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Besset-Manzoni, Yoann. "Améliorer les principes de sélection de nouveaux agents bactériens de biocontrôle contre la fusariose du blé". Thesis, Lyon, 2018. http://www.theses.fr/2018LYSE1124/document.
To combat pests of crops (herbivores and pathogens) new pathways have been explored, in particular biological control. Used the nature and its organisms to regulate the populations of pathogens, that is the goal of the biological fight also called biocontrol. Among the organisms commonly found in biocontrol are micro-organisms, be they fungi or bacteria. These microorganisms have very interesting capabilities for farmers and agronomists. Indeed, studies have shown that they are able to interact with plants to allow a better growth and health of it.Then, in this thesis, we were interested in bacteria to find alternative methods of struggle with Fusarium graminearum, a pathogen of cereals responsible for high yield losses, especially thanks to the production of mycotoxins that will make the seeds unfit for human and animal consumption.Through an original approach of keeping noninhibitory strains in vitro for in planta tests, we have been able to show the limitations of in vitro selection. Thanks to the metabolic exploration of a particularly efficient strain, we have also been able to highlight potential new antifungal molecules. Through a model strain, we explored the mechanisms of the establishment of systemic resistance in wheat induced by bacteria. And finally, we have explored the potential of bacterial combinations in wheat protection that seems to represent a real future in the world of biocontrol.The work done is in line with the needs of new resources to limit the use of pesticides, but also in a need to better understand the tripartite interactions between wheat, pathogen and beneficial bacteria
La, Broise Denis de. "Croissance et sporulation de Fusarium oxysporum en milieux liquides et solides : étude des facteurs limitants et application à la production industrielle de spores pour la protection des cultures". Compiègne, 1988. http://www.theses.fr/1988COMPD131.
Habrylo, Olivier. "Une E. S. T. (Expressed Sequence Tag) conduit à la caractérisation, chez le houblon (Humulus lupulus), de trois inhibiteurs de xyloglucanase dont l’expression est influencée par des facteurs biotiques et abiotiques". Strasbourg, 2011. http://www.theses.fr/2011STRA6143.
Phytopathogenic fungi secrete a powerful arsenal of enzymes potentially active on each polysaccharide layer of the plant cell. As a first line of defense, plant cell walls contain several inhibitors to specifically inhibit the activity of these microbial enzymes. In the present study we describe the identification and characterization of three xyloglucan-specific endoglucanase inhibitor proteins (XEGIPs) from hop (Humulus lupulus). Some evidences have been accumulated about the role of these XEGIPs in plant defense. Starting from an expressed sequence tag three genes were isolated by the rapid amplification of cDNA ends, cloned and corresponding proteins expressed in insect cells. The functions of the proteins were validated by enzymatic activity measurements were performed with xyloglucan as substrate. Inhibitor n°1 and inhibitor n°2 were shown to inhibit the hydrolytic activity of xyloglucan-specific endoglucanase from the fungi Aspergillus aculeatus and Fusarium graminearum. The investigation on target enzymes lead to production, expression and characterization of four unknown GH12 from F. Graminearum. Real-time PCR have shown variations in the spatial distribution of inhibitors and differential expression between hop cultivars. The main lines are the following : inhibitor n°1 is expressed as a result of wounding and inhibitor n°2 is inducible by F. Graminearum. Inhibitor n°3 could be have a physiological function with a positive regulation during the germination stages and in the female hop cones
Pellan, Lucile. "Décryptage des mécanismes impliqués dans le biocontrôle des champignons mycotoxinogènes des céréales". Thesis, Montpellier, 2020. http://www.theses.fr/2020MONTG036.
Deciphering the mechanisms involved in the biocontrol of mycotoxinogenic fungi of cereals.Cereals are the first factor of consumer exposure to mycotoxins, toxic secondary metabolites synthesized by particular moulds and which present a risk for human and animal health. The species Fusarium graminearum and Fusarium verticillioides are thus responsible for the production of trichothecenes and fumonisin-like mycotoxins, respectively, with a high impact especially in pre-harvest. With the decrease of pesticide use due to their toxicity, an alternative strategy to control these fungal diseases in the field may be the use of antagonistic microorganisms. Non-pathogenic, these biocontrol agents (BCAs) are able to limit the progression of Fusaria and their synthesis of mycotoxins through various biological mechanisms, however still poorly understood. In this context, the objectives of this study are to evaluate by which mechanisms three selected BCAs (Streptomyces griseoviridis, Trichoderma asperellum, Pythium oligandrum) can modulate the growth and mycotoxin production of Fusarium pathogens, in vitro and in situ. Antagonistic activities and varying levels of inhibition of growth (up to 80%) and mycotoxinogenesis (up to 90%) have been observed in vitro depending on BCAs, pathogens or culture conditions. The hypotheses are then verified and completed thanks to the development of a toolbox of tests specific to certain modes of action. Their chronology is evaluated throughout the interaction, from pathogenic spore germination to the formation of perithecia, by testing a wide variety of BCA mechanisms: synthesis of anti-germinative compounds, mycophagy, chitinolytic enzyme synthesis, emission of volatile antifungal compounds, inhibition of mycotoxin biosynthesis pathways, mycotoxin bio-transformation, spatial and nutritional competition or impact on pathogen conservation. S. griseoviridis presents nutritional competition capacities, but its main strategy is based on antibiosis, through the synthesis of numerous antifungal compounds that offsets a significant deficit in spatial colonization capacity. However, it can stimulate the mycotoxin production. T. asperellum is capable of activating a very wide range of defenses and attacks combining the synthesis of various antifungal compounds (metabolite, enzymes, VOCs), with different targets (spores, mycelium, mycotoxins), and a direct action by mycoparasitism. The efficacy of P. oligandrum is mainly due to its strong capacity to colonize the environment, with a direct action via microbial predation and reduction of perithecia formation. These in vitro performances could also be analyzed in F. graminearum in situ throughout its life cycle (from colonization of ears to survival in culture residues), and put into perspective with the different modes of action identified in each of the BCAs. The whole project has led to important advances in deciphering the mechanisms of action of BCAs and proposes ways of improvement to optimize the use and efficacy of these antagonists. Thus limit the use of chemical plant protection products, while maintaining a healthy production with low levels of mycotoxins
Legrand, Fabienne. "Gestion des communautés microbiennes telluriques pour réduire l'incidence des Fusarium toxinogènes sur céréales à pailles et développer une stratégie de lutte biologique". Thesis, Brest, 2017. http://www.theses.fr/2017BRES0080.
