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At least 1,027 records · Page 57Linked to original sources
PubMed1990

Construction of genetically engineered baculovirus insecticides containing the Bacillus thuringiensis subsp. kurstaki HD-73 delta endotoxin.

The delta-endotoxin gene from Bacillus thuringiensis subsp. kurstaki HD-73 was inserted into Autographa californica nuclear polyhedrosis virus (AcMNPV) using two transfer vector systems. In the first, the delta-endotoxin gene was placed under the control of the polyhedrin gene promoter in lieu of the polyhedrin coding sequences, thus deriving a polyhedrin-negative virus. In the second, it was inserted under the control of a copy of the AcMNPV p10 promoter positioned upstream of the polyhedrin gene to produce a polyhedrin-positive virus. Analysis of infected cell extracts showed that the delta-endotoxin was expressed in insect cells as 130K, 62K and 44K proteins, with peak syntheses at 18 h post-infection. Each of these products reacted with antisera specific for the complete protoxin and the cleaved, active form. When extracts from the cells infected with the polyhedrin-negative virus were fed to Trichoplusia ni larvae, feeding by the insects was inhibited and deaths occurred that were inconsistent with virus infection. This effect was also observed after the inoculum had been treated with detergents to inactivate virus particles prior to feeding to the larvae. These data indicate that the expression of the B. thuringiensis delta-endotoxin gene by a baculovirus in insect cells produces material with insecticidal activity. The biological activities of the two recombinant viruses were assessed in conventional bioassay tests by feeding virus particles or occlusion bodies to the insects. The polyhedrin-negative virus preparation appeared to be contaminated with endotoxin which inhibited feeding of the insects and prevented determination of the LD50 value. The polyhedrin-positive virus had an LD50 value about twofold higher than that of unmodified AcMNPV. The significance of these data for the genetic engineering of virus insecticides is discussed.

Animals↗
PubMed1994

The chemical and biological control of Lymnaea truncatula in natural watercress beds in the Limousin region (France).

The snails present in 17 natural watercress beds have been treated during 1 or 2 years by a control associating the use of a molluscicide (CuCl2) and the introduction of a predatory snail, Zonitoides nitidus. Lymnea truncatula was eliminated in only one year of treatment in 14 stations, and in two years in the three others. Elimination of other aquatic pulmonate snails was effected in two years for L. glabra, in 3 years for L. palustris, and in only one year for Physa acuta. Z. nitidus has disappeared from 12 watercress beds during the 4th year after treatment; in the five others, the numbers of this predator increased during 1 or 2 years and then decreased before their disappearance.

Animals↗
PubMed2002

Effective dose of a microbial inoculant is one to four cells in the rhizosphere.

A single-cell approach for studying the growth potential and the establishment of bacteria in the barley phytosphere is presented, using Pseudomonas fluorescens strain with the capability for biological control. The incidence of growth of one to four bacterial cells dispersed to the young rhizosphere approximated to 100%, and specific growth rate averaged 0.05. Net growth occurred for cells added to the rhizosphere at densities between 1 and 100,000 cells, while at higher densities population sizes declined, but always approached 10(5)-10(6) cells per rhizosphere. No net growth was observed in bulk soil, and cells died in the phyllosphere. Our results showed that bacterial establishment was more related to the availability of microhabitats supporting growth, than related to the number of bacteria released.

Biodegradation, Environmental↗
PubMed2000

Spider mites of Japan: their biology and control.

Spider mite biology and control in Japan were reviewed. Seventy-eight spider mite species of 16 genera (Family Tetranychidae) have been recorded in Japan. Several of the species recently described were separated from a species complex comprising strains with different ecological performance such as host range. These separations were first supported by crossing experiments and then confirmed by molecular genetic studies. Spider mite control in Japan is still dependent on heavy acaricide spraying in order to attain products of extremely high quality. The commercial use of natural enemies in spider mite management has just started.

Animals↗
PubMed2003

Managing the mycorrhizosphere--an approach to sustainable agriculture after the phaseout of methyl bromide?

