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At least 1,063 records · Page 59Linked to original sources
PubMed1997

Biological control studies of soft and hard ticks in Egypt. I. The effect of Bacillus thuringiensis varieties on soft and hard ticks (ixodidae).

The potential activity of three varieties of Bacillus thuringiensis (kurstaki, israeliensis, and thuringiensis) against the soft tick Argas persicus and the hard tick Hyalomma dromedarii was investigated. Soft ticks succumbed within a period ranging from 36 h to 5 days and hard ticks died at between 48 h and 10 days posttreatment, depending on the dose. Concentrations lethal to 50% of tick populations (LC50 values) indicated that Dipel 2x (B. thuringiensis var. kurstaki) was the most potent, followed by Vectobac (B. thuringiensis var. israeliensis), then HD 703 (B. thuringiensis var. thuringiensis). A. persicus was more affected than H. dromedarii by B: thuringiensis varieties. Eggs were mostly affected at 16 and 25 days after deposition for A. persicus and H. dromedarii, respectively.

Animals↗
PubMed2006

Limonoids: overview of significant bioactive triterpenes distributed in plants kingdom.

The search for limonoids started long back when scientists started looking for the factor responsible for bitterness in citrus which has negative impact on citrus fruit and juice industry worldwide. The term limonoids was derived from limonin, the first tetranortriterpenoid obtained from citrus bitter principles. Compounds belonging to this group have exhibited a range of biological activities like insecticidal, insect antifeedant and growth regulating activity on insects as well as antibacterial, antifungal, antimalarial, anticancer, antiviral and a number of other pharmacological activities on humans. Although hundreds of limonoids have been isolated from various plants but, their occurrence in the plant kingdom is confined to only plant families of order Rutales and that too more abundantly in Meliaceae and Rutaceae, and less frequently in Cneoraceae and Harrisonia sp. of Simaroubaceae. Limonoids are highly oxygenated, modified terpenoids with a prototypical structure either containing or derived from a precursor with a 4,4,8-trimethyl-17-furanylsteroid skeleton. All naturally occurring citrus limonoids contain a furan ring attached to the D-ring, at C-17, as well as oxygen containing functional groups at C-3, C-4, C-7, C-16 and C-17. The structural variations of limonoids found in Rutaceae are less than in Meliaceae and are generally limited to the modification of A and B rings, the limonoids of Meliaceae are more complex with very high degree of oxidation and rearrangement exhibited in the parent limonoid structure. To counter the problem of bitterness in citrus juice and products genetic engineering of citrus to maximize the formation of limonoid glucosides for reducing limonoid bitterness is the focus of recent and future research. Regarding the biological activities of limonoids the investigations are to be directed towards detailed characterization, quantification, and designing a simple as well as versatile synthetic route of apparently important limonoids. Extraction methods too should be optimized; evaluation and establishment of pharmaco-dynamic and kinetic principles, and structure activity relationships should be a key goal associated with limonoids so that they can be safely introduced in our arsenal of pharmaceuticals to safeguard the humanity from the wrath of disease and its discomfort.

Anti-Infective Agents↗
PubMed2004

Biological control of chickpea Fusarium wilt by antagonistic bacteria under greenhouse condition.

In this survey, Fusarium oxysporum was isolated from roots infected plants and was shown to be pathogenic. Experiment were carried out with seven antagonistic bacteria. Based on biochemical, Physiological and morphological tests, isolates B-120, B-32, B-28 and B-22 were identified as Bacillus subtilis and isolates Pf-100, Pf-10 and CHAO as Pseudomonas fluorescens. In greenhouse studies, only isolate B-120 (Less than benomyl) reduced Fusarium wilt of chickpea in both seed and soil treatments. The application of antagonistic bacteria had no different effects on plant growth factors. Soil treatment of bacteria had a better effects on plant growth than that of bacterial seed treatment. The use of antagonists (B-120, B-28, B-120 and CHAO) in combination had no significant effect on plant growth factors and reduction wilt disease than that each isolate was applied individually.