Fusarium Head Blight (FHB) is a devastating disease for cereals, and for wheat in particular, threatening both crop yields and quality, given the ability of Fusarium spp. to produce mycotoxins. Among the Fusarium species complex, Fusarium graminearum is the most common causal agent of the disease. The incidence of FHB in Brittany (France) can be particularly high. Indeed, the agronomic practices include cereal rotations with frequent wheat and maize crops which increase the risk of FHB. Moreover, the climate favors the pathogen development.Currently, appropriate management of the residues, on which F. graminearum grows saprophytically, and the use of fungicide treatments at flowering constitute the two main ways to manage FHB. However, these strategies do not always guaranty an appropriate crop protection. The low and variable efficacy of these methods, combined to the socio-economic pressures, urge to find effective and sustainable alternatives. In this context, the first objective of this work was to develop, evaluate and optimize a biocontrol strategy aiming to reduce F. graminearum primary inoculum in soils, and thus reduce FHB risk for the crops, using both laboratory and field experiments. Although the biocontrol product was able to limit the pathogen growth in autcolaved soils, its efficacy was reduced when taking the interactions with the soil microbiota into account. The diversity and the structure of soil microbial communities were then studied for 31 agricultural fields using a metabarcoding approach in order to highlight the influence of climatic conditions, agronomic practices and soil physicochemical factors. Metabarcoding analysis revealed the importance of diversity and abundance of the soil microbial communities to reduce F. graminearum primary inoculum. This microbiota was also found to be influenced by agronomic practices and physico-chemical factors. Finally, the abundance of specific bacterial genera was related to the reduction of F. graminearum primary inoculum. Outcomes of this work highlight the importance of the soil biological activity and suggest that a manipulation of the soil microbial communities might lead to a better FHB management
Neched, Hassiba. "Étude comparative des traitements de semences sans fongicide chez les céréales à l'aide de l'ozone et de l'oxygène pur". Master's thesis, Université Laval, 2015. http://hdl.handle.net/20.500.11794/25888.
Seedling blight and root rot are part of cereal diseases of field crops in Quebec. They are caused by two pathogens, Fusarium graminearum and Bipolaris sorokiniana, which contaminate the seed grain, especially wheat and barley, which causes both decreased, lift and lower performance. Organic farmers are trying to find a seed without fungicide treatment to fight against these fungi, which are harmful to cereal farming. Our project has as goal to use the oxidative action of oxygen or ozone moistened to cause oxidative stress in order to reduce the impact of the two pathogens responsible for this disease, F. graminearum and B. sorokiniana, while preserving the germinability of the seeds. The dose in oxidizing agent, the flow of oxidizing gases (ozone and/or oxygen) and the time of exposure are key parameters to optimize for this oxidative treatment and germination kinetics treated cereal seed. Such treatment looked promising for the seed of wheat. It was however a little less for the seed of barley because it’s fairly rigid envelope which made difficult the penetration of ozone and oxygen. To remedy this problem, we have preliminary tests on barley using sonication ultrasonic as pre-treatment of barley oxidative pre-treatment. The results suggest that, such treatment is promising and significant in order to optimize our oxidative treatment and subsequently, reduce the causative agents of disease without harming the quality of cereal seed. This point has been addressed in our work by a preliminary test on barley, and this approach looks very promising for our future research.
Lecomte, Charline. "Fusariose du cyclamen : détection préventive du risque et contrôle biologique". Thesis, Dijon, 2016. http://www.theses.fr/2016DIJOS002/document.
Fusarium wilt of cyclamen is one of the most damaging diseases of cyclamen. The causal agent, Fusarium oxysporum f. sp. cyclaminis, is a soil-borne fungus. Losses can reach more than 50 % of the production. Several methods of control are available, but none of them offer an efficient and environmentally friendly solution. In this context, a project was developed in collaboration with the French institute of horticulture, Astredhor, which represents the producers, the INRA of Dijon, for its expertise on F. oxysporum and the company Agrene for its expertise in biological control. The project has two goals: i) design a molecular marker specific of Fusarium oxysporum f. sp. cyclaminis allowing a better management of the disease, ii) identify one or several efficient biological control agents.A collection of strains representative of the diversity of F. oxysporum f. sp. cyclaminis populations was made up with strains from international collections and isolates collected from symptomatic and asymptomatic cyclamens. A molecular study of the collection demonstrated the high genetic diversity of the forma specialis, which makes the identification of a specific molecular marker more complicated. However, a specific DNA fragment was identified by random amplified polymorphic DNA. A primer pairs was designed and a specific tool of detection was developed. Thanks to this tool, it is now possible to detect the fungus in planta by conventional and real-time PCR.Simultaneously, a broad literature analysis on the biocontrol of ornamental plant diseases caused by F. oxysporum was performed. The review emphasized that biocontrol of F. oxysporum encompassed both microbial biocontrol agents and botanicals. To avoid the laborious and time-consuming screening step, we decided to assess the antagonistic activity of seven commercial products containing bacteria, fungi or a combination of both microorganisms. Greenhouse trials were performed under conditions similar to those of the production. First trial led to the exclusion of the less efficient products. Other trials were conducted with the three remaining products. Disease reduction was obtained with one of these products although it must be validated in production.Finally, the molecular tool of detection will allow producers to insure the health status of the culture. In addition, the efficient biocontrol agent identified will prevent the disease progress for a while but more investigations are needed to obtain reliable, efficient and sustainable biocontrol agents. Proposals to improve Fusarium wilt control are discussed
Mephane, Eléonore. "Conception de cocktails issus de co-cultures de bactéries et champignons pour de nouveaux bio-fongicides". Electronic Thesis or Diss., Université de Lille (2022-....), 2022. https://pepite-depot.univ-lille.fr/ToutIDP/EDSMRE/2022/2022ULILR074.pdf.