Plant Health Promoting Rhizobacteria (PHPR) with known biocontrol activity toward the root knot nematode, Meloidogyne incognito, were tested for their ability to promote root colonization of arbuscular mycorrhizal fungi on tomato under greenhouse conditions. In addition, bacteria isolated from mycorrhizal spores were tested for their direct biological control activity on nematode early root penetration. The nematode antagonistic rhizobacteria Rhizobium etli G12 significantly increased mycorrhizal establishment. In addition, two of nine bacteria isolated from the mycorrhizosphere were shown to significantly reduce M. incognita early root penetration. The experiments produced important data on the interaction between rhizobacteria and the symbiotic fungus that in some combinations work synergistically in controlling the root-knot nematode. The potential of using such multitrophic treatment combinations in integrated management targeted first at reducing nematode early root penetration in young transplants and then later for sustainable biocontrol of root-knot under field conditions are discussed.

Animals↗
PubMed2006

The effects of the slug biological control agent, Phasmarhabditis hermaphrodita (Nematoda), on non-target aquatic molluscs.

The nematode Phasmarhabditis hermaphrodita is used as a commercial biological control agent of slugs in the UK. Although it is known to affect other terrestrial mollusc species, its effects on freshwater molluscs are not known. The present study investigated the effects of P. hermaphrodita on the survival of juvenile Lymnaea stagnalis and Physa fontinalis, two common freshwater snails, at 'spray tank' concentration and a 50% diluted 'spray tank' concentration over a 14-day period. Survival of L. stagnalis was significantly reduced at both application levels but P. fontinalis suffered no mortalities over the experimental period. The possible differential mechanisms of pathology between the two host species are discussed.

Animals↗
PubMed2004

Effects of endophytic Fusarium oxysporum towards Radopholus similis activity in absence of banana.

Four endophytic fungi (Fusarium spp.) isolated from the cortical tissue of surface-sterilised banana as well as from tomato roots were tested for their capacity of biological control towards the burrowing nematode Radopholus similis on banana. The pathogenic and parasitic capacities of endophytic fungi towards R. similis were tested in in vitro experiments. No parasitism of fungi on R. similis was observed. However, nematode activity decreased significantly in the presence of all endophytic fungi in vitro when compared to nematodes in the absence of fungi. The effects of fungi on R. similis activities in the soil were tested in the absence of plants. Nematode activities were reduced significantly by 16-30% by endophytic fungi when compared to untreated soil.

Animals↗
PubMed1990

Evaluation of cyclopoid copepods for Aedes albopictus control in tires.

Six species of cyclopoid copepods in New Orleans were tested for biological control of Aedes albopictus larvae in discarded tires. Six to 8 weeks after introduction, Diacyclops navus, Acanthocyclops vernalis, Mesocyclops ruttneri and Mesocyclops edax reduced the number of Ae. albopictus larvae by 83, 90, 95 and 96%, respectively. Macrocyclops albidus and Mesocyclops longisetus were the most effective species. Six to 8 weeks after introduction, Macrocyclops albidus reduced Ae. albopictus larvae by 99%. Three months after introduction Macrocyclops albidus reduced Ae. albopictus larvae by 100%, and Mesocyclops longisetus reduced Ae. albopictus larvae by 99.8%. Macrocyclops albidus and Mesocyclops longisetus were equally effective at eliminating Ae. aegypti and Ae. triseriatus larvae.

Aedes↗
PubMed2000

Effects of biorational pesticides on four coccinellid species (Coleoptera: Coccinellidae) having potential as biological control agents in interiorscapes.

The direct toxicity of insecticidal soap, horticultural oil, Azatin, an extract from the Neem tree containing azadiractin, and BotainiGard, a commercial formulation of the entomopathogenic fungus Beauveria bassiana, was assessed on adults of four species of coccinellids--Hippodamia convergens (Guérin-Ménéville), Coleomegilla maculata (DeGeer), Harmonia axyridis Pallas, and Cryptolaemus montrouzieri Mulsant. All biorationals caused less mortality than a conventional pesticide, carbaryl (Sevin). Horticultural oil (Sunspray ultrafine oil) consistently had no effect on beetle survivorship. Insecticidal soap (M-Pede) significantly reduced survival in all replicates for C. maculata and in at least one of the three replicates for the other three coccinellid species. Beauveria bassiana (BotaniGard) significantly reduced survival of C. montrouzieri at 72 h after spray in all three replicates. Azatin reduced survivorship in only one species, C. maculata, in only one of the three replicates.

Animals↗
PubMed1991

Comparative toxicity of seven insecticides to immature stages of Musca domestica (Diptera: Muscidae) and two of its important biological control agents, Muscidifurax raptor and Spalangia cameroni (Hymenoptera: Pteromalidae).

