Control of schistosomiasis by use of biological control of snail hosts with special reference to competition.
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Animals↗
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Carl Freiherr von Tubeuf: pioneer in biological control of plant diseases.
Carl von Tubeuf, a founder of plant pathology in Europe, pioneered biological control of a major plant disease and introduced the term "biological control" to plant pathology. His book on plant diseases was one of the first to be published in English. He was proficient in many areas, and his interests included plant diseases, mycology, forest insects, white pine blister rust, the mistletoes, plant protection laws, and nature conservation.
Europe↗
Plant-related factors influence the effectiveness of Neoseiulus fallacis (Acari: Phytoseiidae), a biological control agent of spider mites on landscape ornamental plants.
The predatory mite Neoseiulus fallacis (Garman) was evaluated as a biological control agent of herbivorous mites on outdoor-grown ornamental landscape plants. To elucidate factors that may affect predator efficiency, replicated tests were conducted on 30 ornamental plant cultivars that varied in relationship to their generalized morphology (e.g., conifers, shade trees, evergreen shrubs, deciduous shrubs, and herbaceous perennials), production method (potted or field grown), canopy density, and the prey species present on each. Plant morphological grouping and foliar density appeared to be the most influential factors in predicting successful biological control. Among plant morphological groups, N. fallacis was most effective on shrubs and herbaceous perennials and less effective on conifers and shade trees. N. fallacis was equally effective at controlling spider mites on containerized (potted) and field grown plants, and there was no difference in control of mites on plants with Tetranychus spp. versus those with Oligonychus or Schizotetranychus spp. Moderate to unsuccessful control of spider mites by N. fallacis occurred mostly on tall, vertical plants with sparse canopies. Acceptable spider mite control occurred in four large-scale releases of N. fallacis into production plantings of Abies procera, Thuja occidentalis 'Emerald', Malus rootstock, and Viburnum plicatum 'Newport'. These data suggest that N. fallacis can be an effective biological control agent of multiple spider mite species in a range of low-growing and selected higher growing ornamental plants.
Acari↗
Biological control of Botrytis gray mould and Sclerotinia drop in lettuce.
Research was carried out to evaluate the effectiveness of the biological control of two most important fungal diseases of lettuce (Lactuca sativa L.): 1) Botrytis Gray Mould caused by Botrytis cinerea Pers. ex Fr.; 2) Sclerotinia Drop caused by two pathogenic fungi, Sclerotinia sclerotiorum (Lib.) De Bary and/or Sclerotinia minorJagger. Biological control in lettuce was carried out: 1) using Coniothyrium minitans Campbell, an antagonist fungus that attacks and destroys sclerotia within the soil; 2) identifying lettuce genotypes showing less susceptibility or tolerance. The object of this research was to find control strategies to reduce chemical treatments. The use of resistant varieties is one of the most economical ways to control vegeTable diseases. The lettuce genotypes showing in preliminary trials the best behaviour to the sclerotial diseases were compared in a randomized complete block experiment design and replicated four times. Observations were carried out from February up to April registering the number of diseased plants and yield. The pathogens were isolated on PDA medium and identified. The isolates grown onto PDA plates, after incubation for 6 weeks, allowed obtaining sclerotia that were the target of C. minitans in biological control trials. In laboratory, in controlled conditions, 27 small plots (30 cm in diameter each) with disinfected soil were performed. In 18 plots 9 sclerotia were inoculated (per plot, three of each fungus) and in 9 plots of them a suspension of the antagonist fungus was added. Subsequently, three lettuce varieties were transplanted. For each variety were compared: 1) untreated plots; 2) treated plots with sclerotia only; 3) treated plots with sclerotia and C. minitans suspension. The number of diseased plants was recorded. According to symptom evaluation scale, ranged from 0 (no disease) up to 10 (100% necrotic leaves or dead plants) the plants were grouped into infection classes, calculating the McKinney index. In greenhouse trials, "LM 1307" genotype showed less significant susceptibility to Botrytis Gray Mould (0-2% of affected plants), while "Ninja" and "Charmy" showed 4-11% and 16-26% of diseased plants, respectively. The yields were 69.7, 62.7, 55.3 t/Ha, respectively. In laboratory tests, the McKinney index gave the following results: no disease in all untreated plants; 38.3, 54.2 and 89.2% in "LM 1307", "Ninja" and "Charmy" treated with sclerotia only, respectively; 2.5, 7.5 and 20.8% in "LM 1307", "Ninja" and "Charmy" treated with sclerotia and C. minitans, respectively. In conclusion, the less susceptibility of the genotypes to sclerotial diseases and the use of hyperparasites of sclerotia of phytopathogenic fungi exhibited best results.
