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PubMed2004

The use of the copepod Mesocyclops longisetus as a biological control agent for Aedes aegypti in Cali, Colombia.

We present data on the efficacy of Mesocyclops longisetus as a biocontrol agent in controlling Aedes aegypti larvae in catch basins in Cali, Colombia. Additionally, we determined some of the features that facilitated the establishment of the copepods in catch basins. Between June 1999 and February 2000, 201 catch basins were treated with an average of 500 adult copepods. The copepods had established in 49.2% of all the basins and they maintained Ae. aegypti larvae at low densities until the end of the 8-month study. The corrected efficacy percent was 90.4%. The copepods established in basins located in a flat area as opposed to those in steep areas, exposed to sunlight and with 0-10% of floating organic matter. When the catch basins were contaminated with synthetic washing agents, like detergents, the copepods did not survive. The copepod M. longisetus could be incorporated as a biological control agent in an integrated Ae. aegypti control program.

Aedes↗
PubMed2005

Biological control agent of common scab disease by antagonistic strain Bacillus sp. sunhua.

AIMS: To identify an antagonistic strain against Streptomyces scabiei and to characterize the antibiotic agent. The efficacy of the isolated strain in controlling common scab disease was also evaluated. METHODS AND RESULTS: A bacterial strain antagonistic against S. scabiei was isolated from the soil of a potato-cultivating area. This bacterium was identified as a Bacillus species by 16S rRNA gene sequence analysis and was designated Bacillus sp. sunhua. Antibiotics produced by this strain were proven to be stable within a broad pH range and at high temperatures. The culture broth was extracted with ethyl acetate, and then the crude extract was applied to HPLC. Two compounds were isolated and identified as iturin A and macrolactin A by 1H-NMR, 13C-NMR, HMBC, HMQC and mass spectrometer. The culture broth of Bacillus sp. sunhua had a suppressive effect on common scab disease in a pot assay, decreasing the infection rate from 75 to 35%. This strain also suppressed Fusarium oxysporum, the pathogen of potato dry rot disease. CONCLUSIONS: Bacillus sp. sunhua was shown to inhibit S. scabiei effectively. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first report demonstrating that macrolactin A and iturin A inhibit S. scabiei. This study demonstrated the possibility of controlling potato scab disease using Bacillus sp. sunhua.

Anti-Bacterial Agents↗
PubMed1995

RAPD-PCR for identification of Zoophthora radicans isolates in biological control of the potato leafhopper.

Biological control studies require the ability to distinguish released pathogens from locally occurring isolates of the same species. We have developed a technique that differentiates genotypes using random amplified polymorphic DNA (RAPD) for the apomictic species Zoophthora radicans (Zygomycota: Entomophthorales), a pathogen of the potato leafhopper, Empoasca fabae (Homoptera: Cicadellidae). RAPD analysis was performed on Z. radicans isolates released in test plots in 1990 and 1991 for leafhopper control; isolates later recovered from the same plots and diverse other isolates were included in the analysis. RAPD fragment profiles of five recovered isolates proved very similar to those of the released isolates and different from all other isolates tested; they are probable descendants of the released isolates. One of the recovered isolates had RAPD profiles similar to isolates derived from aphids and probably represents a population endemic at the release site. In addition to verifying the successful establishment of our experimental releases, RAPD analysis revealed clear relationships among isolates derived from the same host taxon. We propose that this simple and relatively inexpensive method will be valuable in determining the establishment and spread of organisms released in biological control studies.

Animals↗
PubMed2005

Characterization of a novel vip3-type gene from Bacillus thuringiensis and evidence of its presence on a large plasmid.

A novel vip3-type gene named vip3LB has been isolated from Bacillus thuringiensis strain BUPM95. The corresponding secreted vegetative insecticidal protein was active against the lepidopteran insect Ephestia kuehniella. The vip3LB gene was shown, for the first time, to be carried by the large plasmid containing the cry1Ia genes of B. thuringiensis. The nucleotide sequence predicted a protein of 789 amino acids residues with a calculated molecular mass of 88.5kDa. Both nucleotide and amino acid sequences similarity analysis revealed that vip3LB is a new vip3-type gene, presenting several differences with the other vip3-type genes. Heterologous expression of the vip3LB under the control of the strong promoter P(BAD) was performed in Escherichia coli and the produced protein conferred insecticidal activity against Ephestia kuehniella. This novel vegetative insecticidal protein Vip3LB could be a very useful biological control agent.

Animals↗
PubMed1997

The potential of nematophagous fungi to control the free-living stages of nematode parasites of sheep: comparison between Australian isolates of Arthrobotrys spp. and Duddingtonia flagrans.