The toxicity of seven insecticides was evaluated against unparasitized Musca domestica L. pupae and pupae parasitized by Muscidifurax raptor Girault & Sanders or Spalangia cameroni Perkins, two important biological control agents. Only pyrethrins + piperonyl butoxide (Pyrenone) was less toxic to M. raptor compared with house flies. Conversely, all of the insecticides except crotoxyphos were less toxic to S. cameroni compared with house flies. A plateau in the tetrachlorvinphos bioassay line for S. cameroni suggested that this colony had approximately 45% resistant individuals. The selectivity observed between immature stages of house flies and M. raptor or S. cameroni is different from that reported against adult stages of these same species, suggesting that selectivity of an insecticide varies considerably between different life stages.

Animals↗
PubMed1991

Biological control of Culex mosquitoes (Diptera: Culicidae) by the tadpole shrimp, Triops longicaudatus (Notostraca: Triopsidae).

Laboratory oviposition choice tests and behavioral observations indicated that the activity of tadpole shrimp, Triops longicaudatus (LeConte), near the water surface deterred gravid Culex quinquefasciatus Say from ovipositing. In the cities of Oasis and Riverside, Calif., tadpole shrimp significantly reduced the abundance of immature mosquitoes (Cx. tarsalis Coquillett and Cx. quinquefasciatus) probably due to lowered oviposition rates, as well as tadpole shrimp predation. Generally, mosquito oviposition rates in field ponds with tadpole shrimp were lower than that of controls, except when tadpole shrimp were very young (4 d after flooding) or when their abundance had declined late in the flooding period. When analyzed by pond, tadpole shrimp size was correlated inversely with abundance; however, differences in size or abundance did not affect their capacity to reduce mosquito populations.

Animals↗
PubMed2003

Biological control of greenhouse whitefly (Trialeurodes vaporariorum) with fungal insecticides.

The influence of the biological insecticide Botanigard (Beauveria bassiana) on different developmental stages of the greenhouse whitefly (Trialeurodes vaporariorum) has been tested and compared with the influence of Preferal (Paecilomyces fumosoroseus), also a biological product. Six experiments were set up to test the two products on eggs, which were four and seven days old, on larvae of the first, second/third and fourth stage and to test the effect on egg-deposition. These experiments were all conducted on cucumber. Egg-deposition was limited to a small area on the leaf by using leaf cages. To evaluate these tests the number of eggs or larvae developed to the next stage has been counted and compared to the total amount of eggs or larvae on the leaves. The results revealed that Botanigard has an effect on the larval stages. The first larval stage is most sensitive; the next stages have a decreasing sensitivity. There was no influence on the hatching of the eggs, but a treatment short before the hatching could have a residual effect on the new nymphs. When the treatment with Botanigard is performed shortly before a moult or a fungicide treatment, the efficacy of the product decreases significantly. The influence of Preferal on the greenhouse whitefly is, under the same circumstances, less obvious.

Animals↗
PubMed1976

The suppression, by Helisoma duryi, of the cercarial production of Schistosoma mansoni-infected Biomphalaria pfeifferi.

Biological control of the intermediate hosts of Schistosoma mansoni and S. haematobium by means of a competitor snail, Helisoma duryi, has been suggested. In the present laboratory study, the influence of H. duryi on the relationship between the parasite and the intermediate host was investigated. The results indicated that H. duryi behaves as a "decoy" if it is present when Biomphalaria pfeifferi is exposed to the miracidia of S. mansoni, and that the continued presence of H. duryi in the aquarium after B. pfeifferi has been exposed greatly reduces cercarial production. When these two species were present in equal numbers, cercarial production was reduced by 95.9% in comparison with a control group.

Animals↗
PubMed2003

[Advances in vermiculture and inhibition of vermicompost to soil-borne disease].

The transformation of organic wastes into useful resources by vermiculture has been a biological technology for ages, and obtained a new development in 1970s. This paper mainly reviewed the methods of vermiculture, the physical and chemical aspects of vermicompost, and the comprehensive utilization of vermicompost, and emphasized the inhibition of vermicompost to soil-borne disease. Although the mechanisms of inhibition have not been fully understood, the application has great potentiality. The disease inhibition is related with the microflora, especially the large number antagonisms enriched in vermicompost.

