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PubMed1998

Systematics and environmental application of the genus Trichoderma.

Trichoderma, an anamorphic Hypocreaceae (class Ascomycetes), is common in the environment, especially in soils. Species of this genus have been used in the production of cellulolytic and hemicellulolytic enzymes, biological control of plant disease, biodegradation of chlorophenolic compounds, and soil bioremediation. They are also the cause of disease in commercially produced mushrooms. The species Trichoderma has not been clearly defined yet, despite being a very common fungus with an expanding number of applications. Therefore, we highlight the importance of the use of molecular techninques along with conventional methodologies based on morphological characters in order to achieve a "natural" taxonomic system for this group of fungi, as well as for any other complex group of fungi.

Biodegradation, Environmental↗

PubMedDate not supplied

Schistosomiasis: eradication or control?

Schistosomiasis cannot be eradicated from the world at this time. However, it can be eradicated from focal areas where major improvements in the standard of living have occurred. In most areas control of biological transmission can be obtained by a systematic use of chemotherapy along with other methods including control of snails and reduction in both water contamination and contact. In some areas, where the prevalence and intensity of infection are very high, the only reasonable objective is control of the disease (although reduction in transmission should be attempted). Disease morbidity correlates with intensity of infection and can probably be reduced with repeated courses of chemotherapy. The appropriate application of a schistosomal vaccine, when it becomes available, will expedite the eradication of this parasite, which infects greater than 200 million people.

Global Health↗

PubMed1992

[A preliminary study of variation in Tarebia granifera (Lamarck), Río Hatibonico, Camagüey].

A study was carried out on Tarebia granifera in Camagüey which allowed to gather ecological evidence in order to know this freshwater mollusk species likely to act as a biological control agent of intermediate hosts for tropical diseases. Highest density was observed in November, coinciding with the highest temperatures of a running water habitat. Also, there was an influence of density variations according to variations of ions NH4+, NO2- and NO3- concentrations in the medium. These data are useful to know the right time for extracting Tarebia granifera from the habitat and using it as competitor without considerable alterations in the population stability.

Animals↗

PubMed2000

Evaluation and host specificity of two seed flies Mesoclanis polana and M. magnipalpis (Diptera: Tephritidae): biological control agents for Chrysanthemoides monilifera (Asteraceae) in Australia.

Larvae of the South African tephritid flies Mesoclanis polana Munro and M. magnipalpis Bezzi feed in the developing seeds of Chrysanthemoides monilifera. Host specificity evaluation using 109 plant species from 25 families indicated that complete development was restricted to their natural host C. monilifera. Minor feeding and limited development was detected on 18 species, but was of no ecological or economic significance. Mesoclanis polana and M. magnipalpis have been released in Australia and M. polana has established and dispersed widely. Mesoclanis magnipalpis has not yet become naturalized. Parasitism of M. polana in Australia by several species of Hymenoptera has been detected, but is not expected to limit the establishment and impact of these flies.

Animals↗

PubMed2004

Yeasts as biological agents to control Botrytis cinerea.

Yeasts, isolated from different sources, were identified and tested for inhibition using YMA-MB plates seeded with Botrytis cinerea strains. A total of 42 yeast strains of 20 different species were tested in vitro for antagonism against 18 pathogenic B. cinerea strains. Pichia membranifaciens, P. anomala and Debaryomyces hansenii displayed the most important inhibitory effect against Botrytis strains. In small-scale trials, post-harvest application of P. membranifaciens CYC 1106 to apple wounds inhibited B. cinerea CYC 20010. Purified killer toxin from P. membronifaciens CYC 1106 inhibited B. cinerea CYC 20010. Results indicated that certain yeasts, or their toxins such us P. membranifaciens CYC 1106 killer toxin, might have potential as novel agents to control B. cinerea.

Antibiosis↗

PubMed2006

Cyclosporine A from a nonpathogenic Fusarium oxysporum suppressing Sclerotinia sclerotiorum.