Bacillus subtilis↗
PubMed1972

Experimental introduction of a microsporidian into a wild population of Culex pipiens fatigans Wied.

Chemical control of C. p. fatigans frequently fails because the mosquito rapidly develops resistance to insecticides. A possible alternative or complementary method is biological control, including the introduction of pathogens. The microsporidian Plistophora culicis was known to infect readily and have an adverse effect on C. p. fatigans populations in the laboratory, so an attempt was made to introduce and establish this pathogen in a wild population of the mosquito on the Pacific island of Nauru. Two years after introduction the pathogen was still present in the wild population. However, the infection rate was similar to that found in naturally occurring infections in other mosquitos and is almost certainly not high enough to affect a natural population of C. p. fatigans adversely.

Animals↗
PubMed2003

Efficacy of different fungicides against Rhizoctonia brown patch and Pythium blight on turfgrass in Italy.

Brown patch, incited by Rhizoctonia solani Kuhn, and Pythium blight, caused by Pythium spp. are two of the diseases most frequently observed on turfgrass in high maintenance stands, as on golf courses. In such conditions the control strategies, based on chemicals, are particularly difficult due to the scarcity of fungicides registered for turf in Italy. The results obtained in experimental trials carried out to evaluate the efficacy of chemical and biological products against brown patch and Pythium blight are reported. On mature turfgrass, maintained under fairway conditions, azoxystrobin, and trifoxystrobin, not yet registered on turf, were very effective against brown patch. Tebuconazole, applied in three different formulations, was very effective against R. solani, while Trichoderma spp. and azadiractine did not control the pathogen. In greenhouse conditions on Agrostis stolonifera, in the presence of severe disease incidence, due to artificial inoculation, benalaxyl-M satisfactorily controlled Pythium blight; Trichoderma spp. as well as a commercial formulation of T. harzianum, applied one week before the inoculation, were not effective. Among the fungicides not yet registered for use on turfgrass in Italy, metalaxyl-M + mancozeb was effective against Pythium blight.

Fungicides, Industrial↗
PubMedDate not supplied

[Phagolysates of cyanobacteria: their biocidal properties and use].

Data on the biological activity of cyanobacterial phagolysates were obtained in experiments. They concern the organisms of different evolutional level, such as some conventional pathogenic bacteria, plant and root parasitic nematodes and phytophagous insects. The authors suppose the specific mechanism of biocidal and inhibitory action of cyanobacteria and their phagolysates in respect to different living systems. These facts are very important for the elaboration of practical aspects of algal metabolites employment in agriculture and medicine.

Animals↗
PubMed2001

Biological control of field infections of nematode parasites of young sheep with Duddingtonia flagrans and effects of spore intake on efficacy.

A field study was undertaken to determine the effects of feeding Duddingtonia flagrans to young Merino sheep on pasture. A total of 60 mixed sex lambs 4-5 months old were divided into six even groups on the basis of liveweight. On Monday to Friday, each week for 6 months, three groups were offered barley grains on which D. flagrans had been cultured while the other three groups remained untreated. Every 4 weeks liveweights were recorded and faecal samples collected for nematode egg count estimation. Feeding D. flagrans reduced faecal egg counts and tended to improve liveweight gains, but considerable differences were observed between groups within treatment. These differences are thought to result from variations between the groups in consumption of the treated barley with the "best" consumers showing the greater effects of treatment.

Animals↗
PubMed1986

Snail control in relation to a strategy for reduction of morbidity due to schistosomiasis.

