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Diversity, ecology, and biotechnological potential of yeasts associated with bark beetles
Havlíček, Václav ; Kolařík, Miroslav (advisor) ; Novotný, David (referee)
Bark beetles (Coleoptera; Scolytinae) attack woody plants, which is why they are considered pests from a human perspective. They owe their evolutionary success, among other factors, to numerous symbioses with microorganisms, with fungi playing a significant role. The mycobiome of bark beetles is dominated by yeasts, which, nevertheless, are widely overlooked. Intestinal yeasts not only from Ips typographus but also from other species of bark beetles have potential for future biotechnological applications. The aim of this study was to examine their diversity and physiological activities, which will help clarify their ecological role and biotechnological potential. Collections were conducted in the Czech Republic from larvae of the spruce bark beetle Ips typographus and from various species of subcortical insects in Kenya. Yeasts were identified and taxonomically classified based on rDNA sequencing. A total of 133 yeast strains belonging to 37 species were identified, including 9 species that could not be identified and belong to previously undescribed species and in two cases also genera. A total of 133 yeast strains belonging to 37 species were identified, including 9 species that could not be identified and belong to previously undescribed species and in two cases also genera. The most frequently...
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Natural enemies of the European spruce bark beetle \kur{Ips typographus}
BÁRTA, Jiří
Bark beetles (Scolitynae) are among the most important pests of forest stands, where they cause extensive damage, especially in spruce monocultures. Their negative effect is to attack the host tree, which is its source of food and at the same time provides them with space for reproduction. The bark beetle is able to have several generations per year under suitable temperature conditions. One of the most widespread is consi-dered to be the European spruce bark beetle Ips typographus. This species is able to search for weakened and abiotically damaged trees. Integrated Pest Management of forests includes several effective methods against bark beetles. The most used met-hods include the installation of feromone traps, traps trees and poisoned tripods. The European spruce bark beetle is in their population regulated by many natural enemies. From parasitoids such as Coeloides bostrichorum and Rhopalicus tutela and predators Thanasimus formicarius and Medetera spp. to pathogenic microorganisms such as entomopathogenic viruses, bacteria, protozoa, microsporidia and especially entomo-pathogenic fungi belonging to the order Hypocreales. The most important species is the fungus Beauveria bassiana, which has the greatest potential in the biological pro-tection of spruce stands.
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Establish a standard laboratory bioassay of efficacy of entomopathogenic fungi \kur{Beauveria bassiana}on adults of spruce bark beetle ips typographus L. (Coleoptera, Scolytidae).
SKALICKÝ, Aleš
During monitoring on chosen localities of National Park and the Protected Landscape Area of Šumava were isolated native strains of entomopathogenic fungus Beauveria bassiana. Strains were consequently tested on efficacy against adults of spruce bark beetle Ips typographus L. (Coleoptera, Scolytidae). The general aim of this thesis was the development of a standard laboratory bioassay procedure. For the purpose of the bioassay as the most appropriate arena for the incubation appears sterile plastic containers with moist pulp at the bottom. The next step is to insert a standard number of adults Ips typographus on sterile spruce bark in a container that serves as a natural culture medium for incubation. Course of individual experiments showed that the most appropriate term is the initial evaluation of 144 hours from the beginning of an attempt, following an evaluation is performed 168, 192 and 216 hours. Within bioassay of efficacy were tested different applications of bio-preparation based on entomopathogenic fungus Beauveria bassiana.
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Evaluation of genetic strains polymorphism of \kur{Beauveria bassiana} based on analyses of using microsatellite markers
PUDIL, Jiří
Microsatellites, or Simple Sequence Repeats (SSRs), are highly polymorphic loci present in nuclear and organellar DNA that consist of repeating units of 1-6 base pairs in length. Microsatellites are very effective molecular markers, which allow us to examine various aspects of organisms. The aim of thesis is to carry out analyzes of microsatellites and describe the genetic relationships between individual strains and monosporic isolates, which were derived from these strains. Usind SSR I would like to asses the degree of genetic polymorphism between \kur{Beauveria bassiana} strains, collected during monitoring in the locality of Černá Hora in Šumava. I am also trying to optimize the method of DNA isolation and method of microsatellites analysis. 44 strains of \kur{Beauveria bassiana} isolated from \kur{Ips typographus} were analyzed in total using four primers. Overall, the results that I obtained show high similarity of evaluated strains, and therefore low level of genetic polymorphism. For further work it would be appropriate to enlarge the area, which will be sampled and include sets of strains that were obtained from different developmental stages of the host, as well as other reference strains of entomopathogeníc fungi collected from other localities with similar conditions. For more detailed study it would be useful to use the analysis of ribosomal DNA. Thus selected and evaluated population is likely to provide a more veritable image of strain diversity in observed area.