Antibiosis↗
Biological control of strawberry tarsonemid mite Phytonemus pallidus and two-spotted spider mite Tetranychus urticae on strawberry in the UK using species of Neoseiulus (Amblyseius) (Acari: Phytoseiidae).
Two species of Neoseiulus, N. californicus and N. cucumeris, showed potential for biocontrol of phytophagous mites on strawberry. N. californicus controlled Tetranychus urticae on potted strawberry plants in a gauze-sided glasshouse at temperatures comparable to early summer in the UK (8-20 degrees C). Both species of phytoseiid reduced numbers of the tarsonemid Phytonemus pallidus on potted strawberry plants under glasshouse conditions (15-23 degrees C). In several experiments reductions in the range of 71-81% in numbers of tarsonemid active stages and eggs, compared to non-release plants, were obtained. The importance of establishing a suitable predator: prey ratio at an early stage was demonstrated in an experiment where an initial ratio of 1 N. cucumeris: 10 P. pallidus gave a greater degree of control than 1:20 or 1:40.
Animals↗
Susceptibility of the leaf-eating beetle, Galerucella calmariensis, a biological control agent for purple loosestrife (Lythrum salcaria), to three mosquito control larvicides.
We evaluated the susceptibility of Galerucella calmariensis, a species used to control purple loosestrife (Lythrum salicaria), to three mosquito control larvicides. Larvae and adults were fed loosestrife cuttings dipped in Abate (< or = 375 g x L(-1)), Altosid (< or = 250 g x L(-1)), and Bacillus thuringiensis var israeliensis (Bti) (< or = 110 g x L(-1)). Eggs on cuttings were dipped in the same concentrations. Pupae were immersed in Abate and Altosid solutions (< or = 474.4 microg x L(-1) and < or = 1,169.2 microg x L(-1), respectively). Hatching success of eggs dipped in Abate (> or = 3.75 g x L(-1)) was reduced significantly and survival was significantly lower among larvae and adults eating cuttings dipped in Abate (> or = 0.17 g x L(-1) and > or = 2.27 g x L(-1), respectively). Hatching success of eggs dipped in Altosid (> or = 2.52 g x L(-1)) was reduced significantly. With exposure to Altosid, larval survival to pupation and adult emergence was reduced significantly at concentrations of > or = 2.92 g x L(-1) and > or = 0.63 g x L(-1), respectively. Altosid (> or = 0.23 g x L(-1)) also delayed the onset of pupation and adult emergence among larvae that survived to pupate. Larvae that survived with exposure to Altosid (> or = 1.72 g x L(-1)) grew to 70% larger than those exposed to lower concentrations. Pupal survival was unaffected with exposure to Abate and Altosid and adult survival was unaffected with exposure to Altosid. Bacillus thuringiensis var israeliensis did not adversely affect any life stage of G. calmariensis. The mean Abate concentration on cuttings exposed to operational spraying was in the range that reduced egg hatchability and adult survival but was higher than concentrations that caused complete mortality of larvae. The mean Altosid concentration on cuttings exposed to operational spraying was in the range that reduced hatching success in eggs and delayed pupation and adult emergence of larvae.
Animals↗
A clp gene homologue belonging to the Crp gene family globally regulates lytic enzyme production, antimicrobial activity, and biological control activity expressed by Lysobacter enzymogenes strain C3.