The control of schistosomal disease is now distinctly feasible in endemic situations where a capable health care delivery system exists. Effective integrated control of schistosomiasis morbidity, within available resources at national level, is now being carried out in many countries. The control of snail hosts by chemical, environmental and/or biological means can still play a significant supporting role in many endemic situations. Today, however, as compared to earlier decades when disease control procedures were far less advanced, there is need for reappraisal of snail host control strategies to ensure that objectives are now correctly set, that the potential operational mechanisms are carefully chosen under the headings of desirability, feasibility and cost-effectiveness and that implementation and evaluation of the operations have, as far as possible, both theoretical and practical validity. Nowadays snail host control procedures must be intimately linked to knowledge of transmission sites and seasonal patterns, focal and periodic transmission being the rule rather than exception; in particular, they must be associated with local schemes for the delivery and evaluation of population based chemotherapy campaigns.

Animals↗
PubMed2006

Additive effects of vertebrate predators on insects in a Puerto Rican coffee plantation.

A variety of studies have established the value of shaded coffee plantations as habitat for birds. While the value of birds as biological controls in coffee has received some attention, the interactions between birds and other predators of insects have not been tested. We used exclosures to examine the effects of vertebrate predators on the arthropods associated with coffee, in particular the coffee leafminer (Leucoptera coffeella) and the flatid planthopper Petrusa epilepsis, in a shaded coffee plantation in Puerto Rico. We used a 2 x 2 factorial design with four treatments: exclusion of birds, lizards, birds and lizards, and control (no exclusion). Abundance of insects > 5 mm increased when birds or both birds and lizards were removed. Birds and lizards had an additive effect for insects < 5 mm and for all insects combined. Coffee leafminers showed a weak response to removal of predators while planthopper abundance increased significantly in the absence of avian predators. Arthropod predators and parasitoids did not differ significantly between treatments. Our findings suggest that vertebrate insectivores have an additive effect on insects in coffee and may help control abundances of some coffee pests. Equally important, we present evidence suggesting that they do not interfere with other known natural enemies of coffee pests.

Animals↗
PubMed2005

Effects of community versus single strain inoculants on the biocontrol of Salmonella and microbial community dynamics in alfalfa sprouts.

Potential biological control inoculants, Pseudomonas fluorescens 2-79 and microbial communities derived from market sprouts or laboratory-grown alfalfa sprouts, were introduced into alfalfa seeds with and without a Salmonella inoculum. We examined their ability to inhibit the growth of this foodborne pathogen and assess the relative effects of the inoculants on the alfalfa microbial community structure and function. Alfalfa seeds contaminated with a Salmonella cocktail were soaked for 2 h in bacterial suspensions from each inoculant tested. Inoculated alfalfa seeds were grown for 7 days and sampled during days 1, 3, and 7. At each sampling, alfalfa sprouts were sonicated for 7 min to recover microflora from the surface, and the resulting suspensions were diluted and plated on selective and nonselective media. Total bacterial counts were obtained using acridine orange staining, and the percentage culturability was calculated. Phenotypic potential of sprout-associated microbial communities inoculated with biocontrol treatments was assessed using community-level physiological profiles based on patterns of use of 95 separate carbon sources in Biolog plates. Community-level physiological profiles were also determined using oxygen-sensitive fluorophore in BD microtiter plates to examine functional patterns in these communities. No significant differences in total and mesophilic aerobe microbial cell density or microbial richness resulting from the introduction of inoculants on alfalfa seeds with and without Salmonella were observed. P. fluorescens 2-79 exhibited the greatest reduction in the growth of Salmonella early during alfalfa growth (4.22 log at day 1), while the market sprout inoculum had the reverse effect, resulting in a maximum log reduction (5.48) of Salmonella on day 7. Community-level physiological profiles analyses revealed that market sprout communities peaked higher and faster compared with the other inoculants tested. These results suggest that different modes of actions of single versus microbial consortia biocontrol treatments may be involved.

Colony Count, Microbial↗
PubMed2004

Wasp parasitoid disruption of host development: implications for new biologically based strategies for insect control.

