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Effective Biocontrol Agent (effective + biocontrol_agent)
Selected AbstractsDevelopment of a biological control-based Integrated Pest Management method for Bemisia tabaci for protected sweet pepper cropsENTOMOLOGIA EXPERIMENTALIS ET APPLICATA, Issue 1 2009F. J. Calvo Abstract The tobacco whitefly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), is a key pest in commercial sweet pepper crops in southeast Spain. Its biological control is currently based on augmentative introductions of the parasitic wasp Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae), which need to be occasionally supplemented with pesticide applications. These pesticides can be harmful for the biological control agents. Therefore, it is important to improve the current strategy by reducing dependency on pesticides. Two potential solutions are conceivable: addition of another effective biocontrol agent or application of pesticide prior to the release of biocontrol agents. The mirid bug Nesidiocoris tenuis Reuter (Heteroptera: Miridae) and the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) are promising candidates as additional biocontrol agents. The aim of the present study was to test these possible solutions in two subsequent trials, i.e., a ,selection' and an ,improvement' experiment. In the selection experiment, four treatments were compared: E. mundus, N. tenuis + E. mundus, A. swirskii + E. mundus, and A. swirskii + N. tenuis + E. mundus. Amblyseius swirskii appeared able to significantly increase effectiveness against the pest, in contrast to N. tenuis, which did not contribute to whitefly control. The best strategy was the combination of E. mundus and A. swirskii. In the improvement experiment, three treatments were compared: E. mundus, A. swirskii + E. mundus, and A. swirskii + E. mundus + pesticides. Amblyseius swirskii again proved capable of significantly reducing whitefly populations, and the implementation of pesticides before the release of the biocontrol agents was shown to increase the effectiveness against the pest even more. [source] Specific identification of Aureobasidium pullulans strain L47 using Scorpion PCR,EPPO BULLETIN, Issue 3-4 2000L. Schena Strain L47 of Aureobasidium pullulans is an effective biocontrol agent for several post-harvest fruit diseases, even when applied in the field before harvesting. This strategy requires a specific method of monitoring in order to optimize formulations and to evaluate the level of colonization and dispersal in the environment. We have detected strain L47 among other morphologically indistinguishable isolates of A. pullulans using Scorpion PCR, an automated real-time fluorescence detection system that targets a 145-bp fragment of the L47 genome. We propose this approach as a specific, rapid and reliable method of monitoring A. pullulans, strain L47. [source] The development and endophytic nature of the fungus Heteroconium chaetospiraFEMS MICROBIOLOGY LETTERS, Issue 2 2005Teruyoshi Hashiba Abstract The root endophytic fungus Heteroconium chaetospira was isolated from roots of Chinese cabbage grown in field soil in Japan. This fungus penetrates through the outer epidermal cells of its host, passes into the inner cortex, and grows throughout the cortical cells, including those of the root tip region, without causing apparent pathogenic symptoms. There are no ultrastructural signs of host resistance responses. H. chaetospira has been recovered from 19 plant species in which there was no disruption of host growth. H. chaetospira has a symbiotic association with Chinese cabbage. The fungus provides nitrogen in exchange for carbon. These associations are beneficial for the inoculated plants, as demonstrated by increased growth rate. When used as a preinoculum, H. chaetospira suppresses the incidence of clubroot and Verticillium yellows when the test plant is post-inoculated with the causal agents of these diseases. H. chaetospira is an effective biocontrol agent against clubroot in Chinese cabbage at a low to moderate soil moisture range and a pathogen resting spore density of 105 resting spores per gram of soil in situ. Disease caused by Pseudomonas syringae pv. macricola and Alternaria brassicae on leaves can be suppressed by treatment with H. chaetospira. The fungus persists in the roots and induces systemic resistance to the foliar disease. [source] Interactions between nutrient status and weevil herbivory in the biological control of water hyacinthJOURNAL OF APPLIED ECOLOGY, Issue 1 2000Tim A. Heard Summary 1.,Despite the widespread release of effective biocontrol agents, water hyacinth remains the world's most problematic aquatic weed, particularly in eutrophic waterbodies. However, understanding of the interaction between control and trophic status is still incomplete. 2.,Growth of water hyacinth plants was measured at two water nutrient concentrations (high and medium) and in the presence and absence of two insect biocontrol agents in a large circulating hydroponic system in a glasshouse. 3.,At the high nutrient concentration (1·6 mg l,1 N and 1·0 mg l,1 P), plants multiplied more quickly, attaining greater biomass. Both insect species reduced plant growth at both nutrient concentrations. Neochetina bruchi, however, performed better than N. eichhorniae at the high nutrient concentration by inflicting more damage on the plants and reducing biomass by a greater extent. 4.,Insect damage reduced the concentrations of nitrogen and phosphorus found in plants growing in high nutrient water but not in medium nutrient water (0·4 mg l,1 N and 0·025 mg l,1 P). 5.,The developmental and reproductive performance of N. bruchi was determined at both nutrient concentrations. Water hyacinth plants grown at higher nutrient concentration were superior hosts to N. bruchi than plants grown at medium concentrations. Net reproductive rate and intrinsic rate of increase were significantly greater at the high concentrations. Greater damage by N. bruchi to water hyacinth at the high nutrient concentration was due to the greater production of offspring, and hence greater larval damage. 6.,We predict that water hyacinth problems will be greater in eutrophic waterbodies, where N. bruchi will be a superior biocontrol agent to N. eichhorniae. In low-nutrient waterbodies, local nutrient enrichment of water may assist the establishment of control agents. These results illustrate the importance of wider ecological factors on the success of biological control. [source] Role of 2,4-Diacetylphloroglucinol-Producing Fluorescent Pseudomonas spp. in the Defense of Plant RootsPLANT BIOLOGY, Issue 1 2007D. M. Weller Abstract: Plants have evolved strategies of stimulating and supporting specific groups of antagonistic microorganisms in the rhizosphere as a defense against diseases caused by soilborne plant pathogens owing to a lack of genetic resistance to some of the most common and widespread soilborne pathogens. Some of the best examples of natural microbial defense of plant roots occur in disease suppressive soils. Soil suppressiveness against many different diseases has been described. Take-all is an important root disease of wheat, and soils become suppressive to take-all when wheat or barley is grown continuously in a field following a disease outbreak; this phenomenon is known as take-all decline (TAD). In Washington State, USA and The Netherlands, TAD results from the enrichment during monoculture of populations of 2,4-diacetylphloroglucinol (2,4-DAPG)-producing Pseudomonas fluorescens to a density of 105 CFU/g of root, the threshold required to suppress the take-all pathogen, Gaeumannomyces graminis var. tritici. 2,4-DAPG-producing P. fluorescens also are enriched by monoculture of other crops such as pea and flax, and evidence is accumulating that 2,4-DAPG producers contribute to the defense of plant roots in many different agroecosystems. At this time, 22 distinct genotypes of 2,4-DAPG producers (designated A - T, PfY and PfZ) have been defined by whole-cell repetitive sequence-based (rep)-PCR analysis, restriction fragment length polymorphism (RFLP) analysis of phlD, and phylogenetic analysis of phlD, but the number of genotypes is expected to increase. The genotype of an isolate is predictive of its rhizosphere competence on wheat and pea. Multiple genotypes often occur in a single soil and the crop species grown modulates the outcome of the competition among these genotypes in the rhizosphere. 2,4-DAPG producers are highly effective biocontrol agents against a variety of plant diseases and ideally suited for serving as vectors for expressing other biocontrol traits in the rhizosphere. [source] | ||||||||||