AIMS: To evaluate the antagonistic activity of Fusarium oxysporum nonpathogenic fungal strain S6 against the phytopathogenic fungus Sclerotinia sclerotiorum and to identify the antifungal compounds involved. METHODS AND RESULTS: The antagonistic activity of Fusarium oxysporum strain S6 was determined in vitro by dual cultures. The metabolite responsible for the activity was isolated by chromatographic techniques, purified and identified by spectroscopic methods as cyclosporine A. The antifungal activity against the pathogen was correlated with the presence of this metabolite by a dilution assay and then quantified. Cyclosporine A caused both growth inhibition and suppression of sclerotia formation. In a greenhouse assay, a significant increase in the number of surviving soybean (Glycine max) plants was observed when S. sclerotiorum and F. oxysporum (S6) were inoculated together when compared with plants inoculated with S. sclerotiorum alone. CONCLUSION: Fusarium oxysporum (S6) may be a good fungal biological control agent for S. sclerotiorum and cyclosporine A is the responsible metabolite involved in its antagonistic activity in vitro. SIGNIFICANCE AND IMPACT OF THE STUDY: Cyclosporine A has not been previously described as an inhibitor of S. sclerotiorum. Its minimum inhibitory concentration (MIC) of 0.1 microg disc(-1) makes it suitable to use as a biofungicide. In vivo experiments showed that F. oxysporum (S6) is a good candidate for the biocontrol of S. sclerotiorum in soybean.

Antifungal Agents↗

PubMedDate not supplied

Prospects for integration of novel parasite control options into grazing systems.

Novel parasite control methods are considered under criteria of efficacy, cost, ease of implementation and sustainability, together with a subjective assessment of when they are likely to become available commercially. It is concluded that vaccines, genetically resistant hosts, biological control, anthelmintics directed against free-living stages, and grazing management will probably satisfy all of these criteria, but that most of these methods are at least 5-10 years away from commercial exploitation. The exception is grazing management, which can be used immediately and at low cost, to minimise current use of anthelmintics. Research is required to assess the possibility of control programs based on grazing management that avoid anthelmintic treatment altogether. Extension of such control programs, in a context of declining government enthusiasm for provision of agricultural extension services, may be their greatest barrier to widespread adoption.

Animal Husbandry↗

PubMed1986

[Combined and alternate control of Lymnaea truncatula Müller by chemical and biological means. First experimental trials in the field].

Six Lymnaea truncatula stations located in the department of Haute-Vienne (France) were treated in 1984 by a joint and alternate control with the use of a molluscicide (CuCl2), and the introduction of a predator snail, Zonitoides nitidus. Investigations made during the first rainfalls postestivation had showed the elimination of all the lymnaeid snails in five stations, and the presence of some surviving snails (5%) in the last station. The toxic effects of low concentration CuCl2 were enough important for the invertebrates living in the draining ditches of these stations; they were slight for the ones living in the principal draining furrows.

Animals↗

PubMed2003

Nutritional similarity between leaf-associated nonpathogenic bacteria and the pathogen is not predictive of efficacy in biological control of bacterial spot of tomato.

It has been demonstrated that for a nonpathogenic, leaf-associated bacterium, effectiveness in the control of bacterial speck of tomato is correlated with the similarity in the nutritional needs of the nonpathogenic bacterium and the pathogen Pseudomonas syringae pv. tomato. This relationship was investigated further in this study by using the pathogen Xanthomonas campestris pv. vesicatoria, the causal agent of bacterial spot of tomato, and a collection of nonpathogenic bacteria isolated from tomato foliage. The effects of inoculation of tomato plants with one of 34 nonpathogenic bacteria prior to inoculation with the pathogen X. campestris pv. vesicatoria were quantified by determining (i) the reduction in disease severity (number of lesions per square centimeter) in greenhouse assays and (ii) the reduction in leaf surface pathogen population size (log(10) of the number of CFU per leaflet) in growth chamber assays. Nutritional similarity between the nonpathogenic bacteria and X. campestris pv. vesicatoria was quantified by using either niche overlap indices (NOI) or relatedness in cluster analyses based upon in vitro utilization of carbon or nitrogen sources reported to be present in tomato tissues or in Biolog GN plates. In contrast to studies with P. syringae pv. tomato, nutritional similarity between the nonpathogenic bacteria and the pathogen X. campestris pv. vesicatoria was not correlated with reductions in disease severity. Nutritional similarity was also not correlated with reductions in pathogen population size. Further, the percentage of reduction in leaf surface pathogen population size was not correlated with the percentage of reduction in disease severity, suggesting that the epiphytic population size of X. campestris pv. vesicatoria is not related to disease severity and that X. campestris pv. vesicatoria exhibits behavior in the phyllosphere prior to lesion formation that is different from that of P. syringae pv. tomato.

Carbon↗

PubMed2003

Cytotoxicity against insect cells of entomopathogenic fungi of the genera Hypocrella (anamorph Aschersonia): possible agents for biological control.