Nine isolates of Duddingtonia flagrans and eight isolates of Arthrobotrys spp. which originated from a field survey for the presence of nematophagous fungi in fresh dung of livestock in Australia were used in this study. Comparisons were made between the ability of the different isolates to survive gut passage and subsequently reduce infective larval numbers in sheep faeces. Fungal spores (conidia and/or chlamydospores) were administered orally to sheep in doses ranging from 1 X 10(5) to 4.5 X 10(6) spores. There was no apparent consistent survival of Arthrobotrys spp., whereas D. flagrans showed excellent survival capacity which resulted in profound reductions in Trichostrongylus colubriformis larval numbers in culture. This provides clear evidence that D. flagrans is an ideal candidate as a potential biological control agent for nematode parasites of sheep.

Animals↗
PubMed2001

Evaluation of potential biocontrol rhizobacteria from different host plants of Verticillium dahliae Kleb.

AIMS: A screening approach was developed to assess the potential of rhizobacterial strains to control Verticillium wilt caused by Verticillium dahliae Kleb. METHODS AND RESULTS: Sixty randomly chosen antagonistic bacterial strains originally isolated from rhizosphere of three different host plants of V. dahliae--strawberry, potato and oilseed rape--were evaluated for biocontrol and plant growth promotion by analysing in vitro antagonism towards V. dahliae and other plant pathogenic fungi, production of fungal cell wall-degrading enzymes and plant growth-promoting effects on strawberry seedlings. To test the plant growth-promoting effect, a microplate assay with strawberry seedlings was developed. Although the rhizobacterial strains were isolated from different plants they showed effects on the growth of strawberry seedlings. According to the in vitro biocontrol and plant growth-promoting activity, the three best candidates Pseudomonas putida B E2 (strawberry rhizosphere), Ps. chlororaphis K15 (potato rhizosphere) and Serratia plymuthica R12 (oilseed rape rhizosphere) were selected for greenhouse experiments to verify the in vitro screening results. Under greenhouse conditions the isolates selected according to this strategy were as effective, or more effective than commercial biocontrol agents and may therefore possibly be valuable as antagonists of V. dahliae. CONCLUSIONS: In this study, the screening strategy resulted in a selection of three interesting biocontrol candidates against Verticillium: Ps. putida B E2 (strawberry rhizosphere), Ps. chlororaphis K15 (potato rhizosphere) and Ser. plymuthica R12 (oilseed rape rhizosphere). SIGNIFICANCE AND IMPACT OF THE STUDY: A new combination of in vitro screening methods including a microplate assay with strawberry seedlings to test the plant growth promoting effect which allow to more efficiently select potential biological control agents was developed successfully.

Antibiosis↗
PubMed2000

Predation efficacy of the fish muddy loach, Misgurnus mizolepis, against Aedes and Culex mosquitoes in laboratory and small rice plots.

Assessments of the biological control potential of muddy loaches, Misgurnus mizolepis, were conducted against Aedes togoi, Culex pipiens pallens, and Culex inatomii larvae both in the laboratory and in small rice plots in Pusan, Korea, from June to September 1997. Medium-sized fish consumed almost all of 500 3rd-stage larvae of Cx. pipiens pallens offered daily in the laboratory. Predation by the fish at release rates of 1, 2, 4, 8, and 16 fish per plot resulted in 1,004, 1,197, 1,198, 1,200, and 1,200 larvae of Ae. togoi consumed in 12 h, respectively, when each 1,200 3rd-stage larvae were given in the 1-m2 small rice plots. The average numbers of larvae eaten after introduction of the fish were 1,121.8 larvae in 24 h and 1,195.8 larvae in 36 h. Muddy loaches showed slightly higher predation rates on Cx. pipiens pallens and Culex inatomii larvae than on larvae of Ae. togoi. Therefore, M. mizolepis might be an efficient biological control agent against mosquito species in rice fields.

Aedes↗
PubMed2004

Laboratory evaluation of the predation efficacy of native Australian fish on Culex annulirostris (Diptera: Culicidae).