Lysobacter enzymogenes strain C3, a biological control agent for plant diseases, produces multiple extracellular hydrolytic enzymes and displays antimicrobial activity against various fungal and oomycetous species. However, little is known about the regulation of these enzymes or their roles in antimicrobial activity and biocontrol. A study was undertaken to identify mutants of strain C3 affected in extracellular enzyme production and to evaluate their biocontrol efficacy. A single mini-Tn5-lacZ(1)-cat transposon mutant of L. enzymogenes strain C3 that was globally affected in a variety of phenotypes was isolated. In this mutant, 5E4, the activities of several extracellular lytic enzymes, gliding motility, and in vitro antimicrobial activity were reduced. Characterization of 5E4 indicated that the transposon inserted in a clp gene homologue belonging to the Crp gene family of regulators. Immediately downstream was a second open reading frame similar to that encoding acetyltransferases belonging to the Gcn5-related N-acetyltransferase superfamily, which reverse transcription-PCR confirmed was cotranscribed with clp. Chromosomal deletion mutants with mutations in clp and between clp and the acetyltransferase gene verified the 5E4 mutant phenotype. The clp gene was chromosomally inserted in mutant 5E4, resulting in complemented strain P1. All mutant phenotypes were restored in P1, although the gliding motility was observed to be excessive compared with that of the wild-type strain. clp mutant strains were significantly affected in biological control of pythium damping-off of sugar beet and bipolaris leaf spot of tall fescue, which was partially or fully restored in the complemented strain P1. These results indicate that clp is a global regulatory gene that controls biocontrol traits expressed by L. enzymogenes C3.
Acetyltransferases↗
Differential inactivation of seed exudate stimulation of Pythium ultimum sporangium germination by Enterobacter cloacae influences biological control efficacy on different plant species.
This study was initiated to understand whether differential biological control efficacy of Enterobacter cloacae on various plant species is due to differences in the ability of E. cloacae to inactivate the stimulatory activity of seed exudates to Pythium ultimum sporangium germination. In biological control assays, E. cloacae was effective in controlling Pythium damping-off when placed on the seeds of carrot, cotton, cucumber, lettuce, radish, tomato, and wheat but failed to protect corn and pea from damping-off. Seeds from plants such as corn and pea had high rates of exudation, whereas cotton and cucumber seeds had much lower rates of exudation. Patterns of seed exudation and the release of P. ultimum sporangium germination stimulants varied among the plants tested. Seed exudates of plants such as carrot, corn, lettuce, pea, radish, and wheat were generally more stimulatory to P. ultimum than were the exudates of cotton, cucumber, sunflower, and tomato. However, this was not directly related to the ability of E. cloacae to inactivate the stimulatory activity of the exudate and reduce P. ultimum sporangium germination. In the spermosphere, E. cloacae readily reduced the stimulatory activity of seed exudates from all plant species except corn and pea. Our data have shown that the inability of E. cloacae to protect corn and pea seeds from Pythium damping-off is directly related to its ability to inactivate the stimulatory activity of seed exudates. On all other plants tested, E. cloacae was effective in suppressing damping-off and inactivating the stimulatory activity of seed exudates.
Crops, Agricultural↗
Biological control in greenhouse systems.
The controlled environment of greenhouses, the high value of the crops, and the limited number of registered fungicides offer a unique niche for the biological control of plant diseases. During the past ten years, over 80 biocontrol products have been marketed worldwide. A large percentage of these have been developed for greenhouse crops. Products to control soilborne pathogens such as Sclerotinia, Pythium, Rhizoctonia and Fusarium include Coniothyrium minitans, species of Gliocladium, Trichoderma, Streptomyces, and Bacillus, and nonpathogenic Fusarium. Products containing Trichoderma, Ampelomyces quisqualis, Bacillus, and Ulocladium are being developed to control the primary foliar diseases, Botrytis and powdery mildew. The development of Pseudomonas for the control of Pythium diseases in hydroponics and Pseudozyma flocculosa for the control of powdery mildew by two Canadian research programs is presented. In the future, biological control of diseases in greenhouses could predominate over chemical pesticides, in the same way that biological control of greenhouse insects predominates in the United Kingdom. The limitations in formulation, registration, and commercialization are discussed, along with suggested future research priorities.
Canada↗
The role of nematophagous fungi in the biological control of nematode parasites of livestock.
