SEARCH · PubMed Health

Results for “Pest Control, Biological”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources

PubMed1985

[Reevaluation of the biological control of vector mosquitoes using predatory larvae of Toxorhynchites mosquitoes].

Attempts to control mosquito-borne disease using predatory mosquitoes such as Toxorhynchites larvae have led to indefinite results for many years, mainly because of the lack of adequate species or strains of Toxorhynchites. Recent improvements of natural and artificial matings of adults in the laboratory and of mass breeding of larvae, however, have made it possible to establish laboratory colonies of most Toxorhynchites species whenever and wherever necessary. Effects of biological control by releasing large numbers of Toxorhynchites mosquitoes should be reevaluated from a new concept of comparing the usual chemical insecticides with the living and flying "insecticides" which cause no environmental pollution.

Animals↗

PubMedDate not supplied

[Bases for control of arthropod vectors: II--Present means (author's transl)].

A review of the present means of control of arthropod vectors in which the authors consider:--individual means aimed at the prevention of bites by utilizing clothes, repellents, mosquito nets and insecticide sprays,--collective means which are either physical, biological or chemical. Physical means are specially used for water control either in "peridomestic actions" or in large scale campaign's related to rural or industrial development scheme. Actually biological means are represented only by larvivorous fishes. The chemical control is the most important, its various requisites, and techniques are given.

Animals↗

PubMed2002

Beauveria bassiana yeast phase on agar medium and its pathogenicity against Diatraea saccharalis (Lepidoptera: Crambidae) and Tetranychus urticae (Acari: Tetranychidae).

Beauveria bassiana colonizes insect hosts initially through a yeast phase, which is common in some artificial liquid cultures, but not reported on artificial solid media. We describe a yeast-like phase for B. bassiana isolate 447 (ATCC 20872) on MacConkey agar and its virulence toward Diatraea saccharalis and Tetranychus urticae. The yeast-like cells of B. bassiana developed by budding from germinating conidia after 24-h incubation. Cells were typically 5-10 microm and fungal colonies were initially circular and mucoid, but later were covered with mycelia and conidia. Ability to produce yeast-like cells on MacConkey medium was relatively common among different B. bassiana isolates, but growth rate and timing of yeast-like cell production also varied. Metarhizium anisopliae and Paecilomyces spp. isolates did not grow as yeast-like cells on MacConkey medium. Yeast-like cells of B. bassiana 447 were more virulent against D. saccharalis than conidia when 10(7)cells/ml were used. At 10(8)cells/ml, the estimated mean survival time was 5.4 days for the yeast suspension and 7.7 days for the conidial suspension, perhaps due to faster germination. The LC(50) was also lower for yeast than conidial suspensions. Yeast-like cells and conidia had similar virulence against T. urticae; the average mortalities with yeast-like cells and conidia were, respectively, 42.8 and 45.0%, with 10(7)cells/ml, and 77.8 and 74.4%, with 10(8)cells/ml. The estimated mean survival times were 3.6 and 3.9 for yeast and conidial suspensions, respectively. The bioassay results demonstrate the yeast-like structures produced on MacConkey agar are effective as inoculum for B. bassiana applications against arthropod pests, and possibly superior to conidia against some species. Obtaining well-defined yeast phase cultures of entomopathogenic hyphomycetes may be an important step in studies of the biology and nutrition, pathogenesis, and the genetic manipulation of these fungi.

Agar↗

PubMed2000

[Research progress on PGPR/AMF interactions].

