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Parasitic strategies based on behavioral manipulation of the arthropod host
Janovská, Kateřina ; Straka, Jakub (advisor) ; Votýpka, Jan (referee)
It is well known that parasites can alter the host's behaviour for their benefit or the benefit of their offspring. Arthropods often fall victim to these parasites. Although the parasites of Arthropods come from many different groups (e.g., helminths, insects, fungi, viruses, etc.), we can find some similarities in their strategies. The specific methods and processes of behavioural manipulation are unique to each parasite and depend on whether the arthropod is the parasite's final host or an intermediate host/vector. However, they often lead to the same goal, e.g., to be eaten by another host, to allow the parasite to reproduce or to protect the parasite's offspring. Whether these changes in the host's behaviour are a part of the parasite's life strategy or only a manifestation of an adaptive response of the host remains a question. This thesis discuss specific cases of behavioural manipulation in parasitized arthropods and the common motives parasites use in manipulation. Keywords: behaviour manipulation, Arthropods parasite, parasitoid, host's behaviour, host- parasite interaction, adaptive response
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Biotic, abiotic and symbiotic factors that influence a host-parasitoid food web
BROWN, Joel James
The aim of this thesis was to investigate the deterministic patterns of insect-associated microbiome community composition and to investigate the role of symbiotic bacteria in insect model systems. I have shown that life stage is a key factor influencing microbiome composition, in both holometabolous and hemimetabolous insects, in addition to host species identity and local environment. I was able to find these deterministic patterns by controlling for diet in field studies of microbiomes, which is a well-known influential factor of microbiome communities. My thesis emphasises the importance of investigating the taxonomic and functional diversity of insect microbiomes and including symbiotic microbes in community level studies.
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Community structure of caterpillar parasitoids from tropical rain forest
LIBRA, Martin
The aim of this dissertation is to investigate the community structure of parasitoids and their interactions with their hosts - caterpillars in the rainforest of Papua New Guinea, focusing on beta diversity and altitudinal trends. We show that parasitoid beta diversity is higher than the beta diversity of their hosts, which was also projected in their interactions. The altitude plays important role in the diversity of parasitoids, where we show that Ichneumonidae are more diverse at high elevation than at low elevation, which was not observed for other large insect families. Further, we performed a manipulative experiment, exposing live caterpillars in different elevations of tropical rainforest. Caterpillars faced similar mortality from parasitoids between elevations, but higher mortality from predation at low elevation. In the last chapter, we point out how important is correct species identification because wrong identification can misinterpret observed interactions.
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Phylogeny of selected species groups of the genus Torymus (Hymenoptera: Torymidae)
Křížková, Barbora ; Janšta, Petr (advisor) ; Skuhrovec, Jiří (referee)
Chalcid wasps (Chalciodiodea) is superfamily within parasitic group of the order Hymenoptera. These insects attack other arthropods. My thesis is focused on phylogeny of selected species groups of the genus Torymus Dalman 1820, whose range of hosts includes mainly gall-forming insect as gall wasps (Hymenoptera: Cynipidae) and gall midges (Diptera: Cecidomyiidae). Using genes 28D2 rDNA, COI and CytB, I constructed phylogenetic trees, which helped with discussing current view on classification of the genus and with inferring new findings about co-evolution with host organisms. Previously established morphological - ecological species groups were not supported by my analyses in many cases. Morphological traits seem to be convergent for many species. They often do not support observed monophyla as apomorphies. On the other hand, ecology and natural habitat of species was common for many branches in my cladograms. It was found out, that recent hosts are not probably original hosts of the group. Adaptive radiation in different habitats is likely to be the phenomenon that stands behind present-day host range of Torymus species. This process could have occurred after swapping to gall midges and gall wasps. Key words: Chalcidoidea, Torymus, phylogeny, parasitoid, host specifity, co-evolution
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Hymenopteran parasitoids (Hymenoptera: "Parasitica") and their impact on hosts species behaviour
Stiblík, Petr ; Janšta, Petr (advisor) ; Bogusch, Petr (referee)
Recently, many scientists have been focused on parasite or parasitoid host's manipulation. They don't describe only the changes in host behavior, but they even search for physiological background. Lots of papers dealing with hymenopteran parasitoids (Hymenoptera: Parasitica) host's manipulation have been published. The most studied are strongly adapted and host specific parasitoids, koinobionts. They developed very sophisticated mechanisms to manipulate their hosts for their own benefit. These parasitic wasps are not only very diverse group of the insect, but they even developed various ways to manipulate the hosts and their physiology. Sometimes the parasitoids use their hosts like a "food's vehicle", sometimes they manipulate just rates of some metabolites or suppress host's immune reaction. If the wasp's life-cycle is successful, the host does not develope to the adult's stage and is often consumed by the parasitoid larve.
