Search

Using knowledge about plant–insect interactions in a crop protection perspective is a pre-requisite to promote the development of novel pest management strategies. Enhancing plant natural defenses has been described as a promising way to improve the management of pests. In cotton, plant topping (cutting off the top of the plant) for inducing such defenses has been proposed as a promising tool for integrated pest management. The main objective of this study was to explore the effect of cotton topping on the performance of the cotton aphid, Aphis gosypii, under greenhouse conditions. The effect of plant topping was evaluated on topped and on neighbor non-topped plants. Results showed that cotton topping disturbed A. gossypii aphids not only on the topped plant but also on neighbor non-topped plants. The population of aphids grew slower in the topped compared to the control treatment and lower abundances of aphids were found in the topped treatment up to a distance of 100 cm to the topped plant. When an individual nymph was confined in a clip-cage, the production of winged adults after 15 days of confinement was higher in the topped compared to the control treatment. This difference decreased as the distance to the topped plant increased. In conclusion, our study proves that cotton topping mediates plant-pest interactions on the focal and neighbor plants. We discuss how cotton topping is a promising technique that could be used as part of an integrated pest management program, particularly for smallholders in West Africa, for controlling aphid infestations.

In order to know the local predators of Tuta absoluta Meyrick (1917) in Côte d'Ivoire and their host plants, a survey was carried out in 15 vegetable growing areas in 15 cities across the country. The study took place from November 2019 to February 2020. It concerned mainly tomato crops and African eggplant crops but also some companion plants such as tobacco. Observations were made on 30 plants per plant species. Farmers were questioned about the phytosanitary practices they use to protect their crops against pests. In total, 208 predators were captured. The predators collected were Heteroptera from the Miridae family: Nesidiocoris tenuis Reuter (1895) (51.92%); Nesidiocoris volucer Kirkaldy (1902) (30.28%) and Macrolophus pygmaeus Rambur (1839) (17.78%). These predators were collected on tobacco (45.19%), tomato (32.21%) and African eggplant (22.60%), except for the species N. volucer which was collected only on tobacco. The survey revealed that for pest management, 69% of the producers used conventional products and 31% used biological control method based on plant extracts. Insect predators were mainly collected on non-treated plants such as tobacco or on crops with a biological protection (78.85%). The plant extracts used by farmers, preserved insect predators much better than conventional treatments. Actually, these generalist predators complement the effect of plant extracts as they can feed on a large number of pests from different species such as T. absoluta or Bemisia tabaci and at different stages (eggs, larvae). Host plants such as tobacco could be used by farmers to attract and maintain these insect predators in vegetable areas, or even to introduce them into crops under cover such as greenhouse or net house.

La lutte biologique et le biocontrôle sont des concepts de protection des cultures qui ont des points communs mais qui ont également leurs spécificités. La première est connue depuis les années 1880, alors que le second est apparu dans les années 2010 dans le paysage français. Depuis quelques années, on constate régulièrement une confusion dans les termes et dans les interprétations de ces concepts qui ne sont pas de même nature : la lutte biologique est définie par des stratégies et le biocontrôle par des produits. Ce papier vise donc à répondre à un besoin de clarification : il contribue à distinguer les périmètres et les contenus de ces concepts, à pointer certains rapprochements abusifs et à proposer des clarifications sémantiques. Il passe en revue les termes anglophones et francophones relatifs à la lutte biologique et au biocontrôle à l’échelle européenne. Le papier discute enfin du rôle et de la pertinence des deux concepts dans la protection agroécologique des cultures. La lutte biologique par conservation y occupe une place centrale, car elle relève d’une approche systémique et préventive des risques liés aux bioagresseurs des cultures. Si certains produits de biocontrôle sont prometteurs pour la prévention des risques liés aux bioagresseurs, beaucoup d’autres s’inscrivent dans une démarche curative, similaire à celle de l’utilisation des pesticides chimiques de synthèse, avec les mêmes types de retombées commerciales pour l’agro-industrie.

