Document généré le 28 sept. 2021 07:13 Phytoprotection Use of Fungi for Pest Control in Sustainable Agriculture Siegfried Keller OECD Workshop - Sustainable Pest Management, Safe Utilization of Résumé de l'article New Organisms in Biological Control. Montréal, Québec, Canada. The registration procedures for microbial pesticides have been based by and September 27-30, 1998. large on those developed for registration of chemical pesticides. However, Atelier de l’OCDE - Gestion durable des ennemis des cultures, fungi as living organisms differ in many aspects from inert substances. These Utilisation sécuritaire de nouveaux organismes de lutte biologique. differences are pointed out and discussed in the light of practical experiences. Montréal, Québec, Canada. 27-30 Septembre 1998. A pragmatic registration procedure is proposed taking into account the use of a Volume 79, numéro 4, 1998 fungus based product in relation to its natural distribution and behaviour. On the one hand, the use of a fungus naturally occurring on the target host does not need a sophisticated registration procedure. On the other hand, however, a URI : https://id.erudit.org/iderudit/706158ar genetically altered fungus applied against a non natural host in a non natural DOI : https://doi.org/10.7202/706158ar habitat needs very careful examination. Aller au sommaire du numéro Éditeur(s) Société de protection des plantes du Québec (SPPQ)l ISSN 0031-9511 (imprimé) 1710-1603 (numérique) Découvrir la revue Citer cet article Keller, S. (1998). Use of Fungi for Pest Control in Sustainable Agriculture. Phytoprotection, 79(4), 56–60. https://doi.org/10.7202/706158ar La société de protection des plantes du Québec, 1998 Ce document est protégé par la loi sur le droit d’auteur. L’utilisation des services d’Érudit (y compris la reproduction) est assujettie à sa politique d’utilisation que vous pouvez consulter en ligne. https://apropos.erudit.org/fr/usagers/politique-dutilisation/ Cet article est diffusé et préservé par Érudit. Érudit est un consortium interuniversitaire sans but lucratif composé de l’Université de Montréal, l’Université Laval et l’Université du Québec à Montréal. Il a pour mission la promotion et la valorisation de la recherche. https://www.erudit.org/fr/ Research Challenges and Needs for Safe Use of Microbial Organisms Use of Fungi for Pest Control in Sustainable Agriculture Siegfried Keller Swiss Fédéral Research Station for Agroecology and Agriculture, Reckenholz, CH-8046 Zurich ABSTRACT animais. This diversity bears an enor- mous potential for pest and vector con­ trol. In the future, therefore, and espe- The registration procédures for micro­ cially in the context of the efforts to bial pesticides hâve been based by and favour sustainable agriculture, we can large on those developed for registra­ expect a considérable increase in the tion of chemical pesticides. However, use of fungi for pest control. fungi as living organisms differ in many aspects from inert substances. Thèse The preferred environment for Hy­ différences are pointed out and dis- phomycetes and Cordyceps is the soil cussed in the light of practical expéri­ whereas nearly ail Entomophthorales ences. A pragmatic registration procé­ are found above the soil level. Most dure is proposed taking into account species are spécifie pathogens and at­ the use of a fungus based product in tack single host species or a limited relation to its natural distribution and number of related host species. The behaviour. On the one hand, the use of entomopathogenic soil fungi are char- a fungus naturally occurring on the acterised by small conidia, relatively low target host does not need a sophisticat- virulence (i.e. a large number of conidia ed registration procédure. On the other is needed to infect and kill the host), a hand, however, a genetically altered relatively long incubation time and a fungus applied against a non natural slow self propagation. In contrast, the host in a non natural habitat needs very Entomophthorales hâve large structures careful examination. and resting spores, a single conidium or few conidia can infect and kill the host, death occurs within a few days INTRODUCTION and the self propagation is fast. Thèse characteristics must be considered as Several hundred species of fungi are an adaptation to the environment and known to infect and kill insects and hâve implications for their use as mi­ mites. The most important groups are crobial control agents. the Hyphomycetes within gênera like Beauveria, Metarhizium, Verticillium, Paecilomyces and Hirsutella, the Asco- USE OF FUNGI mycetes within the genus Cordyceps FOR PEST CONTROL and the Entomophthorales with a total of 12 gênera and some 230 insect and Fungi are important enemies of many mite pathogenic species. The