Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    We will mail you new results for this query: keywords==beauveria bassiana
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A multidisciplinary approach to study virulence of the entomopathogenic fungus Beauveria bassiana towards malaria mosquitoes
Valero Jimenez, C.A. - \ 2016
Wageningen University. Promotor(en): Bas Zwaan; Willem Takken, co-promotor(en): Sander Koenraadt; Jan van Kan. - Wageningen : Wageningen University - ISBN 9789462578548 - 131 p.
beauveria bassiana - entomogenous fungi - virulence - vector control - mosquito-borne diseases - malaria - anopheles - culicidae - entomopathogene schimmels - virulentie - vectorbestrijding - ziekten overgebracht door muskieten

Although globally malaria mortality rates have fallen by 48% between 2000 and 2015, malaria is still killing an estimated 438,000 people each year. An effective way to alleviate the burden of malaria is to control its vector (malaria mosquitoes) using insecticides. This can be achieved either with insecticide-treated bed nets (ITNs) or through indoor residual spraying of insecticides (IRS). However, because of rapidly expanding insecticide resistance, there is a need to find alternatives to control the mosquitoes. Entomopathogenic fungi (EPF) could constitute an effective biological control tool, as is able to reduce malaria transmission under laboratory and field conditions. However, fundamental knowledge on the mechanisms and regulation of the infection process of the fungus, as well as insights into the defensive responses of the host insect to EPF, is limited. Therefore, the main goal of this thesis was to study virulence of the entomopathogenic fungus B. bassiana towards malaria mosquitoes using a multidisciplinary approach.

Chapter 2 provides an overview of existing knowledge of genes influencing virulence in EPF, with a special focus on B. bassiana. The infection cycle and virulence mechanisms are discussed, and put in a framework of novel strategies and experimental methods that are needed to better understand virulence and improve the usage of EPF as a biocontrol agent.

The study of natural variation in fungal virulence is a first step towards understanding the genetic mechanisms involved, because it reveals the extent of variation in the different components of virulence and their overall role. Chapter 3 describes the natural variation in virulence for 29 B. bassiana isolates that were tested on malaria mosquitoes. Furthermore, the phenotypic characteristics of the fungal isolates such as sporulation, spore size and growth were evaluated and their relationship with virulence analysed.

Based on the ample natural variation observed in fungal virulence, in Chapter 4, a comparative genomics analysis was performed on five selected isolates of contrasting virulence. In order to understand mechanisms underlying contrasting virulence, a comparison on gene gain/loss, single nucleotide polymorphisms (SNPs), secreted proteins, and secondary metabolites was performed. Insight is provided to the magnitude of the complexity of a trait such as virulence and suggests candidate genes that can be further studied using a functional analysis approach.

Chapter 5 focuses on an experimental evolution approach in which B. bassiana was solely using insects as a nutritional source for ten consecutive passages through malaria mosquitoes. Two isolates of B. bassiana that differed in virulence were compared to their respective ancestors, and they were assayed in virulence, fungal outgrowth, mycelial growth rate (MGR), and sporulation. Passage of the entomopathogenic fungi B. bassiana through the insect host resulted in an altered capacity to grow on different substrates while maintaining the ability to kill insects.

Chapter 6 presents a discussion on the main findings of this thesis and describes future perspectives to study virulence of the entomopathogenic fungi Beauveria bassiana in the context of biological control of malaria mosquitoes.

Cotton in Benin: governance and pest management
Togbe, C.E. - \ 2013
Wageningen University. Promotor(en): Arnold van Huis; D.K. Kossou; S.D. Vodouhe, co-promotor(en): Rein Haagsma. - Wageningen : Wageningen UR - ISBN 9789461738073 - 201
gossypium hirsutum - katoen - plagen - gewasproductie - gewasbescherming - biologische bestrijding - neemextracten - beauveria bassiana - bacillus thuringiensis - veldproeven - participatie - boeren - plagenbestrijding - plagenbehandeling - geïntegreerde plagenbestrijding - benin - cotton - pests - crop production - plant protection - biological control - neem extracts - field tests - participation - farmers - pest control - pest management - integrated pest management

Key words: cotton, synthetic pesticides, neem oil (Azadirachta indica), Beauveria bassiana,

Bacillus thuringiensis, field experiment, farmers’ participation

Pests are one of the main factors limiting cotton production worldwide. Most of the pest

control strategies in cotton production rely heavily on the application of synthetic pesticides.