The African weaver ant Oecophylla longinoda builds woven leaf nests inside tree canopies and is a major conservation biocontrol agent in sub-Saharan Africa. Weaver ant colonies provide well-protected and resource-rich environments for many associated trophobionts, thereby boosting their establishment on host plants. There is very little published literature on O. longinoda, their hosts plants and their associated trophobionts in West Africa. These tri-trophic interactions were studied over a period of four consecutive years (2010–2013) from south to north Benin. Our fieldwork revealed that all O. longinoda colonies were consistently associated with trophobionts. Oecophylla longinoda nests were recorded on 82 plant species belonging to 30 families, with 35 associated trophobiont species representing 11 families. Among cultivated plants, Mangifera indica was the most common species hosting O. longinoda, while Sarcocephalus latifolius the most frequent native one. Among trophobionts, Parasaissetia nigra, Udinia catori, Udinia farquharsoni (Coccidae) and Stictococcus sjostedti (Stictococcidae) were the most common hemipterans associated with O. longinoda. We identified a wide range of host plants that could be preserved (or planted) to promote the establishment of weaver ants to control different insect pests in fruit plantations in sub-Saharan Africa. When planted around fruit plantations with their nests and tended hemipterans, these host plants could facilitate biocontrol of mango fruit flies (Tephritidae) and cashew bugs (Coreidae, Miridae), by O. longinoda in the fruit plantations.

L’utilisation des pesticides chimiques de synthèse dans la protection des cultures a aujourd’hui clairement montré ses limites : risques sanitaires, effets négatifs sur l’environnement, déséquilibres écologiques, pertes d’efficacité et coûts élevés. C’est pourquoi la forte réduction de ces pesticides est maintenant un objectif généralement admis par la plupart des acteurs professionnels et politiques. En France, le biocontrôle est un concept de protection des cultures apparu lors de la dernière décennie et présenté comme une solution permettant de réduire l’utilisation de pesticides. La présente synthèse vise à dresser un état des lieux de ce que recouvre le terme de « biocontrôle » en France. Derrière une définition officielle, la revue des définitions du biocontrôle en France montre une instabilité terminologique significative. La diversité des acceptions du terme de « biocontrôle » est à l’origine d’interprétations variables selon les acteurs. Par ailleurs, l’analyse de l’utilisation du terme « biocontrôle » en France au cours de la dernière décennie montre l’intérêt grandissant du biocontrôle auprès du grand public, des professionnels du monde agricole et agropharmaceutique, des politiques et de la communauté scientifique. L’augmentation de l’usage de ce terme a été observée parallèlement à la diminution de l’usage du terme « lutte biologique », un concept reconnu et stable depuis plus d’un siècle. Enfin, cette diversité des définitions du biocontrôle et cette augmentation de l’utilisation du terme « biocontrôle » induisent des problématiques dans le domaine de la protection des cultures qui sont évoquées dans cette synthèse.

International audience; The authors report the first records of the generalist predator Orius (Dimorphella) maxidentex Ghauri, 1972 (Heteroptera: Anthocoridae) from different cropping systems in Senegal (West Africa) and propose fast and accurate identification based on morphological traits and molecular analyses. Orius maxidentex is a frequent and abundant predatory bug in Senegalese agro-systems, especially, millet, maize and tomato fields. It is likely to play an important role in regulating the populations of several pests, and its potential involvement in natural pest control in these cropping systems is discussed.