Wasp parasitoids use a variety of methods to commandeer their insect hosts in order to create an environment that will support and promote their own development, usually to the detriment of the host insect. Parasitized insects typically undergo developmental arrest and die sometime after the parasitoid has become independent of its host. Parasitoids can deactivate their host's immune system and effect changes in host hormone titers and behavior. Often, host tissues or organs become refractory to stimulation by tropic hormones. Here we present an overview of the manipulative capabilities of wasp-injected calyx fluid containing polydnaviruses and venom, as well as the parasitoid larva and the teratocytes that originate from the serosal membrane that surrounds the developing embryo of the parasitoid. Possibilities for using regulatory molecules produced by the parasitoid or its products that would be potentially useful in developing new, environmentally safe insect control agents are discussed.

Animals↗
PubMed1987

[Method of biological control of Triatominae, vectors of Chagas disease, using entomopathogenic Hyphomycetes. Preliminary study].

Bioassays determined the pathogenic activity of 14 strains of 5 entomopathogenic hyphomycetous species (Fungi imperfecti), Beauveria bassiana, Beauveria brongniartii, Metarhizium anisopliae, Nomuraea rileyi and Paecilomyces fumosoroseus to Rhodnius prolixus. Treatments consisted of direct spraying with conidial titrated suspensions on first instar larvae. When tested at 3 X 10(5) conidia/cm2, only 2 strains, B. bassiana n. 297 and B. bassiana n. 326 killed 100% of larvae at 10 days post-exposure. In the same time their LD50 and their LD90 did not differ significantly. After 3 weeks, the mortality caused by either dose of spores of B. bassiana n. 297 was very high. In contrast, in the case of B. bassiana n. 326 mortality due to reduced doses remained at low rates. This laboratory study demonstrated that the isolate, B. bassiana n. 297 might have potential as microbial control agent against the assassin bugs.

Animals↗
PubMed2000

Surface hydrophobicity, viability and efficacy in biological control of Penicillium oxalicum spores produced in aerial and submerged culture.

The surface hydrophobicity, viability and biocontrol ability of Penicillium oxalicum spores, produced either in aerial or submerged culture, were characterized. A phase distribution test showed that spores produced in both methods of culture were highly hydrophobic, but those produced in aerial culture were more hydrophobic. Spores stored fresh at either 4 or 25 degrees C retained a high viability (80%) after 27 weeks of storage, although aerial spores survived better. Freeze-drying severely affected viability, especially of submerged spores. Biocontrol ability against Fusarium oxysporum f. sp. lycopersici was studied in the growth chamber. Aerially- produced spores were more effective than submerged ones. Aerially-produced P. oxalicum spores appeared to have more advantages than those produced by submerged culture, in relation to both viability and efficacy. These results demonstrate that physiological changes occur depending on production conditions which significantly influences quality of the biocontrol agent.

Air↗
PubMed1998

Development of Bacillus thuringiensis fermentation and process control from a practical perspective.

Bacillus thuringiensis (Bt) is the most widely used biopesticide producer in the biological control market. It is very critical for the Bt pesticide industry to be able to achieve a high yield in the Bt fermentation process in order to reduce its cost and compete with chemical pesticides in the market. We review the overall development of Bt fermentation process research and provide our point of view for the future research opportunities and potential improvements. This minireview covers the areas of fermentation physiology, growth dynamics and high-yield process control. It is pointed out that many studies aimed to improve spore count and process research focusing on toxin protein yield is lacking. In addition, significant development opportunities reside in the process development for the genetically engineered Bt strains expressing multiple toxin proteins.

Bacillus thuringiensis↗
PubMed2001

Management of early-instar Japanese beetle (Coleoptera: Searabaeidae) in field-grown nursery crops.