The recurrent use of synthetic pesticides has large consequences for the environment (air,

water, fauna, and flora) and human health. In cotton growing areas in Benin, targeted pests

develop resistance, and this resistance is extended to malaria mosquitos. Other negative

impacts are pest resurgence and secondary pest outbreaks due to the effects on the beneficial

insect fauna. This dissertation addresses the technical and institutional constraints hindering

the wide-scale use of staggered targeted control, ‘Lutte étagée ciblée’ (LEC, in French) for

cotton production.

Wider adoption of LEC can only be achieved if some institutional changes were to

occur, such as in the role of input suppliers in order to improve the procurement of LEC

pesticides. This can only happen if farmers would be empowered and better organised.

Locally available phytochemicals and biopesticides can be used to address problems related to

the difficulty in obtaining synthetic pesticides, as well as their negative environmental impact.

Neem oil (Azadirachta indica) and Beauveria bassiana are good candidates to be used in an

integrated pest management approach, as their impact on the beneficial fauna is minimal. We

tested whether the efficacy could be enhanced by using mixed formulations of neem oil and

bio-insecticides, but yields obtained with neem oil used alone and mixed with biopesticides

were not different. This suggests an absence of a synergistic effect between neem oil and B.

bassiana (Bb11) and between neem oil and B. thuringiensis. The combination of biopesticides

increased the cost of production more than that of the conventional treatments, compromising

the profitability of such formulations. Participation in the research process increased farmers’

knowledge on pest and natural enemy recognition. The increase in knowledge did not lead to

any modification in farmer practices with respect to the use of neem oil and Beauveria, but it

led to a significant change towards threshold-based pesticide applications. Policy implications

for successfully changing farming practices are discussed.

Eindrapportage gele rozeluis in de teelt van aardbei onder glas
Bloemhard, C.M.J. ; Linden, A. van der - \ 2008
Bleiswijk : Wageningen UR Glastuinbouw (Rapport / Wageningen UR Glastuinbouw 193) - 28
aardbeien - fragaria - rhodobium porosum - predatie - plagenbestrijding - coccinella - beauveria bassiana - aphidoletes aphidimyza - paecilomyces fumosoroseus - glastuinbouw - sluipwespen - strawberries - predation - pest control - greenhouse horticulture - parasitoid wasps
Van de vele soorten bladluizen die op aardbei kunnen voorkomen is de gele rozeluis Rhodobium porosum het moeilijkst chemisch te bestrijden. Dit onderzoek richt zich op de biologische bestrijding van de luis met natuurlijke vijanden als de sluipwespen, gaas en zweefvliegen en insectpathogene schimmels
Bestrijding van de slawortelboorder Hepialus lupulinus met de insectenpathogene schimmel Beauveria bassiana : praktijkproeven pioenroos 2004 - 2005
Boertjes, B.C. - \ 2005
Aalsmeer : Praktijkonderzoek Plant & Omgeving, Sector Glastuinbouw - 21
hepialus lupulinus - plantenplagen - beauveria bassiana - biologische bestrijding - paeonia - bestrijdingsmethoden - plantenziektebestrijding - snijbloemen - nederland - plant pests - biological control - control methods - plant disease control - cut flowers - netherlands
Uit het onderzoek kan geconcludeerd worden dat Beauveria bassiana een goede bestrijder is van de slawortelboorder Hepialus lupulinus L. Door de schimmel aangetaste rupsen zijn makkelijk aan te treffen in en buiten het behandelde perceel. Doordat in deze proeven Beauveria bassiana ook werd aangetroffen in de onbehandelde veldjes en de aantasting bij alle behandelingen sterk daalde, kunnen uit deze proeven geen conclusies worden getrokken over het optimale spuittijdstip en de toe te passen dosering. De beste strategie op dit moment is het opsplitsen van de dosering over meerdere bespuitingen met een interval van één tot twee weken. De bespuitingen moeten worden uitgevoerd op het moment dat de larven boven in de grond aanwezig zijn, op een bij voorkeur vochtige
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