Extracts from entomopathogenic fungi of the genus Hypocrella (7 species) and its anamorph Aschersonia (11 species) were screened for cytotoxicity to Sf9 and C6/36 insect cells and L929, BHK(21)C13 and HepG2 mammalian cells. Cytotoxic extracts to insect cells (ID50's < or = 10 microg ml(-1)) but not to mammalian cells (ID50's > or = 10 microg ml(-1)) conformed to the criteria of the project and were considered 'lead' extracts for further investigation. 'Leads' were found in two of the Hypocrella species: H. discoidea, and H. tamurai and in three of the Aschersonia species: A. samoensis, A. badia, and A. tamurai. Bioassay-guided fractionation of the cell extract of the fungus A. samoensis BCC 1393 led to the identification of two known anthraquinone dimers, (+)rugulosin (1) and skyrin (2) which showed selective toxicity towards insect cells. (+)Rugulosin (1) and skyrin (2) exhibited strong cytotoxic activity against the insect cell line Sf9 with respective ID50 values of 1.2 and 9.6 microg ml(-1), but showed weak activity toward mammalian cells. This first report of (+)rugulosin (1) and skyrin (2) in A. samoensis is confirmed and demonstrated in another four strains of A. samoensis isolated in Thailand. The preferential cytotoxicity against Sf9 insect cells gives evidence that these insect-pathogenic fungi of the Hypocrella/Aschersonia group might be useful as an agent for pest control.

Aedes↗

PubMedDate not supplied

Male-killing bacteria in insects: mechanisms, incidence, and implications.

Bacteria that are vertically transmitted through female hosts and kill male hosts that inherit them were first recorded in insects during the 1950s. Recent studies have shown these "male-killers" to be diverse and have led to a reappraisal of the biology of many groups of bacteria. Rickettsia, for instance, have been regarded as human pathogens transmitted by arthropods. The finding of a male-killing Rickettsia obligately associated with an insect suggests that the genus' members may be primarily associated with arthropods and are only sometimes pathogens of vertebrates. We examined both how killing of male hosts affects the dynamics of inherited bacteria and how male-killing bacteria affect their host populations. Finally, we assessed the potential use of these microorganisms in the control of insect populations.

Animals↗

PubMed2005

Fertility control in wildlife: humans as a model.

In a time of accelerated extinction rates and biodiversity loss, it may seem illogical to be concerned with methods limiting the reproduction of wild populations; however, there is an urgent need to inhibit the proliferation of a wide variety of species. The range of animals for which fertility control is desired makes the development of a single method impossible. The various reproductive strategies used by individual species, the desired outcome of contraceptive programs (reversible or irreversible; male or female directed) and our ignorance of the reproductive biology of many endangered species necessitate thorough species-specific investigations. As fertility control in humans is a reality and research into methods of fertility control is more advanced, humans serve as a model for developing contraceptive approaches for wild species. Population control by traditional methods (indirect or direct intervention by culling, poisoning, translocation, etc.) is increasingly unacceptable to the public, making human studies even more valuable for finding solutions to overabundant wild populations. This review compares and contrasts the range of contraceptive methods used in both wildlife and humans.

Animals↗

PubMed2003

Using fungi and yeasts to manage vegetable crop diseases.

Vegetable crops are grown worldwide as a source of nutrients and fiber in the human diet. Fungal plant pathogens can cause devastation in these crops under appropriate environmental conditions. Vegetable producers confronted with the challenges of managing fungal pathogens have the opportunity to use fungi and yeasts as biological control agents. Several commercially available products have shown significant disease reduction through various mechanisms to reduce pathogen development and disease. Production of hydrolytic enzymes and antibiotics, competition for plant nutrients and niche colonization, induction of plant host defense mechanisms, and interference with pathogenicity factors in the pathogen are the most important mechanisms. Biotechnological techniques are becoming increasingly valuable to elucidate the mechanisms of action of fungi and yeasts and provide genetic characterization and molecular markers to monitor the spread of these agents.

Anti-Bacterial Agents↗

PubMed2003

[Presearch on preventing the medicinal plant diseases with Trichoderma harzianum preparation].

OBJECTIVE: To control the medicinal plant diseases with the preparation of Trichoderma harzianum. METHOD: Antagonistic action of the preparation to the pathogens of the medicinal plants in vitro, and controling effects of the preparation on these diseases in greenhouse and in the field were tested. RESULT: The test in vitro showed that Trichoderma harzianum, used as a biocontrol factor, had stronger antagonistic action to Fusarium equiseti, Sclerotinia sp. and Rhizoctonia solani which were the medicinal plant pathogens of Astragalus membranaceus, Glehnia littoralis and Panax quinquefolium respectively. Biological controling effects on sclerotium root rot of Glehnia littoralis were 83.6% and 72.5% respectively in greenhouse and in the field with the preparation of Trichoderma harzianum. And controling effects on root rot of Astragalus membranaceus and seedling damping-off of Panax quinquefolium were 80% and 60% respectively in the field. The dosage of the preparation used in the field was 10 g.m-2. CONCLUSION: The preparation of Trichoderma harzianum can be used as a substitute for such chemicals as Carbendazim. Using the preparation to control medicinal plant diseases provides a technical safeguard for the good agricultural practice of medicinal plants.