The control of nematode parasites of livestock is presently based entirely on anthelmintic treatment and grazing management. On their own, these methods are not sustainable because parasites invariably develop resistance to anthelmintics and because of increasing public concern about chemical residues in livestock products and the environment. Although alternative, non-chemotherapeutic control strategies, such as vaccines and genetic selection for resistance are the focus of considerable research activity worldwide, biological control of nematode parasites has been virtually ignored. The little work that has been done is restricted largely to western Europe and involves virtually just one fungal species, namely Arthrobotrys oligospora. More recent studies indicate other known nematophagous fungal species are more efficient predators of infective larvae in sheep faeces than A. oligospora, and others have a greater capacity to survive passage through the gastrointestinal tract of ruminants. These findings plus the relatively sparse numbers of microbial competitors in the fresh faecal environment, compared with the plant rhizosphere where biological control of plant parasites is proving a particularly intractable problem, engenders optimism that the biological control of animal parasitic nematodes may become a practical reality. Such control will never be a substitute for chemotherapy, where the primary purpose is worm removal from the host, but should be incorporated together with other options into integrated pest management systems to provide sustainable nematode control of livestock into the twenty-first century.
Animals↗
An attempt to implement the nematode-trapping fungus Duddingtonia flagrans in biological control of trichostrongyle infections of first year grazing calves.
An attempt was made to control Ostertagia ostertagi by feeding the nematode-trapping fungus Duddingtonia flagrans (DSM 6703) to grazing calves. One group of calves (group E) was fed the fungal material in the first two months of the grazing season while another group was a non-treated control group (group C). Group E showed significantly lower faecal egg count in August and September. On four occasions in July and September, the herbage larval counts were significantly lower on the plot with the fungal-treated group than those recorded on the control plot. The average abomasal larval and adult worm counts were significantly reduced in August in group E and the average total worm count in the abomasum of group E was reduced by 87% in August compared to the non-treated group C. In October, the difference in average abomasal worm counts between group E and C was insignificant. Due to weight loss at the end of the grazing season, the control group showed a significantly lower average weight increase.
Abomasum↗
Monoclonal antibodies to Gliocladium roseum, a potential biological control fungus of sap-staining fungi in wood.
Immunological probes were developed to discriminate between a potential biological control fungus and sap-staining fungi present in wood. This paper describes the production of monoclonal antibodies to isolated cell wall fragments of the biological control fungus Gliocladium roseum. Two monoclonals, designated 6A5 and 3F12, were characterized. Their specificity was assessed by ELISA, by immunogold silver staining light microscopy, by immunogold electron microscopy, and by immunoblotting. Monoclonal 6A5 specifically recognized G. roseum and closely related species and did not react with any of 21 sap-staining fungi tested. Monoclonal 3F12 recognized most of the biological control fungi tested and also showed reactivity with two of the 21 sap-staining fungi. Both monoclonals appeared to recognize carbohydrate epitopes of the cell wall in G. roseum. Although the antibodies were produced against the cell wall of fungus grown in liquid culture, they also detected specific fungi in wood and, therefore, can be used for studies of wood colonization by fungi and for investigations of the interactions between different fungi growing on wood.
Antibodies, Fungal↗
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↗
Suitability of two root-mining weevils for the biological control of scentless chamomile, Tripleurospermum perforatum, with special regard to potential non-target effects.
The biology and host range of the two root-mining weevils Diplapion confluens Kirby and Coryssomerus capucinus (Beck), two potential agents for the biological control of scentless chamomile Tripleurospermum perforatum (Mérat) Laínz, were studied in the field in southern Germany and eastern Austria, and in a common garden and under laboratory conditions in Delémont, Switzerland from 1993 to 1999. Both weevils were univoltine, and females started to lay eggs in early spring. Diplapion confluens had three and C. capucinus five instars. Larvae of both species were found in the field from mid-April until the end of July; later instars preferentially fed in the vascular cylinder of the shoot base, root crown or root. Although larvae of both species occupy the same temporal and spatial niche within their host plants, they occurred at all investigated field sites together, and showed a similar distribution within sites. No negative or positive interspecific association was detected. Host-specificity tests including no-choice, single-choice, and multiple-choice tests under confined conditions, as well as tests under field conditions with natural and augmented insect densities revealed that both herbivores were specific to plant species in the tribe Anthemideae. However, their development to mature larva or adult on several cultivated plants, as well as on one plant species native to North America, rendered them unsuitable for field release in North America. It was concluded that to investigate non-target effects reliably, host-specificity tests with biological control agents should be carried out under a variety of conditions, particularly with augmented insect densities, as are expected to occur naturally after release.