Two recent literature reviews have shown that: i) agroecological crop protection (ACP) practices generally reduce risks of viral zoonoses, unlike conventional (agrochemical-based) practices which tend to increase them; ii) substitution-based crop protection (CP) practices (mainly biocontrol-based) could result in fewer health risks from bacterial infectious diseases. Here, we present an analysis of the scientific literature to determine to what extent the conclusions regarding viruses or bacteria can be extended to infectious diseases caused by protozoan or helminthic parasites. This analysis of cases of both vector-transmitted and water- or food-borne parasitic diseases, shows, in terms of reduction of health risks: i) an overall negative effect arising from the use of synthetic plant protection products; ii) the relevance of substitution CP practices not strictly under the ACP banner. On the other hand, the public and veterinary health issue of antiparasitic resistance is not affected by CP practices. The positive effects at the large spatio-temporal scales of ACP approaches remain valid, although to a slightly lesser extent than for bacterial diseases and viral zoonoses, in particular through biodiversity conservation which fosters natural regulations and control, preventing the undesirable effects of synthetic pesticides.

Integrated Pest Management (IPM) provides an illustration of how crop protection has (or has not) evolved over the past six decades. Throughout this period, IPM has endeavored to promote sustainable forms of agriculture, pursued sharp reductions in synthetic pesticide use, and thereby resolved myriad socio-economic, environmental, and human health challenges. Global pesticide use has, however, largely continued unabated, with negative implications for farmer livelihoods, biodiversity conservation, and the human right to food. In this review, we examine how IPM has developed over time and assess whether this concept remains suited to present-day challenges. We believe that despite many good intentions, hard realities need to be faced. 1) We identify the following major weaknesses: i) a multitude of IPM definitions that generate unnecessary confusion; ii) inconsistencies between IPM concepts, practice, and policies; iii) insufficient engagement of farmers in IPM technology development and frequent lack of basic understanding of its underlying ecological concepts. 2) By diverting from the fundamental IPM principles, integration of practices has proceeded along serendipitous routes, proven ineffective, and yielded unacceptable outcomes. 3) We show that in the majority of cases, chemical control still remains the basis of plant health programs. 4) Furthermore, IPM research is often lagging, tends to be misguided, and pays insufficient attention to ecology and to the ecological functioning of agroecosystems. 5) Since the 1960s, IPM rules have been twisted, its foundational concepts have degraded and its serious (farm-level) implementation has not advanced. To remedy this, we are proposing Agroecological Crop Protection as a concept that captures how agroecology can be optimally put to the service of crop protection. Agroecological Crop Protection constitutes an interdisciplinary scientific field that comprises an orderly strategy (and clear prioritization) of practices at the field, farm, and agricultural landscape level and a dimension of social and organizational ecology.

