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The effect of pathogens on invasive plants
Sládečková, Julie ; Koubek, Tomáš (advisor) ; Čuda, Jan (referee)
Invasive plants can destroy entire ecosystems, reduce biodiversity and thus threaten the environment. Number of invasive species is increasing and so their negative impact on the environment. Various reasons can be behind the emergence of invasions, one of them is, for example, escaping from natural enemies. This can make the plant more competitive, have greater reproductive potential and spread better. However, if natural enemies are added to the new area, the number of invasive plants can be regulated. This is the principle of biocontrol, which is a method used to reducing the magnitude of invasions and their consequences. This method has almost no negative impacts on the environment, unlike chemical and mechanical methods of plant removal. Biocontrol has a long-term effect and therefore is also cheaper. However, when biocontrol is used, there is a certain risk that non-target plant species will be affected or that it will not be effective enough. Pathogens are also used as biocontrol agents because they are more specialized than herbivores, so the risk for non-target plants is lower. The aim of this thesis is to compare biological control with other methods used to removing invasive plants and to summarize the most significant positives and negatives of using fungal pathogens in plant biocontrol.
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Využití biologických prostředků na ochranu brambor vůči mandelince bramborové
KURÁŽ, Jakub
The aim of the work was to verify possibilities of biological control against Colorado potato beetle by using cultivated indigenous entomopathogenic fungi and entomopathogenic nematodes from potato fields in Czech Republic before chemical treatment or ecological agriculture and verify their efficacy against Colorado potato beetle. All results are included in attached charts or tables.
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Measurement of predator effectiveness by means of cage exclusion experiments
Fischerová, Laura ; Kindlmann, Pavel (advisor) ; Tropek, Robert (referee)
1 Abstract Cage exclusion experiments are used in ecological and agricultural studies to determine plant- insect interactions (Kidd & Jervis 2005). Cages are used to detect the insect density on the plant, while other influences such as natural predators or other pests are excluded. Exclusion of predators by using physical barriers (different mesh size) is one of the most used ways to determine the impact of natural enemies on the pest population. The results of these experiments suggest, that the pest population on caged plants, from which natural enemies are excluded, has a lower percentage of mortality and parasitism than the population on plants, where the natural enemies have full access to (Luck et al. 1988). Results of this method are used in programs of biocontrol when searching optimal plant treatments and possible alternatives instead of using insecticides (Lawson et al. 1994). The question is, whether cage exclusion experiments are adequately reflecting changes in pest populations and their impact on plants. As a result of caging the area, changes in microclimate and plant growth occur, which subsequently affects present insect populations. Cages do not also allow leaving the pests from the cage and, in some cases, unwanted natural enemies enter them, even though they have been previously...
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Measurement of predator effectiveness by means of cage exclusion experiments
Fischerová, Laura ; Kindlmann, Pavel (advisor) ; Tropek, Robert (referee)
1 Abstract Cage exclusion experiments are used in ecological and agricultural studies to determine plant- insect interactions (Kidd & Jervis 2005). Cages are used to detect the insect density on the plant, while other influences such as natural predators or other pests are excluded. Exclusion of predators by using physical barriers (different mesh size) is one of the most used ways to determine the impact of natural enemies on the pest population. The results of these experiments suggest, that the pest population on caged plants, from which natural enemies are excluded, has a lower percentage of mortality and parasitism than the population on plants, where the natural enemies have full access to (Luck et al. 1988). Results of this method are used in programs of biocontrol when searching optimal plant treatments and possible alternatives instead of using insecticides (Lawson et al. 1994). The question is, whether cage exclusion experiments are adequately reflecting changes in pest populations and their impact on plants. As a result of caging the area, changes in microclimate and plant growth occur, which subsequently affects present insect populations. Cages do not also allow leaving the pests from the cage and, in some cases, unwanted natural enemies enter them, even though they have been previously...
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Genetic variability of \kur{Isaria} genus in Czech Republic
ČÁPOVÁ, Aneta
My diploma thesis deals with genetic variability of entomopathogenic fungi of the Isaria genus encountered in the Czech Republic. Individual representative of the genus can be found in soil where they attack all developmental stages of insects, giving preference to larvae and pupae. The Isaria fungi find application first and foremost where plants have to be provided biological protection. In case of mitosporic fungi is the precise identification very difficult, taxonomy is often unclear in many genera, including the genus Paecilomyces/Isaria to demonstrate their polyphyletic nature. The fungi are classified primarily with reliance on morphological studies. The most common markers used to identify fungi are the shapes and sizes of their conidia and the biological properties (germination of spores, tests of biological efficiency). Identification made in consideration of the morphological markers is inaccurate and very variable. To overcome those accuracies, there are very useful molecular DNA markers, which can be relevant in ecology, biology and in fungi genetics. This paper relies on applying the ITS region (Internal Transcribed Spacer) as a molecular marker. ITS regions are partial constituent rDNA carrying no code - that is why the regions are likely to accumulate evolutionary changes in the DNA sequence, which makes them suitable for extensive use in taxonomic analyses of many organisms. The study results in a phylogenetic trees constructed by comparing different sequences of ITS regions obtained from the samples of entomopathogenic fungi of the Isaria genus gathered in the Czech Republic during the monitoring stage 2013 to 2014. Thereunder detection of Isaria sp. occurring in the Czech Republic.
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