The genus Fusarium causes plant pathologies affecting a wide variety of targets with consequences on yields and consumer health. Among them, F. graminearum and F. oxysporum have the most important economic impacts and sustainable control methods against these pathogens are currently limited. Biocontrol is an alternative to synthetic pesticides. However, it is difficult to fully exploit the potential that exists in nature. One way to discover new molecules of interest is co-culture. Involving two or more populations of cells, it recreates interactions that do not exist in monocultures. The aim of this thesis project was to bring together bacteria and fungi with known activities, and thus to discover associations producing cocktails of antifungal molecules to fight against phytopathogens.The project started with the rational selection of microorganisms with antifungal activity reported in the literature: five bacteria (Bacillus subtilis, Pseudomonas syringae, Dietzia sp., Streptomyces coelicolor, Streptomyces sp.) and five fungi (Pseudozyma aphidis, Trichoderma harzianum, Aspergillus oryzae, Cladosporium cladosporioides, and F. oxysporum) were chosen. Subsequently, culture conditions (medium, temperature) adequate to perform co-cultures and allow the growth of both partners involved were defined and three media were chosen: two rich media (LB, NB) and one minimal medium (GMM).After this selection, tests in a microbioreactor (BioLector) were carried out: these involved the ten selected microorganisms in monocultures and twenty-five co-cultures in the three media conditions. A screening of the antifungal activity of the generated culture supernatants was performed against an environmental strain of F. oxysporum and S. cerevisiae. Thirteen out of twenty-five co-cultures showed activity against at least one of the two targets. After these tests, the selection of co-cultures of interest was reduced from twenty-five to ten. These co-cultures were grown in 50 mL volumes in LB and NB media that showed the best activity under the chosen conditions, and their supernatants tested for antifungal activity. These tests allowed to refine the choice and to focus on six couples: P. syringae + A. oryzae, Streptomyces sp. + A. oryzae, P. syringae + F. oxysporum, P. syringae + P. aphidis, Dietzia sp. + T. harzianum, Streptomyces sp. + C. cladosporioides. These six couples were subjected to a series of cultures and their supernatants tested on agar plates and in liquid media (against F. oxysporum). Three co-cultures showed a more pronounced activity, especially against F. oxysporum and stood out from the monocultures: Streptomyces sp. + A. oryzae, Streptomyces sp. + C. cladosporioides and P. syringae + A. oryzae. The Streptomyces sp. + C. cladosporioides co-culture showed synergistic activity in inhibiting or slowing the growth of F. oxysporum compared to monocultures alone, while P. syringae + A. oryzae and Streptomyces sp. + A. oryzae showed additive activity against F. oxysporum.For the three selected couples, the molecules produced and secreted were studied by proteomics and metabolomics. Whatever the co-culture considered, it induces the activation of genes that remained silent in monoculture. Thus, we can observe the expression of a very high proportion of proteins or secondary metabolites (38 to 50%) exclusively present in the supernatants of co-cultures. Moreover, among the molecules secreted de novo in the co-cultures, some known for their antimicrobial or even antifungal activities could be identified for the three couples that were studied
Roy, Geneviève. "Développement d'un agent de lutte biologique contre Heterobasidion annosum". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ43109.pdf.
Chen, Xin. "Efficacité de Harmonia axyridis (coleoptera : coccinellidae) comme agent de lutte biologique contre Myzus persicae (homoptera : aphididae)". Avignon, 1997. http://www.theses.fr/1997AVIG0005.
Kirk, Alan Alastair. "Utilisation de la lutte biologique en écologie appliquée : contrôle d'insectes et de mauvaises herbes dans des situations de déséquilibre". Aix-Marseille 3, 1992. http://www.theses.fr/1992AIX30081.
Alaphilippe, Aude. "Effets secondaires de l'utilisation d'un agent de lutte biologique : rôle des metabolites primaires de surfaces des feuilles dans l'interaction entre l'agent de lutte biologique et Cydia pomonella L". Paris, AgroParisTech, 2008. http://www.theses.fr/2008AGPT0039.
Koyyappurath, Sayuj. "Étude histo-pathologique et moléculaire de la résistance des vanilliers (Vanilla spp., Orchidaceae) à Fusarium oxysporum f.sp. radicis-vanillae, agent de la pourriture des racines et des tiges". Thesis, La Réunion, 2015. http://www.theses.fr/2015LARE0008/document.
Vanilla is a high value cash crop that is continuously demanded by the agri-food and cosmetics industries for its incomparable flavor. Most of vanilla comes from the cured fruits of V. planifolia G. Jackson, a hemi-epiphytic climbing orchid cultivated in the humid tropics. In all the countries were it is cultivated, the vanilla vines suffer from a root and stem rot (RSR) caused by the soil borne fungus Fusarium oxysporum which dramatically reduces plant production and the durability of plantations. No efficient control method is currently available for this disease. Sources of genetic resistance to RSR exist in few vanilla relatives, but so far no commercial resistant variety has been produced. The purpose of this thesis was to better describe the diversity and histopathology of the causal agent of RSR and to evaluate the potential sources of genetic resistance that could be used in breeding programs. In a first step, a collection of 377 single-spored Fusarium isolates recovered from rotten roots and stems during surveys conducted in 52 vanilla plots from Reunion Island, Madagascar and French Polynesia were characterised. Representative subsets of isolates were genotyped using the Elongation Factor 1α and Intergenic Spacer gene sequences. Their pathogenicity was assayed by root dip inoculation on the susceptible V. planifolia accession pla0001. Results showed that F. oxysporum was the principal species responsible for the disease in the field, although a few F. solani isolates showing slight pathogenicity were also isolated. Fusarium oxysporum isolates were highly polyphyletic regardless of geographic origin or pathogenicity. Remarkably, their pathogenicity varied in gradient between non- pathogenic (about 42% of isolates) to highly pathogenic (14%). In a second step, 254 vanilla accessions comprising 18 species and six types of hybrids were assessed for resistance to RSR in the field (natural inoculum) and in the lab (in-vitro plants inoculated with Fo072). The strong resistance to RSR of all V. pompona accessions and hybrids of V. planifolia X V. pompona or V. phaeantha, were confirmed, and novel sources of resistance to RSR were added including, V. bahiana, V. costariciensis and V. crenulata. Most of the V. planifolia accessions, V. ×tahitensis and V. odorata were susceptible to RSR. However, three inbreeds of V. planifolia showed a high level of resistance to Forv. To our knowledge this is the first report of resistance to RSR in V. planifolia accessions. For the 26 accessions evaluated in both conditions, a strong correlation was observed between long term (9 years) evaluation in the field and ratings on in-vitro plants at 15dpi. Thirdly, we monitored by wide field and multiphoton microscopy the root infection process and the responses of one susceptible accession (V. planifolia pla0001) and two resistant accessions (V. planifolia pla0020 and V. pompona pom0018) to challenge inoculation with the severe isolate Fo072. In the compatible interaction (Fo072 – pla0001) invasion started from penetration of hyphae emitted from germinated conidia in the hairy region of root rapidly colonizing the cortex but never expanded to the vascular bundles up to the 9th dpi. It was therefore suggested to prefix the forma specialis name of the causal agent of RSR with radicis to point out its non-vascular pathogenicity in vanilla. In the two incompatible interactions, the important role played by hypodermis cells for impeding the invasion of the cortex by Fo072 was demonstrated by specific staining and spectral analysis of lignin precursors. Both constitutive and pathogen induced defense mechanism were described in pla0020 and pom0018. The mechanisms included the deposition of lignin in the hypodermal cell wall, entrapment of hyphae in specific hypodemal cells and polyphenolics secretion in intercellular spaces. Further, a de novo transcriptome analysis was experimentedon 8 pooled samples
Benmoussa-Haichour, Dalila. "Relations termites-nématodes entomopathogènes : applications à la lutte biologique". Paris 12, 1999. http://www.theses.fr/1999PA120039.
