expression levels in the root. Mostly all DREB genes were responsive to drought stress. Regulation by drought is not specific to one DREB group but depends on the genes and the group A6 and A1 appeared to be more actively expressed to cope with drought. Conclusions. This study provides insights into the classification, evolution and basic functional analysis of AP2/ERF genes in sesame which revealed their putative involvement in multiple tissue-/developmental stages. Out of 20 genes which were significantly up- /down-regulated under drought stress, the gene AP2si16 may be considered as potential candidate gene for further functional validation as well for utilization in sesame improvement programs for drought stress tolerance. (Résumé d'auteur

Gut microbiota assemblages of generalist predators are driven by local- and landscape-scale factors

ABSTRACT: The gut microbiomes of arthropods have significant impact on key physiological functions such as nutrition, reproduction, behavior, and health. Spiders are diverse and numerically dominant predators in crop fields where they are potentially important regulators of pests. Harnessing spiders to control agricultural pests is likely to be supported by an understanding of their gut microbiomes, and the environmental drivers shaping microbiome assemblages. This study aimed to deciphering the gut microbiome assembly of these invertebrate predators and elucidating potential implications of key environmental constraints in this process. Here, we used high-throughput sequencing to examine for the first time how the assemblages of bacteria in the gut of spiders are shaped by environmental variables. Local drivers of microbiome composition were globally-relevant input use system (organic production vs. conventional practice), and crop identity (Chinese cabbage vs. cauliflower). Landscape-scale factors, proportion of forest and grassland, compositional diversity, and habitat edge density, also strongly affected gut microbiota. Specific bacterial taxa were enriched in gut of spiders sampled from different settings and seasons. These findings provide a comprehensive insight into composition and plasticity of spider gut microbiota. Understanding the temporal responses of specific microbiota could lead to innovative strategies development for boosting biological control services of predators.info:eu-repo/semantics/publishedVersio