As one of the rhizospheric microorganisms PGPR(Plant Growth Promoting Rhizobacteria) and AMF(Arbuscular Mycorrhizal Fungi) play an important role in promoting plant growth. It is of significance to further study and elucidate the interactions between them to utilize and regulate the interactions among rhizospheric microorganisms, and promote and protecte plant growth. Many research results show that on one hand, there exists synergism between PGPR and AMF. AMF can transfer PGPR or act as a media in the process of spread of PGPR along roots, where PGPR create many beneficial conditions for the infection of AMF. Both of them can indirectly enhance the other side's colonization or infection ability through their own promoting role on plant growth. On the other hand, they compete with each other for nutrients and niches, and probably produce some secondary metabolites which cause detrimental effects on the other. However, whether these interactions are synergistic or competitive depends upon the AM fungal or PGPR species involved. So far, the research work is extensive, even in molecular level in some aspects, but not systematic and deep. It is believed however, with the development of techniques in molecular biology and the increasing application of advanced testing methods, the new breakthroughs will be gained in the study and understanding on the interactions.

Bacterial Physiological Phenomena↗

PubMed2004

Biological control of chestnut blight with hypovirulence: a critical analysis.

Most hypovirulence in the chestnut blight fungus, Cryphonectria parasitica, is associated with infection by fungal viruses in the family Hypoviridae. Hypovirulence has controlled chestnut blight well in some locations in Europe and in Michigan in the United States. In contrast, with few exceptions, biological control has failed almost completely in eastern North America. Therapeutic treatment of individual cankers is successful in most cases, but the success of hypovirulence at the population level depends on the natural spread of viruses. Characteristics of three interacting trophic levels (virus, fungus, and tree), plus the environment, determine the success or failure of hypovirulence. Vegetative incompatibility restricts virus transmission, but this factor alone is a poor predictor of biological control. Any factor reducing the rate of chestnut blight epidemics enhances hypovirus invasion. Overall, however, not enough is understood about the epidemiological dynamics of this system to determine the crucial factors regulating the establishment of hypovirulence in chestnut forests.

Aesculus↗

PubMed2004

[Evaluation of the impact on Aedes aegypti infestation in cement tanks of the municipal district of Canindé, Ceará, Brazil after using the Betta splendens fish as an alternative biological control].

Canindé has a population of 71,235 inhabitants. In April 2001, the city started using larvivorous fish in cement water tanks, as a means of biological control of Aedes aegypti larvae. During house-to-house visits by health agents, instead of treating the water tank with larvicide, a Betta splendens fish was introduced into each tank. The number of houses and the number of tanks was estimated by monthly surveys. Then, the number of tanks per house was determined. Taking into account this estimated number and the number of houses visited, the infestation level for each kind of deposit was analyzed. In January 2001, 70.4% of the water tanks presented mosquitoes. Following the intervention, in January 2002 only 7.4% were positive and by December 2002 the rate had dropped to 0.2%. The efficacy of Betta splendens as a biological control agent in cement water tanks was clearly demonstrated, by achieving a 320 times reduction in the infestation level.

Aedes↗

PubMed2003

Preparation of spray-dried wettable powder formulations of Bacillus thuringiensis-based biopesticides.

Bacillus thuringiensis is the most widely used biopesticide among many methods available to control insects. To make a saleable product, B. thuringiensis must be substantially concentrated by removal of water and formulated to improve longevity, efficacy, and ease of transport of the product. B. thuringiensis subsp. aizawai culture broth as an active ingredient was mixed with various adjuvants and then spray dried. The optimum conditions for spray drying were found to be an outlet temperature of 60-85 degrees C and an inlet temperature of 120-180 degrees C. Various adjuvants had different effects on physical and biological properties of the dried product. Gelatinized tapioca starch and milk powder improved suspensibility but adversely affected wettability of the dried formulated product. Vegetable oil and Tween 20 enhanced wettability but resulted in poor suspensibility. Silica fume was used to enhance flowability because it reduced clumping and caking of the powder resulting from the addition of vegetable oil. Formulation containing 10% wt:wt B. thuringiensis, 10% wt:wt gelatinized tapioca starch, 10% wt:wt sucrose, 38% wt:wt tapioca starch, 20% wt:wt milk powder, 10% wt:wt silica fume, 2% wt:wt polyvinyl alcohol, 5% vol:vol Tween 20, 1% vol:vol refined rice bran oil, and 1% vol:vol antifoam solution was found to be optimum in terms of the physical and biological properties of the dried product. This formulation had 55% suspensibility, 24 s for wetting time, and 5.69 x 10(4) CFU/ml of LC50 value against Spodoptera exigua larvae.