Pelat, Thibaut. "Obtention et ingénierie d'anticorps recombinants thérapeutiques et/ou prophylactiques dirigés contre les agents du risque biologique provoqué". Montpellier 2, 2009. http://www.theses.fr/2009MON20093.
Recombinant antibodies isolated from non-human primates represent very promising medical countermeasures against bioweapons. The advantages and methodological aspects of this approach have been described. An scFv, neutralizing the lethal toxin of Bacillus anthracis (2LF: KD= 1. 02 nM) and directed against the “lethal factor” subunit was isolated from a phage-displayed immune library, and characterised. Another scFv, 43RCA, neutralizing ricin, was obtained with the same methodology and tested (in particular: KD= 40 pM). This approach may also be used beyond bioweapons, as an scFv directed toward Aspergillus fumigatus was also isolated (MS130i-IIIC3: KD= 0,96 nM). On-line sequence analysis with IMGT tools allowed to show the high degree of similarity between these scFvs and their human counterparts. Antibody fragments were engineered, including an in vitro affinity maturation (KD initial = 3. 4 nM; KD final = 0. 18 nM). Utilizing IMGT standardisation and on-line tools, a “germline humanization” - utilizing FR derived from IgM, encountered by every Human, as opposed to IgG FR - was realized in order to ensure an optimal tolerance for one of our scFvs. A primatized IgG was tested in vivo and showed therapeutic and prophylactic capacities
Bourarach, Khadija. "Lutte biologique contre les Noctuelles du Maroc : relations hôtes parasitoïdes et biologie de Trichogramma bourarachae Pintureau et Babault (Hym. Trichogrammatidae)". Paris 6, 1990. http://www.theses.fr/1990PA066424.
Gigon, Vincent. "Optimisation de la lutte biologique contre l'acarien Tetranychus urticae en culture de tomate". Thesis, Rennes, Agrocampus Ouest, 2016. http://www.theses.fr/2016NSARA080/document.
To suppress pest populations to such levels that damage to thecrop is minimized, multiple biological control agents are oftenintroduced in greenhouses. However, negative interactionsamong them, such as intraguild predation, might appear thatcan decrease the effi ciency of the plant protection strategy.Furthermore, plant direct (physical or chemical) defenseshave a negative impact on the pests but might also have animpact on the natural enemies. Therefore, the question iswhether it is possible to limit the negative interactions amongbiological control agents and the infl uence of the crop on thebehavior and development of the natural enemies. To optimizebiological control of Tetranychus urticae, a very problematicpest in tomato greenhouses, the effi ciency of the predatorymite Phytoseiulus macropilis was tested on two cultivars withdifferent trichome densities and concentrations of secondarycompounds, in presence or absence of Macrolophus pygmaeus,a mirid often used to regulate whitefl y populations.During two years, under greenhouse conditions, P. macropiliswell-controlled the population of T. urticae. There was no evidenceof intraguild predation between the two predators, butin the presence of M. pygmaeus, P. macropilis tended to havea more clumped spatial distribution. However, in microcosms,M. pygmaeus fed on P. macropilis eggs. Moreover, P. macropilislaid signifi cantly more eggs on the tomato cultivar with thehighest density of non-glandular trichomes, but this resultwas only observed in microcosms. The different dynami
Avis, Tyler. "Spécificité et génétique de Pseudozyma flocculosa, agent de lutte biologique contre le blanc". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ60760.pdf.
Sy, Abdoul Aziz. "Lutte biologique contre la pyriculariose du riz (Pyricularia oryzae cav. ) : stratégie et applications". Toulouse, INPT, 1987. http://www.theses.fr/1987INPT025A.
Masih, Emmanuel Isaac. "Lutte biologique contre Botrytis cinerea, agent de la pourriture grise de la vigne". Dijon, 2005. http://www.theses.fr/2005DIJOS049.
Grey mould disease caused by Botrytis cinerea is one of the most important diseases of the grapevine. The intensive use of the chemical products to irradicate the grey mould disease resulted in environmental pollution, and appearence of the resistant varieties of the pathogen. This study of research showed the antagonism between the B. Cinerea and the bacteria and yeast, and the different isolates of the genus Pythium. The selected antagonistic microbes to Botrytis cinerea, were identified using morphological as well as genetical tools and the study of their mode of action was initiated. The enzymatic activities and the elicitation capability were also studied. These activities have a direct relationship with the trigerring of the natural defence mechanisms of the grapevine. In the following context, the use of the selected micorobes as biocontrol agents can be undertaken for the effective control of Botrytis cinerea
Sy, Abdoul Aziz. "Lutte biologique contre la pyriculariose du riz (Pyricularia oryzae Cav.) stratégie et applications /". Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb37611000t.
Tirilly, Yves. "L'hyperparasitisme du Hansfordia pulvinata envers le Fulvia fulva et les perspectives de lutte intégrée contre la cladosporiose de la tomate". Brest, 1987. http://www.theses.fr/1987BRES2036.
Leroy, Valentin. "Décontamination des grains de blé et d'orge par traitements aux ultrasons". Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27917.
Demeule, Elizabeth. "Effet répressif de Bacillus subtilis et de Bacillus pumilus envers Rhizoctonia solani sur tomate et concombre de serre". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/66758.
Rondeau, Sabrina. "Lutte biologique contre le parasite apicole Varroa destructor à l'aide de l'acarien prédateur Stratiolaelaps scimitus". Master's thesis, Université Laval, 2018. http://hdl.handle.net/20.500.11794/36553.