The introduction and establishment of fish populations can provide long-term, cost-effective mosquito control in habitats such as constructed wetlands and ornamental lakes. The predation efficacy of 7 native Brisbane freshwater fish on 1st and 4th instars of the freshwater arbovirus vector Culex annulirostris was evaluated in a series of 24-h laboratory trials. The trials were conducted in 30-liter plastic carboys at 25+/-1 degrees C under a light:dark cycle of 14:10 h. The predation efficacy of native crimson-spotted rainbowfish Melanotaenia duboulayi (Melanotaeniidae), Australian smelt Retropinna semoni (Retropinnadae), Pacific blue-eye Pseudomugil signifer (Atherinidae), fly-specked hardyhead Craterocephalus stercusmuscarum (Atherinidae), firetail gudgeon Hypseleotris galii (Eleotridae), empire gudgeon Hypseleotris compressa (Eleotridae), and estuary perchlet Ambassis marianus (Ambassidae) was compared with the exotic eastern mosquitofish Gambusia holbrooki (Poeciliidae). This environmentally damaging exotic has been disseminated worldwide and has been declared noxious in Queensland. Melanotaenia duboulayi was found to consume the greatest numbers of both 1st and 4th instars of Cx. annulirostris. The predation efficacy of the remaining Australian native species was comparable with that of the exotic G. holbrooki. With the exception of A. marianus, the maximum predation rates of these native species were not statistically different whether tested individually or in a school of 6. Based on these data, M. duboulayi, H. compressa, and A. marianus warrant further investigation as biological control agents in pilot field trials.

Animals↗
PubMed1985

[Experimental study on the predation of Cionella lubrica Müller by Nesovitrea hammonis Ström].

The predation of C. lubrica by N. hammonis was studied under controlled laboratory conditions. Adult N. hammonis ate mainly prey measuring 2 to 4 mm in height. The predation rate was steady in spite of the increase in number of predators for the same number of prey. Vegetable food was indispensable to N. hammonis' predation. The predation was maximum at 20-25 degrees C. N. hammonis cannot be considered as an agent of biological control against C. lubrica owing to its limited predation.

Animals↗
PubMed1998

Characterization of genes involved in biosynthesis of a novel antibiotic from Burkholderia cepacia BC11 and their role in biological control of Rhizoctonia solani.

Genetic manipulation of fluorescent pseudomonads has provided major insight into their production of antifungal molecules and their role in biological control of plant disease. Burkholderia cepacia also produces antifungal activities, but its biological control activity is much less well characterized, in part due to difficulties in applying genetic tools. Here we report genetic and biochemical characterization of a soil isolate of B. cepacia relating to its production of an unusual antibiotic that is very active against a variety of soil fungi. Purification and preliminary structural analyses suggest that this antibiotic (called AFC-BC11) is a novel lipopeptide associated largely with the cell membrane. Analysis of conditions for optimal production of AFC-BC11 indicated stringent environmental regulation of its synthesis. Furthermore, we show that production of AFC-BC11 is largely responsible for the ability of B. cepacia BC11 to effectively control the damping-off of cotton caused by the fungal pathogen Rhizoctonia solani in a gnotobiotic system. Using Tn5 mutagenesis, we identified, cloned, and characterized a region of the genome of strain BC11 that is required for production of this antifungal metabolite. DNA sequence analysis suggested that this region encodes proteins directly involved in the production of a nonribosomally synthesized lipopeptide.

Amino Acid Sequence↗
PubMed2006

Biological control of postharvest spoilage caused by Penicillium expansum and Botrytis cinerea in apple by using the bacterium Rahnella aquatilis.

The epiphytic bacterium Rahnella aquatilis, isolated from fruit and leaves of apples, was tested for antagonistic properties against Penicillium expansum and Botrytis cinerea on Red Delicious apple fruit. In "in vitro" assays, this bacterium inhibited completely the germination of P. expansum and B. cinerea spores, but it needed direct contact with the spores to do it. However the putative mechanism seemed be different for the two pathogens. The bacterium did not produce extracellular antibiotic substances and when the acute toxicity test was performed no mortality, toxicity symptoms or organ alterations of the test animals (Wistar rats) were observed. Assays of biological control of P. expansum and B. cinerea on apple fruit were carried out at different temperatures. At 15 degrees C and 90% RH, the incidence of disease caused by P. expansum on apples stored for 20 days, was reduced by nearly 100% by R. aquatilis (10(6) cells/ml), while in the case of B. cinerea, the reduction of decay severity was nearly 64% but there was no reduction in the incidence of disease. At 4 degrees C and 90% RH the treatment with the bacterium significantly inhibited the development of B. cinerea on apples stored for 40 days and the incidence of disease was reduced by nearly 100%, while the incidence of disease caused by P. expansum at 4 degrees C was 60%. The results obtained show that R. aquatilis would be an interesting microorganism to be used as a biocontrol agent.

Animals↗
PubMed1997

Is working in greenhouses healthy? Evidence concerning the toxic risks that might affect greenhouse workers.