latter is pest species and are able to control nearly unexploited although 30% of pest populations naturally. There are thèse attack pest species or vectors of twofundamentally différent waysto use diseases of humans and domestic fungi for pest control: 56 1. Favouring those being présent natu- mycélium, hyphal bodies or resting rally by manipulation of the environ- stages. ment (e.g. habitat management). This Under favourable conditions the fun­ will not be discussed hère although gus switches to the saprophytic phase. it is an important strategy for sus- Hyphae or conidiophores émerge from tainable agriculture. their host by penetrating the host cuti- 2. In vitro or in vivo production and cle from within the cadaver. The Ento- application. The fungus can be intro- mophthorales form a single layer of duced into the host population with conidia on the host surface, whereas a single application using technical the Hyphomycetes form a more or less equipment or autodissemination conspicuous mycelial mat around the techniques, or it can be applied re- host which produces the conidia, the peatedly like a chemical. The aim of structures responsible for dissémina­ the application is to achieve short- tion and infection of new hosts. term or long-term control, to enhance epizootics and/or to establish the Factors related to the organismic pathogen in the host population. character Genetic diversity: Any fungal species There are several examples in the possesses a genetic diversity which can literature demonstrating the successful be used to subdivide it into strains. use of thèse techniques for pest control Thèse strains can show différent reac­ like the introduction and release of tions to abiotic factors such as environ- Entomophaga maimaiga resulting in mental conditions, nutrients or Chemi­ epizootics and long-term control of the cals including pesticides, or to biotic gypsy moth in north-eastern USA, the factors such as virulence or persistence. treatmentof adultcockchaferwith Beau- veria brongniartii using the females as Host range/specificity: Under natural vectors of the disease to contaminate conditions most species hâve a limited the breeding sites resulting in long-term host range. But species with a wide host control in north-eastern Switzerland or range also tend to be more virulent for the repeated treatment of spittle-bugs the host from which they were original- with Metarhizium anisopliae in Brazil. ly isolated. They can be classified into Other techniques applied to ento- pathotypes based on their specificity. mopathogenic fungi like transgenic or Self-propagation: A limited number of genetically altered strains or their use fungal spores are able to start a multi­ as endophytes are not discussed hère. plication process, which results in a thousand to billion fold increase of the spore amount. This can also happen at FUNGI ARE DIFFERENT the population level as a resuit of an FROM CHEMICALS outbreak or the induction of an epizoot- ic which can resuit in remarkable aerial spore densities. Life cycle Dissémination: With the ability to project Fungi are organisms, living beings. They conidia or to grow saprophytically the infect their hosts with spores (conidia) entomopathogenic fungi hâve a limited which germinate on the epidermis. The possibility to actively disseminate. The germ tubes penetrate the skin and en- most important way of dissémination terthe body cavity where multiplication occurs passively via infected hosts, starts. The fungi develop vegetatively other individuals or transportation of as protoplasts, hyphal bodies, hyphae spores in the wind. or yeast-lîke structures called blas- tospores. Most tissues become invad- Metabolites: Metabolites are mainly ed. Some fungi produce metabolites known from Hyphomycetes. Than can which are toxic to the host or compet- be toxic for the host and reduce the ing microorganims. At the end of the incubation time or they can help the parasitic stage the host dies and its body fungus to compete with other microor- is filled with fungal material, either ganisms. 57 WHITE GRUB CONTROL remarks are presented in the following WITH BEAUVERIA sections. BRONGNIARTII WITH REGARD TO REGISTRATION STEPS IN THE DEVELOPMENT OF A The European cockchafer Melolontha MYCOINSECTICIDE melolontha L. (Coleoptera, Scara- baeidae) is a serious pest in many ré­ Strains with the desired characteristics gions of central Europe. A génération must be selected before production can lasts three years. It develops synchro- start. Desired characteristics are mainly nously in outbreak areas resulting in virulence for given hosts, production flights every three years. During the criteria (nutrients, time) and specificity, flight period the adults concentrate at especially absence of adverse