En se nourrissant de l’hémolymphe et des corps gras de l’abeille domestique (Apis mellifera L.) et en lui transmettant de nombreux virus, l’acarien parasite Varroa destructor (Acari : varroidae) constitue la principale cause de mortalité des colonies d’abeilles. Les traitements chimiques présentement utilisés pour lutter contre le varroa comportent plusieurs désavantages, tels que le développement de résistance de l’acarien aux acaricides de synthèse et une toxicité variable pour l’abeille. Via l’utilisation d’ennemis naturels du parasite, la lutte biologique pourrait représenter une avenue durable et sécuritaire pour la santé des colonies. L’objectif principal de cette étude était de tester l’efficacité de l’acarien prédateur Stratiolaelaps scimitus (Acari : Lealapidae) comme moyen de lutte biologique contre le varroa. Une étude du comportement alimentaire du prédateur a d’abord été réalisée afin d’évaluer le risque de prédation du couvain d’abeille (oeufs, larves et pupes) par S. scimitus, ainsi que son potentiel de prédation envers les varroas phorétiques (se trouvant sur le corps des abeilles adultes). Des essais in vivo ont ensuite permis d’évaluer l’efficacité de deux doses d’introduction du prédateur (6 250 ou 12 500 acariens/colonie) à contrôler les populations de varroa dans les colonies d’abeilles en septembre (en comparaison avec l’acaricide biologique Thymovar®) et en novembre (en comparaison avec l’acide oxalique). Bien que S. scimitus soit capable de s’alimenter sur tous les stades de développement de l’abeille en laboratoire, nos résultats suggèrent que le prédateur ne représente pas une menace pour le couvain lorsqu’il est introduit dans la colonie. Par contre, nos résultats démontrent que le prédateur n’est pas en mesure de contrôler les populations de varroas dans les colonies d’abeilles sous les conditions testées, c’est-à-dire lorsqu’il est introduit à l’automne selon la dose actuellement recommandée par certains distributeurs. Cette inefficacité est probablement liée à l’incapacité du prédateur à s’attaquer aux varroas phorétiques.
By feeding on the hemolymph and fat bodies of the honey bee (Apis mellifera L.) and transmitting many viruses, the parasitic mite Varroa destructor (Acari: varroidae) is considered as the main cause of honey bee colony losses. The use of chemicals in varroa control shows many disadvantages, such as the development of mite resistance to synthetic acaricides and a variable toxicity for bees. Through the use of natural enemies, the biological control of varroa mites could represent a sustainable and safe avenue for colony health. The main objective of this study was to test the effectiveness of the predatory mite Stratiolaelaps scimitus (Acari: Lealapidae) as a means of biological control against varroa mites. A study of the predator’s feeding behaviour was first performed to evaluate the risk of predation of bee brood (eggs, larvae and pupae) by S. scimitus, as well as its predation potential upon phoretic varroa mites (varroa parasitizing adult bees). In vivo trials were then carried out to evaluate the effectiveness of two predator introduction rates (6,250 or 12,500 mites / colony) to control varroa populations in honey bee colonies in September (compared to the organic acaricide Thymovar®) and in November (compared to oxalic acid). Although S. scimitus is able to feed on all bee developmental stages in the laboratory, our results suggest that the predator does not pose a threat to the bee brood when introduced into the colony. On the other hand, our results demonstrate that the predator is not able to control varroa populations in bee colonies under the tested conditions, that is, when it is introduced in fall according to the rate currently recommended by some biocontrol suppliers. This ineffectiveness is probably related to the inability of the predator to attack phoretic varroa mites.
Desgranges, Catherine. "Contribution à la lutte contre la pyrale du maïs : optimisation d'un procédé de production par fermentation en milieu solide, d'un champignon entomopathogène, Beauveria bassiana". Compiègne, 1991. http://www.theses.fr/1991COMPD428.
Gravel, Valérie. "Lutte contre Pythium ultimum chez la tomate de serre : une approche microbienne". Thesis, Université Laval, 2007. http://www.theses.ulaval.ca/2007/24523/24523.pdf.
Bouchard-Rochette, Mathieu, i Mathieu Bouchard-Rochette. "Bacillus pumilus et Bacillus subtilis pour lutter contre la pourriture grise chez la tomate et le concombre de serre". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38128.
Cette étude s’inscrit dans le cadre d’un programme de recherche destiné à évaluer le potentiel d’utilisation en horticulture des bactéries Bacillus pumilus souche PTB180 et Bacillus subtilis souche PTB185. Elle avait pour objectifs (1) d’évaluer in vitro l’activité antagoniste contre Botrytis cinerea des souches PTB180 et PTB185, (2) d’estimer leur capacité à survivre sur la phyllosphère de la tomate et du concombre et 3) d’évaluer leur effet sur le développement de la pourriture grise (B. cinerea) sur des plants de tomate et de concombre cultivés en serre. L'activité antagoniste de PTB180 et PTB185 a été évaluée en boîtes de Pétri sur géloses, sur tissus foliaires de tomate et de concombre et sur fruits de tomate. Les deux souches ont inhibé très fortement la croissance mycélienne et la germination des spores de B. cinerea sur géloses. Sur feuilles de tomate et sur disques foliaires de concombre, PTB185 et le mélange (1:1) des deux souches ont réduit significativement (p ≤ 0,01) la croissance mycélienne de B. cinerea comparativement aux témoins. PTB180 a réprimé significativement la croissance mycélienne de B. cinerea sur les fruits de tomate. Afin d'estimer la survie de PTB180 et PTB185 sur la phyllosphère, des plants de tomate et de concombre ont été pulvérisés jusqu'à ruissellement avec une suspension (1×107 unités formatrices de colonies [UFC]/mL) de PTB180, PTB185 ou d'un mélange (1:1) des deux souches. Les populations de chaque souche ont ensuite été suivies au cours du temps sur les feuilles. Les résultats obtenus montrent que les souches survivent au moins 21 jours sur les plants de tomate et de concombre avec un taux de survie variant de 43% à 100%. De plus, pratiquement aucune variation dans les proportions de chaque souche n'a été observée au fil du temps lorsque PTB180 et PTB185 étaient appliquées en mélange. Enfin, l’application foliaire de PTB180, PTB185 et du mélange (1:1) des deux souches a permis une réduction significative de l’incidence et de la sévérité de la pourriture grise chez des plants de tomate et de concombre inoculés avec B. cinerea et cultivés en serre. Les souches PTB180 et PTB185 ont montré au cours de cette étude une forte activité antagoniste envers B. cinerea, la capacité de survivre sur la phyllosphère de plants de tomate et de concombre et de réprimer le développement de la pourriture grise chez ces derniers. Ces souches pourraient éventuellement être utilisées comme agents de lutte biologique contre la pourriture grise du concombre et de la tomate de serre.
Dianzinga, Niry Tiana. "Diversité des communautés d’arthropodes et efficacité de la lutte biologique contre les insectes ravageurs". Thesis, La Réunion, 2020. http://www.theses.fr/2020LARE0006.