Greenhouses are essentially microcosms aimed at providing physical environments suitable for the survival and growth of plants. Crops grown intensively in greenhouses in Great Britain include cut flowers, pot plants and edible crops such as tomato, lettuce cucumber and celery. The enclosed conditions mean that greenhouse workers are more likely to be exposed to higher levels of plant material, plant pests and plant protection products than general horticulture workers. The potential for ill-health in greenhouse workers is examined with particular reference to Great Britain. The principal potential effects expected include irritancy, asthma, allergic aleveolitis and dermatitis. Although biological control agents are widely used, there were no reports of their having caused ill-health in greenhouse workers. About two people per year are found to have suffered ill-health as a consequence of greenhouse exposure to chemical pesticides in reported pesticides incidents in Great Britain.

Agricultural Workers' Diseases↗
PubMed1999

Construction of plant vectors with high level expression of B.t. toxin gene and studies on their expression behavior in transgenic tobaccos.

Breeding pest-resistant plants using plant genetic engineering technique is an effective strategy in integrated pest management (IPM). Increasing the expression level of foreign insecticidal protein by using a strong promoter is a useful method. In this work, a plant expression vector, pBinMoBc, was constructed. It contained the CryIA(c) gene under the control of a chimeric OM promoter and the omega factor. As a control, another vector, pBinoBc, was also constructed in this study. pBinoBc carrying CryIA(c) gene was under the control of a CaMV 35S promoter. The vectors were transferred into tobacco plants via Agrobacterium-mediated transformation. ELISA assay showed that the average expression level of the CryIA(c) gene in pBinMoBc transgenic tobacco plants is 2.44-times that in pBinoBc transgenic tobacco plants. The expression of B.t. toxin in individual plant can be up to 0.255% of total soluble proteins. Bioassay showed that pBinMoBc transgenic tobacco plants had more notable insecticidal effects than pBinoBc transgenic tobacco plants. The above results showed that the chimeric OM promoter is a stronger promoter than the CaMV 35S promoter that was widely used in plant genetic engineering. This is very useful in pest-resistant plant genetic engineering.

Animals↗
PubMed2002

Verticillium wilt of cauliflower in Belgium.

Since several years commercial cauliflower in Belgium is severely affected by a vascular wilt disease. Plants wilt and a vascular discoloration of the cauliflower stems can be observed. The pathogen causes significant yield and quality losses. The first objective of this study was to isolate and characterise the causal agent of this disease. Verticillium species could be isolated out of the vascular tissue of symptomatic cauliflower plants. Morphological and physiological characteristics indicated that the isolates from cauliflower could be identified as the new and brassica-related species V. longisporum. Secondly, the susceptibility of several cauliflower cultivars to V. longisporum was evaluated by way of field experiments in naturally infested soil. At harvest, vascular discoloration was evaluated by a visual score. These experiments pointed to considerable differences between cultivars in their susceptibility to V. longisporum. The final goal of this study was to find a way to control the wilt disease on cauliflower. A field experiment showed that vascular discoloration of cauliflower was significantly reduced when soil was incorporated with broccoli residues, two Brassica green manures (B. juncea or B. nigra) or two commercial biological products based on Talaromyces flavus or Trichoderma sp..

Belgium↗
PubMed2006

Potential of selective insecticides for managing Uraba lugens (Lepidoptera: Nolidae) on Eucalypts.

The leaf skeletonizer Uraba lugens Walker (Lepidoptera: Nolidae), an Australian species, locally known as "gumleaf skeletonizer", is well established in New Zealand. This insect has the potential to become a serious pest of forestry and amenity eucalypts (Eucalyptus spp.) and is the focus of a long-term management program. The use of synthetic chemical or biological insecticides is one possible control method within an integrated control program. A series of dose-response trials were conducted using laboratory bioassays to test the efficacy of several insecticides against U. lugens: pyrethroids, spinosad, Bacillus thuringiensis kurstaki Berliner (Btk) and an insect growth regulator, Mimic. Pyrethroids and spinosad proved highly effective against U. lugens larvae, achieving 100% mortality after 3-6-d exposure. The performance of Btk was lower against gregarious skeletonizing larvae compared with solitary chewing larvae. When good coverage of the target foliage is achieved, >90% mortality is possible with Btk. Mimic performed poorly against U. lugens compared with other insecticides tested (<60% mortality). The Eucalyptus species on which larvae were feeding significantly altered insecticide efficacy. Treatments applied to Eucalyptus nitens (Deane & Maiden) Maiden had reduced efficacy compared with E. cinerea F. Muell. ex Benth. or E. fastigata Deane & Maiden. Cooler temperatures also reduced insecticide efficacy, presumably by decreasing movement and food consumption by U. lugens. Recommendations on spray applications to control U. lugens in New Zealand are given.

Animals↗