Agrochemicals↗

PubMed1975

Studies of the infection of the cockroaches (Blattella germanica[L.]) with Bac. thuringensis.

The results of an experimental infection of the cockroaches Blattella germanica (L.) with some trade preparations containing Bac. thuringensis spores are presented. Biological studies supported by bacteriological and histological examinations of the excised intestines of the above insects have shown that the microorganisms studied are pathogenic for the cockroaches. This effect might be eventually applied as a biological method of eradication of the cockroaches in such environments, where chemical preparations can not be used or this disinfestation method would be complementary to the other method of disinfestation.

Animals↗

PubMed2002

Biological control of Fusarium head blight of wheat and deoxynivalenol levels in grain via use of microbial antagonists.

Efforts to reduce mycotoxin contamination in food logically start with minimizing plant infection by mycotoxin producing pathogens. Fusarium graminearum (perfect state, Gibberella zeae) infects wheat heads at flowering, causing the disease Fusarium head blight (FHB) and losses of over 2.6 billion dollars in the U.S. during the last 10 years. The pathogen often produces deoxynivalenol (DON) resulting in grain size and quality reduction. Highly resistant wheat cultivars currently are not available for reducing FHB, and labeled fungicides are not consistently effective. The feasibility of biologically controlling FHB is currently being evaluated. Microbial isolates obtained from wheat anthers were screened for their ability to utilize tartaric acid, a compound that is poorly utilized by F. graminearum and could be utilized in formulations of biological control agents. Four strains that utilized tartaric acid and three that did not were effective in reducing FHB disease severity by up to 95% in greenhouse and 56% in field trials. Additional research programs around the globe have identified other antagonist strains with potential for biologically controlling FHB. Though a considerable body of research remains to be completed, strategies and microorganisms for biologically controlling FHB have reached an advanced stage of development and offer the promise of being an effective tool that could soon contribute to the reduction of FHB severity and DON contamination of grain in commercial agriculture.

Fungicides, Industrial↗

PubMed1992

Traits of fluorescent Pseudomonas spp. involved in suppression of plant root pathogens.

Certain members of the fluorescent pseudomonad group have been shown to be potential agents for the biocontrol of plant root diseases. The major problems with the commercialization of these beneficial strains are that few wild-type strains contain all the desired characteristics for this process and the performance of strains in different soil and climatic conditions is not reproducible. Consequently, prior to selection and/or improvement of suitable strains for biocontrol purposes, it is necessary to understand the important traits required for this purpose. The production of fluorescent siderophores (iron-binding compounds) and antibiotic compounds has been recognized as important for the inhibition of plant root pathogens. Efficient root colonization is also a prerequisite for successful biocontrol strains. This review discusses some of the characteristics of fluorescent pseudomonads that have been suggested to be important for biocontrol. The genetic organization and regulation of these processes is also examined. This information is necessary for attempts aimed at the improvement of strains based on deregulating pathways or introducing traits from one strain to another. The release of genetically engineered organisms into the environment is governed by regulations, and this aspect is summarized. The commercialization of fluorescent pseudomonads for the biological control of plant root diseases remains an exciting possibility. The understanding of the relevant characteristics will facilitate this process by enabling the direct selection and/or construction of strains which will perform under a variety of environmental conditions.

Anti-Bacterial Agents↗

PubMed2001

Potential for areawide integrated management of Mediterranean fruit fly (Diptera: Tephritidae) with a braconid parasitoid and a novel bait spray.