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Phylogeny of parasitic wasps of Torymidae (Hymenoptera: Chalcidoidea) and evolution of their life-strategies
Janšta, Petr ; Vilímová, Jitka (advisor) ; Bryja, Josef (referee) ; Melika, George (referee)
The thesis is focused on phylogeny of the family Torymidae (Hymenoptera: Chalcidoidea) and evolution of their life-strategies. The study consists of general introduction to the phylogeny and classification of the family Torymidae chapter, four published papers in international journals and one manuscript prepared for submission. Firstly, our aim was to figure out the phylogenetic position of Torymidae as well as the position of other chalcidoid families inside superfamily Chalcidoidea (paper I and II). The supermatrix of sequencies of two ribosomal genes (18S rDNA and 28S rDNA) were developed for 649 species of chalcidoid taxa. However, family Torymidae was considered as polyphyletic group with the subfamily Megastigminae unrelated to the subfamily Toryminae (paper I). Monophyly of Torymidae was corroborated in another study (paper II) focused on molecular and morphological characters. We used a web-based, systematics workbench mx database for scoring 233 characters of 300 members of all chalcidoid families. Contrary to our previous only DNA-based study, we revealed also potential sister relationships of Torymidae with Ormyridae+Colotrechninae or Cerocephalinae+Diparinae respectively. Other paper (paper V) was focused on detailed study of Torymidae phylogeny. A total of 5 genes (18S rDNA, 28S rDNA,...
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Phylogeny of selected species groups of the genus Torymus (Hymenoptera: Torymidae)
Křížková, Barbora
Chalcid wasps (Chalciodiodea) is superfamily within parasitic group of the order Hymenoptera. These insects attack other arthropods. My thesis is focused on phylogeny of selected species groups of the genus Torymus Dalman 1820, whose range of hosts includes mainly gall-forming insect as gall wasps (Hymenoptera: Cynipidae) and gall midges (Diptera: Cecidomyiidae). Using genes 28D2 rDNA, COI and CytB, I constructed phylogenetic trees, which helped with discussing current view on classification of the genus and with inferring new findings about co-evolution with host organisms. Previously established morphological - ecological species groups were not supported by my analyses in many cases. Morphological traits seem to be convergent for many species. They often do not support observed monophyla as apomorphies. On the other hand, ecology and natural habitat of species was common for many branches in my cladograms. It was found out, that recent hosts are not probably original hosts of the group. Adaptive radiation in different habitats is likely to be the phenomenon that stands behind present-day host range of Torymus species. This process could have occurred after swapping to gall midges and gall wasps. Key words: Chalcidoidea, Torymus, phylogeny, parasitoid, host specifity, co-evolution
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Phylogeny and evolution of the family Megastigmidae (Hymenoptera: Chalcidoidea)
Böhmová, Julie ; Janšta, Petr (advisor) ; Opatová, Věra (referee)
The family Megastigmidae (Hymenoptera: Chalcidoidea), one of the hymenopteran parasitoid families, is unique in containing many species with phytophagous larval feeding strategy. A number of species of different genera are seed-feeders and the genus Bortesia is even capable of inducing galls. The family Megastigmidae is found mainly in the Australian region but a few genera/species groups are widespread throughout different areas, mainly in the Oriental and the Holarctic region. The main goal of this study was to map phylogenetic relationships among genera and clarify the following: the overall number of transitions between a parasitoid and a phytophagous way of life, the ancestral feeding strategy of the family, the evolution of feeding strategies in the genus Megastigmus, and the geographical area of origin of the family. The questions were tested based on a phylogeny reconstructed by a state-of-the-art method - sequencing of "Ultra-Conserved Elements (UCEs)" - using 100 specimens of Megastigmidae from 11 out of 12 currently valid genera selected taking into consideration their feeding strategy and biogeographical origin. The final dataset contains 1210 loci (570,000 base pairs in length) and most nodes are supported by bootstrap value 100. The results show that the family can be divided into 3...