Animals↗
PubMed1994

[Testing effectiveness of selected bio-insecticides for reducing the population of cockroaches (Blattella germanica L.)].

The usefulness was tested of the biological insecticides containing B. thuringiensis available in the market in the eradication of cockroaches. Thuridan was the most effective out of the tested insecticides in reducing the number of the insects. Its higher activity in relation to Thuricide was evident at all tested concentrations. Males were more sensitive than females. On the other hand, no significant response of cockroaches to M-one preparation was noted, since the per cent of dying insects was only slightly higher than in the control group.

Animals↗
PubMed2001

Biological control of Fusarium moniliforme in maize.

Fusarium moniliforme Sheldon, a biological species of the mating populations within the (italic)Gibberella fujikuroi species complex, i.e., population A [= G. moniliformis (Sheld.) Wineland], is an example of a facultative fungal endophyte. During the biotrophic endophytic association with maize, as well as during saprophytic growth, F. moniliforme produces the fumonisins. The fungus is transmitted vertically and horizontally to the next generation of plants via clonal infection of seeds and plant debris. Horizontal infection is the manner by which this fungus is spread contagiously and through which infection occurs from the outside that can be reduced by application of certain fungicides. The endophytic phase is vertically transmitted. This type infection is important because it is not controlled by seed applications of fungicides, and it remains the reservoir from which infection and toxin biosynthesis takes place in each generation of plants. Thus, vertical transmission of this fungus is just as important as horizontal transmission. A biological control system using an endophytic bacterium, Bacillus subtilis, has been developed that shows great promise for reducing mycotoxin accumulation during the endophytic (vertical transmission) growth phase. Because this bacterium occupies the identical ecological niche within the plant, it is considered an ecological homologue to F. moniliforme, and the inhibitory mechanism, regardless of the mode of action, operates on the competitive exclusion principle. In addition to this bacterium, an isolate of a species of the fungus Trichoderma shows promise in the postharvest control of the growth and toxin accumulation from F. moniliforme on corn in storage.

Antibiosis↗
PubMed2004

Biological control of fire ants: an update on new techniques.

OBJECTIVE: To review the present understanding of biological control methods for imported fire ants (IFAs). DATA SOURCES: We searched MEDLINE, Biological Abstracts, and the US Department of Agriculture Formis Ant Literature database. STUDY SELECTION: All articles published in the last 10 years on biological control of fire ants were selected. RESULTS: The decapitating flies Pseudacteon tricuspis, Pseudacteon curvatus, and Pseudacteon litoralis have been successfully released in the United States. The continued releases of multiple species of decapitating flies will expand the area of impact, applying greater pressure on IFA populations throughout the southern United States. The microsporidium Thelohania solenopsae causes the slow demise of a fire ant colony. The advantages of T. solenopsae as a biological control agent include debilitation of queens, specificity for IFAs, self-sustaining infections, and lower relative tolerance to chemical pesticides. Solenopsis daguerrei has also been shown to have detrimental effects on IFA colony growth, the number of sexual reproductives produced, and the number of host queens in multiple queen colonies; however, this parasite is difficult to rear in the laboratory and to introduce into IFA colonies. CONCLUSIONS: It is unlikely that IFAs can be completely eradicated from the United States. However, technology using chemicals and/or natural control agents could eventually maintain populations at low levels if an integrated approach is used for control.

Animals↗
PubMed2000

Feasibility of controlling Ixodes scapularis ticks (Acari: Ixodidae), the vector of Lyme disease, by parasitoid augmentation.

A theoretical analysis of the feasibility of controlling tick populations (Ixodidae) by the release of reared Ixodiphagus parasitoids in tick ecosystems yielded promising results. The analysis suggested that if reasonable progress could be made in mass-rearing the parasitoids, it would be possible to control the blacklegged tick, Ixodes scapularis (Say), the vector of Lyme disease, by this biological control procedure. Lyme disease has become the most important vector-borne disease in the United States. In a field-release experiment conducted in Africa by members of the International Center for Insect Physiology and Ecology, effective control of Amblyomma variegatum (F.) was obtained by the release of Ixodiphagus parasitoids in tick habitats. Encouraging theoretical results along with the encouraging results of a field-release experiment indicate the need for civil and political leaders in countries where ticks are a major problem to sponsor strong and well-coordinated research initiatives focused on the development of this new method of dealing with tick problems.

Animals↗