The braconid wasp, Fopius arisanus (Sonan), a biological control agent for Mediterranean fruit fly, Ceratitis capitata (Wiedemann), was studied in coffee, Coffea arabica L. Fopius arisanus, comprised 79.3% of the total parasitoids (7,014) recovered from fruits collected at three small coffee farms. Data from seasonal host/parasitoid studies at a large coffee plantation also suggested that the most effective natural enemy of C. capitata in coffee may now reside in Hawaii. The original parasitoids introduced into Hawaii for C. capitata control (Diachasmimorpha tryoni (Cameron), Tetrastichus giffardianus Silvestri, and Dirhinus giffardii Silvestri) are now rare. Abundance of F. arisanus with respect to other parasitoids collected was influenced by elevation (274, 457, 610 m). Fopius arisanus was the dominant parasitoid at all three elevations, Diachasmimorpha longicaudata (Ashmead) occurred consistently, and T. giffardianus was abundant only at low elevation. The impacts on C. capitata and F. arisanus populations of bait sprays containing malathion, spinosad, or phloxine B applied to coffee were also evaluated. All three bait sprays suppressed C. capitata populations. Spinosad and phloxine B bait sprays appeared less harmful to the wasp than malathion. Fopius arisanus offers the potential for areawide management of C. capitata that includes biological control and integration with more environmentally safe chemical controls such as spinosad and phloxine B bait sprays.

Animals↗

PubMed2003

Animal self-medication and ethno-medicine: exploration and exploitation of the medicinal properties of plants.

Early in the co-evolution of plant-animal relationships, some arthropod species began to utilize the chemical defences of plants to protect themselves from their own predators and parasites. It is likely, therefore, that the origins of herbal medicine have their roots deep within the animal kingdom. From prehistoric times man has looked to wild and domestic animals for sources of herbal remedies. Both folklore and living examples provide accounts of how medicinal plants were obtained by observing the behaviour of animals. Animals too learn about the details of self-medication by watching each other. To date, perhaps the most striking scientific studies of animal self-medication have been made on the African great apes. The great ape diet is often rich in plants containing secondary compounds of non-nutritional, sometimes toxic, value that suggest medicinal benefit from their ingestion. Chimpanzees (Pan troglodytes), bonobos (Pan paniscus) and gorillas (Gorilla gorilla) are known to swallow whole and defecate intact leaves. The habit has been shown to be a physical means of purging intestinal parasites. Chimpanzees and man co-existing in sub-Saharan Africa are also known to ingest the bitter pith of Vernonia amygdalina for the control of intestinal nematode infections. Phytochemical studies have demonstrated a wide array of biologically-active properties in this medicinal plant species. In light of the growing resistance of parasites and pathogens to synthetic drugs, the study of animal self-medication and ethno-medicine offers a novel line of investigation to provide ecologically-sound methods for the treatment of parasites using plant-based medicines in populations and their livestock living in the tropics.

Animals↗

PubMed1984

Socio-economic problems related to animal trypanosomiasis in Africa.

Animal trypanosomiasis is one of the major constraints of rural development in Africa. If trypanosomiasis did not exist in these areas, it is estimated that some regions could carry 3-5 times more livestock. Chemotherapy and chemoprophylaxis are old methods used to tackle the problem and are still valuable, provided the number of interventions is limited. Tse-tse fly control is a very useful tool to combat trypanosomiasis but expensive. The sterile male release technique is not economically feasible on a wide scale. Immunization or vaccination is not yet available. Trypanotolerance is a biological phenomenon; it seems to be a valid method, which allow African countries to keep and increase livestock within economically feasible conditions; but inevitably it will be a long exercise.

Africa↗

PubMed2001

Suppression of maize root diseases caused by Macrophomina phaseolina, Fusarium moniliforme and Fusarium graminearum by plant growth promoting rhizobacteria.

