|
|
The parasitoid community of two microlepidopteran species living on hops
Hovorka, Tomáš ; Janšta, Petr (advisor) ; Libra, Martin (referee)
Interactions between parasitoids, phytophagous insects and their host plants play one of the crucial role in the trophic relationships of terrestrial food webs. According to current knowledge, more than half of all known terrestrial species are part of this food web (parasitoids- herbivores-plants). In many species of herbivore hosts, interactions with parasitoids have led to the evolution and diversification of different defense strategies. An example of a primary defense strategy against predators and parasitoids is the formation of shelters such as leaf mines, leaf cocoons or galls. These strategies are a key factor influencing the composition of the parasitoid community. In this thesis, the complex of parasitoids in two microlepidopteran species with different life strategies living on hops (Humulus lupulus) was investigated. The caterpillars of Caloptilia fidella (Lepidoptera: Gracillaridae) first mine within leaves of hops, later, when they start to feed exophagously, they create leaf rolls and cocoons on the outer surface of the leaf. Caterpillars of the species Cosmopterix zieglerella (Lepidoptera: Cosmopterigidae) remain in the mine throughout their larval development. The obtained parasitoids were identified both based on morphology and with the help of two gene fragments, namely CO1 and...
|
|
|
Ambrosia galls - neglected model of fungus farming evolution
Zelinková, Barbora ; Kolařík, Miroslav (advisor) ; Janšta, Petr (referee)
Ambrosia galls are a unique type of insect gall created by Cecidomyiidae gall midges. Their association with a fungal symbiont, which forms a layer of ambrosia mycelium inside the gall is unique and reminiscent of fungal farming in other insect groups. To date, not much research has been done on the individual components of ambrosia galls: the galling insect, the symbiotic fungus, and the host plant. This paper provides an insight into fungal farming insects, a description of the ambrosia gall midges and their fungal symbiont, an overview of the mechanisms of each component on gall initiation and the relationships between them, and finally, explores the possible influence of fungal secondary metabolites. The bachelor thesis puts into context long-known and newly acquired information on the mutual interactions and shows that the previously accepted functions are not precise and that each component of the ambrosia gall is partially involved in its formation. Key words: ambrosia gall midges, nutritive mycelium, fungus farming, host specialization, species diversity, phyto-mycophagy, trophic interactions, Cecidomyiidae, Botryosphaeria dothidea, secondary metabolites
|
|
|
Design and functional morphology of insect wings
Jechová, Kateřina ; Prokop, Jakub (advisor) ; Janšta, Petr (referee)
Animal fly ability is undoubtedly one of the biggest innovation in evolution that allow animals to settle down another space on the Earth - the air. However, there are significant impacts on the other organisms during the evolution, too. The insect is single group of invertebrates with abilities to fly and because of that it became the most diversified group of organisms. There are a couple of theories about origin of the insect wings. Two major hypotheses considering the recent insects with their fossil record are widely known. Nevertheless, there is no direct clue to the first Pterygota due to the discontinuity of fossil record in the initial phase of their evolution The wing is very complex and unique structure throughout organisms. Insects became very good fliers during the evolution and wings are also used to protect of the body, carrying sensory organs, etc. Nevertheless, only very few insect species are well explored in term of flight and, an open theme for future studies. Aim of the present work is to describe the significance of the wing and to briefly review its morphological and design properties. Key words: Insecta, Pterygota, wing, venation, morphology, flight, evolution.
|
|
| |
|
| |
|
|
Biology of gall wasps (Diplolepis spp.) (Hymenoptera: Cynipidae) in palearctic region
Vitáček, Jakub ; Janšta, Petr (advisor) ; Holý, Kamil (referee)
This bachelor thesis is focussed on description of biology of gall wasps from the genus Diplolepis spp. (Hymenoptera: Cynipidae) in the palearctic region with the emphasis on some interesting phenomenons in their life cycle. These wasps induce galls obligatory on roses (Rosa spp.) and are widely distributed in the holarctic region. Many authors focussed on research of parasitoids, which use wasps larvae as food source. It was also recognized that inquilines lost their ability to induce own galls. However, their development is still dependent on galls tissues, because they feed on cells within galls. Rose gall wasps reproduce mostly without any mating. Female lay unfertilized eggs and males are very rare. Recently, development of modern techniques enable authors to study infection by bacteria of the genus Wolbachia and its role in the wasps parthenogenetic development. It is also apparent difference between the levels of our knowledge about individual species in this bachelor thesis. We have relative rich knowledges about European rose gall wasps, on the other hand biology of some Asian species is still very poor.
|
|
|
Flow cytometry and its use for study of insects
Stuchlíková, Magdalena ; Janšta, Petr (advisor) ; Sadílek, David (referee)
Flow cytometry is a modern technique in research, playing a significant role in biomedicine and botanics. Despite its benefits (speed, simplicity, low costs), flow cytometry is currently not used in the study of insects on a large scale. This thesis gives an overview as to how flow cytometry is used in research on insects and summarises the results of such study. This pertains to genome size and its connections to other phenomena. Other focal points of research, such as ploidy and base pair ratios, are addressed to a lesser extent. Key words: flow cytometry, use in study of insects, genome size, ploidy, invertebrates
|
|
| |
|
|
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
|
|
|
Ecology of pollination networks
Hadrava, Jiří ; Janšta, Petr (advisor) ; Novotný, Vojtěch (referee)
In communities, plants and pollinators are organized into complex network of relations. Description of structure in this network can contribute to understanding of community dynamics and persistence of biodiversity. Better understanding of patterns in assemblages of plants and pollinators may also help in their protection. The aim of this work is to review recent methodological principles in the pollination network analyses and to show potential problems in concept of ecological networks. Graph theory is breefly summarized and applied to the description of pollination networks. As an example, results on comparison of communities from different geographical sites are given.
|
guest ::