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Determination of volatile isoprenoids as water stress markers of spruce resistance against bark beetle
Slušná, Michaela ; Kalinová, Blanka (advisor) ; Hoškovec, Michal (referee)
Isoprenoids are important components of conifer resin and represent an important part of constituted defence system against herbivores and pathogens. Drought is one of the most important factors that influences the tree physiology and resitance. Due to decreased turgor of resin canal cells, the water insufficiency affects the pressure of the resin and thereby the ability of trees to physically prevent pathogen or herbivore invasion by effective outpouring of the resin. In addition, drought can also change the resin composition and thus can influence the quality of volatiles emitted by the tree. The Norway spruce, Picea abies, is the predominant species of production forests in moderate climate zone. Bark beetles, Ips typographus, represent the most important pest species of spruce. In general, pioneer bark beetles use host volatiles to orient themselves toward the tree suitable for colonization and in many species host volatiles synergize bark beetle aggregation pheromones. Thus the host volatile composition could affect significantly host colonization. This diploma thesis studied the influence of drought on the production and composition of isoprenoid volatile organic compounds in 80 - 100 years old spruce trees. Using I. typographus antennae as biological detectors, we also studied which resin...
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Spatial correlations in population dynamics of spruce bark beetle (Ips typographus): Example of Mantel test usage
Šimera, Ondřej ; Kindlmann, Pavel (advisor) ; Ferenc, Michal (referee)
Spruce bark beetle (Ips typographus L.) is the most common and abundant beetle from the Scolytidae family in European forests. It is the most important biotic factor causing disturbances and affecting forest ecosystems. Thus, it recently became a subject of discussions, how to manage the forests properly in order to find an adequate equilibrium among economical, turistic and natural values of the forest. Many studies have shown a positive effect of bark beetle outbreaks on biodiversity and natural forest regeneration. It is hard to tell if these outbreaks are regular or not because there are many factors which can elicit them. However, just these factors can help us predict the probability of unforseen population outbreak. One of these methods can be monitoring of surrounding areas because these areas tend to be synchronised. For this purpose, multiple mathematical models can be performed, such as the Mantel test, which determines the correlation between two matrices. Keywords: Spruce bark beetle, Ips typographus, population dynamics, spatial correlations, Mantel test
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The role of microbial symbionts in the life cycle of Ips typographus
Havlíček, Václav ; Kolařík, Miroslav (advisor) ; Veselská, Tereza (referee)
Bark beetles (Coleoptera;Scolytinae) are usually considered as pests, because they attack trees in the protected and recreational forests and in the forests with economic importance. Their larvae develop under the bark, where it disturb the conductive tissues and affect the nutrient transport. Ips typographus attack Norway spruce (Picea abies). P. abies is an economic important woody plant. The life cycle of bark beetle is affected by its microbial symbionts in both positive and negative manner. Most of these organisms are facultative symbionts and they aren't completely depend on bark beetles. However, bark beetles are completely depend on its microbial symbionts. Symbiotic bacteria and fungus can be disseminated without bark beetles, but they are often spread by beetles. Microbial symbionts help overcome the defence mechanism of attacked trees, later they help with food digestion. Some fungi species can accumulate nitrogen in areas near the feeding chambers and improve ratio between carbon and nitrogen in plant tissue. Some bacteria are able to fix atmospheric nitrogen or use uric acid, helping with nitrogen recycling. Number of intestinal symbiont diversity increase in the course of host development. This symbionts are probably gained during feeding. The presence and prevalence of the...
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Neglected aspects of bark beetle (Coleoptera: Scolytinae) ecophysiology
DAVÍDKOVÁ, Markéta
The thesis describes several unknown aspects of the spruce bark beetle, Ips typographus (L.), and the double-spined bark beetle, Ips duplicatus (Sahlberg.), life-cycles and ecophysiology. The first study focuses on I. typographus and its dispersal under epidemic conditions in the National park Šumava and introduces a novel method of fluorescent marking and detection of captured specimens. The second study is focused on ability of I. typographus to establish so-called sister-broods, i.e. re-emergence of females that are capable to continue egg laying without a need to mate again. The importance of sister-broods becomes apparent mainly in recent hot and dry vegetation seasons, which is demonstrated by a comparison of recent and historical data. The third study focuses on temperature-dependent development of I. duplicatus under laboratory conditions by the means of sandwich method. Altogether, the studies underline practical importance of ecophysiological studies on bark beetles as one of the tools for their effective management.
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Spatial correlations in population dynamics of spruce bark beetle (Ips typographus): Example of Mantel test usage
Šimera, Ondřej ; Kindlmann, Pavel (advisor) ; Ferenc, Michal (referee)
Spruce bark beetle (Ips typographus L.) is the most common and abundant beetle from the Scolytidae family in European forests. It is the most important biotic factor causing disturbances and affecting forest ecosystems. Thus, it recently became a subject of discussions, how to manage the forests properly in order to find an adequate equilibrium among economical, turistic and natural values of the forest. Many studies have shown a positive effect of bark beetle outbreaks on biodiversity and natural forest regeneration. It is hard to tell if these outbreaks are regular or not because there are many factors which can elicit them. However, just these factors can help us predict the probability of unforseen population outbreak. One of these methods can be monitoring of surrounding areas because these areas tend to be synchronised. For this purpose, multiple mathematical models can be performed, such as the Mantel test, which determines the correlation between two matrices. Keywords: Spruce bark beetle, Ips typographus, population dynamics, spatial correlations, Mantel test
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