Understanding of driving forces that affect diversity in herbivorous insect communities figures prominently in ecological research, and is necessary for integrated pest management, because some herbivorous insect can become crop pests. Natural enemies and environmental variables are among factors that structure herbivorous insect communities. While natural enemies regulate herbivorous insects, environmental variables affect their diversity and their spatial distribution. The main goal of this thesis was to understand effects of landscape features on diversity of herbivorous thrips communities along elevational gradients in Reunion, and to investigate effects of natural enemy diversity in biological control of pest thrips. In first study, thrips were sampled along replicated elevational gradients, and at each sampling site, landscape features and abiotic variables were estimated within buffers surrounding the site. Study has shown that the greatest diversity of thrips in Reunion is concentrated at lower elevation, although habitats situated in these localities are highly degraded. Thrips diversity was not affected by fragmentation but landscape heterogeneity and habitat amount interacted to affect positively thrips diversity.In second study, we manipulated communities composed of two pest thrips Thrips parvispinus and Frankliniella occidentalis, and two predatory mites Amblyseius swirskii and Proprioseiopis mexicanus. These communities were in cages and were established in greenhouse. Study has shown that both predators are better than one in thrips regulation. That confirms the necessity to maintain biodiversity at the upper trophic level for herbivore control. Moreover, this study revealed that despite intraguild predation, predators would have coexisted because of competition-colonization trade-off
Barbar, Aline. "Caractérisation de la farnésyl diphosphate synthase et de la géranylgéranyl diphosphate synthase chez les Lépidoptères: cibles potentielles pour la lutte bio-rationnelle contre les ravageurs". Thesis, Université Laval, 2014. http://www.theses.ulaval.ca/2014/30307/30307.pdf.
The present thesis focuses on the characterization of two lepidopteran prenyltransferases, namely farnesyl diphosphate synthase (FPPS), for which there are two paralogs, FPPS-1 and FPPS2, and geranylgeranyl diphosphate synthase (GGPPS). The main goal of this research was to identify features that are unique to the lepidopteran enzymes so as to assess their suitability as targets for bio-rational pest control. In this study, we clarified the implication of each FPPS paralog in juvenile hormone (JH) biosynthesis, based on the evaluation of their tissue distribution and kinetic properties. Transcriptional quantification and immunodetection analyses confirmed the ubiquitous expression of FPPS-1 and its high titres in Malpighian tubules, while FPPS-2 expression was confined to the corpora allata (CA). Kinetic analysis of an N-terminally truncated form of FPPS-2 revealed certain unique features to the Lepidoptera. However, a similarly truncated form of FPPS-1 was inactive in vitro. Altogether, these results suggest that FPPS-2 is the lepidopteran FPPS paralog involved in JH biosynthesis in the CA at all stages of development, while preliminary transcriptional analysis suggests that FPPS-1 could play a role in protein prenylation. Characterization of a lepidopteran GGPPS indicated that it belongs to the type III group of GGPPSs, as do the human and bovine GGPPSs. Kinetic analysis of this GGPPS and its molecular modeling pointed to alternative binding modes for its allylic substrate and product, both of which can induce enzyme inhibition. Substrate inhibition appears unique to the lepidopteran GGPPS, possibly due to structural differences that were revealed by homology modeling. Globally, the findings reported herein highlight the unique features of these enzymes in the Lepidoptera and suggest the possibility of using them as targets for the development of insecticidal inhibitors that could block JH biosynthesis and protein prenylation, thereby disrupting development, metamorphosis and reproduction in lepidopteran pests.
Tachapattaworakul, Thunwadee. "Optimisation de la culture et de la traçabilité de la culture de Trichoderma atroviride destiné à la lutte biologique". Montpellier 2, 2006. http://www.theses.fr/2006MON20076.
Ferry, Antonin. "Écologie chimique appliquée à la lutte contre Delia radicum, la mouche du chou". Rennes 1, 2007. http://www.theses.fr/2007REN1S131.
Delia radicum, the cabbage root-fly, is the principal pest of cabbage crops in Brittany, France. Using odours in Brassicaceae crops to manipulate both the fly and the behaviour of its predators/parasitoids is the aim of this PhD thesis. This work revealed the existence of a major volatile signal driving Brassicaceae-D. Radicum-control agent interactions. Using this compound allowed to attract several bio control agents and to deter the fly. However, initial agronomical studies indicated that using this odour can have adverse effects on the predatory efficiency of the bio control agents. Another experiment unravelled the role of odours in complex interactions that drive species community structure. Results obtained highlight the need to have a fine knowledge of ecosystem functioning to succeed in this approach
Bardon, Céline. "Choix d'une souche de trichogrammes (hyménoptera : trichogrammatidae) pour lutter contre Plutella xylostella L. (lepidoptera : plutellidae)". Toulouse 3, 2004. http://www.theses.fr/2004TOU30276.
Bouchard-Rochette, Mathieu. "Bacillus pumilus et Bacillus subtilis pour lutter contre la pourriture grise chez la tomate et le concombre de serre". Master's thesis, Université Laval, 2020. http://hdl.handle.net/20.500.11794/38128.
Ali-Haimoud, Djamel-Eddine. "Contribution à l'étude de la lutte biologique contre Drechslera teres (Sacc. ) Shoem. , parasite de l'orge". Toulouse, INPT, 1994. http://www.theses.fr/1994INPT007A.
Mousques, Adeline. "Mise en évidence d'une nouvelle substance antifongique produite par une souche de Pseudomonas cepacia isolée du sol : action sur Botrytis Cinerea". Bordeaux 2, 1996. http://www.theses.fr/1996BOR20446.
Hoffman, Gérard. "Contribution à l'étude des phanérogames parasites du Burkina Faso et du Mali : quelques aspects de leur écologie, biologie et techniques de lutte". Aix-Marseille 3, 1994. http://www.theses.fr/1994AIX30083.
Braham, Mohamed. "Analyse structurelle et fonctionnelle de la biocoenose de la mineuse des agrumes, phyllocnistis citrella (Lep. , gracillariidae) en Tunisie. Application à la lutte biologique contre le ravageur". Aix-Marseille 3, 2001. http://www.theses.fr/2001AIX30030.
The aim of this work is the best knowledge of the biology and ecology of the Citrus leaf miner, Phyllocnistis citrella Stainton (Lepidoptera, Gracillariidae) with the emphasis of its biological control. The population dynamic of the insect was studied on 5 different species and varieties of Citrus in 1996,1997 and 1998. The screening of the Tunisian cultivars of Citrus was undertaken including the percentage of infested leaves, the abundance of eggs, larva and nymphs and shows that all species and varieties were attacked. The location of pre-imaginal stages on the upper and under side of leaves was specified. The parameters a and b from Taylor Power model and Iwao's Patchiness line regression formula were calculated for two cultivars : Citrus sinensis cv Thomson and C. Grandis. The sequential sampling plan was used to determine the number of samples to take for the latest cultivar
Munsch, Patricia. "Lutte biologique contre la tache bactérienne du champignon de Paris au moyen de bactériophages : Spécificité et efficacité du bactériophage TO.1". Pau, 1994. http://www.theses.fr/1994PAUU3008.