A plant growth-promoting isolate of a fluorescent Pseudomonas sp. EM85 and two bacilli isolates MR-11(2) and MRF, isolated from maize rhizosphere, were found strongly antagonistic to Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina, causal agents of foot rots and wilting, collar rots/stalk rots and root rots and wilting, and charcoal rots of maize, respectively. Pseudomonas sp. EM85 produced antifungal antibiotics (Afa+), siderophore (Sid+), HCN (HCN+) and fluorescent pigments (Flu+) besides exhibiting plant growth promoting traits like nitrogen fixation, phosphate solubilization, and production of organic acids and IAA. While MR-11(2) produced siderophore (Sid+), antibiotics (Afa+) and antifungal volatiles (Afv+), MRF exhibited the production of antifungal antibiotics (Afa+) and siderophores (Sid+). Bacillus spp. MRF was also found to produce organic acids and IAA, solubilized tri-calcium phosphate and fixed nitrogen from the atmosphere. All three isolates suppressed the diseases caused by Fusarium moniliforme, Fusarium graminearum and Macrophomina phaseolina in vitro. A Tn5:: lacZ induced isogenic mutant of the fluorescent Pseudomonas EM85, M23, along with the two bacilli were evaluated for in situ disease suppression of maize. Results indicated that combined application of the two bacilli significantly (P = 0.05) reduced the Macrophomina-induced charcoal rots of maize by 56.04%. Treatments with the MRF isolate of Bacillus spp. and Tn5:: lacZ mutant (M23) of fluorescent Pseudomonas sp. EM85 significantly reduced collar rots, root and foot rots, and wilting of maize caused by Fusarium moniliforme and F. graminearum (P = 0.05) compared to all other treatments. All these isolates were found very efficient in colonizing the rhizotic zones of maize after inoculation. Evaluation of the population dynamics of the fluorescent Pseudomonas sp. EM85 using the Tn5:: lacZ marker and of the Bacillus spp. MRF and MR-11(2) using an antibiotic resistance marker revealed that all the three isolates could proliferate successfully in the rhizosphere, rhizoplane and endorhizosphere of maize, both at 30 and 60 days after seeding. Four antifungal compounds from fluorescent Pseudomonas sp. EM85, one from Bacillus sp. MR-11(2) and three from Bacillus sp. MRF were isolated, purified and tested in vitro and in thin layer chromatography bioassays. All these compounds inhibited R. solani, M. phaseolina, F. moniliforme, F. graminearum and F. solani strongly. Results indicated that antifungal antibiotics and/or fluorescent pigment of fluorescent Pseudomonas sp. EM85, and antifungal antibiotics of the bacilli along with the successful colonization of all the isolates might be involved in the biological suppression of the maize root diseases.

Antibiosis↗

PubMed2000

Prospects for the biological control of subterranean termites (Isoptera: rhinotermitidae), with special reference to Coptotermes formosanus.

Costs associated with subterranean termite damage and control are estimated to approach $2 billion annually in the United States alone. The Formosan subterranean termite, Coptotermes formosanus Shiraki, is one of the more economically important subterranean species. In recent years, the shortcomings associated with conventional chemical control methods have prompted policymakers and scientists to evaluate the potential for biological control of subterranean termites (C. formosanus in particular), that is, to determine the potential for natural enemies - predators, parasitoids and pathogens - to suppress termite populations. Ants are the greatest predators of termites, and may have a considerable local impact on termite populations in some areas of the world. A few parasitoids of termites are known, but their potential for regulating termite populations seems negligible. Characteristics of the colony, such as a protected, underground location (and, for the C. formosanus nest, its modular and dispersed nature), are likely to limit the impact predators and parasitoids have on subterranean termites. Thus, there seems little potential for use of these agents for subterranean termite control. For various reasons, pathogenic organisms, such as viruses, bacteria, Protozoa, nematodes and most fungi, have shown little promise for use in biological termite control. However, research suggests that strains of two well-studied, endoparasitic fungi, Beauveria bassiana and Metarhizium anisopliae, when employed in baiting schemes, may offer the potential for at least some measure of subterranean termite control, although their successful use is compromised by a number of inherent biological limitations and logistical problems that have yet to be solved. Although not strictly in the realm of classical biological control, recent studies suggest that natural products, such as ant semiochemicals and fungal metabolites (siderophores), or their synthetic analogues, eventually might find a use in termite control programmes as repellents or insecticides in wood treatments or soil applications if stable formulations can be developed.