Description of the subject. The real-time management of residues of plant protection products is a general issue for food producers and/or exporters. Authorized pesticides under European Regulation (EC) No 1107/2009 (Reg. 1107/2009) are granted a maximum residue limit (MRL) defined by the European Chemicals Agency (ECHA). These maximum residue limits are managed by the European Commission and listed in EC Regulation No 396/2005. MRLs for newly approved substances are set for pesticide residues present in products or groups of products covered by Annex I with a default value of 0.01 mg·kg-1, unless they have been considered, elaborated upon on approval and affected in one of the six other Annexes (II to VII). Substances listed in Annex IV are favoured in the selection of substances to be used by producers as it is for substances with very low potential impacts (low-risk substances [Art. 22 of Reg. 1107/2009] which therefore require no MRL; basic substances [Art. 23 of Reg. 1107/2009]; and microorganisms). The number of substances affected by this lack of an MRL (without residues survey requirement) has been steadily increasing since the publication of the SANCO/11188/2013 Guideline. Many biocontrol agents are listed in Annex IV, including microbial insecticides (e.g. Bacillus thuringiensis, Cydia pomonella granulosis virus), semiochemicals used in traps (e.g. ammonium acetate, putrescine) and some natural substances (e.g. sulphur) as well as all the currently listed basic substances. Objectives. To show that plant protection may be achieved with less concern or control (auto + external) than with certain agrochemical pesticides, including those without maximum residue limits (MRL). Method. Analysis of EU Pesticide Database and EU Regulation (EU) No 540/2011.Results. All approved pesticide active substances with no MRL included in Annex IV of Regulation (EC) No 396/2005, listed by substance status type (active, low-risk or basic) and category (microorganism, semiochemical or natural). Conclusions. These results may be used to help achieve plant protection with much less risk of contaminations, while noting the necessity for controls, analytical issues, positive controls, as well as the possibility of downgrading and withdrawal of approval from the market., Intérêt majeur des substances actives en protection des cultures sans limite maximale de résidu (LMR)Description du sujet. La gestion quotidienne des résidus de produits phytosanitaires est un problème général pour les producteurs et/ou les exportateurs de denrées alimentaires. Les pesticides autorisés par le règlement phytosanitaire européen CE No 1107/2009 (RCE No 1107/2009) sont affectés d’une limite maximale de résidus (LMR) définies par l’Agence Européenne des produits chimiques (ECHA). Cette LMR est gérée par la Commission européenne et déclinée dans le Règlement (CE) No 396/2005. Les LMR des substances nouvellement approuvées sont fixées dans les produits ou groupes de produits visés à l’Annexe I avec une valeur par défaut de 0,01 mg·kg-1 (sauf si elles ont été considérées et calculées lors de l’approbation et affectées dans l’une des six autres Annexes [II à VII]). L’utilisation des substances contenues dans l’annexe IV est à privilégier par les producteurs : en effet, elle confère une absence de LMR pour des substances à très faibles impacts potentiels (substances à faibles risques [Art. 22 du RCE 1107/2009], substances de base [Art. 23 du RCE 1107/2009], micro-organismes). Le nombre de substances affectées par cette absence de LMR et donc l’absence de recherche de résidus, est en constante augmentation depuis la publication du Guideline SANCO/11188/2013. Les catégories et les substances correspondantes placées dans l’annexe IV sont présentées : de nombreux agents de biocontrôle comme les micro-organismes insecticides (Bacillus thuringiensis, virus de la granulose de Cydia pomonella), de nombreux médiateurs chimiques utilisés dans les pièges (acétate d’ammonium, putrescine) et certaines substances naturelles (soufre), ainsi que toutes les substances de base actuelles.Objectifs. Ces résultats peuvent être utilisés pour montrer que la protection des plantes peut être effectuée avec plus de prévention des contaminations, moins de crainte de résidus, de nécessité de contrôle, de besoin de contrôles et de problèmes analytiques, de contrôles positifs, de déclassement et de retrait du marché en utilisant certains types de pesticides, ceux sans LMR.Méthode. Une analyse de la base de données de pesticides de l\'UE et du Règlement (UE) No 540/2011.Résultats. Toutes les substances actives pesticides approuvées sans LMR (inclus dans l\'annexe IV du Règlement [CE] No 396/2005) listées par type de statut (active, faible risque ou de base) et catégorie (micro-organisme, médiateur chimique ou naturel).Conclusions. Ces résultats peuvent être utilisés pour la protection des plantes afin d\'éviter les contaminations, contrôles positifs, problèmes analytiques, les déclassements ou les retraits du marché.

International audience; Banana (Musa spp.) is one of the most widely cultivated subtropical fruits around the globe. Banana cultivation has been extensively increased in southeastern Iran over the last two decades. Recently, banana fruits possessing rotten and blackened fingertip symptoms were observed in Sistan‐Baluchestan, Iran. Isolation and characterization of the causal agent showed that the pathogen belongs to the multifaceted bacterial species Burkholderia cenocepacia. Pathogenicity tests and host range assays showed that the strains were pathogenic on banana, as well as carrot, onion and potato. All the strains were resistant to 50 mg L−1 rifampicin and 200 mg L−1 copper sulphate. Phylogenetic analysis of 16S rRNA and recA gene sequences showed that the strains belong to two different genomovars of B. cenocepacia (III‐A and III‐B), which also include environmental and cystic fibrosis associated strains of the species. The results obtained from recA phylogeny were confirmed using multilocus sequence analysis (MLSA), although MLSA showed that the banana strains were clustered as a novel phylogroup among the members of both genomovars. Banana‐pathogenic B. cenocepacia strains isolated in Iran were different from the strains isolated in Taiwan, as the ‘B. cepacia epidemic strain marker’ reported in the Taiwanese strains was absent from Iranian strains. To the authors’ knowledge, this is the first MLSA‐based study on the banana‐pathogenic strains of B. cenocepacia. However, further in‐depth molecular studies are needed to decipher the relationships between the banana fingertip rot pathogen and the clinical strains of B. cenocepacia.