Animals↗
Biological control of cereal aphids in north america and mediating effects of host plant and habitat manipulations.
The predator and parasitoid fauna associated with cereal aphids is described, emphasizing the fauna associated with classical biological control efforts against the greenbug and Russian wheat aphid. We focus on literature from North America and include work from Europe and elsewhere when it is desirable to draw contrasts between approaches that affect cereal aphid biological control. Effects on natural enemies of cereal aphids are described that appear associated with plant traits that are innate, bred, or induced by aphid feeding. Examples of habitat manipulations, within and bordering cereal fields and within the broader landscape in which cereal production resides, affecting predators and parasitoids of cereal aphids are presented. These mediating effects of host plant and habitat manipulations on cereal aphid biological control provide significant and underexplored avenues to optimize cereal aphid management.
Animals↗
Biological control of the snail hosts of schistosomiasis in areas of low transmission: the example of the Caribbean area.
The biological control of schistosomiasis has already proven its efficiency in several habitats in the Caribbean area. Two main types of biological control agents, either trematode parasites or competitor snails have been studied and tested against the snail hosts of schistosomiasis in this region. The first one, Ribeiroia guadeloupensis, a trematode sterilizing Biomphalaria glabrata was successfully tested in a Guadeloupean pond housing a natural population of B. glabrata. The second agent involves several species of competitor snails belonging to the Ampullariidae (Pomacea glauca, Marisa cornuarietis) and Thiaridae (Tarebia granifera, Melanoides tuberculata) families. Ampullarid snails were tested with success in several West Indian islands such as Guadeloupe. Thiarid snails have also proven their efficiency but also their limits in several types of habitats in Guadeloupe, Martinique, St. Lucia and Venezuela. Competitor snails have also proven to be useful in preventing the recolonization by the snail hosts after molluscicide treatments. The case of the rivers of the littoral central part of Venezuela is particularly relevant to this issue. The island of Martinique also constitutes a good example of the importance of competitor snails in a post-transmission phase of schistosomiasis control. This island is a well-developed country where schistosomiasis transmission was interrupted in the 1970s. However, the reactivation of some transmission sites was observed in the 1980s. The introduction of M. tuberculata into these sites resulted in the interruption of transmission and the near total disappearance of the snail hosts. Presently, the thiarid snails have colonized the whole Martinican hydrographic system and maintain dense populations preventing an eventual recolonization by the planorbid snails and thus are maintaining a sustainable control.
Animals↗
Ecology. Biological control of invading species--risk and reform.
Conservation relies increasingly on biological control (BC) of organisms that invade in natural and agricultural areas throughout the world. However, some BC organisms have harmed native species. In the United States, regulations are based on old laws meant to bar agricultural pests, and these are particularly ineffective in protecting native invertebrate animals. Improved ecological safety of BC depends on recognizing that BC is not appropriate for every pest, factoring ecological safety into the selection of BC agents, and limiting the importation and dissemination of agents that can harm either native animals or plants. Reasonable reform of BC will insure the viability of this valuable tool for both agriculture and conservation.
Animals↗
The multicolored Asian lady beetle, Harmonia axyridis: a review of its biology, uses in biological control, and non-target impacts.
Throughout the last century, the multicolored Asian lady beetle, Harmonia axyridis (Pallas) has been studied quite extensively, with topics ranging from genetics and evolution to population dynamics and applied biological control being covered. Much of the early work on H. axyridis was conducted in the native Asian range. From the 1980's to the present, numerous European and North American studies have added to the body of literature on H. axyridis. H. axyridis has recently gained attention in North America both as a biological control agent and as a pest. This literature review was compiled for two reasons. First, to assist other researchers as a reference, summarizing most of the voluminous body of literature on H. axyridis pertaining to its biology, life history, uses in biological control, and potential non-target impacts. Secondly, to be a case study on the impacts of an exotic generalist predator.
Animals↗