Arous, Safia. "Etude du régulon sigma-54 et de son implication dans la sensibilité aux bactériocines de sous-classe IIa chez Listeria monocytogenes". Poitiers, 2004. http://www.theses.fr/2004POIT2254.
Subclass IIa bacteriocins produced by lactic acid bacteria, are peptides active against Listeria. The s54 transcriptional factor is involved in the sensitivity of Listeria monocytogenes to these peptides. Three s54 associated activators were identified in L. Monocytogenes genome, ManR, LacR and CotR. The s54 factor and ManR regulated the EIItMan synthesis, a mannose PTS permease, which is crucial in sensitivity to IIa bacteriocins. EIItMan is composed of a cytoplasmic subunit, IIABtMan, and a membrane complex IICtMan-IIDtMan. Its membrane localization led our group to suggest that it could be a receptor to antibacterial peptides. The role of s54 and EIItMan in sensitivity to IIa bacteriocins was investigated through two approaches. First, we realised a global analysis of genes regulated by s54, by the comparison of the transcriptome and proteome profiles of a s54 mutant and the wild type EGDe strain. In our conditions study, mptACD, encoding EIItMan, is the only operon shown to be directly regulated by s54. The s54 mutation has a main influence on sugars metabolism, may be due to the repression of mptACD. Second, we study the implication of EIItMan in sensitivity mechanism to IIa bacteriocins. The analysis by RT-PCR of the mptACD expression suggested a link between its level expression and the level of sensitivity of L. Monocytogenes mutants. Besides, the heterologous expression of mptACD in an insensitive species, Lactococcus lactis, led to sensitize the strains to IIa bacteriocins. We also show that only the mptC expression (encoding IICtMan) is necessary to induce sensitivity in L. Lactis. Thus, the membrane subunit, IICtMan is crucial for the sensitivity and could be the particular target of IIa bacteriocins
Agbessi, Sonya. "Caractérisation moléculaire et pouvoir antagoniste de souches de S. mélanosporofaciens, agents potentiels de lutte biologique contre des agents phytopathogènes". Sherbrooke : Université de Sherbrooke, 2002.
Bompard, Laure. "Etude théorique des conséquences démographiques et évolutives des processus s'exprimant à faible densité dans les systèmes hote-parasitoide". Paris 7, 2014. http://www.theses.fr/2014PA077085.
In low-density populations, genetic diversity is decreased and mate-finding is increasingly difficult, two phenomena that may induce extinctions if the demography is simple. During my thesis, I used mathematical modeling to investigate the impact of such phenomena on parasitoids in which population dynamics are more complex (due to the close interaction between the parasitoid and its host. The study of the fate of small parasitoid populations is particularly justified in the context of biological control, in which parasitoids are widely used and often introduced in low densities. This manuscript is built on scientific papers and organized into three parts: i) a literature synthesis; ii) the theoretical impact of mate-finding Allee effect on the demography of parasitoids and iii) the theoretical impact of Complementary Sex Determination (CSD), which induces a genetic load specific to the Hymenoptera, on the demography of parasitoids on the evolution of mate-choice to avoid the deleterious consequences of this burden at the individual level. I conclude that considering the presence of an interspecific interaction, such as the host-parasitoid interaction, is crucial to predict the consequences of Allee effects and genetic load. We show that parasitoid survival can be very sensitive to mate-finding Allee effects, depending on the host dynamics. We also show that contrary to what has been described in non parasitoid populations, CSD does not induce an extinction vortex in parasitoids, but on the contrary limits their extinction risk. This highly innovative result provides a new look at the demographic and evolutionary consequences of genetic load in interacting populations
Frey, Pascal. "Lutte biologique contre le fletrissement bacterien des solanacees a l'aide de mutants hrp#- de pseudomonas solanacearum". Paris 11, 1994. http://www.theses.fr/1994PA112337.
Gubanti, Paul. "Contribution à l'étude de l'efficacité de la coccinelle aphidiphage Coccinella septempunctata L (Col. Coccinellidae) en culture céréalière sous climat méditerranéen". Aix-Marseille 3, 1988. http://www.theses.fr/1988AIX3A001.
Kahia, Mouna. "Lutte biologique contre deux pucerons ravageurs en serre (Aphis gossypii et Aulacorthum solani) par l'utilisation des microorganismes du sol". Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/35001.
The foxglove aphid Aulacorthum solani (Kaltenbach) and the melon aphid Aphis gossypii (Glover) are among the most harmful aphids for greenhouse crops. Microbial biological control may be an effective method against these insects. The combination of different microbial agents can increase their efficiency. This work evaluates the efficacy of Beauveria bassiana ANT-03, Bacillus pumilus PTB180 and B. subtilis PTB185, used individually or in combination, to control A. gossypii and A. solani on cucumber and tomato, respectively. In the laboratory, ten L2 larvae of each aphid were placed in Petri dishes containing a tomato leaf or a cucumber leaf disc fixed in the agar plate. These larvae were sprayed with 1 mL of suspensions prepared according to the treatment (Control, B. pumilus, B. subtilis, B. bassiana, B. pumilus+ B. subtilis, B. bassiana+ B. pumilus, B bassiana+B. subtilis, B. bassiana+ B. pumilus+ B. subtilis). The same treatments used in the laboratory were applied in the greenhouse, but adult aphids were used. Laboratory and greenhouse test results revealed that by causing A. solani mortality and by affecting A. gossypii reproduction, both bacteria (B. pumilus PTB180 and B. subtilis PTB185) were able to demonstrate aphicide effect equivalent to that of the commercial product (Bioceres) containing the fungus. When used as a mixture, no additive effect between the three microorganisms studied was observed. Spore survival tests of the two bacteria and the fungus conducted in a greenhouse have shown that they retain a high level of population 106CF U/g fresh leaves up to nine days after the application when used alone or as a mixture. Thus, on plants, the two bacilli do not exhibit antifungal effect against B. bassiana ANT-03.
puceron de la digitale, puceron tacheté de la pomme de terre, puceron du melon, puceron du cotonnier
Duchet, Claire. "Evaluation du risque environnemental lié à l’utililsation des larvicides d’origine biologique dans le cadre de la lutte anti-culicides : Développement et validation expérimentale de méthodes de suivi des effets à différents niveaux d’organisation biologique chez daphnia pulex et daphnia magna". Rennes, Agrocampus Ouest, 2010. http://www.theses.fr/2010NSARB058.