International audience; 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.

International audience; Intensive chayote cultivation in Réunion almost disappeared in the 2000s due to significant yield losses from fruit fly attacks on this historically important crop (Dacus ciliatus, Zeugodacus cuurbitae and Dacus demmerezi). Since the late 2000s, the adoption of agroecological crop protection practices have led to the effective management of fruit fly populations, a significant reduction in pesticide use, an increase in chayote production and plantations, and the development of organic production. To assist in fruit fly management, a qualitative model which simulates fruit fly damage to chayote crops, known as IPSIM-chayote, was developed, providing satisfactory prediction results. It has a user-friendly interface and is now available free of charge online, in three languages (French, English and Spanish): https://pvbmt-apps.cirad.fr/apps/ipsim-chayote/?lang=en. The IPSIM-chayote modeling platform can be used by farmers as a diagnosis to simulate fruit fly damage to their crops and as a decision-making tool for their agricultural practices. The model can be used as a training resource in agroecological crop protection. Public authorities and local government can use it as a tool in planning and forecasting agricultural development. Finally, researchers can use it as a prediction tool and a resource for the exchange of information, allowing them to review scientific knowledge or identify new, relevant research areas suited to the context and challenges. IPSIM-chayote can be considered as a forum for exchange and can stimulate collaborative work between individuals. It is a flexible model, as it allows variables to be added. IPSIM-chayote is the first qualitative model developed for crop pests in a tropical environment. It could serve as a basis for the development of other similar models simulating crop pest incidence, thus contributing significantly to the development of agroecological crop protection.

Une revue bibliographique récente montre que les pratiques de protection agroécologique des cultures (PAEC) contre les ravageurs, pathogènes et adventices, réduisent généralement les risques zoonotiques viraux en santé publique et vétérinaire, alors que les pratiques conventionnelles (à base agrochimique) tendent à les augmenter. Nous avons analysé la littérature scientifique pour déterminer si ces conclusions pouvaient être élargies aux infections bactériennes, avec focus sur les agroécosystèmes tropicaux. En santé publique et vétérinaire, les principales infections bactériennes impactées par des pratiques de protection des cultures sont celles ayant pour réservoirs des rongeurs (avec arthropodes vecteurs, comme la peste, ou pas, comme la leptospirose), et les maladies à entérobactéries (e.g., Salmonella) et autres bactéries opportunistes (e.g., Pseudomonas). La problématique d’antibiorésistance en santé publique est peu affectée par les pratiques de protection des cultures conventionnelles. Des pratiques relevant de la substitution aux intrants de synthèse (variétés résistantes aux attaques de rongeurs ou à la colonisation par des entérobactéries ; pesticides minéraux; solarisation) peuvent se traduire par une réduction plus importante du risque sanitaire que certaines pratiques relevant de la reconception des agroécosystèmes (push-pull ; intégration agriculture-élevage). Toutefois, vu ses effets vertueux en termes de réduction des pollutions, conservation de la biodiversité et résilience climatique, la PAEC, basée sur la reconception, contribue, à des échelles spatiotemporelles supérieures, à la réduction du risque sanitaire lié aux infections bactériennes. Les impacts des pratiques de protection des cultures, basées sur l’amélioration de l’efficience des pratiques conventionnelles, sur la substitution ou sur la reconception, sur les risques d’infection bactérienne en santé publique et vétérinaire, sont sensiblement différents de ceux observés avec les risques zoonotiques viraux. Des recherches sont encore nécessaires pour concilier, dans une perspective « Une seule santé », les trois types de pratiques, afin de réduire les risques sanitaires liés aux maladies infectieuses autant à bactéries qu’à virus, parasites (protozoaires et vers) ou champignons.