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Parasitic wasps Anaphes flavipes Förster, 1841 (Hymenoptera: Mymaridae) as model for parasitoid-host interactions study
Samková, Alena ; Janšta, Petr (advisor) ; Honěk, Alois (referee) ; Hrček, Jan (referee)
Parasitic wasps have a wide range of specific developmental interactions with their hosts due to a close "parasitoid-host" relationship and that allows the study of many ecological and evolutionary questions. In our work, we focused on the parasitoid-host interactions in the parasitic wasp Anaphes flavipes (Förster, 1841) (Hymenoptera: Mymaridae). Because A. flavipes show a high variability of morphology and size, they have been repeatedly described as a new species in the past. Thus, we first redescribed the species and we compared the variability of some morphological structures for wasps from different localities (Paper 1). The high variability of the body size of wasps is reviewed in the second article, where we propose that females of A. flavipes do not decide according to the generally known "trade-off" scheme, if they will have more smaller offspring or fewer bigger offspring. In fact, the number of offspring depends on the body size of the female ("body size-fitness" hypothesis), which determines the variable reproductive strategies of mothers (the number of individuals that are laid into one host by a single female) (Paper 2). The third manuscript deals with the reproductive strategy of gregarious parasitoids. The reproductive strategy does not have to be stable; in the case of A....
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Use of macroorganisms and microorganisms in biological control of whiteflies
ŽÁKOVÁ, Erika
Whitefly is one of the most important greenhouse pests that can cause significant damage to crops. Whitefly suck juice from plants and produce honeydew which is sugar source for saprotrophic fungi called sooty mold. Fungi cover the leaves and reduce the leaf assimilation area. The most serious harm of whiteflies is attributed to transfer of many plant viruses. The most serious whiteflies commonly found in the greenhouses are Trialeurodes vaporariorum and Bemisia tabaci. For the control of whitefly populations, the seasonal inoculum strategy of biological control is used, with the aim of immediately overlapping the pest with the right choice of natural enemies. Biological control contributes to the control of whiteflies in the greenhouse, specifically the use of natural enemies based on macro-organisms and microorganisms. The macroorganisms include parasitoids and predators. The most important commercially used whitefly parasitoids are Encarsia formosa, Eretmocerus eremicus and E. mundus. Predators used in biological control against whitely is the predatory bug Macrolophus caliginosus, the predatory ladybug Delphastus catalinae and the predatory mite Amlyseius swirskii. Parasitic wasps are narrowly specialized in both whitefly species, while predators are polyphagous species that can feed on more pest species. Bioproducts based on entomopathogenic fungi are also used against whiteflies in the abroad. The most important species are Aschersonia aleyrodis, Isaria fumosorosea, Beauveria bassiana and Lecanicillim muscarium. For the effective use of these bioagents, it is important to have knowledges not only about pest, but also about interaction among pest - natural enemy - host plant. So it is important to perform quality monitoring of whiteflies in the greenhouse to make the use of natural enemies profitable.
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