Call number: LD2668 .T4 1948 V35 / Master of Science

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Physiological factors that might influence ecological dynamics were investigated to better explain the biology of Bemisia tabaci in the desert southwest. Trehalulose, a unique disaccharide only found in unusually large quantities in B. tabaci honeydew, was shown not to be different from sucrose in promoting longevity in honeydew-consuming parasitoids, indicating this insect-modified sugar does not affect the nutritional quality of aleyrodid excreta. Trehalulose is not believed to function as a feeding deterrent to natural enemies. Experiments were designed to examine the effect of temperature on sorbitol and trehalulose production by the whitefly. High performance liquid chromatography analysis of honeydew and whole body extractions revealed a negative relationship between amounts of trehalulose in the honeydew and sorbitol accumulation in the whitefly body, linking these two molecules as important to the nutritional ecology of whiteflies. In another experiment to better understand the dispersal of whiteflies across the landscape, studies of flight over multiple days were conducted to describe the role of prior flight experience on dispersal and migratory flight. Flight performance traits were measured over multiple days of flight to compare two groups of B. tabaci, those trapped moving outside of planted fields with those collected within fields. Trap-caught individuals exhibited flights of significantly shorter duration in a vertical flight chamber. Flights determined to have characteristics of migratory behaviors were initially of longer duration for trap-captured whiteflies than their field-collected counterparts. Over the context of multiple days, however, their longer flights were followed by much shorter flights on subsequent days. Although many insects from both groups were capable of movement on multiple days, almost all of these flights were of a foraging nature. Foraging flights of short duration would likely not add to dispersal distances, thereby limiting whiteflies to their originating patch.

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No description available.

Common gromwell (Lithospermum officinale) acts as a host plant for the monophagous moth Ethmia dodecea  whose larvae are completely dependent on the leaves. As conservation authorities now want to reinstate the regionally extinct moth to Mälardalen, a stable population of its host plant is a requirement. To facilitate the work of strengthening the presence of gromwell a partnership was therefore initiated between Västmanland County Board and Uppsala University. In this cooperation, I performed two studies. In the first one I examined how water and temperature affect plant germination and how nutrient levels affect early growth. In the second study I investigated whether the germination is influenced by chemical treatment (soaking in acid) and mechanical damage (seeds scratched with sandpaper) on the seeds. I worked with the hypothesis that gromwell is grazed by cows and is therefore dispersed and germinates in the spring. This should mean high water levels combined with high temperatures would produce higher germination. For the second study, it means that the germination rate should be higher in the seeds treated with the acid than in the scratched and control treatments. In the first study, so few seeds germinated that I could not draw any conclusions, but germinations appear to go faster in the combination with high nutrients high temperature and frequent watering. In the second study, the seeds scraped with sandpaper had the highest germination rate. This indicates that gromwell may be dispersed by birds, and I propose sandpaper rubbing as a method to easily increase the germination rates of L. officinale in greenhouses in order to reinforce small populations in the field.

This investigation was concerned with three aspects of the problem of passive dispersal of algae and protozoa by aquatic insects: the role of odonates in passive dispersal of viable small aquatic organisms, the passage of viable algae and protozoa through digestive tracts of field-collected herbivorous and carnivorous aquatic insects, and the viability duration of selected algae, during insect transport under monitored conditions.

We carried out a pilot study of local dispersion and patterns of movement of Golden- ringed dragonfly Cordulegaster boltonii (Odonata: Cordulegasteridae). Cordulegasteridae is a family with many primitive traits present and rather restricted geographical distribution ranges (at least among European species). Their migration seems to be limited despite the body size that predetermines them to high mobility over large spatial scale. Linear habitat (upper parts of narrow forest streams) specialisation along with behavioural ecology (peculiar premating habit of scanning streams for females) is a unique life history, which bring lot of questions. We collected mark-release-recapture data during two adult flight seasons in year 2010 and 2011. We were simultaneously capturing patrolling males along three separate streams (Dračice, Koštěnický and Struha) in total length of 9.9 km in, located in the Natural park Česká Kanada, in the Southern Czech Republic. We captured and marked 440 individuals and recorded 113 recapture events (26 % recapture rate) in year 2010 and 355 individuals were marked, 171 recapture events made (48 % recapture rate) in 2011. Our data suggested high level of stream fidelity (only 10 inter stream dispersal events, 2.8 % dispersal rate). What was as well reflected in a closeness of...

Genus Frustulia was chosen for this work due to the continuity of the previous research of our phycological group. Using molecular techniques, it was found that a number of morphologically defined species of diatoms is cryptic species complex, which may have limited dispersal. The aim of this study was to: 1) evaluate the diversity of the genus Frustulia in northern Europe by molecular methods and classify found species in the phylogenetic context of related species; 2) find out if it possible to identify the isolated species in natural samples by using morphological characters. There have been analyzed 234 strains by molecular methods. Isolated ones were in four clades. 86 % of the strains belonged to a generic complex F. crassinervia-saxonica. Two strains were identified as species F. gaertnerae and F. septentrionalis. The last line was not described yet so it was labeled as F. sp. This line is closely related to the species F. maoriana, which is considered to be endemic in New Zealand. Phylogeny of the genus was created based on a dataset of four molecular markers. Published morphometric data were then compared with 264 cells photos taken by scanning electron microscope. There was done surveillance comparison of the results of the analysis of quantitative and qualitative characters with...

The skin microbiome is a critical component of human health, however, little is understood about the daily dynamics of skin microbiome community assembly and the skin’s potential to acquire microorganisms from the external environment. I performed a series of microbial transfers using three skin habitat types (dry, moist, sebaceous) on human subject volunteers. Microbial communities were transferred to recipient skin using a sterile swab 1) from other skin sites on the same individual, 2) from other skin sites on a different individual, 3) and from two environmental donor sources (plant leaf surfaces and farm soil). With these experiments I was able to test for the presence of initial transfer effects and for the persistence of those effects over the time period sampled (2-, 4-, 8-, and 24-hours post-transfer). The sebaceous skin community was associated with the strongest initial effect of transfer and persistence on the moist recipient skin site, and to a lesser extent the dry skin site. The soil donor community when transferred to dry skin resulted in the strongest initial transfer effect and was persistent over 8- and even 24-hours post-transfer. These experiments are the first in scope and scale to directly demonstrate that dispersal from other human or environmental microbial communities are plausible drivers of community dynamics in the skin microbiome.