Recent viral zoonotic epidemics have been attributed partially to the negative impact of human activities on ecosystem biodiversity. Agricultural activities, particularly conventional crop protection (CP) practices, are a major threat to global biodiversity, ecosystem health and human health. Here we review interactions between CP practices and viral zoonoses (VZs), the first time this has been done. It should be noted that a) VZs stand at the interface between human, animal and ecosystem health; b) some VZs involve arthropod vectors that are affected by CP practices; and c) some crop pests, or their natural enemies are vertebrate reservoirs/carriers of certain VZs, and their contact with humans or domestic animals is affected by CP practices. Our review encompasses examples highlighting interactions between VZs and CP practices, both efficiency improvement-based (i.e. conventional with agrochemical insecticides and rodenticides), substitution-based (i.e. mainly with physical/mechanical or biopesticidal pest control), and redesign-based (i.e. mainly with conservation biological pest control, including some forms of crop-livestock integration). These CP practices mainly target arthropod and vertebrate pests. They also target, to a lesser extent, weeds and plant pathogens. Conventional and some physical/mechanical control methods and some forms of biopesticidal and crop-livestock integration practices were found to have mixed outcomes in terms of VZ risk management. Conversely, practices based on biological control by habitat conservation of arthropod or vertebrate natural enemies, falling within the Agroecological Crop Protection (ACP) framework, result in VZ prevention at various scales (local to global, and short-term to long-term). ACP addresses major global challenges including climate resilience, biodiversity conservation and animal welfare, and helps integrate plant health within the extended “One Health” concept.

The health benefits of fruit and vegetable consumption can be jeopardized by pesticide residues, especially in developing countries, due to their misuse. While vegetable growing under cover is growing in popularity worldwide as an effective technique for improving yields while reducing pesticide use, these protected cultivation techniques often remain underutilized by smallholder farmers. A cost-benefit analysis was conducted with fifty smallholder farmers in northern Tanzania over two seasons to compare the profitability of growing cabbage in open plots and under inexpensive low tunnels. Although all farmers significantly improved their yields under nets over the two seasons (9.85, as opposed to 6.80 kg m−2 and 10.09, as opposed to 8.63 kg m−2, in each season respectively) and reduced their pesticide use (by 3.5 and 2.8 times), the large variations in market prices observed between seasons called into question the profitability of this cultivation technique. With the conducive market conditions of the second season, it would have taken 5.3 crops cycle on average, i.e. less than 2 years, to recoup the investment costs of low tunnels, whereas with the poor market conditions observed in the first season, the investment in tunnels compounded the negative economic results obtained from growing cabbages in an open field. Consequently, our results showed that using low tunnels could be a suitable alternative for reducing pesticide use, but this technique was not economically viable with the existing marketing systems used by the farmers. For this technique to be adopted, further work is needed to identify changes in vegetable marketing systems that would promote the use of cultivation techniques that reduce pesticide use.