Animals↗

PubMed1994

Potential of genes and gene products from Trichoderma sp. and Gliocladium sp. for the development of biological pesticides.

Fungal cell wall degrading enzymes produced by the biocontrol fungi Trichoderma harzianum and Gliocladium virens are strong inhibitors of spore germination and hyphal elongation of a number of phytopathogenic fungi. The purified enzymes include chitinolytic enzymes with different modes of action or different substrate specificity and glucanolytic enzymes with exo-activity. A variety of synergistic interactions were found when different enzymes were combined or associated with biotic or abiotic antifungal agents. The levels of inhibition obtained by using enzyme combinations were, in some cases, comparable with commercial fungicides. Moreover, the antifungal interaction between enzymes and common fungicides allowed the reduction of the chemical doses up to 200-fold. Chitinolytic and glucanolytic enzymes from T. harzianum were able to improve substantially the antifungal ability of a biocontrol strain of Enterobacter cloacae. DNA fragments containing genes encoding for different chitinolytic enzymes were isolated from a cDNA library of T. harzianum and cloned for mechanistic studies and biocontrol purposes. Our results provide additional information on the role of lytic enzymes in processes of biocontrol and strongly suggest the use of lytic enzymes and their genes for biological control of plant diseases.

Acetylglucosaminidase↗

PubMed2003

Phytoseiid predators of whiteflies feed and reproduce on non-prey food sources.

Two phytoseiid species, Euseius scutalis (Athias-Henriot) and Typhlodromips swirskii (Athias-Henriot), are able to suppress whitefly populations on single plants and are candidate biological control agents for whiteflies such as Bemisia tabaci (Gennadius). These species can feed on pollen and insect-produced honeydew and these food sources are likely to be available in crops. If the utilization of these food types results in increased reproduction or survival, populations of predators can persist when whitefly prey is scarce or absent. We studied the impact of pollen and whitefly-produced honeydew on the life history of the two phytoseiids. Cattail pollen allowed for survival, development and reproduction of both predators. Whitefly-produced honeydew greatly increased survival of E. scutalis, allowed for development into adulthood and for a sustained low rate of oviposition. The survival of adult T. swirskii was high on cucumber leaf tissue, either with or without pollen or honeydew. Oviposition by adults and juvenile survival of T. swirskii was very low in presence of honeydew. Biological control of whiteflies may benefit from both pollen and honeydew because these non-prey food sources have a positive effect on the life history of the two predator species, especially E. scutalis.

Acari↗

PubMed2001

Population dynamics of the white wax scale, Ceroplastes destructor (Hemiptera: Coccidae), on citrus in South Africa, with implications for biological control.

The population dynamics of the white wax scale, Ceroplastes destructor Newstead, was studied intensively in four easy-peel citrus orchards in the Western Cape Province of South Africa over three consecutive years (1997-1999). Key factor analysis was used to determine and quantify the contribution of individual mortality factors to the total generation mortality. Key stage mortality, determined from a cohort life table, was in the third instar and pre-ovipositing female stages. Mortality of C. destructor was caused primarily by parasitoids, predators and miscellaneous factors. Parasitoids and miscellaneous factors acted as density-dependent regulatory agents during the pre-ovipositional and first instar stages respectively. This has implications for biological control of C. destructor. Some of the mortality factors acted either randomly with no reference to the population densities or in an inverse density-dependent manner during the egg-crawler, second or third instar stages.

Animals↗