Apiaceae↗

PubMed2001

[Ecological characteristics of phytoplankton in waters of biological-controlling and ordinary rice fields].

Through investigations from March to June 1998 on the phytoplankton in waters of biological-controlled and ordinary rice fields, 112 species of phytoplankton were found, of which, Bacillariophyta, Euglenophyta and Chlorophyta were dominant. The comparison of the species in two rice fields showed that in biological-controlled rice field, there were more species of Euglenophyta, with 5 most dominant species, i.e., 2 of Euglenophyta, 2 of Bacillariophyta and 1 of Chlorophyta. In ordinary rice field, there were more Bacillariophyta species, in which, 5 most dominant species belonged to Bacillariophyta, except Scenedesmus bijuga to Chlorophyta. The biodiversities of phytoplankton and their evennesses were also analyzed with the period from the seedlings being planted to the rice fields being dried, showing that a little increase in their biodiversity mainly caused by the increase of species number and an evident decrease in their evennesses.

Ecosystem↗

PubMed2001

Viability and stability of biological control agents on cotton and snap bean seeds.

Cotton and snap bean were selected for a multi-year, multi-state regional (south-eastern USA) research project to evaluate the efficacy of both commercial and experimental bacterial and fungal biological control agents for the management of damping-off diseases. The goal for this portion of the project was to determine the viability and stability of biological agents after application to seed. The biological seed treatments used included: (1) Bacillaceae bacteria, (2) non-Bacillaceae bacteria, (3) the fungus Trichoderma and (4) the fungus Beauveria bassiana. Seed assays were conducted to evaluate the following application factors: short-term (< or = 3 months) stability after seed treatment; quality (i.e. isolate purity); compatibility with chemical pesticides and other biocontrol agents; application uniformity between years and plant species. For the bacterial treatments, the Bacillaceae genera (Bacillus and Paenibacillus) maintained the greatest population of bacteria per seed, the best viability over time and the best application uniformity across years and seed type. The non-Bacillaceae genera Burkholderia and Pseudomonas had the least viability and uniformity. Although Beauveria bassiana was only evaluated one year, the seed fungal populations were high and uniform. The seed fungal populations and uniformity for the Trichoderma isolates were more variable, except for the commercial product T-22. However, this product was contaminated with a Streptomyces isolate in both the years that it was evaluated. The study demonstrated that Bacillaceae can be mixed with Trichoderma isolates or with numerous pesticides to provide an integrated pest control/growth enhancement package.

Bacillaceae↗

PubMed2003

Regulation of antibiotic production in root-colonizing Peudomonas spp. and relevance for biological control of plant disease.

Certain strains of fluorescent pseudomonads are important biological components of agricultural soils that are suppressive to diseases caused by pathogenic fungi on crop plants. The biocontrol abilities of such strains depend essentially on aggressive root colonization, induction of systemic resistance in the plant, and the production of diffusible or volatile antifungal antibiotics. Evidence that these compounds are produced in situ is based on their chemical extraction from the rhizosphere and on the expression of antibiotic biosynthetic genes in the producer strains colonizing plant roots. Well-characterized antibiotics with biocontrol properties include phenazines, 2,4-diacetylphloroglucinol, pyoluteorin, pyrrolnitrin, lipopeptides, and hydrogen cyanide. In vitro, optimal production of these compounds occurs at high cell densities and during conditions of restricted growth, involving (i) a number of transcriptional regulators, which are mostly pathway-specific, and (ii) the GacS/GacA two-component system, which globally exerts a positive effect on the production of extracellular metabolites at a posttranscriptional level. Small untranslated RNAs have important roles in the GacS/GacA signal transduction pathway. One challenge in future biocontrol research involves development of new strategies to overcome the broad toxicity and lack of antifungal specificity displayed by most biocontrol antibiotics studied so far.

Anti-Bacterial Agents↗

PubMedDate not supplied

[Comparative study of aerosol and oral methods of infection of Lympantria dispar L. caterpillars with nuclear polyhedrosis virus].

The aerosol and oral routes of infection of Gypsy moth larvae with nuclear polyhedrosis virus are compared. The virus in aerosol retains its biological activity. The virus output/expenditure ratio is virtually the same in the studied routes of infection. Aerosol method of inoculation saves 30% components of media and is 6-8 times less labor consuming. This method permits complete automation of infection of larvae, thus essentially improving the efficacy of baculovirus production.

Administration, Oral↗