Reducing the environmental impact of plant pest control practices is a current issue and one strategy is the development of new eco-friendly biocontrol molecules as an alternative to the intensive use of pesticides. The CowPea Mosaic Virus (CPMV) is a phytopathogenic agent which can be modified to produce empty virus-like particles (eCPMV), i.e. devoid of RNA harbouring selected peptides on their outer surface. The combination of naturally occurring peptides, like ITPs or AMPs – able to induce plant defence or displaying antimicrobial activity respectively – together with the structural stability of eCPMV would give rise to the development of new nano-compounds for plant disease management. In the frame of the NANOBIOAGRI project, five diverse functionalised nanoparticles were previously designed and expressed in N. benthamiana plants by agro-infiltration; La réduction de l’impact environnemental des méthodes de lutte contre les agents phytopathogènes est un enjeu actuel et une stratégie envisageable consiste à développer de nouvelles molécules de biocontrôle comme alternative à l’usage intensif de pesticides. Le CowPea Mosaic Virus (CPMV) est un agent phytopathogène modifiable pour l’obtention de capsides vides (eCPMV) – dépourvues d’ARN – et l’exposition de peptides à leur surface. L’association de l’activité de peptides naturels, d’induction des mécanismes de défense des plantes (ITPs) ou antimicrobienne (AMPs) à la stabilité structurale d’eCPMV permet de produire de nouveaux nano-composés biodégradables pour la protection des plantes. Dans le cadre du projet NANOBIOAGRI, cinq types de particules fonctionnalisées avec AMP ou ITP ont été conçues et exprimées chez N. benthamiana par agro-infiltration

This chapter focuses on protected cultivation (PC), defined as the protection of crops against adverse climatic and biological factors using physical means. As natural resources become scarcer, farm inputs become more expensive and consumers more attentive to the sanitary and nutritious aspects of food produced, PC has become one promising yet improvable way to address these challenges. As the global demand for high value crops, such as vegetables, increases, PC appears an opportunity for farmers to increase their income, improve their working conditions and secure their production, thereby attracting youth to enter the crucial but aging farming sector. In Sub-Saharan Africa, farmers constantly face the threat of losing their crops due to pests, diseases or harsh climatic conditions, with no insurance to cover their loss. A case study, comparing PC of tomatoes in Benin and Tanzania, showed that PC is profitable despite high initial investments, provided there is a market for high quality produce. Favourable policies, farmers' training and agronomic research are prerequisites to the adoption and development of PC technologies and techniques in Sub-Saharan Africa. PC has the potential to enhance bioeconomy in the region and at the same time achieve some of the SDGs.

SummaryAlthough several studies have underlined the advantages of using insect-proof nets to improve yields while reducing the use of pesticides, one obstacle to the diffusion of this technique in tropical conditions is the associated increase in temperature in the tunnel. The aim of this work was to assess the interest of combining the physical protection provided by nets against insect pests with the beneficial impacts of using shade nets to grow cabbages. A two-season experiment was set up to compare temperature conditions, insect pest populations, yields, and the quality of cabbage crops grown in the open field and in low tunnels covered with nets providing different degrees of shading, 17.2% by white and 50.1% by silver nets. During the day, the temperature under the white and silver nets was 10.4 °C and 6.3 °C higher, respectively, than in the open field in the first season, and 6.5 °C and 5.9 °C higher in the second season. Both insect-proof nets significantly reduced insect pest populations and hence the need for insecticide treatments. The white nets increased marketable yield by 45.4% in the first season and by 16.4% in the second compared to yields in the open field, whereas silver nets reduced yield by 18.6% and 15.0%, respectively. The reduction in yield under silver nets was attributed to excessive shading that prevented the light requirements of cabbage crops from being fulfilled. Economic analysis raised some concerns about the profitability of the use of netting to grow cabbage due to investment costs and the lack of premium prices for vegetables produced with fewer pesticides in local markets.