Numerous field studies were conducted in commercial nurseries in Tennessee from 1996 through 1999 to evaluate chemical and biological treatments, application timing and rates, and method of application for control of early instars of Japanese beetle, Popillia japonica Newman. Insecticide treatments included bifenthrin, bendiocarb, chlorpyrifos, carbaryl, fipronil, halofenozide, imidacloprid, permethrin, tefluthrin, thiamethoxam, and trichlorfon. Biological treatments included entomopathogenic nematodes (Heterorhabditis bacteriophora HP88 or H. marelatus, Bacillus thuringiensis Berliner subspecies japonensis Buibui strain, and Beauveria bassiana (Balsamo) Vuillemin. All treatments were applied on the soil surface or injected into the soil around the base of each tree. Tree type and size varied among and within tests, however, the sampling unit (61-cm-diameter root ball) remained the same throughout all tests. The biological treatments provided poor-to-moderate control (0-75%) of Japanese beetle larvae. Imidacloprid was the most frequently evaluated insecticide and achieved 91-100, 87-100, 83-100, and 41-100% control with applications in May, June, July, and August, respectively. Halofenozide treatments were not significantly different from imidacloprid treatments with one exception. Halofenozide provided 60-87, 85-100, and 82-92 control with applications made in June, July, and August, respectively. Fipronil and thiamethoxam were evaluated to a lesser extent but both performed similarly to imidacloprid. Most other insecticide treatments were less successful in reducing numbers of Japanese beetle larvae and with few exceptions achieved <50% control.

Animals↗
PubMed2004

Biological control of Phytophthora ramorumon rhododendron.

Phytophthora ramorum was found in Poland in 2000 as the causal agent of rhododendron blight. Besides eradication of diseased plants and rhododendron growing around, chemical and biological control of the pathogen is necessary. In this study in vitro activity of grapefruit extract and chitosan in the inhibition of P. ramorum growth and sporulation and their efficacy in the control of leaf and stem rot development was evaluated. Amendment of V8 juice agar and soil leachate with grapefruit extract resulted in the inhibition of colony growth and sporulation of P. ramorum. Zoosporangia were more susceptible to the extract than pathogen hyphae and chlamydospores. Chitosan only slightly inhibited the colony growth and zoosporngia production. Spraying of rhododendron inoculated with P. ramorum with grapefruit extract at conc. 165 microg/cm3 inhibited 2-3 times the spread of necrosis on stems and leaves. Pre- and postinoculation spraying of rhododendrons with chitosan at conc. of 1000 microg/cm3 suppressed the disease spread about 40%.

Chitosan↗
PubMed1997

28s rDNA group-I introns: a powerful tool for identifying strains of Beauveria brongniartii.

The nuclear ribosomal DNA of the entomopathogenic fungus Beauveria brongniartii is polymorphic in terms of both restriction site and length. Insertions of 350-450 bp long, identified as group-I introns, were detected in the 28s rDNA. A panel of 47 strains of B. brongniartii, two B. bassiana and one Metarhizium anisopliae of various geographical and biological origins were found to contain 14 variant forms of intron differing in size and restriction pattern, at four different positions. Twelve types of ribosomal large subunit were defined on the basis of variant distribution and compared with strain clustering based on internal transcribed spacers analysis. There was a correlation between the characteristic introns and isolates collected from the sugar cane pest Hoplochelus marginalis. Primers for polymerase chain reaction amplification were chosen from these variants, and used to develop a specific method for detecting strains pathogenic towards Hoplochelus.

Animals↗
PubMed1997

In vitro studies on the potential for biological control of Aspergillus flavus and Fusarium moniliforme by Trichoderma species. 1. Macroscopical and microscopical observations of fungal interactions.

The possible biological control of the seed-associated fungi, Aspergillus flavus and Fusarium moniliforme by Trichoderma species was investigated. A study of the fungal growth in dual cultures revealed that four of nine isolates of two Trichoderma spp. (T. harzianum and T. viride) inhibited fungal growth. A scanning electron microscopical investigation of fungal interactions demonstrated no obvious hyphae penetration of A. flavus or F. moniliforme by Trichoderma spp. Morphological alteration of Fusarium hyphae with pronounced collapse and the production of aberrant conidial heads and microheads by A. flavus were observed. The results suggest that mycoparasitism is not the mechanism involved in the inhibitory interaction of either A. flavus or F. moniliforme with Trichoderma spp.

Antibiosis↗