This study focused on the development and use of methods for assessing the environmental risk of biolarvicides (Bacillus thuringiensis serovar israelensis — Bti and spinosad) in the context of mosquito control in coastal wetlands of two French ecoregions: Morbihan (south Brittany) and Grande Camargue (southern France). Daphnia pulex and Daphnia magna were used as model species in laboratory bioassays and as sentinel species in field studies performed in in situ microcosrns (enclosures). The scientific approach aims at determining whether the toxic effects (lethal and non lethal) that affect individuels can be detected at the population lever. Modelling with RAMAS GIS was used to simulate effects of the larvicides on population dynamics. In ail the experiments that revealed larvicide effects, spinosad always showed highly significant impacts on both D. Pulex and D. Magna, whereas no clear tendency was observed for BU. The methods that were developed allowed a proper detection and quantification of the effects of spinosad in daphnids. In addition, they demonstrated that alterations of individuel performances affected population dynamics in both species. Chitobiase activity appeared as an early waming signal of population changes through a relation between the enzyme activity and the cumulated fecundity. Population dynamics, as simulated using RAMAS GIS, confirmed the results obtained in in situ microcosms, and extinction risk of the exposed populations was estirnated. The studies conducted in microcosms also showed (i) the recovery of D. Pulex population when exposed to the lowest spinosad concentration (8 pg/L) and (ii) indirect effects of spinosad application, related to naturel environmental factors (e. G. , salinity) which might have impeded D. Magna recovery. Combination of laboratory bioassays and field microcosm studies provides a sound and reproducible methodological framework that could be used to deflne a strategy for the risk assessment of biolarvicides used for mosquito control in coastal wetlands
Gallet, Jean-Philippe. "Sélection et mode d'action de Trichoderma et de Basidiomycètes lignivores, antagonistes de l'Armillaire (Armillaria ostoyae (Romagn. ) Herink) en vue de leur utilisation comme agents de lutte biologique contre le pourridie du pin maritime". Bordeaux 2, 1994. http://www.theses.fr/1994BOR28322.
Amillaria exerts a powerful, pathogenic action against the maritime pine. Among control methods sudied, biological control seems to be appropriate for use in the forest massif of Gascony. This is the subject of the author's study. The antagonistic action of isolates of T. Harzianum on Amillaria were evaluated. The isolates demonstrating a certain efficaciousness in vitro and in situ provide only temporary protection of young pines in the contex of controlled inoculation in the nursery. The search for fungi of the order Basidiomycetes being wood-degrading and antogonistic was understaken on a forest-wide scale. Intensive collection allowed for obtaining diverse isolates. Among these the white not fungi which demonstrated considerable wood-degrading action were singled out. A method for quantifying antagonistic action in vitro was perfected then applied to the group of isolates previously selected. For the most efficacious among these, a study of their individual antagonistic action in semi-natural conditions was carried out. Four basidiomycetes Bjerkandera adusta, Gymnopilus spectabilis, Hygropsis aurantiaca and Hypholoma fasciculare are able to colonize wood rapidly under non sterile conditions. Additionally, they are capable of eliminating the amillaria inoculum present in the root. The various phenomena present in antagonistic and wood-degrading action were identified. The production of enzymes and of toxins was revealed when amillaria and the different basidiomycetes were paired in a liquid medium. The mycoparasitic action of certain isolates on the root not fungus was demonstrated. The study of enzymatic action inherent in the degradation of the wood was carried out. For B. Adusta ; G. Spectabilis, H. Fasciculare and H. Aurantiaca the lignolytic systems are lire efficacious than these of amillaria. The root bot fungus is characterized by a greater pectinase action than that of the other fungi
St-Laurent, Marianne. "Amélioration de la lutte biologique contre le tétranyque à deux points en framboisières sous grands tunnels : essais d'un supplément nutritif, de plantes-réservoirs et de brumisation". Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/29866.
High tunnels show many benefits for raspberry production, including increased yield and improved fruit quality. However, this crop management approach also provides an environment that fosters outbreaks of the two-spotted spider mite, Tetranychus urticae. Although some miticides are available, pre-harvest application intervals and pesticide resistance development can be problematic. Phytoseiid predatory mites, such as Neoseiulus fallacis, are recognized for their efficacy in controlling spider mites. However, repeated introductions often must be made during a season, resulting in significant cost. To reduce these costs and thereby make biological control more attractive to growers, we tested a food supplement for predators, a banker plant and misting. The main objective of this study was to improve the effectiveness of integrated control against spider mites while decreasing the number of predator introductions in raspberry production under high tunnels. The specific objectives were to determine the effectiveness of four integrated pest management (IPM) strategies in raspberry under high tunnels and estimate their cost ($ / ha) in comparison to conventional control (mitices only) methods. The tested approaches combined different strategies: introduction of Neoseiulus fallacis predators; addition of Sorbaria sorbifolia as a banker plant; use of a pollen-based food supplement for predators, “Nutrimite", from Biobest; and misting. Tests were conducted at two raspberry farms in the greater Quebec City (Quebec, Canada) area. Data collected by monitoring populations of both spider mites and predators show that the pollen supplement has a positive effect on the predatory ability of N. fallacis and that misting tends to reduce T. urticae densities.
Fruit, Laetitia. "Etude des facteurs d'efficacité d'un agent de lutte biologique (Ulocladium atrum) pour la protection des plaies d'effeuillage sur tomate contre Botrytis cinerea". Lyon 1, 2001. http://www.theses.fr/2001LYO10030.
David, Jean-Philippe. "Les xénobiotiques des litières végétales en décomposition, médiateurs d'une relation plante-arthropode dans les gîtes à moustiques pré-alpins : de l'écologie chimique à la lutte biologique". Université Joseph Fourier (Grenoble), 2002. http://www.theses.fr/2002GRE10177.
The vegetation surrounding subalpine mosquito breeding sites is involved in ecological segregation among aquatic detritivorous arthropods, through differential toxicity of the decomposed leaf litter. Toxic leaf litter ingested by those consumers generates deleterious effects against the midgut epithelial barrier. Purification of the toxic fraction revealed its belonging to a cell-wall insoluble fraction, associated to lignins and gradually generated in natura during the decaying process. Biochemical and molecular data demonstrated the involvement of detoxifying enzymes in the resistance of the tolerant fauna against these xenobiotics. Population genetic studies suggested that the adaptation of this detritivorous fauna to the leaf litter toxic compounds is a recent and labile trait. Besides its interest in evolutive biology, this investigation suggests a new integrated larvicidal strategy based upon natural water-insoluble dietary phytochemicals