Au Mali, l’efficacité de la lutte chimique systématique (traitements calendaires) contre les ravageurs du cotonnier est régulièrement remise en cause. Des alternatives à cette lutte, comme la lutte étagée ciblée, l’intervention sur seuil et la culture biologique, visant toutes à réduire les quantités de pesticides utilisées, sont diffusées ; d’autres sont testées chez les producteurs, comme l’écimage du cotonnier. Cette étude analyse la perception de la technique de l’écimage du cotonnier par des producteurs. Elle a été conduite dans quatre villages de la zone cotonnière, à l’aide de focus groups d’hommes et de femmes et d’entretiens avec 40 producteurs ayant pratiqué ou non l’écimage. Les avantages de l’écimage identifiés par la majorité des producteurs interrogés sont : (i) une technique manuelle facile à mettre en œuvre, (ii) la diminution des risques de chute d’organes fructifères, (iii) la réduction de la hauteur des plants, s’étalant davantage (iv) une amélioration du rendement et (v) la réduction de la population des ravageurs et donc de l’utilisation des pesticides, ayant des effets positifs sur la santé humaine et l’environnement, et diminuant les coûts de production. Ses principales contraintes sont le besoin supplémentaire de main-d’œuvre et son coût par rapport à la culture de coton non écimé. Des partenariats avec les sociétés cotonnières et les organisations paysannes et la formation de leurs agents à l’écimage sont indispensables pour une adoption de cette technique à une plus large échelle.

Avant d'entamer le dossier, voici un petit glossaire à l'usage des gestionnaires de la résistance aux produits phytopharmaceutiques.La résistance aux PPP est un phénomène souvent complexe, faisant appel à des notions de biochimie, génétique, sciences de l’évolution. De ce fait, pour apprécier au mieux les articles de ce dossier, il apparaît utile d’avoir sous la main un mémento donnant une définition scientifique des termes les plus courants.

The objective was to further the understanding of the complex interaction between the soil microbiota, a plant pathogen and the host plant. The effect of different soil microbial diversities on the level of disease and on the transcriptomes of the interacting pathogen and host plant was studied., Summary The contribution of surrounding plant microbiota to disease development has led to the ‘pathobiome’ concept, which represents the interaction between the pathogen, the host plant and the associated biotic microbial community, resulting or not in plant disease. The aim herein is to understand how the soil microbial environment may influence the functions of a pathogen and its pathogenesis, and the molecular response of the plant to the infection, with a dual‐RNAseq transcriptomics approach. We address this question using Brassica napus and Plasmodiophora brassicae, the pathogen responsible for clubroot. A time‐course experiment was conducted to study interactions between P. brassicae, two B. napus genotypes and three soils harbouring high, medium or low microbiota diversities and levels of richness. The soil microbial diversity levels had an impact on disease development (symptom levels and pathogen quantity). The P. brassicae and B. napus transcriptional patterns were modulated by these microbial diversities, these modulations being dependent on the host genotype plant and the kinetic time. The functional analysis of gene expressions allowed the identification of pathogen and plant host functions potentially involved in the change of plant disease level, such as pathogenicity‐related genes (NUDIX effector) in P. brassicae and plant defence‐related genes (glucosinolate metabolism) in B. napus.

Pests, diseases and weeds are major constraints to cropping system intensification in sub-Saharan Africa. Four major intensification systems to achieve sustainable agriculture have been identified: conventional with high input, organic, agroecological and eco-technical 'sustainable intensive'. Those systems display advanced crop protection. Here we review the performance of those systems in the context of sub-Saharan Africa. The major points are: (1) Unlike economies of Europe and North America following World War 2, and of Asia and Latin America following the Green Revolution, sub-Saharan Africa rural economies were not transformed by conventional intensification involving cultivation of cash crops for export and over-reliance on pesticides. Genetically modified crops were used only to a limited extent at the regional level. (2) Most staple food-based cropping systems are de facto organic due to the unavailability of synthetic inputs. Organic systems are thus developing for some export cash crop sectors, with synthetic pesticides are being substituted by non-chemical pesticides. (3) Agroecological crop protection focuses on biological pest regulations such as the replacement of chemical inputs, thus implying the re-design of cropping systems. (4) For crop protection, the eco-technical pathway, which is based on principles of integrated pest management and ecological intensification, is more flexible and pragmatic than the other systems. In this review we compare the different systems, notably their contribution to six ecosystem services connected with crop protection issues: biomass production, pest and disease regulation, maintenance of water quality, biodiversity conservation, pollination and climate change mitigation. We then identify research needs in the context of food security, urbanization, trade globalization and climate change.